1// Copyright 2014 PDFium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5// Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
6
7#ifndef CORE_FXCRT_FX_BIDI_H_
8#define CORE_FXCRT_FX_BIDI_H_
9
10#include <memory>
11#include <vector>
12
13#include "core/fxcrt/fx_string.h"
14#include "core/fxcrt/fx_system.h"
15
16// Processes characters and group them into segments based on text direction.
17class CFX_BidiChar {
18 public:
19  enum Direction { NEUTRAL, LEFT, RIGHT };
20  struct Segment {
21    int32_t start;        // Start position.
22    int32_t count;        // Character count.
23    Direction direction;  // Segment direction.
24  };
25
26  CFX_BidiChar();
27
28  // Append a character and classify it as left, right, or neutral.
29  // Returns true if the character has a different direction than the
30  // existing direction to indicate there is a segment to process.
31  bool AppendChar(FX_WCHAR wch);
32
33  // Call this after the last character has been appended. AppendChar()
34  // must not be called after this.
35  // Returns true if there is still a segment to process.
36  bool EndChar();
37
38  // Call after a change in direction is indicated by the above to get
39  // information about the segment to process.
40  Segment GetSegmentInfo() const { return m_LastSegment; }
41
42 private:
43  void StartNewSegment(CFX_BidiChar::Direction direction);
44
45  Segment m_CurrentSegment;
46  Segment m_LastSegment;
47};
48
49class CFX_BidiString {
50 public:
51  using const_iterator = std::vector<CFX_BidiChar::Segment>::const_iterator;
52
53  explicit CFX_BidiString(const CFX_WideString& str);
54  ~CFX_BidiString();
55
56  // Overall direction is always LEFT or RIGHT, never NEUTRAL.
57  CFX_BidiChar::Direction OverallDirection() const {
58    return m_eOverallDirection;
59  }
60
61  // Force the overall direction to be R2L regardless of what was detected.
62  void SetOverallDirectionRight();
63
64  FX_WCHAR CharAt(size_t x) const { return m_Str[x]; }
65  const_iterator begin() const { return m_Order.begin(); }
66  const_iterator end() const { return m_Order.end(); }
67
68 private:
69  const CFX_WideString m_Str;
70  std::unique_ptr<CFX_BidiChar> m_pBidiChar;
71  std::vector<CFX_BidiChar::Segment> m_Order;
72  CFX_BidiChar::Direction m_eOverallDirection;
73};
74
75#endif  // CORE_FXCRT_FX_BIDI_H_
76