graphql-php/src/Language/Visitor.php

459 lines
16 KiB
PHP

<?php
namespace GraphQL\Language;
use GraphQL\Language\AST\Node;
use GraphQL\Utils\TypeInfo;
class Visitor
{
/**
* Break visitor
*
* @return VisitorOperation
*/
public static function stop()
{
$r = new VisitorOperation();
$r->doBreak = true;
return $r;
}
/**
* Skip current node
*/
public static function skipNode()
{
$r = new VisitorOperation();
$r->doContinue = true;
return $r;
}
/**
* Remove current node
*/
public static function removeNode()
{
$r = new VisitorOperation();
$r->removeNode = true;
return $r;
}
public static $visitorKeys = array(
Node::NAME => [],
Node::DOCUMENT => ['definitions'],
Node::OPERATION_DEFINITION => ['name', 'variableDefinitions', 'directives', 'selectionSet'],
Node::VARIABLE_DEFINITION => ['variable', 'type', 'defaultValue'],
Node::VARIABLE => ['name'],
Node::SELECTION_SET => ['selections'],
Node::FIELD => ['alias', 'name', 'arguments', 'directives', 'selectionSet'],
Node::ARGUMENT => ['name', 'value'],
Node::FRAGMENT_SPREAD => ['name', 'directives'],
Node::INLINE_FRAGMENT => ['typeCondition', 'directives', 'selectionSet'],
Node::FRAGMENT_DEFINITION => ['name', 'typeCondition', 'directives', 'selectionSet'],
Node::INT => [],
Node::FLOAT => [],
Node::STRING => [],
Node::BOOLEAN => [],
Node::ENUM => [],
Node::LST => ['values'],
Node::OBJECT => ['fields'],
Node::OBJECT_FIELD => ['name', 'value'],
Node::DIRECTIVE => ['name', 'arguments'],
Node::NAMED_TYPE => ['name'],
Node::LIST_TYPE => ['type'],
Node::NON_NULL_TYPE => ['type'],
Node::SCHEMA_DEFINITION => ['directives', 'operationTypes'],
Node::OPERATION_TYPE_DEFINITION => ['type'],
Node::SCALAR_TYPE_DEFINITION => ['name', 'directives'],
Node::OBJECT_TYPE_DEFINITION => ['name', 'interfaces', 'directives', 'fields'],
Node::FIELD_DEFINITION => ['name', 'arguments', 'type', 'directives'],
Node::INPUT_VALUE_DEFINITION => ['name', 'type', 'defaultValue', 'directives'],
Node::INTERFACE_TYPE_DEFINITION => [ 'name', 'directives', 'fields' ],
Node::UNION_TYPE_DEFINITION => [ 'name', 'directives', 'types' ],
Node::ENUM_TYPE_DEFINITION => [ 'name', 'directives', 'values' ],
Node::ENUM_VALUE_DEFINITION => [ 'name', 'directives' ],
Node::INPUT_OBJECT_TYPE_DEFINITION => [ 'name', 'directives', 'fields' ],
Node::TYPE_EXTENSION_DEFINITION => [ 'definition' ],
Node::DIRECTIVE_DEFINITION => [ 'name', 'arguments', 'locations' ]
);
/**
* visit() will walk through an AST using a depth first traversal, calling
* the visitor's enter function at each node in the traversal, and calling the
* leave function after visiting that node and all of it's child nodes.
*
* By returning different values from the enter and leave functions, the
* behavior of the visitor can be altered, including skipping over a sub-tree of
* the AST (by returning false), editing the AST by returning a value or null
* to remove the value, or to stop the whole traversal by returning BREAK.
*
* When using visit() to edit an AST, the original AST will not be modified, and
* a new version of the AST with the changes applied will be returned from the
* visit function.
