Fix CS in src/Language

composer.json

@@ -10,6 +10,7 @@
   ],
   "require": {
     "php": "^7.1",
+    "ext-json": "*",
     "ext-mbstring": "*"
   },
   "require-dev": {

phpcs.xml.dist

@@ -90,4 +90,11 @@
             />
         </properties>
     </rule>
+
+    <!-- IDEs sort by PSR12, Slevomat coding standard uses old sorting for BC -->
+    <rule ref="SlevomatCodingStandard.Namespaces.AlphabeticallySortedUses">
+        <properties>
+            <property name="psr12Compatible" type="bool" value="true" />
+        </properties>
+    </rule>
 </ruleset>

src/Language/AST/ArgumentNode.php

@@ -1,17 +1,19 @@
 <?php
+
+declare(strict_types=1);
+
 namespace GraphQL\Language\AST;
 
 class ArgumentNode extends Node
 {
+    /** @var string */
     public $kind = NodeKind::ARGUMENT;
 
-    /**
-     * @var ValueNode
-     */
+    /** @var ValueNode */
     public $value;
 
-    /**
-     * @var NameNode
-     */
+    /** @var NameNode */
     public $name;
+
+
 }

src/Language/AST/BooleanValueNode.php

@@ -1,13 +1,15 @@
 <?php
-namespace GraphQL\Language\AST;
 
+declare(strict_types=1);
+
+namespace GraphQL\Language\AST;
 
 class BooleanValueNode extends Node implements ValueNode
 {
+    /** @var string */
     public $kind = NodeKind::BOOLEAN;
 
-    /**
-     * @var string
-     */
+    /** @var string */
     public $value;
+
 }

src/Language/AST/DefinitionNode.php

@@ -1,11 +1,14 @@
 <?php
+
+declare(strict_types=1);
+
 namespace GraphQL\Language\AST;
 
-interface DefinitionNode
-{
 /**
  * export type DefinitionNode =
  *   | ExecutableDefinitionNode
  *   | TypeSystemDefinitionNode; // experimental non-spec addition.
  */
+interface DefinitionNode
+{
 }

src/Language/AST/DirectiveDefinitionNode.php

@@ -1,30 +1,24 @@
 <?php
+
+declare(strict_types=1);
+
 namespace GraphQL\Language\AST;
 
 class DirectiveDefinitionNode extends Node implements TypeSystemDefinitionNode
 {
-    /**
-     * @var string
-     */
+    /** @var string */
     public $kind = NodeKind::DIRECTIVE_DEFINITION;
 
-    /**
-     * @var NameNode
-     */
+    /** @var NameNode */
     public $name;
 
-    /**
-     * @var ArgumentNode[]
-     */
+    /** @var ArgumentNode[] */
     public $arguments;
 
-    /**
-     * @var NameNode[]
-     */
+    /** @var NameNode[] */
     public $locations;
 
-    /**
-     * @var StringValueNode|null
-     */
+    /** @var StringValueNode|null */
     public $description;
+
 }

src/Language/AST/DirectiveNode.php

@@ -1,17 +1,18 @@
 <?php
+
+declare(strict_types=1);
+
 namespace GraphQL\Language\AST;
 
 class DirectiveNode extends Node
 {
+    /** @var string */
     public $kind = NodeKind::DIRECTIVE;
 
-    /**
-     * @var NameNode
-     */
+    /** @var NameNode */
     public $name;
 
-    /**
-     * @var ArgumentNode[]
-     */
+    /** @var ArgumentNode[] */
     public $arguments;
+
 }

src/Language/AST/DocumentNode.php

@@ -1,12 +1,15 @@
 <?php
+
+declare(strict_types=1);
+
 namespace GraphQL\Language\AST;
 
 class DocumentNode extends Node
 {
+    /** @var string */
     public $kind = NodeKind::DOCUMENT;
 
-    /**
-     * @var DefinitionNode[]
-     */
+    /** @var DefinitionNode[] */
     public $definitions;
+
 }

src/Language/AST/EnumTypeDefinitionNode.php

@@ -1,30 +1,25 @@
 <?php
+
+declare(strict_types=1);
+
 namespace GraphQL\Language\AST;
 
 class EnumTypeDefinitionNode extends Node implements TypeDefinitionNode
 {
-    /**
-     * @var string
-     */
+    /** @var string */
     public $kind = NodeKind::ENUM_TYPE_DEFINITION;
 
-    /**
-     * @var NameNode
-     */
+    /** @var NameNode */
     public $name;
 
-    /**
-     * @var DirectiveNode[]
-     */
+    /** @var DirectiveNode[] */
     public $directives;
 
-    /**
-     * @var EnumValueDefinitionNode[]|null|NodeList
-     */
+    /** @var EnumValueDefinitionNode[]|null|NodeList */
     public $values;
 
-    /**
-     * @var StringValueNode|null
-     */
+    /** @var StringValueNode|null */
     public $description;
+
+
 }

src/Language/AST/EnumTypeExtensionNode.php

@@ -1,25 +1,21 @@
 <?php
+
+declare(strict_types=1);
+
 namespace GraphQL\Language\AST;
 
 class EnumTypeExtensionNode extends Node implements TypeExtensionNode
 {
-    /**
-     * @var string
-     */
+    /** @var string */
     public $kind = NodeKind::ENUM_TYPE_EXTENSION;
 
-    /**
-     * @var NameNode
-     */
+    /** @var NameNode */
     public $name;
 
-    /**
-     * @var DirectiveNode[]|null
-     */
+    /** @var DirectiveNode[]|null */
     public $directives;
 
-    /**
-     * @var EnumValueDefinitionNode[]|null
-     */
+    /** @var EnumValueDefinitionNode[]|null */
     public $values;
+
 }

src/Language/AST/EnumValueDefinitionNode.php

@@ -1,25 +1,21 @@
 <?php
+
+declare(strict_types=1);
+
 namespace GraphQL\Language\AST;
 
 class EnumValueDefinitionNode extends Node
 {
-    /**
-     * @var string
-     */
+    /** @var string */
     public $kind = NodeKind::ENUM_VALUE_DEFINITION;
 
-    /**
-     * @var NameNode
-     */
+    /** @var NameNode */
     public $name;
 
-    /**
-     * @var DirectiveNode[]
-     */
+    /** @var DirectiveNode[] */
     public $directives;
 
-    /**
-     * @var StringValueNode|null
-     */
+    /** @var StringValueNode|null */
     public $description;
+
 }

src/Language/AST/EnumValueNode.php

@@ -1,12 +1,15 @@
 <?php
+
+declare(strict_types=1);
+
 namespace GraphQL\Language\AST;
 
 class EnumValueNode extends Node implements ValueNode
 {
+    /** @var string */
     public $kind = NodeKind::ENUM;
 
-    /**
-     * @var string
-     */
+    /** @var string */
     public $value;
+
 }

src/Language/AST/ExecutableDefinitionNode.php

@@ -1,11 +1,14 @@
 <?php
+
+declare(strict_types=1);
+
 namespace GraphQL\Language\AST;
 
-interface ExecutableDefinitionNode extends DefinitionNode
-{
 /**
  * export type ExecutableDefinitionNode =
  *   | OperationDefinitionNode
  *   | FragmentDefinitionNode;
  */
+interface ExecutableDefinitionNode extends DefinitionNode
+{
 }

src/Language/AST/FieldDefinitionNode.php

@@ -1,35 +1,27 @@
 <?php
+
+declare(strict_types=1);
+
 namespace GraphQL\Language\AST;
 
 class FieldDefinitionNode extends Node
 {
-    /**
-     * @var string
-     */
+    /** @var string */
     public $kind = NodeKind::FIELD_DEFINITION;
 
-    /**
-     * @var NameNode
-     */
+    /** @var NameNode */
     public $name;
 
-    /**
-     * @var InputValueDefinitionNode[]|NodeList
-     */
+    /** @var InputValueDefinitionNode[]|NodeList */
     public $arguments;
 
-    /**
-     * @var TypeNode
-     */
+    /** @var TypeNode */
     public $type;
 
-    /**
-     * @var DirectiveNode[]|NodeList
-     */
+    /** @var DirectiveNode[]|NodeList */
     public $directives;
 
-    /**
-     * @var StringValueNode|null
-     */
+    /** @var StringValueNode|null */
     public $description;
+
 }

src/Language/AST/FieldNode.php

@@ -6,35 +6,22 @@ namespace GraphQL\Language\AST;
 
 class FieldNode extends Node implements SelectionNode
 {
+    /** @var string */
     public $kind = NodeKind::FIELD;
 
-    /**
-     * @var NameNode
-     */
+    /** @var NameNode */
     public $name;
 
-    /**
-     * @var NameNode|null
-     */
+    /** @var NameNode|null */
     public $alias;
 
-    /**
-     * @var ArgumentNode[]|null
-     */
+    /** @var ArgumentNode[]|null */
     public $arguments;
 
-    /**
-     * @var DirectiveNode[]|null
-     */
+    /** @var DirectiveNode[]|null */
     public $directives;
 
-    /**
-     * @var SelectionSetNode|null
-     */
+    /** @var SelectionSetNode|null */
     public $selectionSet;
 
-    public function getKind() : string
-    {
-        return NodeKind::FIELD;
-    }
 }

src/Language/AST/FloatValueNode.php

@@ -1,12 +1,15 @@
 <?php
+
+declare(strict_types=1);
+
 namespace GraphQL\Language\AST;
 
 class FloatValueNode extends Node implements ValueNode
 {
+    /** @var string */
     public $kind = NodeKind::FLOAT;
 
-    /**
-     * @var string
-     */
+    /** @var string */
     public $value;
+
 }

src/Language/AST/FragmentDefinitionNode.php

@@ -1,13 +1,15 @@
 <?php
+
+declare(strict_types=1);
+
 namespace GraphQL\Language\AST;
 
 class FragmentDefinitionNode extends Node implements ExecutableDefinitionNode, HasSelectionSet
 {
+    /** @var string */
     public $kind = NodeKind::FRAGMENT_DEFINITION;
 
-    /**
-     * @var NameNode
-     */
+    /** @var NameNode */
     public $name;
 
     /**
@@ -18,18 +20,14 @@ class FragmentDefinitionNode extends Node implements ExecutableDefinitionNode, H
      */
     public $variableDefinitions;
 
-    /**
-     * @var NamedTypeNode
-     */
+    /** @var NamedTypeNode */
     public $typeCondition;
 
-    /**
-     * @var DirectiveNode[]|NodeList
-     */
+    /** @var DirectiveNode[]|NodeList */
     public $directives;
 
-    /**
-     * @var SelectionSetNode
-     */
+    /** @var SelectionSetNode */
     public $selectionSet;
+
+
 }

src/Language/AST/FragmentSpreadNode.php

@@ -1,23 +1,18 @@
 <?php
 
+declare(strict_types=1);
+
 namespace GraphQL\Language\AST;
 
 class FragmentSpreadNode extends Node implements SelectionNode
 {
+    /** @var string */
     public $kind = NodeKind::FRAGMENT_SPREAD;
 
-    /**
-     * @var NameNode
-     */
+    /** @var NameNode */
     public $name;
 
-    /**
-     * @var DirectiveNode[]
-     */
+    /** @var DirectiveNode[] */
     public $directives;
 
-    public function getKind() : string
-    {
-        return NodeKind::FRAGMENT_SPREAD;
-    }
 }

src/Language/AST/HasSelectionSet.php

@@ -1,4 +1,7 @@
 <?php
+
+declare(strict_types=1);
+
 namespace GraphQL\Language\AST;
 
 interface HasSelectionSet

src/Language/AST/InlineFragmentNode.php

@@ -1,28 +1,21 @@
 <?php
 
+declare(strict_types=1);
+
 namespace GraphQL\Language\AST;
 
 class InlineFragmentNode extends Node implements SelectionNode
 {
+    /** @var string */
     public $kind = NodeKind::INLINE_FRAGMENT;
 
-    /**
-     * @var NamedTypeNode
-     */
+    /** @var NamedTypeNode */
     public $typeCondition;
 
-    /**
-     * @var DirectiveNode[]|null
-     */
+    /** @var DirectiveNode[]|null */
     public $directives;
 
-    /**
-     * @var SelectionSetNode
-     */
+    /** @var SelectionSetNode */
     public $selectionSet;
 
-    public function getKind() : string
-    {
-        return NodeKind::INLINE_FRAGMENT;
-    }
 }

src/Language/AST/InputObjectTypeDefinitionNode.php

@@ -1,30 +1,24 @@
 <?php
+
+declare(strict_types=1);
+
 namespace GraphQL\Language\AST;
 
 class InputObjectTypeDefinitionNode extends Node implements TypeDefinitionNode
 {
-    /**
-     * @var string
-     */
+    /** @var string */
     public $kind = NodeKind::INPUT_OBJECT_TYPE_DEFINITION;
 
-    /**
-     * @var NameNode
-     */
+    /** @var NameNode */
     public $name;
 
-    /**
-     * @var DirectiveNode[]|null
-     */
+    /** @var DirectiveNode[]|null */
     public $directives;
 
-    /**
-     * @var InputValueDefinitionNode[]|null
-     */
+    /** @var InputValueDefinitionNode[]|null */
     public $fields;
 
-    /**
-     * @var StringValueNode|null
-     */
+    /** @var StringValueNode|null */
     public $description;
+
 }

src/Language/AST/InputObjectTypeExtensionNode.php

@@ -1,25 +1,21 @@
 <?php
+
+declare(strict_types=1);
+
 namespace GraphQL\Language\AST;
 
 class InputObjectTypeExtensionNode extends Node implements TypeExtensionNode
 {
-    /**
-     * @var string
-     */
+    /** @var string */
     public $kind = NodeKind::INPUT_OBJECT_TYPE_EXTENSION;
 
-    /**
-     * @var NameNode
-     */
+    /** @var NameNode */
     public $name;
 
-    /**
-     * @var DirectiveNode[]|null
-     */
+    /** @var DirectiveNode[]|null */
     public $directives;
 
-    /**
-     * @var InputValueDefinitionNode[]|null
-     */
+    /** @var InputValueDefinitionNode[]|null */
     public $fields;
+
 }

src/Language/AST/InputValueDefinitionNode.php

@@ -1,35 +1,27 @@
 <?php
+
+declare(strict_types=1);
+
 namespace GraphQL\Language\AST;
 
 class InputValueDefinitionNode extends Node
 {
-    /**
-     * @var string
-     */
+    /** @var string */
     public $kind = NodeKind::INPUT_VALUE_DEFINITION;
 
-    /**
-     * @var NameNode
-     */
+    /** @var NameNode */
     public $name;
 
-    /**
-     * @var TypeNode
-     */
+    /** @var TypeNode */
     public $type;
 
-    /**
-     * @var ValueNode
-     */
+    /** @var ValueNode */
     public $defaultValue;
 
-    /**
-     * @var DirectiveNode[]
-     */
+    /** @var DirectiveNode[] */
     public $directives;
 
-    /**
-     * @var StringValueNode|null
-     */
+    /** @var StringValueNode|null */
     public $description;
+
 }

src/Language/AST/IntValueNode.php

@@ -1,12 +1,15 @@
 <?php
+
+declare(strict_types=1);
+
 namespace GraphQL\Language\AST;
 
 class IntValueNode extends Node implements ValueNode
 {
+    /** @var string */
     public $kind = NodeKind::INT;
 
-    /**
-     * @var string
-     */
+    /** @var string */
     public $value;
+
 }

src/Language/AST/InterfaceTypeDefinitionNode.php

@@ -1,30 +1,24 @@
 <?php
+
+declare(strict_types=1);
+
 namespace GraphQL\Language\AST;
 
 class InterfaceTypeDefinitionNode extends Node implements TypeDefinitionNode
 {
-    /**
-     * @var string
-     */
+    /** @var string */
     public $kind = NodeKind::INTERFACE_TYPE_DEFINITION;
 
-    /**
-     * @var NameNode
-     */
+    /** @var NameNode */
     public $name;
 
-    /**
-     * @var DirectiveNode[]|null
-     */
+    /** @var DirectiveNode[]|null */
     public $directives;
 
-    /**
-     * @var FieldDefinitionNode[]|null
-     */
+    /** @var FieldDefinitionNode[]|null */
     public $fields;
 
-    /**
-     * @var StringValueNode|null
-     */
+    /** @var StringValueNode|null */
     public $description;
+
 }

src/Language/AST/InterfaceTypeExtensionNode.php

@@ -1,25 +1,21 @@
 <?php
+
+declare(strict_types=1);
+
 namespace GraphQL\Language\AST;
 
 class InterfaceTypeExtensionNode extends Node implements TypeExtensionNode
 {
-    /**
-     * @var string
-     */
+    /** @var string */
     public $kind = NodeKind::INTERFACE_TYPE_EXTENSION;
 
-    /**
-     * @var NameNode
-     */
+    /** @var NameNode */
     public $name;
 
-    /**
-     * @var DirectiveNode[]|null
-     */
+    /** @var DirectiveNode[]|null */
     public $directives;
 
-    /**
-     * @var FieldDefinitionNode[]|null
-     */
+    /** @var FieldDefinitionNode[]|null */
     public $fields;
+
 }

src/Language/AST/ListTypeNode.php

@@ -1,12 +1,15 @@
 <?php
+
+declare(strict_types=1);
+
 namespace GraphQL\Language\AST;
 
 class ListTypeNode extends Node implements TypeNode
 {
+    /** @var string */
     public $kind = NodeKind::LIST_TYPE;
 
-    /**
-     * @var Node
-     */
+    /** @var Node */
     public $type;
+
 }

src/Language/AST/ListValueNode.php

@@ -1,13 +1,15 @@
 <?php
 
+declare(strict_types=1);
+
 namespace GraphQL\Language\AST;
 
 class ListValueNode extends Node implements ValueNode
 {
+    /** @var string */
     public $kind = NodeKind::LST;
 
-    /**
-     * @var ValueNode[]|NodeList
-     */
+    /** @var ValueNode[]|NodeList */
     public $values;
+
 }

src/Language/AST/Location.php

@@ -1,4 +1,7 @@
 <?php
+
+declare(strict_types=1);
+
 namespace GraphQL\Language\AST;
 
 use GraphQL\Language\Source;
@@ -46,8 +49,8 @@ class Location
     public $source;
 
     /**
-     * @param $start
-     * @param $end
+     * @param int $start
+     * @param int $end
      * @return static
      */
     public static function create($start, $end)
@@ -58,15 +61,17 @@ class Location
         return $tmp;
     }
 
-    public function __construct(Token $startToken = null, Token $endToken = null, Source $source = null)
+    public function __construct(?Token $startToken = null, ?Token $endToken = null, ?Source $source = null)
     {
         $this->startToken = $startToken;
         $this->endToken   = $endToken;
         $this->source     = $source;
 
-        if ($startToken && $endToken) {
+        if (! $startToken || ! $endToken) {
+            return;
+        }
+
         $this->start = $startToken->start;
         $this->end   = $endToken->end;
     }
-    }
 }

src/Language/AST/NameNode.php

@@ -1,12 +1,15 @@
 <?php
+
+declare(strict_types=1);
+
 namespace GraphQL\Language\AST;
 
 class NameNode extends Node implements TypeNode
 {
+    /** @var string */
     public $kind = NodeKind::NAME;
 
-    /**
-     * @var string
-     */
+    /** @var string */
     public $value;
+
 }

src/Language/AST/NamedTypeNode.php

@@ -1,12 +1,15 @@
 <?php
+
+declare(strict_types=1);
+
 namespace GraphQL\Language\AST;
 
 class NamedTypeNode extends Node implements TypeNode
 {
+    /** @var string */
     public $kind = NodeKind::NAMED_TYPE;
 
-    /**
-     * @var NameNode
-     */
+    /** @var NameNode */
     public $name;
+
 }

src/Language/AST/Node.php

@@ -1,50 +1,54 @@
 <?php
+
+declare(strict_types=1);
+
 namespace GraphQL\Language\AST;
 
 use GraphQL\Utils\Utils;
+use function get_object_vars;
+use function is_array;
+use function is_scalar;
+use function json_encode;
 
+/**
+ * type Node = NameNode
+ * | DocumentNode
+ * | OperationDefinitionNode
+ * | VariableDefinitionNode
+ * | VariableNode
+ * | SelectionSetNode
+ * | FieldNode
+ * | ArgumentNode
+ * | FragmentSpreadNode
+ * | InlineFragmentNode
+ * | FragmentDefinitionNode
+ * | IntValueNode
+ * | FloatValueNode
+ * | StringValueNode
+ * | BooleanValueNode
+ * | EnumValueNode
+ * | ListValueNode
+ * | ObjectValueNode
+ * | ObjectFieldNode
+ * | DirectiveNode
+ * | ListTypeNode
+ * | NonNullTypeNode
+ */
 abstract class Node
 {
-    /**
-      type Node = NameNode
-    | DocumentNode
-    | OperationDefinitionNode
-    | VariableDefinitionNode
-    | VariableNode
-    | SelectionSetNode
-    | FieldNode
-    | ArgumentNode
-    | FragmentSpreadNode
-    | InlineFragmentNode
-    | FragmentDefinitionNode
-    | IntValueNode
-    | FloatValueNode
-    | StringValueNode
-    | BooleanValueNode
-    | EnumValueNode
-    | ListValueNode
-    | ObjectValueNode
-    | ObjectFieldNode
-    | DirectiveNode
-    | ListTypeNode
-    | NonNullTypeNode
-     */
-
-    public $kind;
-
-    /**
-     * @var Location
-     */
+    /** @var Location */
     public $loc;
 
