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/*
* Copyright (C) 2000 Lars Knoll (knoll@kde.org)
* Copyright (C) 2003-2017 Apple Inc. All right reserved.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public License
* along with this library; see the file COPYING.LIB. If not, write to
* the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
* Boston, MA 02110-1301, USA.
*
*/
#include "config.h"
#include "BidiContext.h"
#include <mutex>
#include <wtf/NeverDestroyed.h>
#include <wtf/Vector.h>
namespace WebCore {
struct SameSizeAsBidiContext : public ThreadSafeRefCounted<SameSizeAsBidiContext> {
uint32_t bitfields : 16;
void* parent;
};
static_assert(sizeof(BidiContext) == sizeof(SameSizeAsBidiContext), "BidiContext should stay small");
inline BidiContext::BidiContext(unsigned char level, UCharDirection direction, bool override, BidiEmbeddingSource source, BidiContext* parent)
: m_level(level)
, m_direction(direction)
, m_override(override)
, m_source(source)
, m_parent(parent)
{
}
inline Ref<BidiContext> BidiContext::createUncached(unsigned char level, UCharDirection direction, bool override, BidiEmbeddingSource source, BidiContext* parent)
{
return adoptRef(*new BidiContext(level, direction, override, source, parent));
}
Ref<BidiContext> BidiContext::create(unsigned char level, UCharDirection direction, bool override, BidiEmbeddingSource source, BidiContext* parent)
{
ASSERT(direction == (level % 2 ? U_RIGHT_TO_LEFT : U_LEFT_TO_RIGHT));
if (parent)
return createUncached(level, direction, override, source, parent);
ASSERT(level <= 1);
if (!level) {
if (!override) {
static NeverDestroyed<RefPtr<BidiContext>> ltrContext;
static std::once_flag ltrContextOnceFlag;
std::call_once(ltrContextOnceFlag, [&]() {
ltrContext.get() = createUncached(0, U_LEFT_TO_RIGHT, false, FromStyleOrDOM, 0);
});
return *ltrContext.get();
}
static NeverDestroyed<RefPtr<BidiContext>> ltrOverrideContext;
static std::once_flag ltrOverrideContextOnceFlag;
std::call_once(ltrOverrideContextOnceFlag, [&]() {
ltrOverrideContext.get() = createUncached(0, U_LEFT_TO_RIGHT, true, FromStyleOrDOM, 0);
});
return *ltrOverrideContext.get();
}
if (!override) {
static NeverDestroyed<RefPtr<BidiContext>> rtlContext;
static std::once_flag rtlContextOnceFlag;
std::call_once(rtlContextOnceFlag, [&]() {
rtlContext.get() = createUncached(1, U_RIGHT_TO_LEFT, false, FromStyleOrDOM, 0);
});
return *rtlContext.get();
}
static NeverDestroyed<RefPtr<BidiContext>> rtlOverrideContext;
static std::once_flag rtlOverrideContextOnceFlag;
std::call_once(rtlOverrideContextOnceFlag, [&]() {
rtlOverrideContext.get() = createUncached(1, U_RIGHT_TO_LEFT, true, FromStyleOrDOM, 0);
});
return *rtlOverrideContext.get();
}
static inline Ref<BidiContext> copyContextAndRebaselineLevel(BidiContext& context, BidiContext* parent)
{
auto newLevel = parent ? parent->level() : 0;
if (context.dir() == U_RIGHT_TO_LEFT)
newLevel = nextGreaterOddLevel(newLevel);
else if (parent)
newLevel = nextGreaterEvenLevel(newLevel);
return BidiContext::create(newLevel, context.dir(), context.override(), context.source(), parent);
}
// The BidiContext stack must be immutable -- they're re-used for re-layout after
// DOM modification/editing -- so we copy all the non-Unicode contexts, and
// recalculate their levels.
Ref<BidiContext> BidiContext::copyStackRemovingUnicodeEmbeddingContexts()
{
Vector<BidiContext*, 64> contexts;
for (auto* ancestor = this; ancestor; ancestor = ancestor->parent()) {
if (ancestor->source() != FromUnicode)
contexts.append(ancestor);
}
ASSERT(contexts.size());
auto topContext = copyContextAndRebaselineLevel(*contexts.last(), nullptr);
for (unsigned i = contexts.size() - 1; i; --i)
topContext = copyContextAndRebaselineLevel(*contexts[i - 1], topContext.ptr());
return topContext;
}
bool operator==(const BidiContext& c1, const BidiContext& c2)
{
if (&c1 == &c2)
return true;
if (c1.level() != c2.level() || c1.override() != c2.override() || c1.dir() != c2.dir() || c1.source() != c2.source())
return false;
if (!c1.parent())
return !c2.parent();
return c2.parent() && *c1.parent() == *c2.parent();
}
} // namespace WebCore
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