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// Copyright 2017 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/backward_code_point_state_machine.h"
#include "base/notreached.h"
namespace blink {
enum class BackwardCodePointStateMachine::BackwardCodePointState {
kNotSurrogate,
kTrailSurrogate,
kInvalid,
};
BackwardCodePointStateMachine::BackwardCodePointStateMachine()
: state_(BackwardCodePointState::kNotSurrogate) {}
TextSegmentationMachineState
BackwardCodePointStateMachine::FeedPrecedingCodeUnit(UChar code_unit) {
switch (state_) {
case BackwardCodePointState::kNotSurrogate:
if (U16_IS_LEAD(code_unit)) {
code_units_to_be_deleted_ = 0;
state_ = BackwardCodePointState::kInvalid;
return TextSegmentationMachineState::kInvalid;
}
++code_units_to_be_deleted_;
if (U16_IS_TRAIL(code_unit)) {
state_ = BackwardCodePointState::kTrailSurrogate;
return TextSegmentationMachineState::kNeedMoreCodeUnit;
}
return TextSegmentationMachineState::kFinished;
case BackwardCodePointState::kTrailSurrogate:
if (U16_IS_LEAD(code_unit)) {
++code_units_to_be_deleted_;
state_ = BackwardCodePointState::kNotSurrogate;
return TextSegmentationMachineState::kFinished;
}
code_units_to_be_deleted_ = 0;
state_ = BackwardCodePointState::kInvalid;
return TextSegmentationMachineState::kInvalid;
case BackwardCodePointState::kInvalid:
code_units_to_be_deleted_ = 0;
return TextSegmentationMachineState::kInvalid;
}
NOTREACHED();
return TextSegmentationMachineState::kInvalid;
}
TextSegmentationMachineState
BackwardCodePointStateMachine::FeedFollowingCodeUnit(UChar code_unit) {
NOTREACHED();
return TextSegmentationMachineState::kInvalid;
}
bool BackwardCodePointStateMachine::AtCodePointBoundary() {
return state_ == BackwardCodePointState::kNotSurrogate;
}
int BackwardCodePointStateMachine::GetBoundaryOffset() {
return -code_units_to_be_deleted_;
}
void BackwardCodePointStateMachine::Reset() {
code_units_to_be_deleted_ = 0;
state_ = BackwardCodePointState::kNotSurrogate;
}
} // namespace blink
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