1 files changed, 172 insertions, 0 deletions
diff --git a/Source/JavaScriptCore/wtf/text/StringBuilder.cpp b/Source/JavaScriptCore/wtf/text/StringBuilder.cpp
new file mode 100644
index 0000000..dfc9ff3
--- /dev/null
+++ b/Source/JavaScriptCore/wtf/text/StringBuilder.cpp
@@ -0,0 +1,172 @@
+/*
+ * 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