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/*
* Copyright (C) 2010, 2013, 2016 Apple Inc. All rights reserved.
* Copyright (C) 2012 Google 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.
*/
#include "config.h"
#include "StringBuilder.h"
#include "IntegerToStringConversion.h"
#include "MathExtras.h"
#include "WTFString.h"
#include <wtf/dtoa.h>
namespace WTF {
static unsigned expandedCapacity(unsigned capacity, unsigned requiredLength)
{
static const unsigned minimumCapacity = 16;
return std::max(requiredLength, std::max(minimumCapacity, capacity * 2));
}
void StringBuilder::reifyString() const
{
// Check if the string already exists.
if (!m_string.isNull()) {
ASSERT(m_string.length() == m_length);
return;
}
// Check for empty.
if (!m_length) {
m_string = StringImpl::empty();
return;
}
// Must be valid in the buffer, take a substring (unless string fills the buffer).
ASSERT(m_buffer && m_length <= m_buffer->length());
if (m_length == m_buffer->length())
m_string = m_buffer.get();
else
m_string = StringImpl::createSubstringSharingImpl(*m_buffer, 0, m_length);
}
void StringBuilder::resize(unsigned newSize)
{
// Check newSize < m_length, hence m_length > 0.
ASSERT(newSize <= m_length);
if (newSize == m_length)
return;
ASSERT(m_length);
// If there is a buffer, we only need to duplicate it if it has more than one ref.
if (m_buffer) {
m_string = String(); // Clear the string to remove the reference to m_buffer if any before checking the reference count of m_buffer.
if (!m_buffer->hasOneRef()) {
if (m_buffer->is8Bit())
allocateBuffer(m_buffer->characters8(), m_buffer->length());
else
allocateBuffer(m_buffer->characters16(), m_buffer->length());
}
m_length = newSize;
ASSERT(m_buffer->length() >= m_length);
return;
}
// Since m_length && !m_buffer, the string must be valid in m_string, and m_string.length() > 0.
ASSERT(!m_string.isEmpty());
ASSERT(m_length == m_string.length());
ASSERT(newSize < m_string.length());
m_length = newSize;
m_string = StringImpl::createSubstringSharingImpl(*m_string.impl(), 0, newSize);
}
// Allocate a new 8 bit buffer, copying in currentCharacters (these may come from either m_string
// or m_buffer, neither will be reassigned until the copy has completed).
void StringBuilder::allocateBuffer(const LChar* currentCharacters, unsigned requiredLength)
{
ASSERT(m_is8Bit);
// Copy the existing data into a new buffer, set result to point to the end of the existing data.
auto buffer = StringImpl::createUninitialized(requiredLength, m_bufferCharacters8);
memcpy(m_bufferCharacters8, currentCharacters, static_cast<size_t>(m_length) * sizeof(LChar)); // This can't overflow.
// Update the builder state.
m_buffer = WTFMove(buffer);
m_string = String();
ASSERT(m_buffer->length() == requiredLength);
}
// Allocate a new 16 bit buffer, copying in currentCharacters (these may come from either m_string
// or m_buffer, neither will be reassigned until the copy has completed).
void StringBuilder::allocateBuffer(const UChar* currentCharacters, unsigned requiredLength)
{
ASSERT(!m_is8Bit);
// Copy the existing data into a new buffer, set result to point to the end of the existing data.
auto buffer = StringImpl::createUninitialized(requiredLength, m_bufferCharacters16);
memcpy(m_bufferCharacters16, currentCharacters, static_cast<size_t>(m_length) * sizeof(UChar)); // This can't overflow.
