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 "platform/text/BidiContext.h"
24
25#include "wtf/StdLibExtras.h"
26#include "wtf/Vector.h"
27
28namespace blink {
29
30using namespace WTF::Unicode;
31
32struct SameSizeAsBidiContext : public RefCounted<SameSizeAsBidiContext> {
33    uint32_t bitfields : 16;
34    void* parent;
35};
36
37COMPILE_ASSERT(sizeof(BidiContext) == sizeof(SameSizeAsBidiContext), BidiContext_should_stay_small);
38
39inline PassRefPtr<BidiContext> BidiContext::createUncached(unsigned char level, Direction direction, bool override, BidiEmbeddingSource source, BidiContext* parent)
40{
41    return adoptRef(new BidiContext(level, direction, override, source, parent));
42}
43
44PassRefPtr<BidiContext> BidiContext::create(unsigned char level, Direction direction, bool override, BidiEmbeddingSource source, BidiContext* parent)
45{
46    ASSERT(direction == (level % 2 ? RightToLeft : LeftToRight));
47
48    if (parent)
49        return createUncached(level, direction, override, source, parent);
50
51    ASSERT(level <= 1);
52    if (!level) {
53        if (!override) {
54            DEFINE_STATIC_REF(BidiContext, ltrContext, (createUncached(0, LeftToRight, false, FromStyleOrDOM, 0)));
55            return ltrContext;
56        }
57
58        DEFINE_STATIC_REF(BidiContext, ltrOverrideContext, (createUncached(0, LeftToRight, true, FromStyleOrDOM, 0)));
59        return ltrOverrideContext;
60    }
61
62    if (!override) {
63        DEFINE_STATIC_REF(BidiContext, rtlContext, (createUncached(1, RightToLeft, false, FromStyleOrDOM, 0)));
64        return rtlContext;
65    }
66
67    DEFINE_STATIC_REF(BidiContext, rtlOverrideContext, (createUncached(1, RightToLeft, true, FromStyleOrDOM, 0)));
68    return rtlOverrideContext;
69}
70
71static inline PassRefPtr<BidiContext> copyContextAndRebaselineLevel(BidiContext* context, BidiContext* parent)
72{
73    ASSERT(context);
74    unsigned char newLevel = parent ? parent->level() : 0;
75    if (context->dir() == RightToLeft)
76        newLevel = nextGreaterOddLevel(newLevel);
77    else if (parent)
78        newLevel = nextGreaterEvenLevel(newLevel);
79
80    return BidiContext::create(newLevel, context->dir(), context->override(), context->source(), parent);
81}
82
83// The BidiContext stack must be immutable -- they're re-used for re-layout after
84// DOM modification/editing -- so we copy all the non-unicode contexts, and
85// recalculate their levels.
86PassRefPtr<BidiContext> BidiContext::copyStackRemovingUnicodeEmbeddingContexts()
87{
88    Vector<BidiContext*, 64> contexts;
89    for (BidiContext* iter = this; iter; iter = iter->parent()) {
90        if (iter->source() != FromUnicode)
91            contexts.append(iter);
92    }
93    ASSERT(contexts.size());
94
95    RefPtr<BidiContext> topContext = copyContextAndRebaselineLevel(contexts.last(), 0);
96    for (int i = contexts.size() - 1; i > 0; --i)
97        topContext = copyContextAndRebaselineLevel(contexts[i - 1], topContext.get());
98
99    return topContext.release();
100}
101
102bool operator==(const BidiContext& c1, const BidiContext& c2)
103{
104    if (&c1 == &c2)
105        return true;
106    if (c1.level() != c2.level() || c1.override() != c2.override() || c1.dir() != c2.dir() || c1.source() != c2.source())
107        return false;
108    if (!c1.parent())
109        return !c2.parent();
110    return c2.parent() && *c1.parent() == *c2.parent();
111}
112
113} // namespace blink
114