Move state machines to state_machines subdir

third_party/WebKit/Source/core/editing/BackspaceStateMachine.h

 // 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.
 
 #ifndef BackspaceStateMachine_h
 #define BackspaceStateMachine_h
 
 #include "core/CoreExport.h"
 #include "wtf/Allocator.h"
 #include "wtf/Noncopyable.h"
 #include "wtf/text/Unicode.h"
 
 namespace blink {
 
 class CORE_EXPORT BackspaceStateMachine {
     STACK_ALLOCATED();
     WTF_MAKE_NONCOPYABLE(BackspaceStateMachine);
 public:
+    enum class State {
+        Unknown, // Indicates the state machine is in unknown state.
+        NeedMoreCodeUnit, // Indicates the state machine needs more code units to transit the state.
+        NeedFollowingCodeUnit, // Indicates the state machine needs following code units to transit the state.
+        Finished, // Indicates the state machine found a boundary.
+    };
     BackspaceStateMachine() = default;
 
-    // Returns true when the state machine has stopped.
-    bool updateState(UChar codeUnit);
+    // Prepares by feeding preceding text.
+    // This method must not be called after feedFollowingCodeUnit().
+    State feedPrecedingCodeUnit(UChar codeUnit);
 
-    // Finalize the state machine and returns the code unit count to be deleted.
-    // If the state machine hasn't finished, this method finishes the state
-    // machine first.
-    int finalizeAndGetCodeUnitCountToBeDeleted();
+    // Notify the end of preceding text to the state machine.
+    State notifyEndOfPrecedingText();

[yosin_UTC9, 2016/03/30 07:43:07]

How about |tellEndOfPrecedingText()|. It seems |notifyXXX| is used with
observers.

[Seigo Nonaka, 2016/03/30 08:13:09]

Done.

+
+    // Find boundary offset by feeding following text.
+    // This method must be called after feedPrecedingCodeUnit() returns NeedsFollowingCodeUnit.
+    State feedFollowingCodeUnit(UChar codeUnit);
+
+    // Returns the next boundary offset. This method finalizes the state machine if it is not finished.
+    int finalizeAndGetBoundaryOffset();
 
     // Resets the internal state to the initial state.
     void reset();
 
 private:
     int m_codeUnitsToBeDeleted = 0;
 
     // Used for composing supplementary code point with surrogate pairs.
     UChar m_trailSurrogate = 0;
 };
 
 } // namespace blink
 
 #endif