*
* var editedAST = visit(ast, {
* enter(node, key, parent, path, ancestors) {
* // @return
* // undefined: no action
* // false: skip visiting this node
* // visitor.BREAK: stop visiting altogether
* // null: delete this node
* // any value: replace this node with the returned value
* },
* leave(node, key, parent, path, ancestors) {
* // @return
* // undefined: no action
* // visitor.BREAK: stop visiting altogether
* // null: delete this node
* // any value: replace this node with the returned value
* }
* });
*
* Alternatively to providing enter() and leave() functions, a visitor can
* instead provide functions named the same as the kinds of AST nodes, or
* enter/leave visitors at a named key, leading to four permutations of
* visitor API:
*
* 1) Named visitors triggered when entering a node a specific kind.
*
* visit(ast, {
* Kind(node) {
* // enter the "Kind" node
* }
* })
*
* 2) Named visitors that trigger upon entering and leaving a node of
* a specific kind.
*
* visit(ast, {
* Kind: {
* enter(node) {
* // enter the "Kind" node
* }
* leave(node) {
* // leave the "Kind" node
* }
* }
* })
*
* 3) Generic visitors that trigger upon entering and leaving any node.
*
* visit(ast, {
* enter(node) {
* // enter any node
* },
* leave(node) {
* // leave any node
* }
* })
*
* 4) Parallel visitors for entering and leaving nodes of a specific kind.
*
* visit(ast, {
* enter: {
* Kind(node) {
* // enter the "Kind" node
* }
* },
* leave: {
* Kind(node) {
* // leave the "Kind" node
* }
* }
* })
*/
public static function visit($root, $visitor, $keyMap = null)
{
$visitorKeys = $keyMap ?: self::$visitorKeys;
$stack = null;
$inArray = is_array($root);
$keys = [$root];
$index = -1;
$edits = [];
$parent = null;
$path = [];
$ancestors = [];
$newRoot = $root;
$UNDEFINED = null;
do {
$index++;
$isLeaving = $index === count($keys);
$key = null;
$node = null;
$isEdited = $isLeaving && count($edits) !== 0;
if ($isLeaving) {
$key = count($ancestors) === 0 ? $UNDEFINED : array_pop($path);
$node = $parent;
$parent = array_pop($ancestors);
if ($isEdited) {
if ($inArray) {
// $node = $node; // arrays are value types in PHP
} else {
$node = clone $node;
}
$editOffset = 0;
for ($ii = 0; $ii < count($edits); $ii++) {
$editKey = $edits[$ii][0];
$editValue = $edits[$ii][1];
if ($inArray) {
$editKey -= $editOffset;
}
if ($inArray && $editValue === null) {
array_splice($node, $editKey, 1);
$editOffset++;
} else {
if (is_array($node)) {
$node[$editKey] = $editValue;
} else {
$node->{$editKey} = $editValue;
}
}
}
}
$index = $stack['index'];
$keys = $stack['keys'];
$edits = $stack['edits'];
$inArray = $stack['inArray'];
$stack = $stack['prev'];
} else {
$key = $parent ? ($inArray ? $index : $keys[$index]) : $UNDEFINED;
$node = $parent ? (is_array($parent) ? $parent[$key] : $parent->{$key}) : $newRoot;
if ($node === null || $node === $UNDEFINED) {
continue;
}
if ($parent) {
$path[] = $key;
}
}
$result = null;
if (!is_array($node)) {
if (!($node instanceof Node)) {
throw new \Exception('Invalid AST Node: ' . json_encode($node));
}
$visitFn = self::getVisitFn($visitor, $node->kind, $isLeaving);
if ($visitFn) {
$result = call_user_func($visitFn, $node, $key, $parent, $path, $ancestors);
if ($result !== null) {
if ($result instanceof VisitorOperation) {
if ($result->doBreak) {
break;
}
if (!$isLeaving && $result->doContinue) {
array_pop($path);
continue;
}
if ($result->removeNode) {
$editValue = null;
}
} else {
$editValue = $result;
}
$edits[] = [$key, $editValue];