     /**
-     * @param array $vars
+     * @param (string|NameNode|NodeList|SelectionSetNode|Location|null)[] $vars
      */
     public function __construct(array $vars)
     {
-        if (!empty($vars)) {
-            Utils::assign($this, $vars);
+        if (empty($vars)) {
+            return;
         }
+
+        Utils::assign($this, $vars);
     }
 
     /**
@@ -56,8 +60,8 @@ abstract class Node
     }
 
     /**
-     * @param $value
-     * @return array|Node
+     * @param string|NodeList|Location|Node|(Node|NodeList|Location)[] $value
+     * @return string|NodeList|Location|Node
      */
     private function cloneValue($value)
     {
@@ -66,7 +70,7 @@ abstract class Node
             foreach ($value as $key => $arrValue) {
                 $cloned[$key] = $this->cloneValue($arrValue);
             }
-        } else if ($value instanceof Node) {
+        } elseif ($value instanceof self) {
             $cloned = clone $value;
             foreach (get_object_vars($cloned) as $prop => $propValue) {
                 $cloned->{$prop} = $this->cloneValue($propValue);
@@ -84,34 +88,34 @@ abstract class Node
     public function __toString()
     {
         $tmp = $this->toArray(true);
+
         return (string) json_encode($tmp);
     }
 
     /**
      * @param bool $recursive
-     * @return array
+     * @return mixed[]
      */
     public function toArray($recursive = false)
     {
         if ($recursive) {
             return $this->recursiveToArray($this);
-        } else {
+        }
+
         $tmp = (array) $this;
 
         if ($this->loc) {
             $tmp['loc'] = [
                 'start' => $this->loc->start,
-                    'end' => $this->loc->end
+                'end'   => $this->loc->end,
             ];
         }
 
         return $tmp;
     }
-    }
 
     /**
-     * @param Node $node
-     * @return array
+     * @return mixed[]
      */
     private function recursiveToArray(Node $node)
     {
@@ -122,25 +126,27 @@ abstract class Node
         if ($node->loc) {
             $result['loc'] = [
                 'start' => $node->loc->start,
-                'end' => $node->loc->end
+                'end'   => $node->loc->end,
             ];
         }
 
         foreach (get_object_vars($node) as $prop => $propValue) {
-            if (isset($result[$prop]))
+            if (isset($result[$prop])) {
                 continue;
+            }
 
-            if ($propValue === null)
+            if ($propValue === null) {
                 continue;
+            }
 
             if (is_array($propValue) || $propValue instanceof NodeList) {
                 $tmp = [];
                 foreach ($propValue as $tmp1) {
                     $tmp[] = $tmp1 instanceof Node ? $this->recursiveToArray($tmp1) : (array) $tmp1;
                 }
-            } else if ($propValue instanceof Node) {
+            } elseif ($propValue instanceof Node) {
                 $tmp = $this->recursiveToArray($propValue);
-            } else if (is_scalar($propValue) || null === $propValue) {
+            } elseif (is_scalar($propValue) || $propValue === null) {
                 $tmp = $propValue;
             } else {
                 $tmp = null;
@@ -148,6 +154,7 @@ abstract class Node
 
             $result[$prop] = $tmp;
         }
+
         return $result;
     }
 }

src/Language/AST/NodeKind.php

@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace GraphQL\Language\AST;
 
 class NodeKind
@@ -7,7 +9,6 @@ class NodeKind
     // constants from language/kinds.js:
 
     const NAME = 'Name';
-
     // Document
 
     const DOCUMENT             = 'Document';
@@ -17,13 +18,11 @@ class NodeKind
     const SELECTION_SET        = 'SelectionSet';
     const FIELD                = 'Field';
     const ARGUMENT             = 'Argument';
-
     // Fragments
 
     const FRAGMENT_SPREAD     = 'FragmentSpread';
     const INLINE_FRAGMENT     = 'InlineFragment';
     const FRAGMENT_DEFINITION = 'FragmentDefinition';
-
     // Values
 
     const INT          = 'IntValue';
@@ -35,22 +34,18 @@ class NodeKind
     const LST          = 'ListValue';
     const OBJECT       = 'ObjectValue';
     const OBJECT_FIELD = 'ObjectField';
-
     // Directives
 
     const DIRECTIVE = 'Directive';
-
     // Types
 
     const NAMED_TYPE    = 'NamedType';
     const LIST_TYPE     = 'ListType';
     const NON_NULL_TYPE = 'NonNullType';
-
     // Type System Definitions
 
     const SCHEMA_DEFINITION         = 'SchemaDefinition';
     const OPERATION_TYPE_DEFINITION = 'OperationTypeDefinition';
-
     // Type Definitions
 
     const SCALAR_TYPE_DEFINITION       = 'ScalarTypeDefinition';
@@ -62,7 +57,6 @@ class NodeKind
     const ENUM_TYPE_DEFINITION         = 'EnumTypeDefinition';
     const ENUM_VALUE_DEFINITION        = 'EnumValueDefinition';
     const INPUT_OBJECT_TYPE_DEFINITION = 'InputObjectTypeDefinition';
-
     // Type Extensions
 
     const SCALAR_TYPE_EXTENSION       = 'ScalarTypeExtension';
@@ -71,75 +65,71 @@ class NodeKind
     const UNION_TYPE_EXTENSION        = 'UnionTypeExtension';
     const ENUM_TYPE_EXTENSION         = 'EnumTypeExtension';
     const INPUT_OBJECT_TYPE_EXTENSION = 'InputObjectTypeExtension';
-
     // Directive Definitions
 
     const DIRECTIVE_DEFINITION = 'DirectiveDefinition';
 
-    /**
-     * @todo conver to const array when moving to PHP5.6
-     * @var array
-     */
+    /** @var string[] */
     public static $classMap = [
-        NodeKind::NAME => NameNode::class,
+        self::NAME                         => NameNode::class,
 
         // Document
-        NodeKind::DOCUMENT => DocumentNode::class,
-        NodeKind::OPERATION_DEFINITION => OperationDefinitionNode::class,
-        NodeKind::VARIABLE_DEFINITION => VariableDefinitionNode::class,
-        NodeKind::VARIABLE => VariableNode::class,
-        NodeKind::SELECTION_SET => SelectionSetNode::class,
-        NodeKind::FIELD => FieldNode::class,
-        NodeKind::ARGUMENT => ArgumentNode::class,
+        self::DOCUMENT                     => DocumentNode::class,
+        self::OPERATION_DEFINITION         => OperationDefinitionNode::class,
+        self::VARIABLE_DEFINITION          => VariableDefinitionNode::class,
+        self::VARIABLE                     => VariableNode::class,
+        self::SELECTION_SET                => SelectionSetNode::class,
+        self::FIELD                        => FieldNode::class,
+        self::ARGUMENT                     => ArgumentNode::class,
 
         // Fragments
-        NodeKind::FRAGMENT_SPREAD => FragmentSpreadNode::class,
-        NodeKind::INLINE_FRAGMENT => InlineFragmentNode::class,
-        NodeKind::FRAGMENT_DEFINITION => FragmentDefinitionNode::class,
+        self::FRAGMENT_SPREAD              => FragmentSpreadNode::class,
+        self::INLINE_FRAGMENT              => InlineFragmentNode::class,
+        self::FRAGMENT_DEFINITION          => FragmentDefinitionNode::class,
 
         // Values
-        NodeKind::INT => IntValueNode::class,
-        NodeKind::FLOAT => FloatValueNode::class,
-        NodeKind::STRING => StringValueNode::class,
-        NodeKind::BOOLEAN => BooleanValueNode::class,
-        NodeKind::ENUM => EnumValueNode::class,
-        NodeKind::NULL => NullValueNode::class,
-        NodeKind::LST => ListValueNode::class,
-        NodeKind::OBJECT => ObjectValueNode::class,
-        NodeKind::OBJECT_FIELD => ObjectFieldNode::class,
+        self::INT                          => IntValueNode::class,
+        self::FLOAT                        => FloatValueNode::class,
+        self::STRING                       => StringValueNode::class,
+        self::BOOLEAN                      => BooleanValueNode::class,
+        self::ENUM                         => EnumValueNode::class,
+        self::NULL                         => NullValueNode::class,
+        self::LST                          => ListValueNode::class,
+        self::OBJECT                       => ObjectValueNode::class,
+        self::OBJECT_FIELD                 => ObjectFieldNode::class,
 
         // Directives
-        NodeKind::DIRECTIVE => DirectiveNode::class,
+        self::DIRECTIVE                    => DirectiveNode::class,
 
         // Types
-        NodeKind::NAMED_TYPE => NamedTypeNode::class,
-        NodeKind::LIST_TYPE => ListTypeNode::class,
-        NodeKind::NON_NULL_TYPE => NonNullTypeNode::class,
+        self::NAMED_TYPE                   => NamedTypeNode::class,
+        self::LIST_TYPE                    => ListTypeNode::class,
+        self::NON_NULL_TYPE                => NonNullTypeNode::class,
 
         // Type System Definitions
-        NodeKind::SCHEMA_DEFINITION => SchemaDefinitionNode::class,
-        NodeKind::OPERATION_TYPE_DEFINITION => OperationTypeDefinitionNode::class,
+        self::SCHEMA_DEFINITION            => SchemaDefinitionNode::class,
+        self::OPERATION_TYPE_DEFINITION    => OperationTypeDefinitionNode::class,
 
         // Type Definitions
-        NodeKind::SCALAR_TYPE_DEFINITION => ScalarTypeDefinitionNode::class,
-        NodeKind::OBJECT_TYPE_DEFINITION => ObjectTypeDefinitionNode::class,
-        NodeKind::FIELD_DEFINITION => FieldDefinitionNode::class,
-        NodeKind::INPUT_VALUE_DEFINITION => InputValueDefinitionNode::class,
-        NodeKind::INTERFACE_TYPE_DEFINITION => InterfaceTypeDefinitionNode::class,
-        NodeKind::UNION_TYPE_DEFINITION => UnionTypeDefinitionNode::class,
-        NodeKind::ENUM_TYPE_DEFINITION => EnumTypeDefinitionNode::class,
-        NodeKind::ENUM_VALUE_DEFINITION => EnumValueDefinitionNode::class,
-        NodeKind::INPUT_OBJECT_TYPE_DEFINITION =>InputObjectTypeDefinitionNode::class,
+        self::SCALAR_TYPE_DEFINITION       => ScalarTypeDefinitionNode::class,
+        self::OBJECT_TYPE_DEFINITION       => ObjectTypeDefinitionNode::class,
+        self::FIELD_DEFINITION             => FieldDefinitionNode::class,
+        self::INPUT_VALUE_DEFINITION       => InputValueDefinitionNode::class,
+        self::INTERFACE_TYPE_DEFINITION    => InterfaceTypeDefinitionNode::class,
+        self::UNION_TYPE_DEFINITION        => UnionTypeDefinitionNode::class,
+        self::ENUM_TYPE_DEFINITION         => EnumTypeDefinitionNode::class,
+        self::ENUM_VALUE_DEFINITION        => EnumValueDefinitionNode::class,
+        self::INPUT_OBJECT_TYPE_DEFINITION => InputObjectTypeDefinitionNode::class,
 
         // Type Extensions
-        NodeKind::SCALAR_TYPE_EXTENSION => ScalarTypeExtensionNode::class,
-        NodeKind::OBJECT_TYPE_EXTENSION => ObjectTypeExtensionNode::class,
-        NodeKind::INTERFACE_TYPE_EXTENSION => InterfaceTypeExtensionNode::class,
-        NodeKind::UNION_TYPE_EXTENSION => UnionTypeExtensionNode::class,
-        NodeKind::ENUM_TYPE_EXTENSION => EnumTypeExtensionNode::class,
-        NodeKind::INPUT_OBJECT_TYPE_EXTENSION => InputObjectTypeExtensionNode::class,
+        self::SCALAR_TYPE_EXTENSION        => ScalarTypeExtensionNode::class,
+        self::OBJECT_TYPE_EXTENSION        => ObjectTypeExtensionNode::class,
+        self::INTERFACE_TYPE_EXTENSION     => InterfaceTypeExtensionNode::class,
+        self::UNION_TYPE_EXTENSION         => UnionTypeExtensionNode::class,
+        self::ENUM_TYPE_EXTENSION          => EnumTypeExtensionNode::class,
+        self::INPUT_OBJECT_TYPE_EXTENSION  => InputObjectTypeExtensionNode::class,
 
         // Directive Definitions
-        NodeKind::DIRECTIVE_DEFINITION => DirectiveDefinitionNode::class
+        self::DIRECTIVE_DEFINITION         => DirectiveDefinitionNode::class,
     ];
 }

src/Language/AST/NodeList.php

@@ -1,22 +1,22 @@
 <?php
+
+declare(strict_types=1);
+
 namespace GraphQL\Language\AST;
 
 use GraphQL\Utils\AST;
+use function array_merge;
+use function array_splice;
+use function count;
+use function is_array;
 
-/**
- * Class NodeList
- *
- * @package GraphQL\Utils
- */
 class NodeList implements \ArrayAccess, \IteratorAggregate, \Countable
 {
-    /**
-     * @var array
-     */
+    /** @var Node[]|mixed[] */
     private $nodes;
 
     /**
-     * @param array $nodes
+     * @param Node[]|mixed[] $nodes
      * @return static
      */
     public static function create(array $nodes)
@@ -25,8 +25,8 @@ class NodeList implements \ArrayAccess, \IteratorAggregate, \Countable
     }
 
     /**
-     * NodeList constructor.
-     * @param array $nodes
+     *
+     * @param Node[]|mixed[] $nodes
      */
     public function __construct(array $nodes)
     {
@@ -89,12 +89,12 @@ class NodeList implements \ArrayAccess, \IteratorAggregate, \Countable
     }
 
     /**
-     * @param $list
+     * @param NodeList|Node[] $list
      * @return NodeList
      */
     public function merge($list)
     {
-        if ($list instanceof NodeList) {
+        if ($list instanceof self) {
             $list = $list->nodes;
         }
         return new NodeList(array_merge($this->nodes, $list));

src/Language/AST/NonNullTypeNode.php

@@ -1,12 +1,15 @@
 <?php
+
+declare(strict_types=1);
+
 namespace GraphQL\Language\AST;
 
 class NonNullTypeNode extends Node implements TypeNode
 {
+    /** @var string */
     public $kind = NodeKind::NON_NULL_TYPE;
 
-    /**
-     * @var NameNode | ListTypeNode
-     */
+    /** @var NameNode | ListTypeNode */
     public $type;
+
 }

src/Language/AST/NullValueNode.php

@@ -1,7 +1,12 @@
 <?php
+
+declare(strict_types=1);
+
 namespace GraphQL\Language\AST;
 
 class NullValueNode extends Node implements ValueNode
 {
+    /** @var string */
     public $kind = NodeKind::NULL;
+
 }

src/Language/AST/ObjectFieldNode.php

@@ -1,18 +1,18 @@
 <?php
-namespace GraphQL\Language\AST;
 
+declare(strict_types=1);
+
+namespace GraphQL\Language\AST;
 
 class ObjectFieldNode extends Node
 {
+    /** @var string */
     public $kind = NodeKind::OBJECT_FIELD;
 
-    /**
-     * @var NameNode
-     */
+    /** @var NameNode */
     public $name;
 
-    /**
-     * @var ValueNode
-     */
+    /** @var ValueNode */
     public $value;
+
 }

src/Language/AST/ObjectTypeDefinitionNode.php

@@ -1,35 +1,28 @@
 <?php
+
+declare(strict_types=1);
+
 namespace GraphQL\Language\AST;
 
 class ObjectTypeDefinitionNode extends Node implements TypeDefinitionNode
 {
-    /**
-     * @var string
-     */
+    /** @var string */
     public $kind = NodeKind::OBJECT_TYPE_DEFINITION;
 
-    /**
-     * @var NameNode
-     */
+    /** @var NameNode */
     public $name;
 
-    /**
-     * @var NamedTypeNode[]
-     */
+    /** @var NamedTypeNode[] */
     public $interfaces = [];
 
-    /**
-     * @var DirectiveNode[]|null
-     */
+    /** @var DirectiveNode[]|null */
     public $directives;
 
-    /**
-     * @var FieldDefinitionNode[]|null
-     */
+    /** @var FieldDefinitionNode[]|null */
     public $fields;
 
-    /**
-     * @var StringValueNode|null
-     */
+    /** @var StringValueNode|null */
     public $description;
+
+
 }

src/Language/AST/ObjectTypeExtensionNode.php

@@ -1,30 +1,24 @@
 <?php
+
+declare(strict_types=1);
+
 namespace GraphQL\Language\AST;
 
 class ObjectTypeExtensionNode extends Node implements TypeExtensionNode
 {
-    /**
-     * @var string
-     */
+    /** @var string */
     public $kind = NodeKind::OBJECT_TYPE_EXTENSION;
 
-    /**
-     * @var NameNode
-     */
+    /** @var NameNode */
     public $name;
 
-    /**
-     * @var NamedTypeNode[]
-     */
+    /** @var NamedTypeNode[] */
     public $interfaces = [];
 
-    /**
-     * @var DirectiveNode[]
-     */
+    /** @var DirectiveNode[] */
     public $directives;
 
-    /**
-     * @var FieldDefinitionNode[]
-     */
+    /** @var FieldDefinitionNode[] */
     public $fields;
+
 }

src/Language/AST/ObjectValueNode.php

@@ -1,12 +1,15 @@
 <?php
+
+declare(strict_types=1);
+
 namespace GraphQL\Language\AST;
 
 class ObjectValueNode extends Node implements ValueNode
 {
+    /** @var string */
     public $kind = NodeKind::OBJECT;
 
-    /**
-     * @var ObjectFieldNode[]|NodeList
-     */
+    /** @var ObjectFieldNode[]|NodeList */
     public $fields;
+
 }

src/Language/AST/OperationDefinitionNode.php

@@ -1,35 +1,27 @@
 <?php
+
+declare(strict_types=1);
+
 namespace GraphQL\Language\AST;
 
 class OperationDefinitionNode extends Node implements ExecutableDefinitionNode, HasSelectionSet
 {
-    /**
-     * @var string
-     */
+    /** @var string */
     public $kind = NodeKind::OPERATION_DEFINITION;
 
-    /**
-     * @var NameNode
-     */
+    /** @var NameNode */
     public $name;
 
-    /**
-     * @var string (oneOf 'query', 'mutation'))
-     */
+    /** @var string (oneOf 'query', 'mutation')) */
     public $operation;
 
-    /**
-     * @var VariableDefinitionNode[]
-     */
+    /** @var VariableDefinitionNode[] */
     public $variableDefinitions;
 
-    /**
-     * @var DirectiveNode[]
-     */
+    /** @var DirectiveNode[] */
     public $directives;
 
-    /**
-     * @var SelectionSetNode
-     */
+    /** @var SelectionSetNode */
     public $selectionSet;
+
 }

src/Language/AST/OperationTypeDefinitionNode.php

@@ -1,11 +1,12 @@
 <?php
+
+declare(strict_types=1);
+
 namespace GraphQL\Language\AST;
 
 class OperationTypeDefinitionNode extends Node
 {
-    /**
-     * @var string
-     */
+    /** @var string */
     public $kind = NodeKind::OPERATION_TYPE_DEFINITION;
 
     /**
@@ -15,8 +16,7 @@ class OperationTypeDefinitionNode extends Node
      */
     public $operation;
 
-    /**
-     * @var NamedTypeNode
-     */
+    /** @var NamedTypeNode */
     public $type;
+
 }

src/Language/AST/ScalarTypeDefinitionNode.php

@@ -1,25 +1,21 @@
 <?php
+
+declare(strict_types=1);
+
 namespace GraphQL\Language\AST;
 
 class ScalarTypeDefinitionNode extends Node implements TypeDefinitionNode
 {
-    /**
-     * @var string
-     */
+    /** @var string */
     public $kind = NodeKind::SCALAR_TYPE_DEFINITION;
 
-    /**
-     * @var NameNode
-     */
+    /** @var NameNode */
     public $name;
 
-    /**
-     * @var DirectiveNode[]
-     */
+    /** @var DirectiveNode[] */
     public $directives;
 
