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60 lines
1.9 KiB
C++
60 lines
1.9 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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// This implementation doesn't use ICU. The ICU macros are oriented towards
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// character-at-a-time processing, whereas byte-at-a-time processing is easier
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// with streaming input.
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#include "base/i18n/streaming_utf8_validator.h"
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#include "base/i18n/utf8_validator_tables.h"
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#include "base/logging.h"
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namespace base {
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namespace {
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uint8_t StateTableLookup(uint8_t offset) {
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DCHECK_LT(offset, internal::kUtf8ValidatorTablesSize);
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return internal::kUtf8ValidatorTables[offset];
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}
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} // namespace
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StreamingUtf8Validator::State StreamingUtf8Validator::AddBytes(const char* data,
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size_t size) {
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// Copy |state_| into a local variable so that the compiler doesn't have to be
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// careful of aliasing.
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uint8_t state = state_;
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for (const char* p = data; p != data + size; ++p) {
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if ((*p & 0x80) == 0) {
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if (state == 0)
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continue;
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state = internal::I18N_UTF8_VALIDATOR_INVALID_INDEX;
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break;
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}
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const uint8_t shift_amount = StateTableLookup(state);
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const uint8_t shifted_char = (*p & 0x7F) >> shift_amount;
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state = StateTableLookup(state + shifted_char + 1);
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// State may be INVALID here, but this code is optimised for the case of
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// valid UTF-8 and it is more efficient (by about 2%) to not attempt an
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// early loop exit unless we hit an ASCII character.
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}
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state_ = state;
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return state == 0 ? VALID_ENDPOINT
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: state == internal::I18N_UTF8_VALIDATOR_INVALID_INDEX
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? INVALID
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: VALID_MIDPOINT;
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}
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void StreamingUtf8Validator::Reset() {
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state_ = 0u;
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}
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bool StreamingUtf8Validator::Validate(const std::string& string) {
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return StreamingUtf8Validator().AddBytes(string.data(), string.size()) ==
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VALID_ENDPOINT;
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}
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} // namespace base
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