// Update the builder state.
m_buffer = WTFMove(buffer);
m_string = String();
ASSERT(m_buffer->length() == requiredLength);
}
// Allocate a new 16 bit buffer, copying in currentCharacters (which is 8 bit and may come
// from either m_string or m_buffer, neither will be reassigned until the copy has completed).
void StringBuilder::allocateBufferUpConvert(const LChar* currentCharacters, unsigned requiredLength)
{
ASSERT(m_is8Bit);
ASSERT(requiredLength >= m_length);
// Copy the existing data into a new buffer, set result to point to the end of the existing data.
auto buffer = StringImpl::createUninitialized(requiredLength, m_bufferCharacters16);
for (unsigned i = 0; i < m_length; ++i)
m_bufferCharacters16[i] = currentCharacters[i];
m_is8Bit = false;
// Update the builder state.
m_buffer = WTFMove(buffer);
m_string = String();
ASSERT(m_buffer->length() == requiredLength);
}
template <>
void StringBuilder::reallocateBuffer<LChar>(unsigned requiredLength)
{
// If the buffer has only one ref (by this StringBuilder), reallocate it,
// otherwise fall back to "allocate and copy" method.
m_string = String();
ASSERT(m_is8Bit);
ASSERT(m_buffer->is8Bit());
if (m_buffer->hasOneRef())
m_buffer = StringImpl::reallocate(m_buffer.releaseNonNull(), requiredLength, m_bufferCharacters8);
else
allocateBuffer(m_buffer->characters8(), requiredLength);
ASSERT(m_buffer->length() == requiredLength);
}
template <>
void StringBuilder::reallocateBuffer<UChar>(unsigned requiredLength)
{
// If the buffer has only one ref (by this StringBuilder), reallocate it,
// otherwise fall back to "allocate and copy" method.
m_string = String();
if (m_buffer->is8Bit())
allocateBufferUpConvert(m_buffer->characters8(), requiredLength);
else if (m_buffer->hasOneRef())
m_buffer = StringImpl::reallocate(m_buffer.releaseNonNull(), requiredLength, m_bufferCharacters16);
else
allocateBuffer(m_buffer->characters16(), requiredLength);
ASSERT(m_buffer->length() == requiredLength);
}
void StringBuilder::reserveCapacity(unsigned newCapacity)
{
if (m_buffer) {
// If there is already a buffer, then grow if necessary.
if (newCapacity > m_buffer->length()) {
if (m_buffer->is8Bit())
reallocateBuffer<LChar>(newCapacity);
else
reallocateBuffer<UChar>(newCapacity);
}
} else {
// Grow the string, if necessary.
if (newCapacity > m_length) {
if (!m_length) {
LChar* nullPlaceholder = 0;
allocateBuffer(nullPlaceholder, newCapacity);
} else if (m_string.is8Bit())
allocateBuffer(m_string.characters8(), newCapacity);
else
allocateBuffer(m_string.characters16(), newCapacity);
}
}
ASSERT(!newCapacity || m_buffer->length() >= newCapacity);
}
// Make 'length' additional capacity be available in m_buffer, update m_string & m_length,
// return a pointer to the newly allocated storage.
template <typename CharType>
ALWAYS_INLINE CharType* StringBuilder::appendUninitialized(unsigned length)
{
ASSERT(length);
// Calculate the new size of the builder after appending.
unsigned requiredLength = length + m_length;
if (requiredLength < length)
CRASH();
if ((m_buffer) && (requiredLength <= m_buffer->length())) {
// If the buffer is valid it must be at least as long as the current builder contents!
ASSERT(m_buffer->length() >= m_length);
unsigned currentLength = m_length;
m_string = String();
m_length = requiredLength;
return getBufferCharacters<CharType>() + currentLength;
}
return appendUninitializedSlow<CharType>(requiredLength);
}
// Make 'length' additional capacity be available in m_buffer, update m_string & m_length,
// return a pointer to the newly allocated storage.
template <typename CharType>
CharType* StringBuilder::appendUninitializedSlow(unsigned requiredLength)
{
ASSERT(requiredLength);
if (m_buffer) {
// If the buffer is valid it must be at least as long as the current builder contents!
