| // Copyright 2016 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/core/editing/state_machines/backspace_state_machine.h" |
| |
| #include <ostream> // NOLINT |
| #include "third_party/blink/renderer/platform/text/character.h" |
| #include "third_party/blink/renderer/platform/wtf/text/character_names.h" |
| #include "third_party/blink/renderer/platform/wtf/text/unicode.h" |
| |
| namespace blink { |
| |
| #define FOR_EACH_BACKSPACE_STATE_MACHINE_STATE(V) \ |
| /* Initial state */ \ |
| V(kStart) \ |
| /* The current offset is just before line feed. */ \ |
| V(kBeforeLF) \ |
| /* The current offset is just before keycap. */ \ |
| V(kBeforeKeycap) \ |
| /* The current offset is just before variation selector and keycap. */ \ |
| V(kBeforeVSAndKeycap) \ |
| /* The current offset is just before emoji modifier. */ \ |
| V(kBeforeEmojiModifier) \ |
| /* The current offset is just before variation selector and emoji*/ \ |
| /* modifier. */ \ |
| V(kBeforeVSAndEmojiModifier) \ |
| /* The current offset is just before variation sequence. */ \ |
| V(kBeforeVS) \ |
| /* The current offset is just before ZWJ emoji. */ \ |
| V(kBeforeZWJEmoji) \ |
| /* The current offset is just before ZWJ. */ \ |
| V(kBeforeZWJ) \ |
| /* The current offset is just before variation selector and ZWJ. */ \ |
| V(kBeforeVSAndZWJ) \ |
| /* That there are odd numbered RIS from the beggining. */ \ |
| V(kOddNumberedRIS) \ |
| /* That there are even numbered RIS from the begging. */ \ |
| V(kEvenNumberedRIS) \ |
| /* This state machine has finished. */ \ |
| V(kFinished) |
| |
| enum class BackspaceStateMachine::BackspaceState { |
| #define V(name) name, |
| FOR_EACH_BACKSPACE_STATE_MACHINE_STATE(V) |
| #undef V |
| }; |
| |
| std::ostream& operator<<(std::ostream& os, |
| BackspaceStateMachine::BackspaceState state) { |
| static const char* const kTexts[] = { |
| #define V(name) #name, |
| FOR_EACH_BACKSPACE_STATE_MACHINE_STATE(V) |
| #undef V |
| }; |
| auto* const* const it = std::begin(kTexts) + static_cast<size_t>(state); |
| DCHECK_GE(it, std::begin(kTexts)) << "Unknown backspace value"; |
| DCHECK_LT(it, std::end(kTexts)) << "Unknown backspace value"; |
| return os << *it; |
| } |
| |
| BackspaceStateMachine::BackspaceStateMachine() |
| : state_(BackspaceState::kStart) {} |
| |
| TextSegmentationMachineState BackspaceStateMachine::FeedPrecedingCodeUnit( |
| UChar code_unit) { |
| DCHECK_NE(BackspaceState::kFinished, state_); |
| uint32_t code_point = code_unit; |
| if (U16_IS_LEAD(code_unit)) { |
| if (trail_surrogate_ == 0) { |
| // Unpaired lead surrogate. Aborting with deleting broken surrogate. |
| ++code_units_to_be_deleted_; |
| return TextSegmentationMachineState::kFinished; |
| } |
| code_point = U16_GET_SUPPLEMENTARY(code_unit, trail_surrogate_); |
| trail_surrogate_ = 0; |
| } else if (U16_IS_TRAIL(code_unit)) { |
| if (trail_surrogate_ != 0) { |
| // Unpaired trail surrogate. Aborting with deleting broken |
| // surrogate. |
| return TextSegmentationMachineState::kFinished; |
| } |
| trail_surrogate_ = code_unit; |
| return TextSegmentationMachineState::kNeedMoreCodeUnit; |
| } else { |
| if (trail_surrogate_ != 0) { |
| // Unpaired trail surrogate. Aborting with deleting broken |
| // surrogate. |
