1 // Copyright 2014 The Chromium Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 // A streaming validator for UTF-8. Validation is based on the definition in 6 // RFC-3629. In particular, it does not reject the invalid characters rejected 7 // by base::IsStringUTF8(). 8 // 9 // The implementation detects errors on the first possible byte. 10 11 #ifndef BASE_I18N_STREAMING_UTF8_VALIDATOR_H_ 12 #define BASE_I18N_STREAMING_UTF8_VALIDATOR_H_ 13 14 #include <string> 15 16 #include "base/basictypes.h" 17 #include "base/i18n/base_i18n_export.h" 18 19 namespace base { 20 21 class BASE_I18N_EXPORT StreamingUtf8Validator { 22 public: 23 // The validator exposes 3 states. It starts in state VALID_ENDPOINT. As it 24 // processes characters it alternates between VALID_ENDPOINT and 25 // VALID_MIDPOINT. If it encounters an invalid byte or UTF-8 sequence the 26 // state changes permanently to INVALID. 27 enum State { 28 VALID_ENDPOINT, 29 VALID_MIDPOINT, 30 INVALID 31 }; 32 33 StreamingUtf8Validator() : state_(0u) {} 34 // Trivial destructor intentionally omitted. 35 36 // Validate |size| bytes starting at |data|. If the concatenation of all calls 37 // to AddBytes() since this object was constructed or reset is a valid UTF-8 38 // string, returns VALID_ENDPOINT. If it could be the prefix of a valid UTF-8 39 // string, returns VALID_MIDPOINT. If an invalid byte or UTF-8 sequence was 40 // present, returns INVALID. 41 State AddBytes(const char* data, size_t size); 42 43 // Return the object to a freshly-constructed state so that it can be re-used. 44 void Reset(); 45 46 // Validate a complete string using the same criteria. Returns true if the 47 // string only contains complete, valid UTF-8 codepoints. 48 static bool Validate(const std::string& string); 49 50 private: 51 // The current state of the validator. Value 0 is the initial/valid state. 52 // The state is stored as an offset into |kUtf8ValidatorTables|. The special 53 // state |kUtf8InvalidState| is invalid. 54 uint8 state_; 55 56 // This type could be made copyable but there is currently no use-case for 57 // it. 58 DISALLOW_COPY_AND_ASSIGN(StreamingUtf8Validator); 59 }; 60 61 } // namespace base 62 63 #endif // BASE_I18N_STREAMING_UTF8_VALIDATOR_H_ 64
