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/*
* Copyright (C) 2012-2016 Apple Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#pragma once
#include "ExceptionHelpers.h"
#include "JSCJSValue.h"
namespace JSC {
class JSStringJoiner {
public:
JSStringJoiner(ExecState&, LChar separator, unsigned stringCount);
JSStringJoiner(ExecState&, StringView separator, unsigned stringCount);
~JSStringJoiner();
void append(ExecState&, JSValue);
bool appendWithoutSideEffects(ExecState&, JSValue);
void appendEmptyString();
JSValue join(ExecState&);
private:
void append(StringViewWithUnderlyingString&&);
void append8Bit(const String&);
void appendLiteral(const Identifier&);
unsigned joinedLength(ExecState&) const;
LChar m_singleCharacterSeparator;
StringView m_separator;
Vector<StringViewWithUnderlyingString> m_strings;
Checked<unsigned, RecordOverflow> m_accumulatedStringsLength;
bool m_isAll8Bit { true };
};
inline JSStringJoiner::JSStringJoiner(ExecState& state, StringView separator, unsigned stringCount)
: m_separator(separator)
, m_isAll8Bit(m_separator.is8Bit())
{
VM& vm = state.vm();
auto scope = DECLARE_THROW_SCOPE(vm);
if (UNLIKELY(!m_strings.tryReserveCapacity(stringCount)))
throwOutOfMemoryError(&state, scope);
}
inline JSStringJoiner::JSStringJoiner(ExecState& state, LChar separator, unsigned stringCount)
: m_singleCharacterSeparator(separator)
, m_separator { &m_singleCharacterSeparator, 1 }
{
VM& vm = state.vm();
auto scope = DECLARE_THROW_SCOPE(vm);
if (UNLIKELY(!m_strings.tryReserveCapacity(stringCount)))
throwOutOfMemoryError(&state, scope);
}
ALWAYS_INLINE void JSStringJoiner::append(StringViewWithUnderlyingString&& string)
{
m_accumulatedStringsLength += string.view.length();
m_isAll8Bit = m_isAll8Bit && string.view.is8Bit();
m_strings.uncheckedAppend(WTFMove(string));
}
ALWAYS_INLINE void JSStringJoiner::append8Bit(const String& string)
{
ASSERT(string.is8Bit());
m_accumulatedStringsLength += string.length();
m_strings.uncheckedAppend({ string, string });
}
ALWAYS_INLINE void JSStringJoiner::appendLiteral(const Identifier& literal)
{
m_accumulatedStringsLength += literal.length();
ASSERT(literal.string().is8Bit());
m_strings.uncheckedAppend({ literal.string(), { } });
}
ALWAYS_INLINE void JSStringJoiner::appendEmptyString()
{
m_strings.uncheckedAppend({ { }, { } });
}
ALWAYS_INLINE bool JSStringJoiner::appendWithoutSideEffects(ExecState& state, JSValue value)
{
// The following code differs from using the result of JSValue::toString in the following ways:
// 1) It's inlined more than JSValue::toString is.
// 2) It includes conversion to WTF::String in a way that avoids allocating copies of substrings.
// 3) It doesn't create a JSString for numbers, true, or false.
// 4) It turns undefined and null into the empty string instead of "undefined" and "null".
// 5) It uses optimized code paths for all the cases known to be 8-bit and for the empty string.
// If we might make an effectful calls, return false. Otherwise return true.
if (value.isCell()) {
JSString* jsString;
if (!value.asCell()->isString())
return false;
jsString = asString(value);
append(jsString->viewWithUnderlyingString(state));
return true;
}
if (value.isInt32()) {
append8Bit(state.vm().numericStrings.add(value.asInt32()));
return true;
}
if (value.isDouble()) {
append8Bit(state.vm().numericStrings.add(value.asDouble()));
return true;
}
if (value.isTrue()) {
append8Bit(state.vm().propertyNames->trueKeyword.string());
return true;
}
if (value.isFalse()) {
append8Bit(state.vm().propertyNames->falseKeyword.string());
return true;
}
ASSERT(value.isUndefinedOrNull());
appendEmptyString();
return true;
}
ALWAYS_INLINE void JSStringJoiner::append(ExecState& state, JSValue value)
{
if (!appendWithoutSideEffects(state, value)) {
JSString* jsString = value.toString(&state);
append(jsString->viewWithUnderlyingString(state));
}
}
} // namespace JSC
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