| return TextSegmentationMachineState::kFinished; |
| } |
| } |
| |
| switch (state_) { |
| case BackspaceState::kStart: |
| code_units_to_be_deleted_ = U16_LENGTH(code_point); |
| if (code_point == kNewlineCharacter) |
| return MoveToNextState(BackspaceState::kBeforeLF); |
| if (u_hasBinaryProperty(code_point, UCHAR_VARIATION_SELECTOR)) |
| return MoveToNextState(BackspaceState::kBeforeVS); |
| if (Character::IsRegionalIndicator(code_point)) |
| return MoveToNextState(BackspaceState::kOddNumberedRIS); |
| if (Character::IsModifier(code_point)) |
| return MoveToNextState(BackspaceState::kBeforeEmojiModifier); |
| if (Character::IsEmoji(code_point)) |
| return MoveToNextState(BackspaceState::kBeforeZWJEmoji); |
| if (code_point == kCombiningEnclosingKeycapCharacter) |
| return MoveToNextState(BackspaceState::kBeforeKeycap); |
| return Finish(); |
| case BackspaceState::kBeforeLF: |
| if (code_point == kCarriageReturnCharacter) |
| ++code_units_to_be_deleted_; |
| return Finish(); |
| case BackspaceState::kBeforeKeycap: |
| if (u_hasBinaryProperty(code_point, UCHAR_VARIATION_SELECTOR)) { |
| DCHECK_EQ(last_seen_vs_code_units_, 0); |
| last_seen_vs_code_units_ = U16_LENGTH(code_point); |
| return MoveToNextState(BackspaceState::kBeforeVSAndKeycap); |
| } |
| if (Character::IsEmojiKeycapBase(code_point)) |
| code_units_to_be_deleted_ += U16_LENGTH(code_point); |
| return Finish(); |
| case BackspaceState::kBeforeVSAndKeycap: |
| if (Character::IsEmojiKeycapBase(code_point)) { |
| DCHECK_GT(last_seen_vs_code_units_, 0); |
| DCHECK_LE(last_seen_vs_code_units_, 2); |
| code_units_to_be_deleted_ += |
| last_seen_vs_code_units_ + U16_LENGTH(code_point); |
| } |
| return Finish(); |
| case BackspaceState::kBeforeEmojiModifier: |
| if (u_hasBinaryProperty(code_point, UCHAR_VARIATION_SELECTOR)) { |
| DCHECK_EQ(last_seen_vs_code_units_, 0); |
| last_seen_vs_code_units_ = U16_LENGTH(code_point); |
| return MoveToNextState(BackspaceState::kBeforeVSAndEmojiModifier); |
| } |
| if (Character::IsEmojiModifierBase(code_point)) |
| code_units_to_be_deleted_ += U16_LENGTH(code_point); |
| return Finish(); |
| case BackspaceState::kBeforeVSAndEmojiModifier: |
| if (Character::IsEmojiModifierBase(code_point)) { |
| DCHECK_GT(last_seen_vs_code_units_, 0); |
| DCHECK_LE(last_seen_vs_code_units_, 2); |
| code_units_to_be_deleted_ += |
| last_seen_vs_code_units_ + U16_LENGTH(code_point); |
| } |
| return Finish(); |
| case BackspaceState::kBeforeVS: |
| if (Character::IsEmoji(code_point)) { |
| code_units_to_be_deleted_ += U16_LENGTH(code_point); |
| return MoveToNextState(BackspaceState::kBeforeZWJEmoji); |
| } |
| if (!u_hasBinaryProperty(code_point, UCHAR_VARIATION_SELECTOR) && |
| u_getCombiningClass(code_point) == 0) |
| code_units_to_be_deleted_ += U16_LENGTH(code_point); |
| return Finish(); |
| case BackspaceState::kBeforeZWJEmoji: |
| return code_point == kZeroWidthJoinerCharacter |
| ? MoveToNextState(BackspaceState::kBeforeZWJ) |
| : Finish(); |
| case BackspaceState::kBeforeZWJ: |
| if (Character::IsEmoji(code_point)) { |
| code_units_to_be_deleted_ += U16_LENGTH(code_point) + 1; // +1 for ZWJ |
| return Character::IsModifier(code_point) |
| ? MoveToNextState(BackspaceState::kBeforeEmojiModifier) |
| : MoveToNextState(BackspaceState::kBeforeZWJEmoji); |