if (!$isLeaving) {
if ($editValue instanceof Node) {
$node = $editValue;
} else {
array_pop($path);
continue;
}
}
}
}
}
if ($result === null && $isEdited) {
$edits[] = [$key, $node];
}
if (!$isLeaving) {
$stack = array(
'inArray' => $inArray,
'index' => $index,
'keys' => $keys,
'edits' => $edits,
'prev' => $stack
);
$inArray = is_array($node);
$keys = ($inArray ? $node : $visitorKeys[$node->kind]) ?: array();
$index = -1;
$edits = [];
if ($parent) {
$ancestors[] = $parent;
}
$parent = $node;
}
} while ($stack);
if (count($edits) !== 0) {
$newRoot = $edits[0][1];
}
return $newRoot;
}
/**
* @param $visitors
* @return array
*/
static function visitInParallel($visitors)
{
$visitorsCount = count($visitors);
$skipping = new \SplFixedArray($visitorsCount);
return [
'enter' => function ($node) use ($visitors, $skipping, $visitorsCount) {
for ($i = 0; $i < $visitorsCount; $i++) {
if (empty($skipping[$i])) {
$fn = self::getVisitFn($visitors[$i], $node->kind, /* isLeaving */ false);
if ($fn) {
$result = call_user_func_array($fn, func_get_args());
if ($result instanceof VisitorOperation) {
if ($result->doContinue) {
$skipping[$i] = $node;
} else if ($result->doBreak) {
$skipping[$i] = $result;
} else if ($result->removeNode) {
return $result;
}
} else if ($result !== null) {
return $result;
}
}
}
}
},
'leave' => function ($node) use ($visitors, $skipping, $visitorsCount) {
for ($i = 0; $i < $visitorsCount; $i++) {
if (empty($skipping[$i])) {
$fn = self::getVisitFn($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) {
return $result;
}
} else if ($result !== null) {
return $result;
}
}
} else if ($skipping[$i] === $node) {
$skipping[$i] = null;
}
}
}
];
}
/**
* Creates a new visitor instance which maintains a provided TypeInfo instance
* along with visiting visitor.
*/
static function visitWithTypeInfo(TypeInfo $typeInfo, $visitor)
{
return [
'enter' => function ($node) use ($typeInfo, $visitor) {
$typeInfo->enter($node);
$fn = self::getVisitFn($visitor, $node->kind, false);
if ($fn) {
$result = call_user_func_array($fn, func_get_args());
if ($result) {
$typeInfo->leave($node);
if ($result instanceof Node) {
$typeInfo->enter($result);
}
}
return $result;
}
return null;
},
'leave' => function ($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 $isLeaving
* @return null
*/
public static function getVisitFn($visitor, $kind, $isLeaving)
{
if (!$visitor) {
return null;
}
$kindVisitor = isset($visitor[$kind]) ? $visitor[$kind] : null;
if (!$isLeaving && is_callable($kindVisitor)) {
// { Kind() {} }
return $kindVisitor;
}
if (is_array($kindVisitor)) {
if ($isLeaving) {
$kindSpecificVisitor = isset($kindVisitor['leave']) ? $kindVisitor['leave'] : null;
} else {
$kindSpecificVisitor = isset($kindVisitor['enter']) ? $kindVisitor['enter'] : null;
}
if ($kindSpecificVisitor && is_callable($kindSpecificVisitor)) {
// { Kind: { enter() {}, leave() {} } }
return $kindSpecificVisitor;
}
return null;
}
$visitor += ['leave' => null, 'enter' => null];
$specificVisitor = $isLeaving ? $visitor['leave'] : $visitor['enter'];
if ($specificVisitor) {
if (is_callable($specificVisitor)) {
// { enter() {}, leave() {} }
return $specificVisitor;
}
$specificKindVisitor = isset($specificVisitor[$kind]) ? $specificVisitor[$kind] : null;
if (is_callable($specificKindVisitor)) {
// { enter: { Kind() {} }, leave: { Kind() {} } }
return $specificKindVisitor;
}
}
return null;
}
}
class VisitorOperation
{
public $doBreak;
public $doContinue;
public $removeNode;
}