-    /**
-     * @var StringValueNode|null
-     */
+    /** @var StringValueNode|null */
     public $description;
+
 }

src/Language/AST/ScalarTypeExtensionNode.php

@@ -1,20 +1,18 @@
 <?php
+
+declare(strict_types=1);
+
 namespace GraphQL\Language\AST;
 
 class ScalarTypeExtensionNode extends Node implements TypeExtensionNode
 {
-    /**
-     * @var string
-     */
+    /** @var string */
     public $kind = NodeKind::SCALAR_TYPE_EXTENSION;
 
-    /**
-     * @var NameNode
-     */
+    /** @var NameNode */
     public $name;
 
-    /**
-     * @var DirectiveNode[]|null
-     */
+    /** @var DirectiveNode[]|null */
     public $directives;
+
 }

src/Language/AST/SchemaDefinitionNode.php

@@ -1,20 +1,18 @@
 <?php
+
+declare(strict_types=1);
+
 namespace GraphQL\Language\AST;
 
 class SchemaDefinitionNode extends Node implements TypeSystemDefinitionNode
 {
-    /**
-     * @var string
-     */
+    /** @var string */
     public $kind = NodeKind::SCHEMA_DEFINITION;
 
-    /**
-     * @var DirectiveNode[]
-     */
+    /** @var DirectiveNode[] */
     public $directives;
 
-    /**
-     * @var OperationTypeDefinitionNode[]
-     */
+    /** @var OperationTypeDefinitionNode[] */
     public $operationTypes;
+
 }

src/Language/AST/SelectionNode.php

@@ -4,10 +4,9 @@ declare(strict_types=1);
 
 namespace GraphQL\Language\AST;
 
-interface SelectionNode
-{
-    /**
+/**
  * export type SelectionNode = FieldNode | FragmentSpreadNode | InlineFragmentNode
  */
-    public function getKind() : string;
+interface SelectionNode
+{
 }

src/Language/AST/SelectionSetNode.php

@@ -1,12 +1,15 @@
 <?php
+
+declare(strict_types=1);
+
 namespace GraphQL\Language\AST;
 
 class SelectionSetNode extends Node
 {
+    /** @var string */
     public $kind = NodeKind::SELECTION_SET;
 
-    /**
-     * @var SelectionNode[]
-     */
+    /** @var SelectionNode[] */
     public $selections;
+
 }

src/Language/AST/StringValueNode.php

@@ -1,17 +1,18 @@
 <?php
+
+declare(strict_types=1);
+
 namespace GraphQL\Language\AST;
 
 class StringValueNode extends Node implements ValueNode
 {
+    /** @var string */
     public $kind = NodeKind::STRING;
 
-    /**
-     * @var string
-     */
+    /** @var string */
     public $value;
 
-    /**
-     * @var boolean|null
-     */
+    /** @var bool|null */
     public $block;
+
 }

src/Language/AST/TypeDefinitionNode.php

@@ -1,14 +1,17 @@
 <?php
+
+declare(strict_types=1);
+
 namespace GraphQL\Language\AST;
 
+/**
+ * export type TypeDefinitionNode = ScalarTypeDefinitionNode
+ * | ObjectTypeDefinitionNode
+ * | InterfaceTypeDefinitionNode
+ * | UnionTypeDefinitionNode
+ * | EnumTypeDefinitionNode
+ * | InputObjectTypeDefinitionNode
+ */
 interface TypeDefinitionNode extends TypeSystemDefinitionNode
 {
-    /**
-    export type TypeDefinitionNode = ScalarTypeDefinitionNode
-    | ObjectTypeDefinitionNode
-    | InterfaceTypeDefinitionNode
-    | UnionTypeDefinitionNode
-    | EnumTypeDefinitionNode
-    | InputObjectTypeDefinitionNode
-     */
 }

src/Language/AST/TypeExtensionNode.php

@@ -1,15 +1,18 @@
 <?php
+
+declare(strict_types=1);
+
 namespace GraphQL\Language\AST;
 
+/**
+ * export type TypeExtensionNode =
+ * | ScalarTypeExtensionNode
+ * | ObjectTypeExtensionNode
+ * | InterfaceTypeExtensionNode
+ * | UnionTypeExtensionNode
+ * | EnumTypeExtensionNode
+ * | InputObjectTypeExtensionNode;
+ */
 interface TypeExtensionNode extends TypeSystemDefinitionNode
 {
-    /**
-    export type TypeExtensionNode =
-      | ScalarTypeExtensionNode
-      | ObjectTypeExtensionNode
-      | InterfaceTypeExtensionNode
-      | UnionTypeExtensionNode
-      | EnumTypeExtensionNode
-      | InputObjectTypeExtensionNode;
-     */
 }

src/Language/AST/TypeNode.php

@@ -1,13 +1,14 @@
 <?php
+
+declare(strict_types=1);
+
 namespace GraphQL\Language\AST;
 
-
+/**
+ * export type TypeNode = NamedTypeNode
+ * | ListTypeNode
+ * | NonNullTypeNode
+ */
 interface TypeNode
 {
-/**
- export type TypeNode = NamedTypeNode
-                    | ListTypeNode
-                    | NonNullTypeNode
- */
 }
-

src/Language/AST/TypeSystemDefinitionNode.php

@@ -1,13 +1,16 @@
 <?php
+
+declare(strict_types=1);
+
 namespace GraphQL\Language\AST;
 
+/**
+ * export type TypeSystemDefinitionNode =
+ * | SchemaDefinitionNode
+ * | TypeDefinitionNode
+ * | TypeExtensionNode
+ * | DirectiveDefinitionNode
+ */
 interface TypeSystemDefinitionNode extends DefinitionNode
 {
-    /**
-    export type TypeSystemDefinitionNode =
-    | SchemaDefinitionNode
-    | TypeDefinitionNode
-    | TypeExtensionNode
-    | DirectiveDefinitionNode
-     */
 }

src/Language/AST/UnionTypeDefinitionNode.php

@@ -1,30 +1,24 @@
 <?php
+
+declare(strict_types=1);
+
 namespace GraphQL\Language\AST;
 
 class UnionTypeDefinitionNode extends Node implements TypeDefinitionNode
 {
-    /**
-     * @var string
-     */
+    /** @var string */
     public $kind = NodeKind::UNION_TYPE_DEFINITION;
 
-    /**
-     * @var NameNode
-     */
+    /** @var NameNode */
     public $name;
 
-    /**
-     * @var DirectiveNode[]
-     */
+    /** @var DirectiveNode[] */
     public $directives;
 
-    /**
-     * @var NamedTypeNode[]|null
-     */
+    /** @var NamedTypeNode[]|null */
     public $types;
 
-    /**
-     * @var StringValueNode|null
-     */
+    /** @var StringValueNode|null */
     public $description;
+
 }

src/Language/AST/UnionTypeExtensionNode.php

@@ -1,25 +1,21 @@
 <?php
+
+declare(strict_types=1);
+
 namespace GraphQL\Language\AST;
 
 class UnionTypeExtensionNode extends Node implements TypeExtensionNode
 {
-    /**
-     * @var string
-     */
+    /** @var string */
     public $kind = NodeKind::UNION_TYPE_EXTENSION;
 
-    /**
-     * @var NameNode
-     */
+    /** @var NameNode */
     public $name;
 
-    /**
-     * @var DirectiveNode[]|null
-     */
+    /** @var DirectiveNode[]|null */
     public $directives;
 
-    /**
-     * @var NamedTypeNode[]|null
-     */
+    /** @var NamedTypeNode[]|null */
     public $types;
+
 }

src/Language/AST/ValueNode.php

@@ -1,4 +1,7 @@
 <?php
+
+declare(strict_types=1);
+
 namespace GraphQL\Language\AST;
 
 /**
@@ -14,5 +17,4 @@ export type ValueNode = VariableNode
  */
 interface ValueNode
 {
-
 }

src/Language/AST/VariableDefinitionNode.php

@@ -1,22 +1,21 @@
 <?php
+
+declare(strict_types=1);
+
 namespace GraphQL\Language\AST;
 
 class VariableDefinitionNode extends Node implements DefinitionNode
 {
+    /** @var string */
     public $kind = NodeKind::VARIABLE_DEFINITION;
 
-    /**
-     * @var VariableNode
-     */
+    /** @var VariableNode */
     public $variable;
 
-    /**
-     * @var TypeNode
-     */
+    /** @var TypeNode */
     public $type;
 
-    /**
-     * @var ValueNode|null
-     */
+    /** @var ValueNode|null */
     public $defaultValue;
+
 }

src/Language/AST/VariableNode.php

@@ -1,12 +1,15 @@
 <?php
+
+declare(strict_types=1);
+
 namespace GraphQL\Language\AST;
 
 class VariableNode extends Node
 {
+    /** @var string */
     public $kind = NodeKind::VARIABLE;
 
-    /**
-     * @var NameNode
-     */
+    /** @var NameNode */
     public $name;
+
 }

src/Language/DirectiveLocation.php

@@ -1,4 +1,7 @@
 <?php
+
+declare(strict_types=1);
+
 namespace GraphQL\Language;
 
 /**
@@ -28,6 +31,7 @@ class DirectiveLocation
     const INPUT_OBJECT           = 'INPUT_OBJECT';
     const INPUT_FIELD_DEFINITION = 'INPUT_FIELD_DEFINITION';
 
+    /** @var string[] */
     private static $locations = [
         self::QUERY => self::QUERY,
         self::MUTATION => self::MUTATION,

src/Language/Lexer.php

@@ -1,9 +1,16 @@
 <?php
+
+declare(strict_types=1);
+
 namespace GraphQL\Language;
 
 use GraphQL\Error\SyntaxError;
-use GraphQL\Utils\Utils;
 use GraphQL\Utils\BlockString;
+use GraphQL\Utils\Utils;
+use function chr;
+use function hexdec;
+use function ord;
+use function preg_match;
 
 /**
  * A Lexer is a stateful stream generator in that every time
@@ -16,14 +23,10 @@ use GraphQL\Utils\BlockString;
  */
 class Lexer
 {
-    /**
-     * @var Source
-     */
+    /** @var Source */
     public $source;
 
-    /**
-     * @var array
-     */
+    /** @var bool[] */
     public $options;
 
     /**
@@ -69,10 +72,7 @@ class Lexer
     private $byteStreamPosition;
 
     /**
-     * Lexer constructor.
-     *
-     * @param Source $source
-     * @param array $options
+     * @param bool[] $options
      */
     public function __construct(Source $source, array $options = [])
     {
@@ -94,6 +94,7 @@ class Lexer
     {
         $this->lastToken = $this->token;
         $token           = $this->token = $this->lookahead();
+
         return $token;
     }
 
@@ -105,11 +106,11 @@ class Lexer
                 $token = $token->next ?: ($token->next = $this->readToken($token));
             } while ($token->kind === Token::COMMENT);
         }
+
         return $token;
     }
 
     /**
-     * @param Token $prev
      * @return Token
      * @throws SyntaxError
      */
@@ -144,6 +145,7 @@ class Lexer
                 return new Token(Token::BANG, $position, $position + 1, $line, $col, $prev);
             case 35: // #
                 $this->moveStringCursor(-1, -1 * $bytes);
+
                 return $this->readComment($line, $col, $prev);
             case 36: // $
                 return new Token(Token::DOLLAR, $position, $position + 1, $line, $col, $prev);
@@ -178,30 +180,82 @@ class Lexer
             case 125: // }
                 return new Token(Token::BRACE_R, $position, $position + 1, $line, $col, $prev);
             // A-Z
-            case 65: case 66: case 67: case 68: case 69: case 70: case 71: case 72:
-            case 73: case 74: case 75: case 76: case 77: case 78: case 79: case 80:
-            case 81: case 82: case 83: case 84: case 85: case 86: case 87: case 88:
-            case 89: case 90:
+            case 65:
+            case 66:
+            case 67:
+            case 68:
+            case 69:
+            case 70:
+            case 71:
+            case 72:
+            case 73:
+            case 74:
+            case 75:
+            case 76:
+            case 77:
+            case 78:
+            case 79:
+            case 80:
+            case 81:
+            case 82:
+            case 83:
+            case 84:
+            case 85:
+            case 86:
+            case 87:
+            case 88:
+            case 89:
+            case 90:
                 // _
             case 95:
                 // a-z
-            case 97: case 98: case 99: case 100: case 101: case 102: case 103: case 104:
-            case 105: case 106: case 107: case 108: case 109: case 110: case 111:
-            case 112: case 113: case 114: case 115: case 116: case 117: case 118:
-            case 119: case 120: case 121: case 122:
+            case 97:
+            case 98:
+            case 99:
+            case 100:
+            case 101:
+            case 102:
+            case 103:
+            case 104:
+            case 105:
+            case 106:
+            case 107:
+            case 108:
+            case 109:
+            case 110:
+            case 111:
+            case 112:
+            case 113:
+            case 114:
+            case 115:
+            case 116:
+            case 117:
+            case 118:
+            case 119:
+            case 120:
+            case 121:
+            case 122:
                 return $this->moveStringCursor(-1, -1 * $bytes)
                     ->readName($line, $col, $prev);
             // -
             case 45:
                 // 0-9
-            case 48: case 49: case 50: case 51: case 52:
-            case 53: case 54: case 55: case 56: case 57:
+            case 48:
+            case 49:
+            case 50:
+            case 51:
+            case 52:
+            case 53:
+            case 54:
+            case 55:
+            case 56:
+            case 57:
                 return $this->moveStringCursor(-1, -1 * $bytes)
                     ->readNumber($line, $col, $prev);
             // "
             case 34:
-                list(,$nextCode) = $this->readChar();
-                list(,$nextNextCode) = $this->moveStringCursor(1, 1)->readChar();
+                list(, $nextCode)     = $this->readChar();
+                list(, $nextNextCode) = $this->moveStringCursor(1, 1)->readChar();
 
                 if ($nextCode === 34 && $nextNextCode === 34) {
                     return $this->moveStringCursor(-2, (-1 * $bytes) - 1)
@@ -213,7 +267,7 @@ class Lexer
         }
 
         $errMessage = $code === 39
-            ? "Unexpected single quote character ('), did you mean to use ". 'a double quote (")?'
+            ? "Unexpected single quote character ('), did you mean to use " . 'a double quote (")?'
             : 'Cannot parse the unexpected character ' . Utils::printCharCode($code) . '.';
 
         throw new SyntaxError(
@@ -230,7 +284,6 @@ class Lexer
      *
      * @param int $line
      * @param int $col
-     * @param Token $prev
      * @return Token
      */
     private function readName($line, $col, Token $prev)
@@ -248,6 +301,7 @@ class Lexer
             $value             .= $char;
             list ($char, $code) = $this->moveStringCursor(1, 1)->readChar();
         }
+
         return new Token(
             Token::NAME,
             $start,
@@ -268,7 +322,6 @@ class Lexer
      *
      * @param int $line
      * @param int $col
-     * @param Token $prev
      * @return Token
      * @throws SyntaxError
      */
@@ -291,7 +344,11 @@ class Lexer
             list ($char, $code) = $this->moveStringCursor(1, 1)->readChar();
 
             if ($code >= 48 && $code <= 57) {
-                throw new SyntaxError($this->source, $this->position, "Invalid number, unexpected digit after 0: " . Utils::printCharCode($code));
+                throw new SyntaxError(
+                    $this->source,
+                    $this->position,
+                    'Invalid number, unexpected digit after 0: ' . Utils::printCharCode($code)
+                );
             }
         } else {
             $value             .= $this->readDigits();
@@ -362,7 +419,6 @@ class Lexer
     /**
      * @param int $line
      * @param int $col
-     * @param Token $prev
      * @return Token
      * @throws SyntaxError
      */
@@ -371,13 +427,12 @@ class Lexer
         $start = $this->position;
 
         // Skip leading quote and read first string char:
-        list ($char, $code, $bytes) = $this->moveStringCursor(1, 1)->readChar();
+        [$char, $code, $bytes] = $this->moveStringCursor(1, 1)->readChar();
 
         $chunk = '';
         $value = '';
 
-        while (
-            $code !== null &&
+        while ($code !== null &&
             // not LineTerminator
             $code !== 10 && $code !== 13
         ) {
@@ -407,18 +462,34 @@ class Lexer
                 list (, $code) = $this->readChar(true);
 
                 switch ($code) {
-                    case 34: $value .= '"'; break;
-                    case 47: $value .= '/'; break;
-                    case 92: $value .= '\\'; break;
-                    case 98: $value .= chr(8); break; // \b (backspace)
-                    case 102: $value .= "\f"; break;
-                    case 110: $value .= "\n"; break;
-                    case 114: $value .= "\r"; break;
-                    case 116: $value .= "\t"; break;
+                    case 34:
+                        $value .= '"';
+                        break;
+                    case 47:
+                        $value .= '/';
+                        break;
+                    case 92:
+                        $value .= '\\';
+                        break;
+                    case 98:
+                        $value .= chr(8);
+                        break; // \b (backspace)
+                    case 102:
+                        $value .= "\f";
+                        break;
+                    case 110:
+                        $value .= "\n";
+                        break;
+                    case 114:
+                        $value .= "\r";
+                        break;
+                    case 116:
+                        $value .= "\t";
+                        break;
                     case 117:
                         $position   = $this->position;
                         list ($hex) = $this->readChars(4, true);
-                        if (!preg_match('/[0-9a-fA-F]{4}/', $hex)) {
+                        if (! preg_match('/[0-9a-fA-F]{4}/', $hex)) {
                             throw new SyntaxError(
                                 $this->source,
                                 $position - 1,
@@ -470,8 +541,8 @@ class Lexer
             // Closing Triple-Quote (""")
             if ($code === 34) {
                 // Move 2 quotes
-                list(,$nextCode) = $this->moveStringCursor(1, 1)->readChar();
-                list(,$nextNextCode) = $this->moveStringCursor(1, 1)->readChar();
+                list(, $nextCode)     = $this->moveStringCursor(1, 1)->readChar();
+                list(, $nextNextCode) = $this->moveStringCursor(1, 1)->readChar();
 
                 if ($nextCode === 34 && $nextNextCode === 34) {
                     $value .= $chunk;
@@ -496,9 +567,9 @@ class Lexer
             $this->assertValidBlockStringCharacterCode($code, $this->position);
             $this->moveStringCursor(1, $bytes);
 
-            list(,$nextCode) = $this->readChar();
-            list(,$nextNextCode) = $this->moveStringCursor(1, 1)->readChar();
-            list(,$nextNextNextCode) = $this->moveStringCursor(1, 1)->readChar();
+            list(, $nextCode)         = $this->readChar();
+            list(, $nextNextCode)     = $this->moveStringCursor(1, 1)->readChar();
+            list(, $nextNextNextCode) = $this->moveStringCursor(1, 1)->readChar();
 
             // Escape Triple-Quote (\""")
             if ($code === 92 &&
@@ -561,11 +632,11 @@ class Lexer
             // tab | space | comma | BOM
             if ($code === 9 || $code === 32 || $code === 44 || $code === 0xFEFF) {
                 $this->moveStringCursor(1, $bytes);
-            } else if ($code === 10) { // new line
+            } elseif ($code === 10) { // new line
                 $this->moveStringCursor(1, $bytes);
                 $this->line++;
                 $this->lineStart = $this->position;
-            } else if ($code === 13) { // carriage return
+            } elseif ($code === 13) { // carriage return
                 list(, $nextCode, $nextBytes) = $this->moveStringCursor(1, $bytes)->readChar();
 
                 if ($nextCode === 10) { // lf after cr
@@ -584,9 +655,8 @@ class Lexer
      *
      * #[\u0009\u0020-\uFFFF]*
      *
-     * @param $line
-     * @param $col
-     * @param Token $prev
+     * @param int $line
+     * @param int $col
      * @return Token
      */
     private function readComment($line, $col, Token $prev)
@@ -598,8 +668,7 @@ class Lexer
         do {
             list ($char, $code, $bytes) = $this->moveStringCursor(1, $bytes)->readChar();
             $value                     .= $char;
-        } while (
-            $code &&
+        } while ($code &&
         // SourceCharacter but not LineTerminator
         ($code > 0x001F || $code === 0x0009)
         );
@@ -620,7 +689,7 @@ class Lexer
      *
      * @param bool $advance
      * @param int  $byteStreamPosition
-     * @return array
+     * @return (string|int)[]
      */
     private function readChar($advance = false, $byteStreamPosition = null)
     {
@@ -638,7 +707,7 @@ class Lexer
 
             if ($ord < 128) {
                 $bytes = 1;
-            } else if ($ord < 224) {
+            } elseif ($ord < 224) {
                 $bytes = 2;
             } elseif ($ord < 240) {
                 $bytes = 3;
@@ -664,40 +733,42 @@ class Lexer
     /**
      * Reads next $numberOfChars UTF8 characters from the byte stream, starting from $byteStreamPosition.
      *
-     * @param $numberOfChars
+     * @param int  $charCount
      * @param bool $advance
      * @param null $byteStreamPosition
-     * @return array
+     * @return (string|int)[]
      */
-    private function readChars($numberOfChars, $advance = false, $byteStreamPosition = null)
+    private function readChars($charCount, $advance = false, $byteStreamPosition = null)
     {
         $result     = '';
         $totalBytes = 0;
         $byteOffset = $byteStreamPosition ?: $this->byteStreamPosition;
 
