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// Copyright 2019 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "third_party/blink/renderer/platform/fonts/utf16_ragel_iterator.h"
#include "third_party/blink/renderer/platform/text/character.h"
#include "third_party/blink/renderer/platform/wtf/text/character_names.h"
namespace blink {
namespace {
char EmojiSegmentationCategory(UChar32 codepoint) {
if (codepoint <= 0x7F) {
if (Character::IsEmojiKeycapBase(codepoint))
return UTF16RagelIterator::KEYCAP_BASE;
return UTF16RagelIterator::kMaxEmojiScannerCategory;
}
// For the grammar to work, we need to check for more specific character
// classes first, then expand towards more generic ones. So we match single
// characters and small ranges first, then return EMOJI and
// EMOJI_TEXT_PRESENTATION for the remaining ones.
if (codepoint == kCombiningEnclosingKeycapCharacter)
return UTF16RagelIterator::COMBINING_ENCLOSING_KEYCAP;
if (codepoint == kCombiningEnclosingCircleBackslashCharacter)
return UTF16RagelIterator::COMBINING_ENCLOSING_CIRCLE_BACKSLASH;
if (codepoint == kZeroWidthJoinerCharacter)
return UTF16RagelIterator::ZWJ;
if (codepoint == kVariationSelector15Character)
return UTF16RagelIterator::VS15;
if (codepoint == kVariationSelector16Character)
return UTF16RagelIterator::VS16;
if (codepoint == 0x1F3F4)
return UTF16RagelIterator::TAG_BASE;
if (Character::IsEmojiTagSequence(codepoint))
return UTF16RagelIterator::TAG_SEQUENCE;
if (codepoint == kCancelTag) {
// http://www.unicode.org/reports/tr51/#def_emoji_tag_sequence
// defines a TAG_TERM grammar rule for U+E007F CANCEL TAG.
return UTF16RagelIterator::TAG_TERM;
}
if (Character::IsEmojiModifierBase(codepoint))
return UTF16RagelIterator::EMOJI_MODIFIER_BASE;
if (Character::IsModifier(codepoint))
return UTF16RagelIterator::EMOJI_MODIFIER;
if (Character::IsRegionalIndicator(codepoint))
return UTF16RagelIterator::REGIONAL_INDICATOR;
if (Character::IsEmojiEmojiDefault(codepoint))
return UTF16RagelIterator::EMOJI_EMOJI_PRESENTATION;
if (Character::IsEmojiTextDefault(codepoint))
return UTF16RagelIterator::EMOJI_TEXT_PRESENTATION;
if (Character::IsEmoji(codepoint))
return UTF16RagelIterator::EMOJI;
// Ragel state machine will interpret unknown category as "any".
return UTF16RagelIterator::kMaxEmojiScannerCategory;
}
} // namespace
UTF16RagelIterator& UTF16RagelIterator::SetCursor(unsigned new_cursor) {
CHECK_GE(new_cursor, 0u);
CHECK_LT(new_cursor, buffer_size_);
cursor_ = new_cursor;
UpdateCachedCategory();
return *this;
}
void UTF16RagelIterator::UpdateCachedCategory() {
if (cursor_ >= buffer_size_)
return;
cached_category_ = EmojiSegmentationCategory(Codepoint());
}
} // namespace blink
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