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/*
* Copyright (C) 2010 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.
*/
#include "config.h"
#include "StringBuilder.h"
#include "WTFString.h"
namespace WTF {
void StringBuilder::reifyString()
{
// 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());
m_string = (m_length == m_buffer->length())
? m_buffer.get()
: StringImpl::create(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) {
if (!m_buffer->hasOneRef())
allocateBuffer(m_buffer->characters(), m_buffer->length());
m_length = newSize;
m_string = String();
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::create(m_string.impl(), 0, newSize);
}
void StringBuilder::reserveCapacity(unsigned newCapacity)
{
if (m_buffer) {
// If there is already a buffer, then grow if necessary.
if (newCapacity > m_buffer->length())
allocateBuffer(m_buffer->characters(), newCapacity);
} else {
// Grow the string, if necessary.
if (newCapacity > m_length)
allocateBuffer(m_string.characters(), newCapacity);
}
}
// Allocate a new 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)
{
// Copy the existing data into a new buffer, set result to point to the end of the existing data.
RefPtr<StringImpl> buffer = StringImpl::createUninitialized(requiredLength, m_bufferCharacters);
memcpy(m_bufferCharacters, currentCharacters, static_cast<size_t>(m_length) * sizeof(UChar)); // This can't overflow.
// Update the builder state.
m_buffer = buffer.release();
m_string = String();
}
// Make 'length' additional capacity be available in m_buffer, update m_string & m_length,
// return a pointer to the newly allocated storage.
UChar* StringBuilder::appendUninitialized(unsigned length)
{
ASSERT(length);
// Calcuate 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);
// Check if the buffer already has sufficient capacity.
if (requiredLength <= m_buffer->length()) {
unsigned currentLength = m_length;
m_string = String();
m_length = requiredLength;
return m_bufferCharacters + currentLength;
}
// We need to realloc the buffer.
allocateBuffer(m_buffer->characters(), std::max(requiredLength, m_buffer->length() * 2));
} else {
ASSERT(m_string.length() == m_length);
allocateBuffer(m_string.characters(), std::max(requiredLength, requiredLength * 2));
}
UChar* result = m_bufferCharacters + m_length;
m_length = requiredLength;
return result;
}
void StringBuilder::append(const UChar* characters, unsigned length)
{
if (!length)
return;
ASSERT(characters);
memcpy(appendUninitialized(length), characters, static_cast<size_t>(length) * 2);
}
void StringBuilder::append(const char* characters, unsigned length)
{
if (!length)
return;
ASSERT(characters);
UChar* dest = appendUninitialized(length);
const char* end = characters + length;
while (characters < end)
*(dest++) = *(const unsigned char*)(characters++);
}
void StringBuilder::shrinkToFit()
{
// If the buffer is at least 80% full, don't bother copying. Need to tune this heuristic!
if (m_buffer && m_buffer->length() > (m_length + (m_length >> 2))) {
UChar* result;
m_string = StringImpl::createUninitialized(m_length, result);
memcpy(result, m_buffer->characters(), static_cast<size_t>(m_length) * 2); // This can't overflow.
m_buffer = 0;
}
}
} // namespace WTF
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