-        for ($i = 0; $i < $numberOfChars; $i++) {
+        for ($i = 0; $i < $charCount; $i++) {
             list ($char, $code, $bytes) = $this->readChar(false, $byteOffset);
             $totalBytes                += $bytes;
             $byteOffset                += $bytes;
             $result                    .= $char;
         }
         if ($advance) {
-            $this->moveStringCursor($numberOfChars, $totalBytes);
+            $this->moveStringCursor($charCount, $totalBytes);
         }
+
         return [$result, $totalBytes];
     }
 
     /**
      * Moves internal string cursor position
      *
-     * @param $positionOffset
-     * @param $byteStreamOffset
+     * @param int $positionOffset
+     * @param int $byteStreamOffset
      * @return self
      */
     private function moveStringCursor($positionOffset, $byteStreamOffset)
     {
         $this->position           += $positionOffset;
         $this->byteStreamPosition += $byteStreamOffset;
+
         return $this;
     }
 }

src/Language/Printer.php

@@ -1,29 +1,32 @@
 <?php
+
+declare(strict_types=1);
+
 namespace GraphQL\Language;
 
 use GraphQL\Language\AST\ArgumentNode;
+use GraphQL\Language\AST\BooleanValueNode;
 use GraphQL\Language\AST\DirectiveDefinitionNode;
+use GraphQL\Language\AST\DirectiveNode;
+use GraphQL\Language\AST\DocumentNode;
 use GraphQL\Language\AST\EnumTypeDefinitionNode;
 use GraphQL\Language\AST\EnumTypeExtensionNode;
 use GraphQL\Language\AST\EnumValueDefinitionNode;
-use GraphQL\Language\AST\FieldDefinitionNode;
-use GraphQL\Language\AST\InputObjectTypeDefinitionNode;
-use GraphQL\Language\AST\InputObjectTypeExtensionNode;
-use GraphQL\Language\AST\InputValueDefinitionNode;
-use GraphQL\Language\AST\InterfaceTypeDefinitionNode;
-use GraphQL\Language\AST\InterfaceTypeExtensionNode;
-use GraphQL\Language\AST\ListValueNode;
-use GraphQL\Language\AST\BooleanValueNode;
-use GraphQL\Language\AST\DirectiveNode;
-use GraphQL\Language\AST\DocumentNode;
 use GraphQL\Language\AST\EnumValueNode;
+use GraphQL\Language\AST\FieldDefinitionNode;
 use GraphQL\Language\AST\FieldNode;
 use GraphQL\Language\AST\FloatValueNode;
 use GraphQL\Language\AST\FragmentDefinitionNode;
 use GraphQL\Language\AST\FragmentSpreadNode;
 use GraphQL\Language\AST\InlineFragmentNode;
+use GraphQL\Language\AST\InputObjectTypeDefinitionNode;
+use GraphQL\Language\AST\InputObjectTypeExtensionNode;
+use GraphQL\Language\AST\InputValueDefinitionNode;
+use GraphQL\Language\AST\InterfaceTypeDefinitionNode;
+use GraphQL\Language\AST\InterfaceTypeExtensionNode;
 use GraphQL\Language\AST\IntValueNode;
 use GraphQL\Language\AST\ListTypeNode;
+use GraphQL\Language\AST\ListValueNode;
 use GraphQL\Language\AST\NamedTypeNode;
 use GraphQL\Language\AST\Node;
 use GraphQL\Language\AST\NodeKind;
@@ -31,6 +34,7 @@ use GraphQL\Language\AST\NonNullTypeNode;
 use GraphQL\Language\AST\NullValueNode;
 use GraphQL\Language\AST\ObjectFieldNode;
 use GraphQL\Language\AST\ObjectTypeDefinitionNode;
+use GraphQL\Language\AST\ObjectTypeExtensionNode;
 use GraphQL\Language\AST\ObjectValueNode;
 use GraphQL\Language\AST\OperationDefinitionNode;
 use GraphQL\Language\AST\OperationTypeDefinitionNode;
@@ -39,11 +43,17 @@ use GraphQL\Language\AST\ScalarTypeExtensionNode;
 use GraphQL\Language\AST\SchemaDefinitionNode;
 use GraphQL\Language\AST\SelectionSetNode;
 use GraphQL\Language\AST\StringValueNode;
-use GraphQL\Language\AST\ObjectTypeExtensionNode;
 use GraphQL\Language\AST\UnionTypeDefinitionNode;
 use GraphQL\Language\AST\UnionTypeExtensionNode;
 use GraphQL\Language\AST\VariableDefinitionNode;
 use GraphQL\Utils\Utils;
+use function count;
+use function implode;
+use function json_encode;
+use function preg_replace;
+use function sprintf;
+use function str_replace;
+use function strpos;
 
 /**
  * Prints AST to string. Capable of printing GraphQL queries and Type definition language.
@@ -70,26 +80,33 @@ class Printer
     {
         static $instance;
         $instance = $instance ?: new static();
+
         return $instance->printAST($ast);
     }
 
     protected function __construct()
-    {}
+    {
+    }
 
     public function printAST($ast)
     {
-        return Visitor::visit($ast, [
+        return Visitor::visit(
+            $ast,
+            [
                 'leave' => [
-                NodeKind::NAME => function(Node $node) {
+                    NodeKind::NAME => function (Node $node) {
                         return '' . $node->value;
                     },
-                NodeKind::VARIABLE => function($node) {
+
+                    NodeKind::VARIABLE => function ($node) {
                         return '$' . $node->name;
                     },
-                NodeKind::DOCUMENT => function(DocumentNode $node) {
+
+                    NodeKind::DOCUMENT => function (DocumentNode $node) {
                         return $this->join($node->definitions, "\n\n") . "\n";
                     },
-                NodeKind::OPERATION_DEFINITION => function(OperationDefinitionNode $node) {
+
+                    NodeKind::OPERATION_DEFINITION => function (OperationDefinitionNode $node) {
                         $op           = $node->operation;
                         $name         = $node->name;
                         $varDefs      = $this->wrap('(', $this->join($node->variableDefinitions, ', '), ')');
@@ -97,229 +114,310 @@ class Printer
                         $selectionSet = $node->selectionSet;
                         // Anonymous queries with no directives or variable definitions can use
                         // the query short form.
-                    return !$name && !$directives && !$varDefs && $op === 'query'
+                        return ! $name && ! $directives && ! $varDefs && $op === 'query'
                             ? $selectionSet
                             : $this->join([$op, $this->join([$name, $varDefs]), $directives, $selectionSet], ' ');
                     },
-                NodeKind::VARIABLE_DEFINITION => function(VariableDefinitionNode $node) {
+
+                    NodeKind::VARIABLE_DEFINITION => function (VariableDefinitionNode $node) {
                         return $node->variable . ': ' . $node->type . $this->wrap(' = ', $node->defaultValue);
                     },
-                NodeKind::SELECTION_SET => function(SelectionSetNode $node) {
+
+                    NodeKind::SELECTION_SET => function (SelectionSetNode $node) {
                         return $this->block($node->selections);
                     },
-                NodeKind::FIELD => function(FieldNode $node) {
-                    return $this->join([
-                        $this->wrap('', $node->alias, ': ') . $node->name . $this->wrap('(', $this->join($node->arguments, ', '), ')'),
+
+                    NodeKind::FIELD => function (FieldNode $node) {
+                        return $this->join(
+                            [
+                                $this->wrap('', $node->alias, ': ') . $node->name . $this->wrap(
+                                    '(',
+                                    $this->join($node->arguments, ', '),
+                                    ')'
+                                ),
                                 $this->join($node->directives, ' '),
-                        $node->selectionSet
-                    ], ' ');
+                                $node->selectionSet,
+                            ],
+                            ' '
+                        );
                     },
-                NodeKind::ARGUMENT => function(ArgumentNode $node) {
+
+                    NodeKind::ARGUMENT => function (ArgumentNode $node) {
                         return $node->name . ': ' . $node->value;
                     },
 
-                // Fragments
-                NodeKind::FRAGMENT_SPREAD => function(FragmentSpreadNode $node) {
+                    NodeKind::FRAGMENT_SPREAD => function (FragmentSpreadNode $node) {
                         return '...' . $node->name . $this->wrap(' ', $this->join($node->directives, ' '));
                     },
-                NodeKind::INLINE_FRAGMENT => function(InlineFragmentNode $node) {
-                    return $this->join([
-                        "...",
+
+                    NodeKind::INLINE_FRAGMENT => function (InlineFragmentNode $node) {
+                        return $this->join(
+                            [
+                                '...',
                                 $this->wrap('on ', $node->typeCondition),
                                 $this->join($node->directives, ' '),
-                        $node->selectionSet
-                    ], ' ');
+                                $node->selectionSet,
+                            ],
+                            ' '
+                        );
                     },
-                NodeKind::FRAGMENT_DEFINITION => function(FragmentDefinitionNode $node) {
-                    // Note: fragment variable definitions are experimental and may be changed
-                    // or removed in the future.
-                    return "fragment {$node->name}"
+
+                    NodeKind::FRAGMENT_DEFINITION => function (FragmentDefinitionNode $node) {
+                        // Note: fragment variable definitions are experimental and may be changed or removed in the future.
+                        return sprintf('fragment %s', $node->name)
                             . $this->wrap('(', $this->join($node->variableDefinitions, ', '), ')')
-                        . " on {$node->typeCondition} "
+                            . sprintf(' on %s ', $node->typeCondition)
                             . $this->wrap('', $this->join($node->directives, ' '), ' ')
                             . $node->selectionSet;
                     },
 
-                // Value
-                NodeKind::INT => function(IntValueNode  $node) {
+                    NodeKind::INT => function (IntValueNode $node) {
                         return $node->value;
                     },
-                NodeKind::FLOAT => function(FloatValueNode $node) {
+
+                    NodeKind::FLOAT => function (FloatValueNode $node) {
                         return $node->value;
                     },
-                NodeKind::STRING => function(StringValueNode $node, $key) {
+
+                    NodeKind::STRING => function (StringValueNode $node, $key) {
                         if ($node->block) {
                             return $this->printBlockString($node->value, $key === 'description');
                         }
+
                         return json_encode($node->value);
                     },
-                NodeKind::BOOLEAN => function(BooleanValueNode $node) {
+
+                    NodeKind::BOOLEAN => function (BooleanValueNode $node) {
                         return $node->value ? 'true' : 'false';
                     },
-                NodeKind::NULL => function(NullValueNode $node) {
+
+                    NodeKind::NULL => function (NullValueNode $node) {
                         return 'null';
                     },
-                NodeKind::ENUM => function(EnumValueNode $node) {
+
+                    NodeKind::ENUM => function (EnumValueNode $node) {
                         return $node->value;
                     },
-                NodeKind::LST => function(ListValueNode $node) {
+
+                    NodeKind::LST => function (ListValueNode $node) {
                         return '[' . $this->join($node->values, ', ') . ']';
                     },
-                NodeKind::OBJECT => function(ObjectValueNode $node) {
+
+                    NodeKind::OBJECT => function (ObjectValueNode $node) {
                         return '{' . $this->join($node->fields, ', ') . '}';
                     },
-                NodeKind::OBJECT_FIELD => function(ObjectFieldNode $node) {
+
+                    NodeKind::OBJECT_FIELD => function (ObjectFieldNode $node) {
                         return $node->name . ': ' . $node->value;
                     },
 
-                // DirectiveNode
-                NodeKind::DIRECTIVE => function(DirectiveNode $node) {
+                    NodeKind::DIRECTIVE => function (DirectiveNode $node) {
                         return '@' . $node->name . $this->wrap('(', $this->join($node->arguments, ', '), ')');
                     },
 
-                // Type
-                NodeKind::NAMED_TYPE => function(NamedTypeNode $node) {
+                    NodeKind::NAMED_TYPE => function (NamedTypeNode $node) {
                         return $node->name;
                     },
-                NodeKind::LIST_TYPE => function(ListTypeNode $node) {
+
+                    NodeKind::LIST_TYPE => function (ListTypeNode $node) {
                         return '[' . $node->type . ']';
                     },
-                NodeKind::NON_NULL_TYPE => function(NonNullTypeNode $node) {
+
+                    NodeKind::NON_NULL_TYPE => function (NonNullTypeNode $node) {
                         return $node->type . '!';
                     },
 
-                // Type System Definitions
-                NodeKind::SCHEMA_DEFINITION => function(SchemaDefinitionNode $def) {
-                    return $this->join([
+                    NodeKind::SCHEMA_DEFINITION => function (SchemaDefinitionNode $def) {
+                        return $this->join(
+                            [
                                 'schema',
                                 $this->join($def->directives, ' '),
-                        $this->block($def->operationTypes)
-                    ], ' ');
+                                $this->block($def->operationTypes),
+                            ],
+                            ' '
+                        );
                     },
-                NodeKind::OPERATION_TYPE_DEFINITION => function(OperationTypeDefinitionNode $def) {
+
+                    NodeKind::OPERATION_TYPE_DEFINITION => function (OperationTypeDefinitionNode $def) {
                         return $def->operation . ': ' . $def->type;
                     },
 
-                NodeKind::SCALAR_TYPE_DEFINITION => $this->addDescription(function(ScalarTypeDefinitionNode $def) {
+                    NodeKind::SCALAR_TYPE_DEFINITION => $this->addDescription(function (ScalarTypeDefinitionNode $def) {
                         return $this->join(['scalar', $def->name, $this->join($def->directives, ' ')], ' ');
                     }),
-                NodeKind::OBJECT_TYPE_DEFINITION => $this->addDescription(function(ObjectTypeDefinitionNode $def) {
-                    return $this->join([
+
+                    NodeKind::OBJECT_TYPE_DEFINITION => $this->addDescription(function (ObjectTypeDefinitionNode $def) {
+                        return $this->join(
+                            [
                                 'type',
                                 $def->name,
                                 $this->wrap('implements ', $this->join($def->interfaces, ' & ')),
                                 $this->join($def->directives, ' '),
-                        $this->block($def->fields)
-                    ], ' ');
+                                $this->block($def->fields),
+                            ],
+                            ' '
+                        );
                     }),
-                NodeKind::FIELD_DEFINITION => $this->addDescription(function(FieldDefinitionNode $def) {
+
+                    NodeKind::FIELD_DEFINITION => $this->addDescription(function (FieldDefinitionNode $def) {
                         return $def->name
                             . $this->wrap('(', $this->join($def->arguments, ', '), ')')
                             . ': ' . $def->type
                             . $this->wrap(' ', $this->join($def->directives, ' '));
                     }),
-                NodeKind::INPUT_VALUE_DEFINITION => $this->addDescription(function(InputValueDefinitionNode $def) {
-                    return $this->join([
+
+                    NodeKind::INPUT_VALUE_DEFINITION => $this->addDescription(function (InputValueDefinitionNode $def) {
+                        return $this->join(
+                            [
                                 $def->name . ': ' . $def->type,
                                 $this->wrap('= ', $def->defaultValue),
-                        $this->join($def->directives, ' ')
-                    ], ' ');
+                                $this->join($def->directives, ' '),
+                            ],
+                            ' '
+                        );
                     }),
-                NodeKind::INTERFACE_TYPE_DEFINITION => $this->addDescription(function(InterfaceTypeDefinitionNode $def) {
-                    return $this->join([
+
+                    NodeKind::INTERFACE_TYPE_DEFINITION => $this->addDescription(
+                        function (InterfaceTypeDefinitionNode $def) {
+                            return $this->join(
+                                [
                                     'interface',
                                     $def->name,
                                     $this->join($def->directives, ' '),
-                        $this->block($def->fields)
-                    ], ' ');
-                }),
-                NodeKind::UNION_TYPE_DEFINITION => $this->addDescription(function(UnionTypeDefinitionNode $def) {
-                    return $this->join([
+                                    $this->block($def->fields),
+                                ],
+                                ' '
+                            );
+                        }
+                    ),
+
+                    NodeKind::UNION_TYPE_DEFINITION => $this->addDescription(function (UnionTypeDefinitionNode $def) {
+                        return $this->join(
+                            [
                                 'union',
                                 $def->name,
                                 $this->join($def->directives, ' '),
                                 $def->types
                                     ? '= ' . $this->join($def->types, ' | ')
-                            : ''
-                    ], ' ');
+                                    : '',
+                            ],
+                            ' '
+                        );
                     }),
-                NodeKind::ENUM_TYPE_DEFINITION => $this->addDescription(function(EnumTypeDefinitionNode $def) {
-                    return $this->join([
+
+                    NodeKind::ENUM_TYPE_DEFINITION => $this->addDescription(function (EnumTypeDefinitionNode $def) {
+                        return $this->join(
+                            [
                                 'enum',
                                 $def->name,
                                 $this->join($def->directives, ' '),
-                        $this->block($def->values)
-                    ], ' ');
+                                $this->block($def->values),
+                            ],
+                            ' '
+                        );
                     }),
-                NodeKind::ENUM_VALUE_DEFINITION => $this->addDescription(function(EnumValueDefinitionNode $def) {
+
+                    NodeKind::ENUM_VALUE_DEFINITION => $this->addDescription(function (EnumValueDefinitionNode $def) {
                         return $this->join([$def->name, $this->join($def->directives, ' ')], ' ');
                     }),
-                NodeKind::INPUT_OBJECT_TYPE_DEFINITION => $this->addDescription(function(InputObjectTypeDefinitionNode $def) {
-                    return $this->join([
+
+                    NodeKind::INPUT_OBJECT_TYPE_DEFINITION => $this->addDescription(function (
+                        InputObjectTypeDefinitionNode $def
+                    ) {
+                        return $this->join(
+                            [
                                 'input',
                                 $def->name,
                                 $this->join($def->directives, ' '),
-                        $this->block($def->fields)
-                    ], ' ');
+                                $this->block($def->fields),
+                            ],
+                            ' '
+                        );
                     }),
-                NodeKind::SCALAR_TYPE_EXTENSION => function(ScalarTypeExtensionNode $def) {
-                    return $this->join([
+
+                    NodeKind::SCALAR_TYPE_EXTENSION => function (ScalarTypeExtensionNode $def) {
+                        return $this->join(
+                            [
                                 'extend scalar',
                                 $def->name,
                                 $this->join($def->directives, ' '),
-                    ], ' ');
+                            ],
+                            ' '
+                        );
                     },
-                NodeKind::OBJECT_TYPE_EXTENSION => function(ObjectTypeExtensionNode $def) {
-                    return $this->join([
+
+                    NodeKind::OBJECT_TYPE_EXTENSION => function (ObjectTypeExtensionNode $def) {
+                        return $this->join(
+                            [
                                 'extend type',
                                 $def->name,
                                 $this->wrap('implements ', $this->join($def->interfaces, ' & ')),
                                 $this->join($def->directives, ' '),
                                 $this->block($def->fields),
-                    ], ' ');
+                            ],
+                            ' '
+                        );
                     },
-                NodeKind::INTERFACE_TYPE_EXTENSION => function(InterfaceTypeExtensionNode $def) {
-                    return $this->join([
+
+                    NodeKind::INTERFACE_TYPE_EXTENSION => function (InterfaceTypeExtensionNode $def) {
+                        return $this->join(
+                            [
                                 'extend interface',
                                 $def->name,
                                 $this->join($def->directives, ' '),
                                 $this->block($def->fields),
-                    ], ' ');
+                            ],
+                            ' '
+                        );
                     },
-                NodeKind::UNION_TYPE_EXTENSION => function(UnionTypeExtensionNode $def) {
-                    return $this->join([
+
+                    NodeKind::UNION_TYPE_EXTENSION => function (UnionTypeExtensionNode $def) {
+                        return $this->join(
+                            [
                                 'extend union',
                                 $def->name,
                                 $this->join($def->directives, ' '),
                                 $def->types
                                     ? '= ' . $this->join($def->types, ' | ')
-                            : ''
-                    ], ' ');
+                                    : '',
+                            ],
+                            ' '
+                        );
                     },
-                NodeKind::ENUM_TYPE_EXTENSION => function(EnumTypeExtensionNode $def) {
-                    return $this->join([
+
+                    NodeKind::ENUM_TYPE_EXTENSION => function (EnumTypeExtensionNode $def) {
+                        return $this->join(
+                            [
                                 'extend enum',
                                 $def->name,
                                 $this->join($def->directives, ' '),
                                 $this->block($def->values),
-                    ], ' ');
+                            ],
+                            ' '
+                        );
                     },
-                NodeKind::INPUT_OBJECT_TYPE_EXTENSION => function(InputObjectTypeExtensionNode $def) {
-                    return $this->join([
+
+                    NodeKind::INPUT_OBJECT_TYPE_EXTENSION => function (InputObjectTypeExtensionNode $def) {
+                        return $this->join(
+                            [
                                 'extend input',
                                 $def->name,
                                 $this->join($def->directives, ' '),
                                 $this->block($def->fields),
-                    ], ' ');
+                            ],
+                            ' '
+                        );
                     },
-                NodeKind::DIRECTIVE_DEFINITION => $this->addDescription(function(DirectiveDefinitionNode $def) {
+
+                    NodeKind::DIRECTIVE_DEFINITION => $this->addDescription(function (DirectiveDefinitionNode $def) {
                         return 'directive @'
                             . $def->name
                             . $this->wrap('(', $this->join($def->arguments, ', '), ')')
                             . ' on ' . $this->join($def->locations, ' | ');
-                })
+                    }),
+                ],
             ]
-        ]);
+        );
     }
 
     public function addDescription(\Closure $cb)
@@ -371,7 +469,9 @@ class Printer
                 $separator,
                 Utils::filter(
                     $maybeArray,
-                    function($x) { return !!$x;}
+                    function ($x) {
+                        return ! ! $x;
+                    }
                 )
             )
             : '';
@@ -382,8 +482,10 @@ class Printer
      * trailing blank line. However, if a block string starts with whitespace and is
      * a single-line, adding a leading blank line would strip that whitespace.
      */
-    private function printBlockString($value, $isDescription) {
+    private function printBlockString($value, $isDescription)
+    {
         $escaped = str_replace('"""', '\\"""', $value);
+
         return (($value[0] === ' ' || $value[0] === "\t") && strpos($value, "\n") === false)
             ? ('"""' . preg_replace('/"$/', "\"\n", $escaped) . '"""')
             : ("\"\"\"\n" . ($isDescription ? $escaped : $this->indent($escaped)) . "\n\"\"\"");

src/Language/Source.php

@@ -1,36 +1,33 @@
 <?php
+
+declare(strict_types=1);
+
 namespace GraphQL\Language;
 
 use GraphQL\Utils\Utils;
+use function is_string;
+use function json_decode;
+use function mb_strlen;
+use function mb_substr;
+use function preg_match_all;
+use const PREG_OFFSET_CAPTURE;
 
