Introduce BackwardGraphemeBoundaryStateMachine

third_party/WebKit/Source/core/editing/state_machines/BackwardGraphemeBoundaryStateMachine.h

Index: third_party/WebKit/Source/core/editing/state_machines/BackwardGraphemeBoundaryStateMachine.h
diff --git a/third_party/WebKit/Source/core/editing/state_machines/BackspaceStateMachine.h b/third_party/WebKit/Source/core/editing/state_machines/BackwardGraphemeBoundaryStateMachine.h
similarity index 57%
copy from third_party/WebKit/Source/core/editing/state_machines/BackspaceStateMachine.h
copy to third_party/WebKit/Source/core/editing/state_machines/BackwardGraphemeBoundaryStateMachine.h
index d073e3ef6450e9514871d0967f61bc7bc03534b6..7db5c0d50573b3304ddb7194a08eb70bdff049d9 100644
--- a/third_party/WebKit/Source/core/editing/state_machines/BackspaceStateMachine.h
+++ b/third_party/WebKit/Source/core/editing/state_machines/BackwardGraphemeBoundaryStateMachine.h
@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#ifndef BackspaceStateMachine_h
-#define BackspaceStateMachine_h
+#ifndef BackwardGraphemeBoundaryStateMachine_h
+#define BackwardGraphemeBoundaryStateMachine_h
 
 #include "core/CoreExport.h"
 #include "core/editing/state_machines/TextSegmentationMachineState.h"
@@ -14,13 +14,14 @@
 
 namespace blink {
 
-class CORE_EXPORT BackspaceStateMachine {
+class CORE_EXPORT BackwardGraphemeBoundaryStateMachine {
     STACK_ALLOCATED();
-    WTF_MAKE_NONCOPYABLE(BackspaceStateMachine);
+    WTF_MAKE_NONCOPYABLE(BackwardGraphemeBoundaryStateMachine);
+
 public:
-    BackspaceStateMachine();
+    BackwardGraphemeBoundaryStateMachine();
 
-    // Prepares by feeding preceding text.
+    // Find boundary offset by feeding preceding text.
     // This method must not be called after feedFollowingCodeUnit().
     TextSegmentationMachineState feedPrecedingCodeUnit(UChar codeUnit);
 
@@ -40,28 +41,31 @@ public:
     void reset();
 
 private:
-    enum class BackspaceState;
-    friend std::ostream& operator<<(std::ostream&, BackspaceState);
+    enum class InternalState;
+    friend std::ostream& operator<<(std::ostream&, InternalState);
+
+    TextSegmentationMachineState moveToNextState(InternalState nextState);
 
-    // Updates the internal state to the |newState| then return
-    // InternalState::NeedMoreCodeUnit.
-    TextSegmentationMachineState moveToNextState(BackspaceState newState);
+    TextSegmentationMachineState staySameState();
 
-    // Update the internal state to BackspaceState::Finished, then return
-    // MachineState::Finished.
+    // Updates the internal state to InternalState::Finished then returns
+    // TextSegmentationMachineState::Finished.
     TextSegmentationMachineState finish();
 
     // Used for composing supplementary code point with surrogate pairs.
     UChar m_trailSurrogate = 0;
 
-    // The number of code units to be deleted.
-    int m_codeUnitsToBeDeleted = 0;
+    // The code point immediately after the m_BoundaryOffset.
+    UChar32 m_nextCodePoint = 0;
+
+    // The relative offset from the begging of this state machine.
+    int m_boundaryOffset = 0;
 
-    // The length of the previously seen variation selector.
-    int m_lastSeenVSCodeUnits = 0;
+    // The number of regional indicator symbols preceding to the begging offset.
+    int m_precedingRISCount = 0;
 
     // The internal state.
-    BackspaceState m_state;
+    InternalState m_internalState;
 };
 
 } // namespace blink