Clean up IFX_BidiChar

- Replace IFX_BidiChar with just CFX_BidiChar
- Document implementation
- Change out parameters to pointers
- Remove dead code
- Add an enum for bidi directions
- Move several externs to a header
- Add unit tests

R=tsepez@chromium.org

Review URL: https://codereview.chromium.org/1197643002 .

1 files changed, 59 insertions, 0 deletions

diff --git a/core/include/fxcrt/fx_bidi.h b/core/include/fxcrt/fx_bidi.h
new file mode 100644
index 0000000000..a55ce6cfd2
--- /dev/null
+++ b/core/include/fxcrt/fx_bidi.h
@@ -0,0 +1,59 @@
+// Copyright 2014 PDFium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
+
+#ifndef CORE_INCLUDE_FXCRT_FX_BIDI_H_
+#define CORE_INCLUDE_FXCRT_FX_BIDI_H_
+
+#include "fx_system.h"
+
+// Processes characters and group them into segments based on text direction.
+class CFX_BidiChar {
+ public:
+  enum Direction { NEUTRAL, LEFT, RIGHT };
+
+  CFX_BidiChar();
+  ~CFX_BidiChar();
+
+  // Append a character and classify it as left, right, or neutral.
+  // Returns true if the character has a different direction than the
+  // existing direction to indicate there is a segment to process.
+  bool AppendChar(FX_WCHAR wch);
+
+  // Call this after the last character has been appended. AppendChar()
+  // must not be called after this.
+  // Returns true if there is still a segment to process.
+  bool EndChar();
+
+  // Get information about the segment to process.
+  // The segment's start position and character count is returned in |iStart|
+  // and |iCount|, respectively. Pass in null pointers if the information is
+  // not needed.
+  // Returns the segment direction.
+  Direction GetBidiInfo(int32_t* iStart, int32_t* iCount) const;
+
+ private:
+  void SaveCurrentStateToLastState();
+
+  // Position of the current segment.
+  int32_t m_iCurStart;
+
+  // Number of characters in the current segment.
+  int32_t m_iCurCount;
+
+  // Direction of the current segment.
+  Direction m_CurBidi;
+
+  // Number of characters in the last segment.
+  int32_t m_iLastStart;
+
+  // Number of characters in the last segment.
+  int32_t m_iLastCount;
+
+  // Direction of the last segment.
+  Direction m_LastBidi;
+};
+
+#endif  // CORE_INCLUDE_FXCRT_FX_BIDI_H_