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#include "config.h"
23#include "BidiContext.h"
24#include <wtf/Vector.h>
25
26namespace WebCore {
27
28using namespace WTF::Unicode;
29
30struct SameSizeAsBidiContext : public RefCounted<SameSizeAsBidiContext> {
31    uint32_t bitfields : 16;
32    void* parent;
33};
34
35COMPILE_ASSERT(sizeof(BidiContext) == sizeof(SameSizeAsBidiContext), BidiContext_should_stay_small);
36
37inline PassRefPtr<BidiContext> BidiContext::createUncached(unsigned char level, Direction direction, bool override, BidiEmbeddingSource source, BidiContext* parent)
38{
39    return adoptRef(new BidiContext(level, direction, override, source, parent));
40}
41
42PassRefPtr<BidiContext> BidiContext::create(unsigned char level, Direction direction, bool override, BidiEmbeddingSource source, BidiContext* parent)
43{
44    ASSERT(direction == (level % 2 ? RightToLeft : LeftToRight));
45
46    if (parent)
47        return createUncached(level, direction, override, source, parent);
48
49    ASSERT(level <= 1);
50    if (!level) {
51        if (!override) {
52            static BidiContext* ltrContext = createUncached(0, LeftToRight, false, FromStyleOrDOM, 0).leakRef();
53            return ltrContext;
54        }
55
56        static BidiContext* ltrOverrideContext = createUncached(0, LeftToRight, true, FromStyleOrDOM, 0).leakRef();
57        return ltrOverrideContext;
58    }
59
60    if (!override) {
61        static BidiContext* rtlContext = createUncached(1, RightToLeft, false, FromStyleOrDOM, 0).leakRef();
62        return rtlContext;
63    }
64
65    static BidiContext* rtlOverrideContext = createUncached(1, RightToLeft, true, FromStyleOrDOM, 0).leakRef();
66    return rtlOverrideContext;
67}
68
69static inline PassRefPtr<BidiContext> copyContextAndRebaselineLevel(BidiContext* context, BidiContext* parent)
70{
71    ASSERT(context);
72    unsigned char newLevel = parent ? parent->level() : 0;
73    if (context->dir() == RightToLeft)
74        newLevel = nextGreaterOddLevel(newLevel);
75    else if (parent)
76        newLevel = nextGreaterEvenLevel(newLevel);
77
78    return BidiContext::create(newLevel, context->dir(), context->override(), context->source(), parent);
79}
80
81// The BidiContext stack must be immutable -- they're re-used for re-layout after
82// DOM modification/editing -- so we copy all the non-unicode contexts, and
83// recalculate their levels.
84PassRefPtr<BidiContext> BidiContext::copyStackRemovingUnicodeEmbeddingContexts()
85{
86    Vector<BidiContext*, 64> contexts;
87    for (BidiContext* iter = this; iter; iter = iter->parent()) {
88        if (iter->source() != FromUnicode)
89            contexts.append(iter);
90    }
91    ASSERT(contexts.size());
92
93    RefPtr<BidiContext> topContext = copyContextAndRebaselineLevel(contexts.last(), 0);
94    for (int i = contexts.size() - 1; i > 0; --i)
95        topContext = copyContextAndRebaselineLevel(contexts[i - 1], topContext.get());
96
97    return topContext.release();
98}
99
100bool operator==(const BidiContext& c1, const BidiContext& c2)
101{
102    if (&c1 == &c2)
103        return true;
104    if (c1.level() != c2.level() || c1.override() != c2.override() || c1.dir() != c2.dir() || c1.source() != c2.source())
105        return false;
106    if (!c1.parent())
107        return !c2.parent();
108    return c2.parent() && *c1.parent() == *c2.parent();
109}
110
111} // namespace WebCore
112