-/**
- * Class Source
- * @package GraphQL\Language
- */
 class Source
 {
-    /**
-     * @var string
-     */
+    /** @var string */
     public $body;
 
-    /**
-     * @var int
-     */
+    /** @var int */
     public $length;
 
-    /**
-     * @var string
-     */
+    /** @var string */
     public $name;
 
-    /**
-     * @var SourceLocation
-     */
+    /** @var SourceLocation */
     public $locationOffset;
 
     /**
-     * Source constructor.
+     *
      *
      * A representation of source input to GraphQL.
      * `name` and `locationOffset` are optional. They are useful for clients who
@@ -41,9 +38,8 @@ class Source
      *
      * @param string      $body
      * @param string|null $name
-     * @param SourceLocation|null $location
      */
-    public function __construct($body, $name = null, SourceLocation $location = null)
+    public function __construct($body, $name = null, ?SourceLocation $location = null)
     {
         Utils::invariant(
             is_string($body),
@@ -66,7 +62,7 @@ class Source
     }
 
     /**
-     * @param $position
+     * @param int $position
      * @return SourceLocation
      */
     public function getLocation($position)
@@ -75,12 +71,13 @@ class Source
         $column = $position + 1;
 
         $utfChars   = json_decode('"\u2028\u2029"');
-        $lineRegexp = '/\r\n|[\n\r'.$utfChars.']/su';
+        $lineRegexp = '/\r\n|[\n\r' . $utfChars . ']/su';
         $matches    = [];
         preg_match_all($lineRegexp, mb_substr($this->body, 0, $position, 'UTF-8'), $matches, PREG_OFFSET_CAPTURE);
 
         foreach ($matches[0] as $index => $match) {
             $line += 1;
+
             $column = $position + 1 - ($match[1] + mb_strlen($match[0], 'UTF-8'));
         }
 

src/Language/SourceLocation.php

@@ -1,11 +1,21 @@
 <?php
+
+declare(strict_types=1);
+
 namespace GraphQL\Language;
 
 class SourceLocation implements \JsonSerializable
 {
+    /** @var int */
     public $line;
+
+    /** @var int */
     public $column;
 
+    /**
+     * @param int $line
+     * @param int $col
+     */
     public function __construct($line, $col)
     {
         $this->line   = $line;
@@ -13,18 +23,18 @@ class SourceLocation implements \JsonSerializable
     }
 
     /**
-     * @return array
+     * @return int[]
      */
     public function toArray()
     {
         return [
             'line'   => $this->line,
-            'column' => $this->column
+            'column' => $this->column,
         ];
     }
 
     /**
-     * @return array
+     * @return int[]
      */
     public function toSerializableArray()
     {
@@ -32,13 +42,9 @@ class SourceLocation implements \JsonSerializable
     }
 
     /**
-     * Specify data which should be serialized to JSON
-     * @link http://php.net/manual/en/jsonserializable.jsonserialize.php
-     * @return mixed data which can be serialized by <b>json_encode</b>,
-     * which is a value of any type other than a resource.
-     * @since 5.4.0
+     * @return int[]
      */
-    function jsonSerialize()
+    public function jsonSerialize()
     {
         return $this->toSerializableArray();
     }

src/Language/Token.php

@@ -1,4 +1,7 @@
 <?php
+
+declare(strict_types=1);
+
 namespace GraphQL\Language;
 
 /**
@@ -66,9 +69,7 @@ class Token
      */
     public $column;
 
-    /**
-     * @var string|null
-     */
+    /** @var string|null */
     public $value;
 
     /**
@@ -80,28 +81,25 @@ class Token
      */
     public $prev;
 
-    /**
-     * @var Token
-     */
+    /** @var Token */
     public $next;
 
     /**
-     * Token constructor.
-     * @param $kind
-     * @param $start
-     * @param $end
-     * @param $line
-     * @param $column
-     * @param Token $previous
-     * @param null $value
+     *
+     * @param string     $kind
+     * @param int        $start
+     * @param int        $end
+     * @param int        $line
+     * @param int        $column
+     * @param mixed|null $value
      */
-    public function __construct($kind, $start, $end, $line, $column, Token $previous = null, $value = null)
+    public function __construct($kind, $start, $end, $line, $column, ?Token $previous = null, $value = null)
     {
         $this->kind   = $kind;
-        $this->start = (int) $start;
-        $this->end = (int) $end;
-        $this->line = (int) $line;
-        $this->column = (int) $column;
+        $this->start  = $start;
+        $this->end    = $end;
+        $this->line   = $line;
+        $this->column = $column;
         $this->prev   = $previous;
         $this->next   = null;
         $this->value  = $value;
@@ -116,7 +114,7 @@ class Token
     }
 
     /**
-     * @return array
+     * @return (string|int|null)[]
      */
     public function toArray()
     {
@@ -124,7 +122,7 @@ class Token
             'kind'   => $this->kind,
             'value'  => $this->value,
             'line'   => $this->line,
-            'column' => $this->column
+            'column' => $this->column,
         ];
     }
 }

src/Language/Visitor.php

@@ -1,19 +1,24 @@
 <?php
+
+declare(strict_types=1);
+
 namespace GraphQL\Language;
 
+use ArrayObject;
 use GraphQL\Language\AST\Node;
 use GraphQL\Language\AST\NodeKind;
 use GraphQL\Language\AST\NodeList;
 use GraphQL\Utils\TypeInfo;
-
-class VisitorOperation
-{
-    public $doBreak;
-
-    public $doContinue;
-
-    public $removeNode;
-}
+use stdClass;
+use function array_pop;
+use function array_splice;
+use function call_user_func;
+use function call_user_func_array;
+use function count;
+use function func_get_args;
+use function is_array;
+use function is_callable;
+use function json_encode;
 
 /**
  * Utility for efficient AST traversal and modification.
@@ -104,6 +109,7 @@ class VisitorOperation
  */
 class Visitor
 {
+    /** @var string[][] */
     public static $visitorKeys = [
         NodeKind::NAME                 => [],
         NodeKind::DOCUMENT             => ['definitions'],
@@ -122,7 +128,7 @@ class Visitor
             'variableDefinitions',
             'typeCondition',
             'directives',
-            'selectionSet'
+            'selectionSet',
         ],
 
         NodeKind::INT           => [],
@@ -158,16 +164,16 @@ class Visitor
         NodeKind::ENUM_TYPE_EXTENSION         => ['name', 'directives', 'values'],
         NodeKind::INPUT_OBJECT_TYPE_EXTENSION => ['name', 'directives', 'fields'],
 
-        NodeKind::DIRECTIVE_DEFINITION => ['description', 'name', 'arguments', 'locations']
+        NodeKind::DIRECTIVE_DEFINITION => ['description', 'name', 'arguments', 'locations'],
     ];
 
     /**
      * Visit the AST (see class description for details)
      *
      * @api
-     * @param Node $root
-     * @param array $visitor
-     * @param array $keyMap
+     * @param Node|ArrayObject|stdClass $root
+     * @param callable[]                $visitor
+     * @param mixed[]|null              $keyMap
      * @return Node|mixed
      * @throws \Exception
      */
@@ -195,7 +201,7 @@ class Visitor
             $isEdited  = $isLeaving && count($edits) !== 0;
 
             if ($isLeaving) {
-                $key = !$ancestors ? $UNDEFINED : $path[count($path) - 1];
+                $key    = ! $ancestors ? $UNDEFINED : $path[count($path) - 1];
                 $node   = $parent;
                 $parent = array_pop($ancestors);
 
@@ -249,8 +255,8 @@ class Visitor
             }
 
             $result = null;
-            if (!$node instanceof NodeList && !is_array($node)) {
-                if (!($node instanceof Node)) {
+            if (! $node instanceof NodeList && ! is_array($node)) {
+                if (! ($node instanceof Node)) {
                     throw new \Exception('Invalid AST Node: ' . json_encode($node));
                 }
 
@@ -264,7 +270,7 @@ class Visitor
                             if ($result->doBreak) {
                                 break;
                             }
-                            if (!$isLeaving && $result->doContinue) {
+                            if (! $isLeaving && $result->doContinue) {
                                 array_pop($path);
                                 continue;
                             }
@@ -276,13 +282,13 @@ class Visitor
                         }
 
                         $edits[] = [$key, $editValue];
-                        if (!$isLeaving) {
-                            if ($editValue instanceof Node) {
-                                $node = $editValue;
-                            } else {
+                        if (! $isLeaving) {
+                            if (! ($editValue instanceof Node)) {
                                 array_pop($path);
                                 continue;
                             }
+
+                            $node = $editValue;
                         }
                     }
                 }
@@ -300,7 +306,7 @@ class Visitor
                     'index'   => $index,
                     'keys'    => $keys,
                     'edits'   => $edits,
-                    'prev' => $stack
+                    'prev'    => $stack,
                 ];
                 $inArray = $node instanceof NodeList || is_array($node);
 
@@ -312,7 +318,6 @@ class Visitor
                 }
                 $parent = $node;
             }
-
         } while ($stack);
 
         if (count($edits) !== 0) {
@@ -332,6 +337,7 @@ class Visitor
     {
         $r          = new VisitorOperation();
         $r->doBreak = true;
+
         return $r;
     }
 
@@ -345,6 +351,7 @@ class Visitor
     {
         $r             = new VisitorOperation();
         $r->doContinue = true;
+
         return $r;
     }
 
@@ -358,64 +365,77 @@ class Visitor
     {
         $r             = new VisitorOperation();
         $r->removeNode = true;
+
         return $r;
     }
 
     /**
-     * @param $visitors
-     * @return array
+     * @param callable[][] $visitors
+     * @return callable[][]
      */
-    static function visitInParallel($visitors)
+    public static function visitInParallel($visitors)
     {
         $visitorsCount = count($visitors);
         $skipping      = new \SplFixedArray($visitorsCount);
 
         return [
-            'enter' => function ($node) use ($visitors, $skipping, $visitorsCount) {
+            'enter' => function (Node $node) use ($visitors, $skipping, $visitorsCount) {
                 for ($i = 0; $i < $visitorsCount; $i++) {
-                    if (empty($skipping[$i])) {
-                        $fn = self::getVisitFn($visitors[$i], $node->kind, /* isLeaving */ false);
+                    if (! empty($skipping[$i])) {
+                        continue;
+                    }
+
+                    $fn = self::getVisitFn(
+                        $visitors[$i],
+                        $node->kind, /* isLeaving */
+                        false
+                    );
+
+                    if (! $fn) {
+                        continue;
+                    }
 
-                        if ($fn) {
                     $result = call_user_func_array($fn, func_get_args());
 
                     if ($result instanceof VisitorOperation) {
                         if ($result->doContinue) {
                             $skipping[$i] = $node;
-                                } else if ($result->doBreak) {
+                        } elseif ($result->doBreak) {
                             $skipping[$i] = $result;
-                                } else if ($result->removeNode) {
+                        } elseif ($result->removeNode) {
                             return $result;
                         }
-                            } else if ($result !== null) {
+                    } elseif ($result !== null) {
                         return $result;
                     }
                 }
-                    }
-                }
             },
-            'leave' => function ($node) use ($visitors, $skipping, $visitorsCount) {
+            'leave' => function (Node $node) use ($visitors, $skipping, $visitorsCount) {
                 for ($i = 0; $i < $visitorsCount; $i++) {
                     if (empty($skipping[$i])) {
-                        $fn = self::getVisitFn($visitors[$i], $node->kind, /* isLeaving */ true);
+                        $fn = self::getVisitFn(
+                            $visitors[$i],
+                            $node->kind, /* isLeaving */
+                            true
+                        );
 
                         if ($fn) {
                             $result = call_user_func_array($fn, func_get_args());
                             if ($result instanceof VisitorOperation) {
                                 if ($result->doBreak) {
                                     $skipping[$i] = $result;
-                                } else if ($result->removeNode) {
+                                } elseif ($result->removeNode) {
                                     return $result;
                                 }
-                            } else if ($result !== null) {
+                            } elseif ($result !== null) {
                                 return $result;
                             }
                         }
-                    } else if ($skipping[$i] === $node) {
+                    } elseif ($skipping[$i] === $node) {
                         $skipping[$i] = null;
                     }
                 }
-            }
+            },
         ];
     }
 
@@ -423,10 +443,10 @@ class Visitor
      * Creates a new visitor instance which maintains a provided TypeInfo instance
      * along with visiting visitor.
      */
-    static function visitWithTypeInfo(TypeInfo $typeInfo, $visitor)
+    public static function visitWithTypeInfo(TypeInfo $typeInfo, $visitor)
     {
         return [
-            'enter' => function ($node) use ($typeInfo, $visitor) {
+            'enter' => function (Node $node) use ($typeInfo, $visitor) {
                 $typeInfo->enter($node);
                 $fn = self::getVisitFn($visitor, $node->kind, false);
 
@@ -438,52 +458,58 @@ class Visitor
                             $typeInfo->enter($result);
                         }
                     }
+
                     return $result;
                 }
+
                 return null;
             },
-            'leave' => function ($node) use ($typeInfo, $visitor) {
+            'leave' => function (Node $node) use ($typeInfo, $visitor) {
                 $fn     = self::getVisitFn($visitor, $node->kind, true);
                 $result = $fn ? call_user_func_array($fn, func_get_args()) : null;
                 $typeInfo->leave($node);
+
                 return $result;
-            }
+            },
         ];
     }
 
     /**
-     * @param $visitor
-     * @param $kind
-     * @param $isLeaving
-     * @return null
+     * @param callable[]|null $visitor
+     * @param string          $kind
+     * @param bool            $isLeaving
+     * @return callable|null
      */
     public static function getVisitFn($visitor, $kind, $isLeaving)
     {
-        if (!$visitor) {
+        if ($visitor === null) {
             return null;
         }
-        $kindVisitor = isset($visitor[$kind]) ? $visitor[$kind] : null;
 
-        if (!$isLeaving && is_callable($kindVisitor)) {
+        $kindVisitor = $visitor[$kind] ?? null;
+
+        if (! $isLeaving && is_callable($kindVisitor)) {
             // { Kind() {} }
             return $kindVisitor;
         }
 
         if (is_array($kindVisitor)) {
             if ($isLeaving) {
-                $kindSpecificVisitor = isset($kindVisitor['leave']) ? $kindVisitor['leave'] : null;
+                $kindSpecificVisitor = $kindVisitor['leave'] ?? null;
             } else {
-                $kindSpecificVisitor = isset($kindVisitor['enter']) ? $kindVisitor['enter'] : null;
+                $kindSpecificVisitor = $kindVisitor['enter'] ?? null;
             }
 
             if ($kindSpecificVisitor && is_callable($kindSpecificVisitor)) {
                 // { Kind: { enter() {}, leave() {} } }
                 return $kindSpecificVisitor;
             }
+
             return null;
         }
 
         $visitor += ['leave' => null, 'enter' => null];
+
         $specificVisitor = $isLeaving ? $visitor['leave'] : $visitor['enter'];
 
         if ($specificVisitor) {
@@ -491,13 +517,14 @@ class Visitor
                 // { enter() {}, leave() {} }
                 return $specificVisitor;
             }
-            $specificKindVisitor = isset($specificVisitor[$kind]) ? $specificVisitor[$kind] : null;
+            $specificKindVisitor = $specificVisitor[$kind] ?? null;
 
             if (is_callable($specificKindVisitor)) {
                 // { enter: { Kind() {} }, leave: { Kind() {} } }
                 return $specificKindVisitor;
             }
         }
+
         return null;
     }
 }

src/Language/VisitorOperation.php

@@ -0,0 +1,17 @@
+<?php
+
+declare(strict_types=1);
+
+namespace GraphQL\Language;
+
+class VisitorOperation
+{
+    /** @var bool */
+    public $doBreak;
+
+    /** @var bool */
+    public $doContinue;
+
+    /** @var bool */
+    public $removeNode;
+}

src/Utils/AST.php

@@ -1,4 +1,7 @@
 <?php
+
+declare(strict_types=1);
+
 namespace GraphQL\Utils;
 
 use GraphQL\Error\Error;
@@ -33,6 +36,22 @@ use GraphQL\Type\Definition\NonNull;
 use GraphQL\Type\Definition\ScalarType;
 use GraphQL\Type\Definition\Type;
 use GraphQL\Type\Schema;
+use function array_combine;
+use function array_key_exists;
+use function array_map;
+use function count;
+use function floatval;
+use function intval;
+use function is_array;
+use function is_bool;
+use function is_float;
+use function is_int;
+use function is_object;
+use function is_string;
+use function iterator_to_array;
+use function json_encode;
+use function property_exists;
+use function substr;
 
 /**
  * Various utilities dealing with AST
@@ -61,16 +80,16 @@ class AST
      * This is a reverse operation for AST::toArray($node)
      *
      * @api
-     * @param array $node
+     * @param mixed[] $node
      * @return Node
      */
     public static function fromArray(array $node)
     {
-        if (!isset($node['kind']) || !isset(NodeKind::$classMap[$node['kind']])) {
-            throw new InvariantViolation("Unexpected node structure: " . Utils::printSafeJson($node));
+        if (! isset($node['kind']) || ! isset(NodeKind::$classMap[$node['kind']])) {
+            throw new InvariantViolation('Unexpected node structure: ' . Utils::printSafeJson($node));
         }
 
-        $kind = isset($node['kind']) ? $node['kind'] : null;
+        $kind     = $node['kind'] ?? null;
         $class    = NodeKind::$classMap[$kind];
         $instance = new $class([]);
 
@@ -78,10 +97,9 @@ class AST
             $instance->loc = Location::create($node['loc']['start'], $node['loc']['end']);
         }
 
-
         foreach ($node as $key => $value) {
-            if ('loc' === $key || 'kind' === $key) {
-                continue ;
+            if ($key === 'loc' || $key === 'kind') {
+                continue;
             }
             if (is_array($value)) {
                 if (isset($value[0]) || empty($value)) {
@@ -92,6 +110,7 @@ class AST
             }
             $instance->{$key} = $value;
         }
+
         return $instance;
     }
 
@@ -99,8 +118,7 @@ class AST
      * Convert AST node to serializable array
      *
      * @api
-     * @param Node $node
-     * @return array
+     * @return mixed[]
      */
     public static function toArray(Node $node)
     {
@@ -126,17 +144,17 @@ class AST
      * | null          | NullValue            |
      *
      * @api
-     * @param $value
-     * @param InputType $type
+     * @param Type|mixed|null $value
      * @return ObjectValueNode|ListValueNode|BooleanValueNode|IntValueNode|FloatValueNode|EnumValueNode|StringValueNode|NullValueNode
      */
-    static function astFromValue($value, InputType $type)
+    public static function astFromValue($value, InputType $type)
     {
         if ($type instanceof NonNull) {
             $astValue = self::astFromValue($value, $type->getWrappedType());
             if ($astValue instanceof NullValueNode) {
                 return null;
             }
+
             return $astValue;
         }
 