ASSERT(m_buffer->length() >= m_length);
reallocateBuffer<CharType>(expandedCapacity(capacity(), requiredLength));
} else {
ASSERT(m_string.length() == m_length);
allocateBuffer(m_length ? m_string.characters<CharType>() : 0, expandedCapacity(capacity(), requiredLength));
}
CharType* result = getBufferCharacters<CharType>() + m_length;
m_length = requiredLength;
ASSERT(m_buffer->length() >= m_length);
return result;
}
void StringBuilder::append(const UChar* characters, unsigned length)
{
if (!length)
return;
ASSERT(characters);
if (m_is8Bit) {
if (length == 1 && !(*characters & ~0xff)) {
// Append as 8 bit character
LChar lChar = static_cast<LChar>(*characters);
append(&lChar, 1);
return;
}
// Calculate the new size of the builder after appending.
unsigned requiredLength = length + m_length;
if (requiredLength < length)
CRASH();
if (m_buffer) {
// If the buffer is valid it must be at least as long as the current builder contents!
ASSERT(m_buffer->length() >= m_length);
allocateBufferUpConvert(m_buffer->characters8(), expandedCapacity(capacity(), requiredLength));
} else {
ASSERT(m_string.length() == m_length);
allocateBufferUpConvert(m_string.isNull() ? 0 : m_string.characters8(), expandedCapacity(capacity(), requiredLength));
}
memcpy(m_bufferCharacters16 + m_length, characters, static_cast<size_t>(length) * sizeof(UChar));
m_length = requiredLength;
} else
memcpy(appendUninitialized<UChar>(length), characters, static_cast<size_t>(length) * sizeof(UChar));
ASSERT(m_buffer->length() >= m_length);
}
void StringBuilder::append(const LChar* characters, unsigned length)
{
if (!length)
return;
ASSERT(characters);
if (m_is8Bit) {
LChar* dest = appendUninitialized<LChar>(length);
if (length > 8)
memcpy(dest, characters, static_cast<size_t>(length) * sizeof(LChar));
else {
const LChar* end = characters + length;
while (characters < end)
*(dest++) = *(characters++);
}
} else {
UChar* dest = appendUninitialized<UChar>(length);
const LChar* end = characters + length;
while (characters < end)
*(dest++) = *(characters++);
}
}
#if USE(CF)
void StringBuilder::append(CFStringRef string)
{
// Fast path: avoid constructing a temporary String when possible.
if (auto* characters = CFStringGetCStringPtr(string, kCFStringEncodingISOLatin1)) {
append(reinterpret_cast<const LChar*>(characters), CFStringGetLength(string));
return;
}
append(String(string));
}
#endif
void StringBuilder::appendNumber(int number)
{
numberToStringSigned<StringBuilder>(number, this);
}
void StringBuilder::appendNumber(unsigned int number)
{
numberToStringUnsigned<StringBuilder>(number, this);
}
void StringBuilder::appendNumber(long number)
{
numberToStringSigned<StringBuilder>(number, this);
}
void StringBuilder::appendNumber(unsigned long number)
{
numberToStringUnsigned<StringBuilder>(number, this);
}
void StringBuilder::appendNumber(long long number)
{
numberToStringSigned<StringBuilder>(number, this);
}
void StringBuilder::appendNumber(unsigned long long number)
{
numberToStringUnsigned<StringBuilder>(number, this);
}
void StringBuilder::appendNumber(double number, unsigned precision, TrailingZerosTruncatingPolicy trailingZerosTruncatingPolicy)
{
NumberToStringBuffer buffer;
append(numberToFixedPrecisionString(number, precision, buffer, trailingZerosTruncatingPolicy == TruncateTrailingZeros));
}
void StringBuilder::appendECMAScriptNumber(double number)
{
NumberToStringBuffer buffer;
append(numberToString(number, buffer));
}
void StringBuilder::appendFixedWidthNumber(double number, unsigned decimalPlaces)
{
NumberToStringBuffer buffer;
append(numberToFixedWidthString(number, decimalPlaces, buffer));
}
bool StringBuilder::canShrink() const
{
// Only shrink the buffer if it's less than 80% full. Need to tune this heuristic!
return m_buffer && m_buffer->length() > (m_length + (m_length >> 2));
}
void StringBuilder::shrinkToFit()
{
if (canShrink()) {
if (m_is8Bit)
reallocateBuffer<LChar>(m_length);
else
reallocateBuffer<UChar>(m_length);
m_string = WTFMove(m_buffer);
}
}
} // namespace WTF