--- /dev/null
+/*
+ * 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
projects / apple / javascriptcore.git / blobdiff