@@ -152,12 +170,16 @@ class AST
                 $valuesNodes = [];
                 foreach ($value as $item) {
                     $itemNode = self::astFromValue($item, $itemType);
-                    if ($itemNode) {
+                    if (! $itemNode) {
+                        continue;
+                    }
+
                     $valuesNodes[] = $itemNode;
                 }
-                }
+
                 return new ListValueNode(['values' => $valuesNodes]);
             }
+
             return self::astFromValue($value, $itemType);
         }
 
@@ -166,42 +188,47 @@ class AST
         if ($type instanceof InputObjectType) {
             $isArray     = is_array($value);
             $isArrayLike = $isArray || $value instanceof \ArrayAccess;
-            if ($value === null || (!$isArrayLike && !is_object($value))) {
+            if ($value === null || (! $isArrayLike && ! is_object($value))) {
                 return null;
             }
             $fields     = $type->getFields();
             $fieldNodes = [];
             foreach ($fields as $fieldName => $field) {
                 if ($isArrayLike) {
-                    $fieldValue = isset($value[$fieldName]) ? $value[$fieldName] : null;
+                    $fieldValue = $value[$fieldName] ?? null;
                 } else {
-                    $fieldValue = isset($value->{$fieldName}) ? $value->{$fieldName} : null;
+                    $fieldValue = $value->{$fieldName} ?? null;
                 }
 
                 // Have to check additionally if key exists, since we differentiate between
                 // "no key" and "value is null":
-                if (null !== $fieldValue) {
+                if ($fieldValue !== null) {
                     $fieldExists = true;
-                } else if ($isArray) {
+                } elseif ($isArray) {
                     $fieldExists = array_key_exists($fieldName, $value);
-                } else if ($isArrayLike) {
+                } elseif ($isArrayLike) {
                     /** @var \ArrayAccess $value */
                     $fieldExists = $value->offsetExists($fieldName);
                 } else {
                     $fieldExists = property_exists($value, $fieldName);
                 }
 
-                if ($fieldExists) {
+                if (! $fieldExists) {
+                    continue;
+                }
+
                 $fieldNode = self::astFromValue($fieldValue, $field->getType());
 
-                    if ($fieldNode) {
+                if (! $fieldNode) {
+                    continue;
+                }
+
                 $fieldNodes[] = new ObjectFieldNode([
                     'name'  => new NameNode(['value' => $fieldName]),
-                            'value' => $fieldNode
+                    'value' => $fieldNode,
                 ]);
             }
-                }
-            }
+
             return new ObjectValueNode(['fields' => $fieldNodes]);
         }
 
@@ -230,9 +257,12 @@ class AST
                 return new IntValueNode(['value' => $serialized]);
             }
             if (is_float($serialized)) {
+                // int cast with == used for performance reasons
+                // @codingStandardsIgnoreLine
                 if ((int) $serialized == $serialized) {
                     return new IntValueNode(['value' => $serialized]);
                 }
+
                 return new FloatValueNode(['value' => $serialized]);
             }
             if (is_string($serialized)) {
@@ -250,7 +280,7 @@ class AST
                 // Use json_encode, which uses the same string encoding as GraphQL,
                 // then remove the quotes.
                 return new StringValueNode([
-                    'value' => substr(json_encode($serialized), 1, -1)
+                    'value' => substr(json_encode($serialized), 1, -1),
                 ]);
             }
 
@@ -280,17 +310,16 @@ class AST
      * | Null Value           | null          |
      *
      * @api
-     * @param $valueNode
-     * @param InputType $type
+     * @param ValueNode|null $valueNode
      * @param mixed[]|null   $variables
-     * @return array|null|\stdClass
+     * @return mixed[]|null|\stdClass
      * @throws \Exception
      */
     public static function valueFromAST($valueNode, InputType $type, $variables = null)
     {
         $undefined = Utils::undefined();
 
-        if (!$valueNode) {
+        if ($valueNode === null) {
             // When there is no AST, then there is also no value.
             // Importantly, this is different from returning the GraphQL null value.
             return $undefined;
@@ -301,6 +330,7 @@ class AST
                 // Invalid: intentionally return no value.
                 return $undefined;
             }
+
             return self::valueFromAST($valueNode, $type->getWrappedType(), $variables);
         }
 
@@ -312,7 +342,7 @@ class AST
         if ($valueNode instanceof VariableNode) {
             $variableName = $valueNode->name->value;
 
-            if (!$variables || !array_key_exists($variableName, $variables)) {
+            if (! $variables || ! array_key_exists($variableName, $variables)) {
                 // No valid return value.
                 return $undefined;
             }
@@ -346,6 +376,7 @@ class AST
                         $coercedValues[] = $itemValue;
                     }
                 }
+
                 return $coercedValues;
             }
             $coercedValue = self::valueFromAST($valueNode, $itemType, $variables);
@@ -353,31 +384,37 @@ class AST
                 // Invalid: intentionally return no value.
                 return $undefined;
             }
+
             return [$coercedValue];
         }
 
         if ($type instanceof InputObjectType) {
-            if (!$valueNode instanceof ObjectValueNode) {
+            if (! $valueNode instanceof ObjectValueNode) {
                 // Invalid: intentionally return no value.
                 return $undefined;
             }
 
             $coercedObj = [];
             $fields     = $type->getFields();
-            $fieldNodes = Utils::keyMap($valueNode->fields, function($field) {return $field->name->value;});
+            $fieldNodes = Utils::keyMap(
+                $valueNode->fields,
+                function ($field) {
+                    return $field->name->value;
+                }
+            );
             foreach ($fields as $field) {
                 /** @var ValueNode $fieldNode */
                 $fieldName = $field->name;
-                $fieldNode = isset($fieldNodes[$fieldName]) ? $fieldNodes[$fieldName] : null;
+                $fieldNode = $fieldNodes[$fieldName] ?? null;
 
-                if (!$fieldNode || self::isMissingVariable($fieldNode->value, $variables)) {
+                if (! $fieldNode || self::isMissingVariable($fieldNode->value, $variables)) {
                     if ($field->defaultValueExists()) {
                         $coercedObj[$fieldName] = $field->defaultValue;
-                    } else if ($field->getType() instanceof NonNull) {
+                    } elseif ($field->getType() instanceof NonNull) {
                         // Invalid: intentionally return no value.
                         return $undefined;
                     }
-                    continue ;
+                    continue;
                 }
 
                 $fieldValue = self::valueFromAST($fieldNode ? $fieldNode->value : null, $field->getType(), $variables);
@@ -388,15 +425,16 @@ class AST
                 }
                 $coercedObj[$fieldName] = $fieldValue;
             }
+
             return $coercedObj;
         }
 
         if ($type instanceof EnumType) {
-            if (!$valueNode instanceof EnumValueNode) {
+            if (! $valueNode instanceof EnumValueNode) {
                 return $undefined;
             }
             $enumValue = $type->getValue($valueNode->value);
-            if (!$enumValue) {
+            if (! $enumValue) {
                 return $undefined;
             }
 
@@ -437,11 +475,12 @@ class AST
      *
      * @api
      * @param Node         $valueNode
-     * @param array|null $variables
+     * @param mixed[]|null $variables
      * @return mixed
      * @throws \Exception
      */
-    public static function valueFromASTUntyped($valueNode, array $variables = null) {
+    public static function valueFromASTUntyped($valueNode, ?array $variables = null)
+    {
         switch (true) {
             case $valueNode instanceof NullValueNode:
                 return null;
@@ -455,7 +494,7 @@ class AST
                 return $valueNode->value;
             case $valueNode instanceof ListValueNode:
                 return array_map(
-                    function($node) use ($variables) {
+                    function ($node) use ($variables) {
                         return self::valueFromASTUntyped($node, $variables);
                     },
                     iterator_to_array($valueNode->values)
@@ -463,16 +502,21 @@ class AST
             case $valueNode instanceof ObjectValueNode:
                 return array_combine(
                     array_map(
-                    function($field) { return $field->name->value; },
+                        function ($field) {
+                            return $field->name->value;
+                        },
                         iterator_to_array($valueNode->fields)
                     ),
                     array_map(
-                    function($field) use ($variables) { return self::valueFromASTUntyped($field->value, $variables); },
+                        function ($field) use ($variables) {
+                            return self::valueFromASTUntyped($field->value, $variables);
+                        },
                         iterator_to_array($valueNode->fields)
                     )
                 );
             case $valueNode instanceof VariableNode:
                 $variableName = $valueNode->name->value;
+
                 return ($variables && isset($variables[$variableName]))
                     ? $variables[$variableName]
                     : null;
@@ -485,7 +529,6 @@ class AST
      * Returns type definition for given AST Type node
      *
      * @api
-     * @param Schema $schema
      * @param NamedTypeNode|ListTypeNode|NonNullTypeNode $inputTypeNode
      * @return Type|null
      * @throws \Exception
@@ -494,10 +537,12 @@ class AST
     {
         if ($inputTypeNode instanceof ListTypeNode) {
             $innerType = self::typeFromAST($schema, $inputTypeNode->type);
+
             return $innerType ? new ListOfType($innerType) : null;
         }
         if ($inputTypeNode instanceof NonNullTypeNode) {
             $innerType = self::typeFromAST($schema, $inputTypeNode->type);
+
             return $innerType ? new NonNull($innerType) : null;
         }
         if ($inputTypeNode instanceof NamedTypeNode) {
@@ -510,21 +555,20 @@ class AST
     /**
      * Returns true if the provided valueNode is a variable which is not defined
      * in the set of variables.
-     * @param $valueNode
-     * @param $variables
+     * @param ValueNode $valueNode
+     * @param mixed[]   $variables
      * @return bool
      */
     private static function isMissingVariable($valueNode, $variables)
     {
         return $valueNode instanceof VariableNode &&
-        (!$variables || !array_key_exists($valueNode->name->value, $variables));
+            (count($variables) === 0 || ! array_key_exists($valueNode->name->value, $variables));
     }
 
     /**
      * Returns operation type ("query", "mutation" or "subscription") given a document and operation name
      *
      * @api
-     * @param DocumentNode $document
      * @param string $operationName
      * @return bool
      */
@@ -532,13 +576,16 @@ class AST
     {
         if ($document->definitions) {
             foreach ($document->definitions as $def) {
-                if ($def instanceof OperationDefinitionNode) {
-                    if (!$operationName || (isset($def->name->value) && $def->name->value === $operationName)) {
+                if (! ($def instanceof OperationDefinitionNode)) {
+                    continue;
+                }
+
+                if (! $operationName || (isset($def->name->value) && $def->name->value === $operationName)) {
                     return $def->operation;
                 }
             }
         }
-        }
+
         return false;
     }
 }

src/Utils/ASTDefinitionBuilder.php

@@ -1,16 +1,21 @@
 <?php
+
+declare(strict_types=1);
+
 namespace GraphQL\Utils;
 
 use GraphQL\Error\Error;
 use GraphQL\Executor\Values;
 use GraphQL\Language\AST\DirectiveDefinitionNode;
 use GraphQL\Language\AST\EnumTypeDefinitionNode;
+use GraphQL\Language\AST\EnumTypeExtensionNode;
 use GraphQL\Language\AST\EnumValueDefinitionNode;
 use GraphQL\Language\AST\FieldDefinitionNode;
 use GraphQL\Language\AST\InputObjectTypeDefinitionNode;
 use GraphQL\Language\AST\InterfaceTypeDefinitionNode;
 use GraphQL\Language\AST\ListTypeNode;
 use GraphQL\Language\AST\NamedTypeNode;
+use GraphQL\Language\AST\Node;
 use GraphQL\Language\AST\NodeKind;
 use GraphQL\Language\AST\NonNullTypeNode;
 use GraphQL\Language\AST\ObjectTypeDefinitionNode;
@@ -19,47 +24,49 @@ use GraphQL\Language\AST\TypeNode;
 use GraphQL\Language\AST\UnionTypeDefinitionNode;
 use GraphQL\Language\Token;
 use GraphQL\Type\Definition\CustomScalarType;
+use GraphQL\Type\Definition\Directive;
 use GraphQL\Type\Definition\EnumType;
+use GraphQL\Type\Definition\FieldArgument;
 use GraphQL\Type\Definition\InputObjectType;
 use GraphQL\Type\Definition\InputType;
-use GraphQL\Type\Definition\Directive;
 use GraphQL\Type\Definition\InterfaceType;
-use GraphQL\Type\Definition\FieldArgument;
 use GraphQL\Type\Definition\NonNull;
 use GraphQL\Type\Definition\ObjectType;
 use GraphQL\Type\Definition\Type;
 use GraphQL\Type\Definition\UnionType;
+use function array_reverse;
+use function implode;
+use function is_array;
+use function is_string;
+use function sprintf;
 
 class ASTDefinitionBuilder
 {
-
-    /**
-     * @var array
-     */
+    /** @var Node[] */
     private $typeDefintionsMap;
 
-    /**
-     * @var callable
-     */
+    /** @var callable */
     private $typeConfigDecorator;
 
-    /**
-     * @var array
-     */
+    /** @var bool[] */
     private $options;
 
-    /**
-     * @var callable
-     */
+    /** @var callable */
     private $resolveType;
 
-    /**
-     * @var array
-     */
+    /** @var Type[] */
     private $cache;
 
-    public function __construct(array $typeDefintionsMap, $options, callable $resolveType, callable $typeConfigDecorator = null)
-    {
+    /**
+     * @param Node[] $typeDefintionsMap
+     * @param bool[] $options
+     */
+    public function __construct(
+        array $typeDefintionsMap,
+        $options,
+        callable $resolveType,
+        ?callable $typeConfigDecorator = null
+    ) {
         $this->typeDefintionsMap   = $typeDefintionsMap;
         $this->typeConfigDecorator = $typeConfigDecorator;
         $this->options             = $options;
@@ -69,19 +76,20 @@ class ASTDefinitionBuilder
     }
 
     /**
-     * @param Type $innerType
      * @param TypeNode|ListTypeNode|NonNullTypeNode $inputTypeNode
      * @return Type
      */
     private function buildWrappedType(Type $innerType, TypeNode $inputTypeNode)
     {
-        if ($inputTypeNode->kind == NodeKind::LIST_TYPE) {
+        if ($inputTypeNode->kind === NodeKind::LIST_TYPE) {
             return Type::listOf($this->buildWrappedType($innerType, $inputTypeNode->type));
         }
-        if ($inputTypeNode->kind == NodeKind::NON_NULL_TYPE) {
+        if ($inputTypeNode->kind === NodeKind::NON_NULL_TYPE) {
             $wrappedType = $this->buildWrappedType($innerType, $inputTypeNode->type);
+
             return Type::nonNull(NonNull::assertNullableType($wrappedType));
         }
+
         return $innerType;
     }
 
@@ -95,6 +103,7 @@ class ASTDefinitionBuilder
         while ($namedType->kind === NodeKind::LIST_TYPE || $namedType->kind === NodeKind::NON_NULL_TYPE) {
             $namedType = $namedType->type;
         }
+
         return $namedType;
     }
 
@@ -104,28 +113,19 @@ class ASTDefinitionBuilder
      * @return Type
      * @throws Error
      */
-    private function internalBuildType($typeName, $typeNode = null) {
-        if (!isset($this->cache[$typeName])) {
+    private function internalBuildType($typeName, $typeNode = null)
+    {
+        if (! isset($this->cache[$typeName])) {
             if (isset($this->typeDefintionsMap[$typeName])) {
                 $type = $this->makeSchemaDef($this->typeDefintionsMap[$typeName]);
                 if ($this->typeConfigDecorator) {
                     $fn = $this->typeConfigDecorator;
                     try {
                         $config = $fn($type->config, $this->typeDefintionsMap[$typeName], $this->typeDefintionsMap);
-                    } catch (\Exception $e) {
-                        throw new Error(
-                            "Type config decorator passed to " . (static::class) . " threw an error " .
-                            "when building $typeName type: {$e->getMessage()}",
-                            null,
-                            null,
-                            null,
-                            null,
-                            $e
-                        );
                     } catch (\Throwable $e) {
                         throw new Error(
-                            "Type config decorator passed to " . (static::class) . " threw an error " .
-                            "when building $typeName type: {$e->getMessage()}",
+                            sprintf('Type config decorator passed to %s threw an error ', static::class) .
+                            sprintf('when building %s type: %s', $typeName, $e->getMessage()),
                             null,
                             null,
                             null,
@@ -133,10 +133,13 @@ class ASTDefinitionBuilder
                             $e
                         );
                     }
-                    if (!is_array($config) || isset($config[0])) {
+                    if (! is_array($config) || isset($config[0])) {
                         throw new Error(
-                            "Type config decorator passed to " . (static::class) . " is expected to return an array, but got " .
+                            sprintf(
+                                'Type config decorator passed to %s is expected to return an array, but got %s',
+                                static::class,
                                 Utils::getVariableType($config)
+                            )
                         );
                     }
                     $type = $this->makeSchemaDefFromConfig($this->typeDefintionsMap[$typeName], $config);
@@ -166,13 +169,13 @@ class ASTDefinitionBuilder
     }
 
     /**
-     * @param TypeNode $typeNode
      * @return Type|InputType
      * @throws Error
      */
     private function internalBuildWrappedType(TypeNode $typeNode)
     {
         $typeDef = $this->buildType($this->getNamedTypeNode($typeNode));
+
         return $this->buildWrappedType($typeDef, $typeNode);
     }
 
@@ -181,9 +184,12 @@ class ASTDefinitionBuilder
         return new Directive([
             'name'        => $directiveNode->name->value,
             'description' => $this->getDescription($directiveNode),
-            'locations' => Utils::map($directiveNode->locations, function ($node) {
+            'locations'   => Utils::map(
+                $directiveNode->locations,
+                function ($node) {
                     return $node->value;
-            }),
+                }
+            ),
             'args'        => $directiveNode->arguments ? FieldArgument::createMap($this->makeInputValues($directiveNode->arguments)) : null,
             'astNode'     => $directiveNode,
         ]);
@@ -203,9 +209,14 @@ class ASTDefinitionBuilder
         ];
     }
 
+    /**
+     * @param ObjectTypeDefinitionNode|InterfaceTypeDefinitionNode|EnumTypeDefinitionNode|ScalarTypeDefinitionNode|InputObjectTypeDefinitionNode|UnionTypeDefinitionNode $def
+     * @return CustomScalarType|EnumType|InputObjectType|InterfaceType|ObjectType|UnionType
+     * @throws Error
+     */
     private function makeSchemaDef($def)
     {
-        if (!$def) {
+        if (! $def) {
             throw new Error('def must be defined.');
         }
         switch ($def->kind) {
@@ -222,13 +233,19 @@ class ASTDefinitionBuilder
             case NodeKind::INPUT_OBJECT_TYPE_DEFINITION:
                 return $this->makeInputObjectDef($def);
             default:
-                throw new Error("Type kind of {$def->kind} not supported.");
+                throw new Error(sprintf('Type kind of %s not supported.', $def->kind));
         }
     }
 
+    /**
+     * @param ObjectTypeDefinitionNode|InterfaceTypeDefinitionNode|EnumTypeExtensionNode|ScalarTypeDefinitionNode|InputObjectTypeDefinitionNode $def
+     * @param mixed[]                                                                                                                           $config
+     * @return CustomScalarType|EnumType|InputObjectType|InterfaceType|ObjectType|UnionType
+     * @throws Error
+     */
     private function makeSchemaDefFromConfig($def, array $config)
     {
-        if (!$def) {
+        if (! $def) {
             throw new Error('def must be defined.');
         }
         switch ($def->kind) {
@@ -245,13 +262,14 @@ class ASTDefinitionBuilder
             case NodeKind::INPUT_OBJECT_TYPE_DEFINITION:
                 return new InputObjectType($config);
             default:
-                throw new Error("Type kind of {$def->kind} not supported.");
+                throw new Error(sprintf('Type kind of %s not supported.', $def->kind));
         }
     }
 
     private function makeTypeDef(ObjectTypeDefinitionNode $def)
     {
         $typeName = $def->name->value;
+
         return new ObjectType([
             'name'        => $typeName,
             'description' => $this->getDescription($def),
@@ -261,7 +279,7 @@ class ASTDefinitionBuilder
             'interfaces'  => function () use ($def) {
                 return $this->makeImplementedInterfaces($def);
             },
-            'astNode' => $def
+            'astNode'     => $def,
         ]);
     }
 
@@ -286,10 +304,14 @@ class ASTDefinitionBuilder
             // Note: While this could make early assertions to get the correctly
             // typed values, that would throw immediately while type system
             // validation with validateSchema() will produce more actionable results.
-            return Utils::map($def->interfaces, function ($iface) {
+            return Utils::map(
+                $def->interfaces,
+                function ($iface) {
                     return $this->buildType($iface);
-            });
                 }
+            );
+        }
+
         return null;
     }
 
