WIP: Introduce CompressibleString

third_party/WebKit/Source/platform/text/CompressableString.h

+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CompressableString_h
+#define CompressableString_h
+
+#include "platform/MemoryPurgeController.h"
+#include "platform/SharedBuffer.h"
+#include "wtf/HashTableDeletedValueType.h"
+#include "wtf/text/Unicode.h"
+#include "wtf/text/WTFString.h"
+
+namespace blink {
+
+struct CompressableStringHash;
+
+class WTF_EXPORT CompressableStringImpl : public RefCounted<CompressableStringImpl> {

[haraken, 2015/11/24 11:15:42]

The design of CompressableStringImpl and CompressableString looks good.

[hajimehoshi, 2015/11/26 10:49:13]

Thanks.

+    WTF_MAKE_NONCOPYABLE(CompressableStringImpl);
+public:
+    static void purgeMemory();
+
+    CompressableStringImpl(PassRefPtr<StringImpl>);
+
+    bool isEmpty() const { return m_originalLength == 0; }
+
+    PassRefPtr<StringImpl> impl() { return m_impl; }
+    PassRefPtr<SharedBuffer> compressedData() { return m_compressedData; }
+    bool isCompressed() const { return !!m_compressedData; }
+    unsigned originalLength() const { return m_originalLength; }
+    bool is8Bit() const { return m_is8Bit; }
+
+    unsigned sizeInBytes() const;
+
+    String toString();
+    const LChar* characters8();
+    const UChar* characters16();
+
+    void compress();
+    void uncompress();
+
+private:
+    RefPtr<StringImpl> m_impl;
+    RefPtr<SharedBuffer> m_compressedData;
+    const unsigned m_originalLength;
+    const bool m_is8Bit;
+};
+
+class WTF_EXPORT CompressableString {
+public:
+    CompressableString();
+    CompressableString(const CompressableString&);
+    explicit CompressableString(PassRefPtr<StringImpl>);
+
+    bool isNull() const { return !m_impl; }
+    bool isEmpty() const { return !m_impl || m_impl->isEmpty(); }
+    unsigned length() const { return !m_impl ? 0 : m_impl->originalLength(); }
+
+    // TODO(hajimehoshi): This name is confusing because StringImpl::sizeInBytes
+    // includes the size of StringImpl itself but this doesn't.
+    unsigned sizeInBytes() const { return !m_impl ? 0 : m_impl->sizeInBytes(); }
+
+    bool isCompressed() const { return m_impl->isCompressed(); }
+    bool is8Bit() const { return m_impl->is8Bit(); }
+
+    String toString() const { return m_impl->toString(); }
+    const LChar* characters8() const { return m_impl->characters8(); }
+    const UChar* characters16() const { return m_impl->characters16(); }
+
+    PassRefPtr<CompressableStringImpl> impl() const { return m_impl; }
+
+private:
+    void compress() const;
+    void uncompress() const;
+
+    mutable RefPtr<CompressableStringImpl> m_impl;
+};
+
+} // namespace blink
+
+#endif