| } |
| if (u_hasBinaryProperty(code_point, UCHAR_VARIATION_SELECTOR)) { |
| DCHECK_EQ(last_seen_vs_code_units_, 0); |
| last_seen_vs_code_units_ = U16_LENGTH(code_point); |
| return MoveToNextState(BackspaceState::kBeforeVSAndZWJ); |
| } |
| return Finish(); |
| case BackspaceState::kBeforeVSAndZWJ: |
| if (!Character::IsEmoji(code_point)) |
| return Finish(); |
| |
| DCHECK_GT(last_seen_vs_code_units_, 0); |
| DCHECK_LE(last_seen_vs_code_units_, 2); |
| // +1 for ZWJ |
| code_units_to_be_deleted_ += |
| U16_LENGTH(code_point) + 1 + last_seen_vs_code_units_; |
| last_seen_vs_code_units_ = 0; |
| return MoveToNextState(BackspaceState::kBeforeZWJEmoji); |
| case BackspaceState::kOddNumberedRIS: |
| if (!Character::IsRegionalIndicator(code_point)) |
| return Finish(); |
| code_units_to_be_deleted_ += 2; // Code units of RIS |
| return MoveToNextState(BackspaceState::kEvenNumberedRIS); |
| case BackspaceState::kEvenNumberedRIS: |
| if (!Character::IsRegionalIndicator(code_point)) |
| return Finish(); |
| code_units_to_be_deleted_ -= 2; // Code units of RIS |
| return MoveToNextState(BackspaceState::kOddNumberedRIS); |
| case BackspaceState::kFinished: |
| NOTREACHED() << "Do not call feedPrecedingCodeUnit() once it finishes."; |
| break; |
| default: |
| NOTREACHED() << "Unhandled state: " << state_; |
| } |
| NOTREACHED() << "Unhandled state: " << state_; |
| return TextSegmentationMachineState::kInvalid; |
| } |
| |
| TextSegmentationMachineState BackspaceStateMachine::TellEndOfPrecedingText() { |
| if (trail_surrogate_ != 0) { |
| // Unpaired trail surrogate. Removing broken surrogate. |
| ++code_units_to_be_deleted_; |
| trail_surrogate_ = 0; |
| } |
| return TextSegmentationMachineState::kFinished; |
| } |
| |
| TextSegmentationMachineState BackspaceStateMachine::FeedFollowingCodeUnit( |
| UChar code_unit) { |
| NOTREACHED(); |
| return TextSegmentationMachineState::kInvalid; |
| } |
| |
| int BackspaceStateMachine::FinalizeAndGetBoundaryOffset() { |
| if (trail_surrogate_ != 0) { |
| // Unpaired trail surrogate. Removing broken surrogate. |
| ++code_units_to_be_deleted_; |
| trail_surrogate_ = 0; |
| } |
| if (state_ != BackspaceState::kFinished) { |
| last_seen_vs_code_units_ = 0; |
| state_ = BackspaceState::kFinished; |
| } |
| return -code_units_to_be_deleted_; |
| } |
| |
| void BackspaceStateMachine::Reset() { |
| code_units_to_be_deleted_ = 0; |
| trail_surrogate_ = 0; |
| state_ = BackspaceState::kStart; |
| last_seen_vs_code_units_ = 0; |
| } |
| |
| TextSegmentationMachineState BackspaceStateMachine::MoveToNextState( |
| BackspaceState new_state) { |
| DCHECK_NE(BackspaceState::kFinished, new_state) << "Use finish() instead."; |
| DCHECK_NE(BackspaceState::kStart, new_state) << "Don't move to Start."; |
| // Below |DCHECK_NE()| prevent us to infinite loop in state machine. |
| DCHECK_NE(state_, new_state) << "State should be changed."; |
| state_ = new_state; |
| return TextSegmentationMachineState::kNeedMoreCodeUnit; |
| } |
| |
| TextSegmentationMachineState BackspaceStateMachine::Finish() { |
| DCHECK_NE(BackspaceState::kFinished, state_); |
| state_ = BackspaceState::kFinished; |
| return TextSegmentationMachineState::kFinished; |
| } |
| |
| } // namespace blink |