@@ -309,11 +331,12 @@ class ASTDefinitionBuilder
                     'name'        => $value->name->value,
                     'type'        => $type,
                     'description' => $this->getDescription($value),
-                    'astNode' => $value
+                    'astNode'     => $value,
                 ];
                 if (isset($value->defaultValue)) {
                     $config['defaultValue'] = AST::valueFromAST($value->defaultValue, $type);
                 }
+
                 return $config;
             }
         );
@@ -322,13 +345,14 @@ class ASTDefinitionBuilder
     private function makeInterfaceDef(InterfaceTypeDefinitionNode $def)
     {
         $typeName = $def->name->value;
+
         return new InterfaceType([
             'name'        => $typeName,
             'description' => $this->getDescription($def),
             'fields'      => function () use ($def) {
                 return $this->makeFieldDefMap($def);
             },
-            'astNode' => $def
+            'astNode'     => $def,
         ]);
     }
 
@@ -347,7 +371,7 @@ class ASTDefinitionBuilder
                         return [
                             'description'       => $this->getDescription($enumValue),
                             'deprecationReason' => $this->getDeprecationReason($enumValue),
-                            'astNode' => $enumValue
+                            'astNode'           => $enumValue,
                         ];
                     }
                 )
@@ -365,9 +389,12 @@ class ASTDefinitionBuilder
             // values below, that would throw immediately while type system
             // validation with validateSchema() will produce more actionable results.
             'types'       => $def->types
-                ? Utils::map($def->types, function ($typeNode) {
+                ? Utils::map(
+                    $def->types,
+                    function ($typeNode) {
                         return $this->buildType($typeNode);
-                }):
+                    }
+                ) :
                 [],
             'astNode'     => $def,
         ]);
@@ -379,7 +406,7 @@ class ASTDefinitionBuilder
             'name'        => $def->name->value,
             'description' => $this->getDescription($def),
             'astNode'     => $def,
-            'serialize' => function($value) {
+            'serialize'   => function ($value) {
                 return $value;
             },
         ]);
@@ -409,7 +436,8 @@ class ASTDefinitionBuilder
     private function getDeprecationReason($node)
     {
         $deprecated = Values::getDirectiveValues(Directive::deprecatedDirective(), $node);
-        return isset($deprecated['reason']) ? $deprecated['reason'] : null;
+
+        return $deprecated['reason'] ?? null;
     }
 
     /**
@@ -433,13 +461,12 @@ class ASTDefinitionBuilder
     private function getLeadingCommentBlock($node)
     {
         $loc = $node->loc;
-        if (!$loc || !$loc->startToken) {
+        if (! $loc || ! $loc->startToken) {
             return null;
         }
         $comments = [];
         $token    = $loc->startToken->prev;
-        while (
-            $token &&
+        while ($token &&
             $token->kind === Token::COMMENT &&
             $token->next && $token->prev &&
             $token->line + 1 === $token->next->line &&

src/Validator/Rules/KnownArgumentNames.php

@@ -6,7 +6,9 @@ namespace GraphQL\Validator\Rules;
 
 use GraphQL\Error\Error;
 use GraphQL\Language\AST\ArgumentNode;
+use GraphQL\Language\AST\Node;
 use GraphQL\Language\AST\NodeKind;
+use GraphQL\Language\AST\NodeList;
 use GraphQL\Utils\Utils;
 use GraphQL\Validator\ValidationContext;
 use function array_map;
@@ -25,6 +27,7 @@ class KnownArgumentNames extends ValidationRule
     {
         return [
             NodeKind::ARGUMENT => function (ArgumentNode $node, $key, $parent, $path, $ancestors) use ($context) {
+                /** @var NodeList|Node[] $ancestors */
                 $argDef = $context->getArgument();
                 if ($argDef !== null) {
                     return;

src/Validator/Rules/LoneAnonymousOperation.php

@@ -6,6 +6,7 @@ namespace GraphQL\Validator\Rules;
 
 use GraphQL\Error\Error;
 use GraphQL\Language\AST\DocumentNode;
+use GraphQL\Language\AST\Node;
 use GraphQL\Language\AST\NodeKind;
 use GraphQL\Language\AST\OperationDefinitionNode;
 use GraphQL\Utils\Utils;
@@ -28,7 +29,7 @@ class LoneAnonymousOperation extends ValidationRule
             NodeKind::DOCUMENT             => function (DocumentNode $node) use (&$operationCount) {
                 $tmp = Utils::filter(
                     $node->definitions,
-                    function ($definition) {
+                    function (Node $definition) {
                         return $definition->kind === NodeKind::OPERATION_DEFINITION;
                     }
                 );

src/Validator/Rules/QuerySecurityRule.php

@@ -111,7 +111,7 @@ abstract class QuerySecurityRule extends ValidationRule
         $_astAndDefs           = $astAndDefs ?: new \ArrayObject();
 
         foreach ($selectionSet->selections as $selection) {
-            switch ($selection->getKind()) {
+            switch ($selection->kind) {
                 case NodeKind::FIELD:
                     /** @var FieldNode $selection */
                     $fieldName = $selection->name->value;

src/Validator/ValidationContext.php

@@ -11,6 +11,7 @@ use GraphQL\Language\AST\FragmentSpreadNode;
 use GraphQL\Language\AST\HasSelectionSet;
 use GraphQL\Language\AST\NodeKind;
 use GraphQL\Language\AST\OperationDefinitionNode;
+use GraphQL\Language\AST\SelectionSetNode;
 use GraphQL\Language\AST\VariableNode;
 use GraphQL\Language\Visitor;
 use GraphQL\Type\Definition\FieldDefinition;
@@ -191,6 +192,7 @@ class ValidationContext
         $spreads = $this->fragmentSpreads[$node] ?? null;
         if (! $spreads) {
             $spreads     = [];
+            /** @var SelectionSetNode[] $setsToVisit */
             $setsToVisit = [$node->selectionSet];
             while (! empty($setsToVisit)) {
                 $set = array_pop($setsToVisit);

tests/Language/VisitorTest.php

@@ -1,4 +1,7 @@
 <?php
+
+declare(strict_types=1);
+
 namespace GraphQL\Tests\Language;
 
 use GraphQL\Language\AST\DocumentNode;
@@ -15,6 +18,14 @@ use GraphQL\Language\Visitor;
 use GraphQL\Tests\Validator\ValidatorTestCase;
 use GraphQL\Type\Definition\Type;
 use GraphQL\Utils\TypeInfo;
+use function array_keys;
+use function array_slice;
+use function count;
+use function file_get_contents;
+use function func_get_args;
+use function gettype;
+use function is_array;
+use function iterator_to_array;
 
 class VisitorTest extends ValidatorTestCase
 {
@@ -34,14 +45,14 @@ class VisitorTest extends ValidatorTestCase
         /** @var Node $node */
         list($node, $key, $parent, $path, $ancestors) = $args;
 
-        $parentArray = $parent && !is_array($parent) ? ($parent instanceof NodeList ? iterator_to_array($parent) : $parent->toArray()) : $parent;
+        $parentArray = $parent && ! is_array($parent) ? ($parent instanceof NodeList ? iterator_to_array($parent) : $parent->toArray()) : $parent;
 
         $this->assertInstanceOf(Node::class, $node);
         $this->assertContains($node->kind, array_keys(NodeKind::$classMap));
 
         $isRoot = $key === null;
         if ($isRoot) {
-            if (!$isEdited) {
+            if (! $isEdited) {
                 $this->assertEquals($ast, $node);
             }
             $this->assertEquals(null, $parent);
@@ -60,7 +71,10 @@ class VisitorTest extends ValidatorTestCase
         $this->assertInternalType('array', $ancestors);
         $this->assertCount(count($path) - 1, $ancestors);
 
-        if (!$isEdited) {
+        if ($isEdited) {
+            return;
+        }
+
         $this->assertEquals($node, $parentArray[$key]);
         $this->assertEquals($node, $this->getNodeByPath($ast, $path));
         $ancestorsLength = count($ancestors);
@@ -69,7 +83,6 @@ class VisitorTest extends ValidatorTestCase
             $this->assertEquals($ancestors[$i], $this->getNodeByPath($ast, $ancestorPath));
         }
     }
-    }
 
     public function testValidatesPathArgument()
     {
@@ -104,9 +117,6 @@ class VisitorTest extends ValidatorTestCase
         $this->assertEquals($expected, $visited);
     }
 
-    /**
-     * @it allows editing a node both on enter and on leave
-     */
     public function testAllowsEditingNodeOnEnterAndOnLeave()
     {
         $ast = Parser::parse('{ a, b, c { a, b, c } }', [ 'noLocation' => true ]);
@@ -114,25 +124,25 @@ class VisitorTest extends ValidatorTestCase
         $selectionSet = null;
         $editedAst    = Visitor::visit($ast, [
             NodeKind::OPERATION_DEFINITION => [
-                'enter' => function(OperationDefinitionNode $node) use (&$selectionSet, $ast) {
+                'enter' => function (OperationDefinitionNode $node) use (&$selectionSet, $ast) {
                     $this->checkVisitorFnArgs($ast, func_get_args());
                     $selectionSet = $node->selectionSet;
 
                     $newNode               = clone $node;
                     $newNode->selectionSet = new SelectionSetNode([
-                        'selections' => []
+                        'selections' => [],
                     ]);
                     $newNode->didEnter     = true;
                     return $newNode;
                 },
-                'leave' => function(OperationDefinitionNode $node) use (&$selectionSet, $ast) {
+                'leave' => function (OperationDefinitionNode $node) use (&$selectionSet, $ast) {
                     $this->checkVisitorFnArgs($ast, func_get_args(), true);
                     $newNode               = clone $node;
                     $newNode->selectionSet = $selectionSet;
                     $newNode->didLeave     = true;
                     return $newNode;
-                }
-            ]
+                },
+            ],
         ]);
 
         $this->assertNotEquals($ast, $editedAst);
@@ -144,9 +154,6 @@ class VisitorTest extends ValidatorTestCase
         $this->assertEquals($expected, $editedAst);
     }
 
-    /**
-     * @it allows editing the root node on enter and on leave
-     */
     public function testAllowsEditingRootNodeOnEnterAndLeave()
     {
         $ast         = Parser::parse('{ a, b, c { a, b, c } }', [ 'noLocation' => true ]);
@@ -161,13 +168,12 @@ class VisitorTest extends ValidatorTestCase
                     $tmp->didEnter    = true;
                     return $tmp;
                 },
-                'leave' => function(DocumentNode $node) use ($definitions, $ast) {
+                'leave' => function (DocumentNode $node) use ($definitions, $ast) {
                     $this->checkVisitorFnArgs($ast, func_get_args(), true);
-                    $tmp = clone $node;
                     $node->definitions = $definitions;
                     $node->didLeave    = true;
-                }
-            ]
+                },
+            ],
         ]);
 
         $this->assertNotEquals($ast, $editedAst);
@@ -179,19 +185,16 @@ class VisitorTest extends ValidatorTestCase
         $this->assertEquals($tmp, $editedAst);
     }
 
-    /**
-     * @it allows for editing on enter
-     */
     public function testAllowsForEditingOnEnter()
     {
         $ast       = Parser::parse('{ a, b, c { a, b, c } }', ['noLocation' => true]);
         $editedAst = Visitor::visit($ast, [
-            'enter' => function($node) use ($ast) {
+            'enter' => function ($node) use ($ast) {
                 $this->checkVisitorFnArgs($ast, func_get_args());
                 if ($node instanceof FieldNode && $node->name->value === 'b') {
                     return Visitor::removeNode();
                 }
-            }
+            },
         ]);
 
         $this->assertEquals(
@@ -204,19 +207,16 @@ class VisitorTest extends ValidatorTestCase
         );
     }
 
-    /**
-     * @it allows for editing on leave
-     */
     public function testAllowsForEditingOnLeave()
     {
         $ast       = Parser::parse('{ a, b, c { a, b, c } }', ['noLocation' => true]);
         $editedAst = Visitor::visit($ast, [
-            'leave' => function($node) use ($ast) {
+            'leave' => function ($node) use ($ast) {
                 $this->checkVisitorFnArgs($ast, func_get_args(), true);
                 if ($node instanceof FieldNode && $node->name->value === 'b') {
                     return Visitor::removeNode();
                 }
-            }
+            },
         ]);
 
         $this->assertEquals(
@@ -230,60 +230,54 @@ class VisitorTest extends ValidatorTestCase
         );
     }
 
-    /**
-     * @it visits edited node
-     */
     public function testVisitsEditedNode()
     {
-        $addedField = new FieldNode(array(
-            'name' => new NameNode(array(
-                'value' => '__typename'
-            ))
-        ));
+        $addedField = new FieldNode([
+            'name' => new NameNode(['value' => '__typename']),
+        ]);
 
         $didVisitAddedField = false;
 
         $ast = Parser::parse('{ a { x } }', ['noLocation' => true]);
 
         Visitor::visit($ast, [
-            'enter' => function($node) use ($addedField, &$didVisitAddedField, $ast) {
+            'enter' => function ($node) use ($addedField, &$didVisitAddedField, $ast) {
                 $this->checkVisitorFnArgs($ast, func_get_args(), true);
                 if ($node instanceof FieldNode && $node->name->value === 'a') {
                     return new FieldNode([
-                        'selectionSet' => new SelectionSetNode(array(
-                            'selections' => NodeList::create([$addedField])->merge($node->selectionSet->selections)
-                        ))
+                        'selectionSet' => new SelectionSetNode([
+                            'selections' => NodeList::create([$addedField])->merge($node->selectionSet->selections),
+                        ]),
                     ]);
                 }
-                if ($node === $addedField) {
+                if ($node !== $addedField) {
+                    return;
+                }
+
                 $didVisitAddedField = true;
-                }
-            }
+            },
         ]);
 
         $this->assertTrue($didVisitAddedField);
     }
 
-    /**
-     * @it allows skipping a sub-tree
-     */
     public function testAllowsSkippingASubTree()
     {
         $visited = [];
         $ast     = Parser::parse('{ a, b { x }, c }', ['noLocation' => true]);
 
         Visitor::visit($ast, [
-            'enter' => function(Node $node) use (&$visited, $ast) {
+            'enter' => function (Node $node) use (&$visited, $ast) {
                 $this->checkVisitorFnArgs($ast, func_get_args());
-                $visited[] = ['enter', $node->kind, isset($node->value) ? $node->value : null];
+                $visited[] = ['enter', $node->kind, $node->value ?? null];
                 if ($node instanceof FieldNode && $node->name->value === 'b') {
                     return Visitor::skipNode();
                 }
             },
             'leave' => function (Node $node) use (&$visited, $ast) {
                 $this->checkVisitorFnArgs($ast, func_get_args());
-                $visited[] = ['leave', $node->kind, isset($node->value) ? $node->value : null];
-            }
+                $visited[] = ['leave', $node->kind, $node->value ?? null];
+            },
         ]);
 
         $expected = [
@@ -301,32 +295,29 @@ class VisitorTest extends ValidatorTestCase
             [ 'leave', 'Field', null ],
             [ 'leave', 'SelectionSet', null ],
             [ 'leave', 'OperationDefinition', null ],
-            [ 'leave', 'Document', null ]
+            [ 'leave', 'Document', null ],
         ];
 
         $this->assertEquals($expected, $visited);
     }
 
-    /**
-     * @it allows early exit while visiting
-     */
     public function testAllowsEarlyExitWhileVisiting()
     {
         $visited = [];
         $ast     = Parser::parse('{ a, b { x }, c }', ['noLocation' => true]);
 
         Visitor::visit($ast, [
-            'enter' => function(Node $node) use (&$visited, $ast) {
+            'enter' => function (Node $node) use (&$visited, $ast) {
                 $this->checkVisitorFnArgs($ast, func_get_args());
-                $visited[] = ['enter', $node->kind, isset($node->value) ? $node->value : null];
+                $visited[] = ['enter', $node->kind, $node->value ?? null];
                 if ($node instanceof NameNode && $node->value === 'x') {
                     return Visitor::stop();
                 }
             },
-            'leave' => function(Node $node) use (&$visited, $ast) {
+            'leave' => function (Node $node) use (&$visited, $ast) {
                 $this->checkVisitorFnArgs($ast, func_get_args());
-                $visited[] = ['leave', $node->kind, isset($node->value) ? $node->value : null];
-            }
+                $visited[] = ['leave', $node->kind, $node->value ?? null];
+            },
         ]);
 
         $expected = [
@@ -342,33 +333,30 @@ class VisitorTest extends ValidatorTestCase
             [ 'leave', 'Name', 'b' ],
             [ 'enter', 'SelectionSet', null ],
             [ 'enter', 'Field', null ],
-            [ 'enter', 'Name', 'x' ]
+            [ 'enter', 'Name', 'x' ],
         ];
 
         $this->assertEquals($expected, $visited);
     }
 
-    /**
-     * @it allows early exit while leaving
-     */
     public function testAllowsEarlyExitWhileLeaving()
     {
         $visited = [];
 
         $ast = Parser::parse('{ a, b { x }, c }', ['noLocation' => true]);
         Visitor::visit($ast, [
-            'enter' => function($node) use (&$visited, $ast) {
+            'enter' => function ($node) use (&$visited, $ast) {
                 $this->checkVisitorFnArgs($ast, func_get_args());
-                $visited[] = ['enter', $node->kind, isset($node->value) ? $node->value : null];
+                $visited[] = ['enter', $node->kind, $node->value ?? null];
             },
-            'leave' => function($node) use (&$visited, $ast) {
+            'leave' => function ($node) use (&$visited, $ast) {
                 $this->checkVisitorFnArgs($ast, func_get_args());
-                $visited[] = ['leave', $node->kind, isset($node->value) ? $node->value : null];
+                $visited[] = ['leave', $node->kind, $node->value ?? null];
 
                 if ($node->kind === NodeKind::NAME && $node->value === 'x') {
                     return Visitor::stop();
                 }
-            }
+            },
         ]);
 
         $this->assertEquals($visited, [
@@ -385,33 +373,30 @@ class VisitorTest extends ValidatorTestCase
             [ 'enter', 'SelectionSet', null ],
             [ 'enter', 'Field', null ],
             [ 'enter', 'Name', 'x' ],
-            [ 'leave', 'Name', 'x' ]
+            [ 'leave', 'Name', 'x' ],
         ]);
     }
 
-    /**
-     * @it allows a named functions visitor API
-     */
     public function testAllowsANamedFunctionsVisitorAPI()
     {
         $visited = [];
         $ast     = Parser::parse('{ a, b { x }, c }', ['noLocation' => true]);
 
         Visitor::visit($ast, [
-            NodeKind::NAME => function(NameNode $node) use (&$visited, $ast) {
+            NodeKind::NAME => function (NameNode $node) use (&$visited, $ast) {
                 $this->checkVisitorFnArgs($ast, func_get_args());
                 $visited[] = ['enter', $node->kind, $node->value];
             },
             NodeKind::SELECTION_SET => [
-                'enter' => function(SelectionSetNode $node) use (&$visited, $ast) {
+                'enter' => function (SelectionSetNode $node) use (&$visited, $ast) {
                     $this->checkVisitorFnArgs($ast, func_get_args());
                     $visited[] = ['enter', $node->kind, null];
                 },
-                'leave' => function(SelectionSetNode $node) use (&$visited, $ast) {
+                'leave' => function (SelectionSetNode $node) use (&$visited, $ast) {
                     $this->checkVisitorFnArgs($ast, func_get_args());
                     $visited[] = ['leave', $node->kind, null];
-                }
-            ]
+                },
+            ],
         ]);
 
         $expected = [
@@ -428,9 +413,6 @@ class VisitorTest extends ValidatorTestCase
         $this->assertEquals($expected, $visited);
     }
 
-    /**
-     * @it Experimental: visits variables defined in fragments
-     */
     public function testExperimentalVisitsVariablesDefinedInFragments()
     {
         $ast     = Parser::parse(
@@ -443,13 +425,13 @@ class VisitorTest extends ValidatorTestCase
         $visited = [];
 
         Visitor::visit($ast, [
-            'enter' => function($node) use (&$visited, $ast) {
+            'enter' => function ($node) use (&$visited, $ast) {
                 $this->checkVisitorFnArgs($ast, func_get_args());
-                $visited[] = ['enter', $node->kind, isset($node->value) ? $node->value : null];
+                $visited[] = ['enter', $node->kind, $node->value ?? null];
             },
-            'leave' => function($node) use (&$visited, $ast) {
+            'leave' => function ($node) use (&$visited, $ast) {
                 $this->checkVisitorFnArgs($ast, func_get_args());
-                $visited[] = ['leave', $node->kind, isset($node->value) ? $node->value : null];
+                $visited[] = ['leave', $node->kind, $node->value ?? null];
             },
         ]);
 
@@ -487,9 +469,6 @@ class VisitorTest extends ValidatorTestCase
         $this->assertEquals($expected, $visited);
     }
 
