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67 lines
2.2 KiB
C++
67 lines
2.2 KiB
C++
// Copyright 2014 The Chromium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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// A streaming validator for UTF-8. Validation is based on the definition in
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// RFC-3629. In particular, it does not reject the invalid characters rejected
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// by base::IsStringUTF8().
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//
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// The implementation detects errors on the first possible byte.
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#ifndef BASE_I18N_STREAMING_UTF8_VALIDATOR_H_
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#define BASE_I18N_STREAMING_UTF8_VALIDATOR_H_
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#include <stddef.h>
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#include <stdint.h>
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#include <string>
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#include "base/i18n/base_i18n_export.h"
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#include "base/macros.h"
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namespace base {
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class BASE_I18N_EXPORT StreamingUtf8Validator {
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public:
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// The validator exposes 3 states. It starts in state VALID_ENDPOINT. As it
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// processes characters it alternates between VALID_ENDPOINT and
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// VALID_MIDPOINT. If it encounters an invalid byte or UTF-8 sequence the
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// state changes permanently to INVALID.
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enum State {
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VALID_ENDPOINT,
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VALID_MIDPOINT,
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INVALID
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};
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StreamingUtf8Validator() : state_(0u) {}
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// Trivial destructor intentionally omitted.
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// Validate |size| bytes starting at |data|. If the concatenation of all calls
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// to AddBytes() since this object was constructed or reset is a valid UTF-8
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// string, returns VALID_ENDPOINT. If it could be the prefix of a valid UTF-8
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// string, returns VALID_MIDPOINT. If an invalid byte or UTF-8 sequence was
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// present, returns INVALID.
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State AddBytes(const char* data, size_t size);
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// Return the object to a freshly-constructed state so that it can be re-used.
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void Reset();
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// Validate a complete string using the same criteria. Returns true if the
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// string only contains complete, valid UTF-8 codepoints.
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static bool Validate(const std::string& string);
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private:
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// The current state of the validator. Value 0 is the initial/valid state.
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// The state is stored as an offset into |kUtf8ValidatorTables|. The special
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// state |kUtf8InvalidState| is invalid.
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uint8_t state_;
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// This type could be made copyable but there is currently no use-case for
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// it.
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DISALLOW_COPY_AND_ASSIGN(StreamingUtf8Validator);
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};
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} // namespace base
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#endif // BASE_I18N_STREAMING_UTF8_VALIDATOR_H_
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