1/*
2 * Copyright (C) 2000 Lars Knoll (knoll@kde.org)
3 * Copyright (C) 2003, 2004, 2006, 2007, 2009, 2010 Apple Inc. All right reserved.
4 *
5 * This library is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU Library General Public
7 * License as published by the Free Software Foundation; either
8 * version 2 of the License, or (at your option) any later version.
9 *
10 * This library is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
13 * Library General Public License for more details.
14 *
15 * You should have received a copy of the GNU Library General Public License
16 * along with this library; see the file COPYING.LIB.  If not, write to
17 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
18 * Boston, MA 02110-1301, USA.
19 *
20 */
21
22#ifndef BidiContext_h
23#define BidiContext_h
24
25#include <wtf/Assertions.h>
26#include <wtf/PassRefPtr.h>
27#include <wtf/RefCounted.h>
28#include <wtf/RefPtr.h>
29#include <wtf/unicode/Unicode.h>
30
31namespace WebCore {
32
33enum BidiEmbeddingSource {
34    FromStyleOrDOM,
35    FromUnicode
36};
37
38// Used to keep track of explicit embeddings.
39class BidiContext : public RefCounted<BidiContext> {
40public:
41    static PassRefPtr<BidiContext> create(unsigned char level, WTF::Unicode::Direction, bool override = false, BidiEmbeddingSource = FromStyleOrDOM, BidiContext* parent = 0);
42
43    BidiContext* parent() const { return m_parent.get(); }
44    unsigned char level() const { return m_level; }
45    WTF::Unicode::Direction dir() const { return static_cast<WTF::Unicode::Direction>(m_direction); }
46    bool override() const { return m_override; }
47    BidiEmbeddingSource source() const { return static_cast<BidiEmbeddingSource>(m_source); }
48
49    PassRefPtr<BidiContext> copyStackRemovingUnicodeEmbeddingContexts();
50private:
51    BidiContext(unsigned char level, WTF::Unicode::Direction direction, bool override, BidiEmbeddingSource source, BidiContext* parent)
52        : m_level(level)
53        , m_direction(direction)
54        , m_override(override)
55        , m_source(source)
56        , m_parent(parent)
57    {
58    }
59
60    static PassRefPtr<BidiContext> createUncached(unsigned char level, WTF::Unicode::Direction, bool override, BidiEmbeddingSource, BidiContext* parent);
61
62    unsigned m_level : 6; // The maximium bidi level is 62: http://unicode.org/reports/tr9/#Explicit_Levels_and_Directions
63    unsigned m_direction : 5; // Direction
64    unsigned m_override : 1;
65    unsigned m_source : 1; // BidiEmbeddingSource
66    RefPtr<BidiContext> m_parent;
67};
68
69inline unsigned char nextGreaterOddLevel(unsigned char level)
70{
71    return (level + 1) | 1;
72}
73
74inline unsigned char nextGreaterEvenLevel(unsigned char level)
75{
76    return (level + 2) & ~1;
77}
78
79bool operator==(const BidiContext&, const BidiContext&);
80
81} // namespace WebCore
82
83#endif // BidiContext_h
84