-    /**
-     * @it visits kitchen sink
-     */
     public function testVisitsKitchenSink()
     {
         $kitchenSink = file_get_contents(__DIR__ . '/kitchen-sink.graphql');
@@ -497,16 +476,16 @@ class VisitorTest extends ValidatorTestCase
 
         $visited = [];
         Visitor::visit($ast, [
-            'enter' => function(Node $node, $key, $parent) use (&$visited, $ast) {
+            'enter' => function (Node $node, $key, $parent) use (&$visited, $ast) {
                 $this->checkVisitorFnArgs($ast, func_get_args());
                 $r         = ['enter', $node->kind, $key, $parent instanceof Node ? $parent->kind : null];
                 $visited[] = $r;
             },
-            'leave' => function(Node $node, $key, $parent) use (&$visited, $ast) {
+            'leave' => function (Node $node, $key, $parent) use (&$visited, $ast) {
                 $this->checkVisitorFnArgs($ast, func_get_args());
                 $r         = ['leave', $node->kind, $key, $parent instanceof Node ? $parent->kind : null];
                 $visited[] = $r;
-            }
+            },
         ]);
 
         $expected = [
@@ -819,17 +798,15 @@ class VisitorTest extends ValidatorTestCase
             [ 'leave', 'Field', 1, null ],
             [ 'leave', 'SelectionSet', 'selectionSet', 'OperationDefinition' ],
             [ 'leave', 'OperationDefinition', 4, null ],
-            [ 'leave', 'Document', null, null ]
+            [ 'leave', 'Document', null, null ],
         ];
 
         $this->assertEquals($expected, $visited);
     }
 
-    // Describe: visitInParallel
-    // Note: nearly identical to the above test of the same test but using visitInParallel.
-
     /**
-     * @it allows skipping a sub-tree
+     * Describe: visitInParallel
+     * Note: nearly identical to the above test of the same test but using visitInParallel.
      */
     public function testAllowsSkippingSubTree()
     {
@@ -838,20 +815,20 @@ class VisitorTest extends ValidatorTestCase
         $ast = Parser::parse('{ a, b { x }, c }');
         Visitor::visit($ast, Visitor::visitInParallel([
             [
-                'enter' => function($node) use (&$visited, $ast) {
+                'enter' => function ($node) use (&$visited, $ast) {
                     $this->checkVisitorFnArgs($ast, func_get_args());
-                    $visited[] = [ 'enter', $node->kind, isset($node->value) ?  $node->value : null];
+                    $visited[] = [ 'enter', $node->kind, $node->value ?? null];
 
                     if ($node->kind === 'Field' && isset($node->name->value) && $node->name->value === 'b') {
                         return Visitor::skipNode();
                     }
                 },
 
-                'leave' => function($node) use (&$visited, $ast) {
+                'leave' => function ($node) use (&$visited, $ast) {
                     $this->checkVisitorFnArgs($ast, func_get_args());
-                    $visited[] = ['leave', $node->kind, isset($node->value) ? $node->value : null];
-                }
-            ]
+                    $visited[] = ['leave', $node->kind, $node->value ?? null];
+                },
+            ],
         ]));
 
         $this->assertEquals([
@@ -873,9 +850,6 @@ class VisitorTest extends ValidatorTestCase
         ], $visited);
     }
 
-    /**
-     * @it allows skipping different sub-trees
-     */
     public function testAllowsSkippingDifferentSubTrees()
     {
         $visited = [];
@@ -883,31 +857,31 @@ class VisitorTest extends ValidatorTestCase
         $ast = Parser::parse('{ a { x }, b { y} }');
         Visitor::visit($ast, Visitor::visitInParallel([
         [
-            'enter' => function($node) use (&$visited, $ast) {
+            'enter' => function ($node) use (&$visited, $ast) {
                 $this->checkVisitorFnArgs($ast, func_get_args());
-                $visited[] = ['no-a', 'enter', $node->kind, isset($node->value) ? $node->value : null];
+                $visited[] = ['no-a', 'enter', $node->kind, $node->value ?? null];
                 if ($node->kind === 'Field' && isset($node->name->value) && $node->name->value === 'a') {
                     return Visitor::skipNode();
                 }
             },
-            'leave' => function($node) use (&$visited, $ast) {
+            'leave' => function ($node) use (&$visited, $ast) {
                 $this->checkVisitorFnArgs($ast, func_get_args());
-                $visited[] = [ 'no-a', 'leave', $node->kind, isset($node->value) ? $node->value : null ];
-            }
+                $visited[] = [ 'no-a', 'leave', $node->kind, $node->value ?? null ];
+            },
         ],
         [
-            'enter' => function($node) use (&$visited, $ast) {
+            'enter' => function ($node) use (&$visited, $ast) {
                 $this->checkVisitorFnArgs($ast, func_get_args());
-                $visited[] = ['no-b', 'enter', $node->kind, isset($node->value) ? $node->value : null];
+                $visited[] = ['no-b', 'enter', $node->kind, $node->value ?? null];
                 if ($node->kind === 'Field' && isset($node->name->value) && $node->name->value === 'b') {
                     return Visitor::skipNode();
                 }
             },
-            'leave' => function($node) use (&$visited, $ast) {
+            'leave' => function ($node) use (&$visited, $ast) {
                 $this->checkVisitorFnArgs($ast, func_get_args());
-                $visited[] = ['no-b', 'leave', $node->kind, isset($node->value) ? $node->value : null];
-            }
-        ]
+                $visited[] = ['no-b', 'leave', $node->kind, $node->value ?? null];
+            },
+        ],
         ]));
 
         $this->assertEquals([
@@ -948,28 +922,26 @@ class VisitorTest extends ValidatorTestCase
         ], $visited);
     }
 
-    /**
-     * @it allows early exit while visiting
-     */
     public function testAllowsEarlyExitWhileVisiting2()
     {
         $visited = [];
 
         $ast = Parser::parse('{ a, b { x }, c }');
         Visitor::visit($ast, Visitor::visitInParallel([ [
-            'enter' => function($node) use (&$visited, $ast) {
+            'enter' => function ($node) use (&$visited, $ast) {
                 $this->checkVisitorFnArgs($ast, func_get_args());
-                $value = isset($node->value) ? $node->value : null;
+                $value     = $node->value ?? null;
                 $visited[] = ['enter', $node->kind, $value];
                 if ($node->kind === 'Name' && $value === 'x') {
                     return Visitor::stop();
                 }
             },
-            'leave' => function($node) use (&$visited, $ast) {
+            'leave' => function ($node) use (&$visited, $ast) {
                 $this->checkVisitorFnArgs($ast, func_get_args());
-                $visited[] = ['leave', $node->kind, isset($node->value) ? $node->value : null];
-            }
-        ] ]));
+                $visited[] = ['leave', $node->kind, $node->value ?? null];
+            },
+        ],
+        ]));
 
         $this->assertEquals([
             [ 'enter', 'Document', null ],
@@ -984,13 +956,10 @@ class VisitorTest extends ValidatorTestCase
             [ 'leave', 'Name', 'b' ],
             [ 'enter', 'SelectionSet', null ],
             [ 'enter', 'Field', null ],
-            [ 'enter', 'Name', 'x' ]
+            [ 'enter', 'Name', 'x' ],
         ], $visited);
     }
 
-    /**
-     * @it allows early exit from different points
-     */
     public function testAllowsEarlyExitFromDifferentPoints()
     {
         $visited = [];
@@ -998,32 +967,32 @@ class VisitorTest extends ValidatorTestCase
         $ast = Parser::parse('{ a { y }, b { x } }');
         Visitor::visit($ast, Visitor::visitInParallel([
         [
-            'enter' => function($node) use (&$visited, $ast) {
+            'enter' => function ($node) use (&$visited, $ast) {
                 $this->checkVisitorFnArgs($ast, func_get_args());
-                $value = isset($node->value) ? $node->value : null;
+                $value     = $node->value ?? null;
                 $visited[] = ['break-a', 'enter', $node->kind, $value];
                 if ($node->kind === 'Name' && $value === 'a') {
                     return Visitor::stop();
                 }
             },
-            'leave' => function($node) use (&$visited, $ast) {
+            'leave' => function ($node) use (&$visited, $ast) {
                 $this->checkVisitorFnArgs($ast, func_get_args());
-                $visited[] = [ 'break-a', 'leave', $node->kind, isset($node->value) ? $node->value : null ];
-            }
+                $visited[] = [ 'break-a', 'leave', $node->kind, $node->value ?? null ];
+            },
         ],
         [
-            'enter' => function($node) use (&$visited, $ast) {
+            'enter' => function ($node) use (&$visited, $ast) {
                 $this->checkVisitorFnArgs($ast, func_get_args());
-                $value = isset($node->value) ? $node->value : null;
+                $value     = $node->value ?? null;
                 $visited[] = ['break-b', 'enter', $node->kind, $value];
                 if ($node->kind === 'Name' && $value === 'b') {
                     return Visitor::stop();
                 }
             },
-            'leave' => function($node) use (&$visited, $ast) {
+            'leave' => function ($node) use (&$visited, $ast) {
                 $this->checkVisitorFnArgs($ast, func_get_args());
-                $visited[] = ['break-b', 'leave', $node->kind, isset($node->value) ? $node->value : null];
-            }
+                $visited[] = ['break-b', 'leave', $node->kind, $node->value ?? null];
+            },
         ],
         ]));
 
@@ -1047,32 +1016,30 @@ class VisitorTest extends ValidatorTestCase
             [ 'break-b', 'leave', 'SelectionSet', null ],
             [ 'break-b', 'leave', 'Field', null ],
             [ 'break-b', 'enter', 'Field', null ],
-            [ 'break-b', 'enter', 'Name', 'b' ]
+            [ 'break-b', 'enter', 'Name', 'b' ],
         ], $visited);
     }
 
-    /**
-     * @it allows early exit while leaving
-     */
     public function testAllowsEarlyExitWhileLeaving2()
     {
         $visited = [];
 
         $ast = Parser::parse('{ a, b { x }, c }');
         Visitor::visit($ast, Visitor::visitInParallel([ [
-            'enter' => function($node) use (&$visited, $ast) {
+            'enter' => function ($node) use (&$visited, $ast) {
                 $this->checkVisitorFnArgs($ast, func_get_args());
-                $visited[] = ['enter', $node->kind, isset($node->value) ? $node->value : null];
+                $visited[] = ['enter', $node->kind, $node->value ?? null];
             },
-            'leave' => function($node) use (&$visited, $ast) {
+            'leave' => function ($node) use (&$visited, $ast) {
                 $this->checkVisitorFnArgs($ast, func_get_args());
-                $value = isset($node->value) ? $node->value : null;
+                $value     = $node->value ?? null;
                 $visited[] = ['leave', $node->kind, $value];
                 if ($node->kind === 'Name' && $value === 'x') {
                     return Visitor::stop();
                 }
-            }
-        ] ]));
+            },
+        ],
+        ]));
 
         $this->assertEquals([
             [ 'enter', 'Document', null ],
@@ -1088,13 +1055,10 @@ class VisitorTest extends ValidatorTestCase
             [ 'enter', 'SelectionSet', null ],
             [ 'enter', 'Field', null ],
             [ 'enter', 'Name', 'x' ],
-            [ 'leave', 'Name', 'x' ]
+            [ 'leave', 'Name', 'x' ],
         ], $visited);
     }
 
-    /**
-     * @it allows early exit from leaving different points
-     */
     public function testAllowsEarlyExitFromLeavingDifferentPoints()
     {
         $visited = [];
@@ -1102,30 +1066,30 @@ class VisitorTest extends ValidatorTestCase
         $ast = Parser::parse('{ a { y }, b { x } }');
         Visitor::visit($ast, Visitor::visitInParallel([
             [
-                'enter' => function($node) use (&$visited, $ast) {
+                'enter' => function ($node) use (&$visited, $ast) {
                     $this->checkVisitorFnArgs($ast, func_get_args());
-                    $visited[] = ['break-a', 'enter', $node->kind, isset($node->value) ? $node->value : null];
+                    $visited[] = ['break-a', 'enter', $node->kind, $node->value ?? null];
                 },
-                'leave' => function($node) use (&$visited, $ast) {
+                'leave' => function ($node) use (&$visited, $ast) {
                     $this->checkVisitorFnArgs($ast, func_get_args());
-                    $visited[] = ['break-a', 'leave', $node->kind, isset($node->value) ? $node->value : null];
+                    $visited[] = ['break-a', 'leave', $node->kind, $node->value ?? null];
                     if ($node->kind === 'Field' && isset($node->name->value) && $node->name->value === 'a') {
                         return Visitor::stop();
                     }
-                }
+                },
             ],
             [
-                'enter' => function($node) use (&$visited, $ast) {
+                'enter' => function ($node) use (&$visited, $ast) {
                     $this->checkVisitorFnArgs($ast, func_get_args());
-                    $visited[] = ['break-b', 'enter', $node->kind, isset($node->value) ? $node->value : null];
+                    $visited[] = ['break-b', 'enter', $node->kind, $node->value ?? null];
                 },
-                'leave' => function($node) use (&$visited, $ast) {
+                'leave' => function ($node) use (&$visited, $ast) {
                     $this->checkVisitorFnArgs($ast, func_get_args());
-                    $visited[] = ['break-b', 'leave', $node->kind, isset($node->value) ? $node->value : null];
+                    $visited[] = ['break-b', 'leave', $node->kind, $node->value ?? null];
                     if ($node->kind === 'Field' && isset($node->name->value) && $node->name->value === 'b') {
                         return Visitor::stop();
                     }
-                }
+                },
             ],
         ]));
 
@@ -1165,13 +1129,10 @@ class VisitorTest extends ValidatorTestCase
             [ 'break-b', 'leave', 'Name', 'x' ],
             [ 'break-b', 'leave', 'Field', null ],
             [ 'break-b', 'leave', 'SelectionSet', null ],
-            [ 'break-b', 'leave', 'Field', null ]
+            [ 'break-b', 'leave', 'Field', null ],
         ], $visited);
     }
 
-    /**
-     * @it allows for editing on enter
-     */
     public function testAllowsForEditingOnEnter2()
     {
         $visited = [];
@@ -1184,17 +1145,17 @@ class VisitorTest extends ValidatorTestCase
                     if ($node->kind === 'Field' && isset($node->name->value) && $node->name->value === 'b') {
                         return Visitor::removeNode();
                     }
-                }
+                },
             ],
             [
                 'enter' => function ($node) use (&$visited, $ast) {
                     $this->checkVisitorFnArgs($ast, func_get_args());
-                    $visited[] = ['enter', $node->kind, isset($node->value) ? $node->value : null];
+                    $visited[] = ['enter', $node->kind, $node->value ?? null];
                 },
                 'leave' => function ($node) use (&$visited, $ast) {
                     $this->checkVisitorFnArgs($ast, func_get_args(), true);
-                    $visited[] = ['leave', $node->kind, isset($node->value) ? $node->value : null];
-                }
+                    $visited[] = ['leave', $node->kind, $node->value ?? null];
+                },
             ],
         ]));
 
@@ -1232,13 +1193,10 @@ class VisitorTest extends ValidatorTestCase
             ['leave', 'Field', null],
             ['leave', 'SelectionSet', null],
             ['leave', 'OperationDefinition', null],
-            ['leave', 'Document', null]
+            ['leave', 'Document', null],
         ], $visited);
     }
 
-    /**
-     * @it allows for editing on leave
-     */
     public function testAllowsForEditingOnLeave2()
     {
         $visited = [];
@@ -1251,17 +1209,17 @@ class VisitorTest extends ValidatorTestCase
                     if ($node->kind === 'Field' && isset($node->name->value) && $node->name->value === 'b') {
                         return Visitor::removeNode();
                     }
-                }
+                },
             ],
             [
                 'enter' => function ($node) use (&$visited, $ast) {
                     $this->checkVisitorFnArgs($ast, func_get_args());
-                    $visited[] = ['enter', $node->kind, isset($node->value) ? $node->value : null];
+                    $visited[] = ['enter', $node->kind, $node->value ?? null];
                 },
                 'leave' => function ($node) use (&$visited, $ast) {
                     $this->checkVisitorFnArgs($ast, func_get_args(), true);
-                    $visited[] = ['leave', $node->kind, isset($node->value) ? $node->value : null];
-                }
+                    $visited[] = ['leave', $node->kind, $node->value ?? null];
+                },
             ],
         ]));
 
@@ -1305,14 +1263,13 @@ class VisitorTest extends ValidatorTestCase
             ['leave', 'Field', null],
             ['leave', 'SelectionSet', null],
             ['leave', 'OperationDefinition', null],
-            ['leave', 'Document', null]
+            ['leave', 'Document', null],
         ], $visited);
     }
 
-    // Describe: visitWithTypeInfo
 
     /**
-     * @it maintains type info during visit
+     * Describe: visitWithTypeInfo
      */
     public function testMaintainsTypeInfoDuringVisit()
     {
@@ -1331,9 +1288,9 @@ class VisitorTest extends ValidatorTestCase
                     'enter',
                     $node->kind,
                     $node->kind === 'Name' ? $node->value : null,
-                    $parentType ? (string)$parentType : null,
-                    $type ? (string)$type : null,
-                    $inputType ? (string)$inputType : null
+                    $parentType ? (string) $parentType : null,
+                    $type ? (string) $type : null,
+                    $inputType ? (string) $inputType : null,
                 ];
             },
             'leave' => function ($node) use ($typeInfo, &$visited, $ast) {
@@ -1345,11 +1302,11 @@ class VisitorTest extends ValidatorTestCase
                     'leave',
                     $node->kind,
                     $node->kind === 'Name' ? $node->value : null,
-                    $parentType ? (string)$parentType : null,
-                    $type ? (string)$type : null,
-                    $inputType ? (string)$inputType : null
+                    $parentType ? (string) $parentType : null,
+                    $type ? (string) $type : null,
+                    $inputType ? (string) $inputType : null,
                 ];
-            }
+            },
         ]));
 
         $this->assertEquals([
@@ -1392,13 +1349,10 @@ class VisitorTest extends ValidatorTestCase
             ['leave', 'Field', null, 'QueryRoot', 'Human', null],
             ['leave', 'SelectionSet', null, 'QueryRoot', 'QueryRoot', null],
             ['leave', 'OperationDefinition', null, null, 'QueryRoot', null],
-            ['leave', 'Document', null, null, null, null]
+            ['leave', 'Document', null, null, null, null],
         ], $visited);
     }
 
-    /**
-     * @it maintains type info during edit
-     */
     public function testMaintainsTypeInfoDuringEdit()
     {
         $visited  = [];
@@ -1417,15 +1371,14 @@ class VisitorTest extends ValidatorTestCase
                     'enter',
                     $node->kind,
                     $node->kind === 'Name' ? $node->value : null,
-                    $parentType ? (string)$parentType : null,
-                    $type ? (string)$type : null,
-                    $inputType ? (string)$inputType : null
+                    $parentType ? (string) $parentType : null,
+                    $type ? (string) $type : null,
+                    $inputType ? (string) $inputType : null,
                 ];
 
                 // Make a query valid by adding missing selection sets.
-                if (
-                    $node->kind === 'Field' &&
-                    !$node->selectionSet &&
+                if ($node->kind === 'Field' &&
+                    ! $node->selectionSet &&
                     Type::isCompositeType(Type::getNamedType($type))
                 ) {
                     return new FieldNode([
@@ -1435,12 +1388,11 @@ class VisitorTest extends ValidatorTestCase
                         'directives' => $node->directives,
                         'selectionSet' => new SelectionSetNode([
                             'kind' => 'SelectionSet',
-                            'selections' => [
-                                new FieldNode([
-                                    'name' => new NameNode(['value' => '__typename'])
-                                ])
-                            ]
-                        ])
+                            'selections' => [new FieldNode([
+                                    'name' => new NameNode(['value' => '__typename']),
+                                ]),
+                            ],
+                        ]),
                     ]);
                 }
             },
@@ -1453,11 +1405,11 @@ class VisitorTest extends ValidatorTestCase
                     'leave',
                     $node->kind,
                     $node->kind === 'Name' ? $node->value : null,
-                    $parentType ? (string)$parentType : null,
-                    $type ? (string)$type : null,
-                    $inputType ? (string)$inputType : null
+                    $parentType ? (string) $parentType : null,
+                    $type ? (string) $type : null,
+                    $inputType ? (string) $inputType : null,
                 ];
-            }
+            },
         ]));
 
         $this->assertEquals(Printer::doPrint(Parser::parse(
@@ -1510,7 +1462,7 @@ class VisitorTest extends ValidatorTestCase
             ['leave', 'Field', null, 'QueryRoot', 'Alien', null],
             ['leave', 'SelectionSet', null, 'QueryRoot', 'QueryRoot', null],
             ['leave', 'OperationDefinition', null, null, 'QueryRoot', null],
-            ['leave', 'Document', null, null, null, null]
+            ['leave', 'Document', null, null, null, null],
         ], $visited);
     }
 }