Extract WebCoreStringResouce out of V8StringResource

third_party/WebKit/Source/bindings/core/v8/V8StringResource.cpp

-/*
- * Copyright (C) 2009 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. AND ITS CONTRIBUTORS ``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 ITS 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 "bindings/core/v8/V8StringResource.h"
-
-#include "bindings/core/v8/V8Binding.h"
-
-namespace blink {
-
-template <class StringClass>
-struct StringTraits {
-  static const StringClass& FromStringResource(WebCoreStringResourceBase*);
-  template <typename V8StringTrait>
-  static StringClass FromV8String(v8::Local<v8::String>, int);
-};
-
-template <>
-struct StringTraits<String> {
-  static const String& FromStringResource(WebCoreStringResourceBase* resource) {
-    return resource->WebcoreString();
-  }
-  template <typename V8StringTrait>
-  static String FromV8String(v8::Local<v8::String>, int);
-};
-
-template <>
-struct StringTraits<AtomicString> {
-  static const AtomicString& FromStringResource(
-      WebCoreStringResourceBase* resource) {
-    return resource->GetAtomicString();
-  }
-  template <typename V8StringTrait>
-  static AtomicString FromV8String(v8::Local<v8::String>, int);
-};
-
-struct V8StringTwoBytesTrait {
-  typedef UChar CharType;
-  ALWAYS_INLINE static void Write(v8::Local<v8::String> v8_string,
-                                  CharType* buffer,
-                                  int length) {
-    v8_string->Write(reinterpret_cast<uint16_t*>(buffer), 0, length);
-  }
-};
-
-struct V8StringOneByteTrait {
-  typedef LChar CharType;
-  ALWAYS_INLINE static void Write(v8::Local<v8::String> v8_string,
-                                  CharType* buffer,
-                                  int length) {
-    v8_string->WriteOneByte(buffer, 0, length);
-  }
-};
-
-template <typename V8StringTrait>
-String StringTraits<String>::FromV8String(v8::Local<v8::String> v8_string,
-                                          int length) {
-  DCHECK_EQ(v8_string->Length(), length);
-  typename V8StringTrait::CharType* buffer;
-  String result = String::CreateUninitialized(length, buffer);
-  V8StringTrait::Write(v8_string, buffer, length);
-  return result;
-}
-
-template <typename V8StringTrait>
-AtomicString StringTraits<AtomicString>::FromV8String(
-    v8::Local<v8::String> v8_string,
-    int length) {
-  DCHECK_EQ(v8_string->Length(), length);
-  static const int kInlineBufferSize =
-      32 / sizeof(typename V8StringTrait::CharType);
-  if (length <= kInlineBufferSize) {
-    typename V8StringTrait::CharType inline_buffer[kInlineBufferSize];
-    V8StringTrait::Write(v8_string, inline_buffer, length);
-    return AtomicString(inline_buffer, length);
-  }
-  typename V8StringTrait::CharType* buffer;
-  String string = String::CreateUninitialized(length, buffer);
-  V8StringTrait::Write(v8_string, buffer, length);
-  return AtomicString(string);
-}
-
-template <typename StringType>
-StringType V8StringToWebCoreString(v8::Local<v8::String> v8_string,
-                                   ExternalMode external) {
-  {
-    // This portion of this function is very hot in certain Dromeao benchmarks.
-    v8::String::Encoding encoding;
-    v8::String::ExternalStringResourceBase* resource =
-        v8_string->GetExternalStringResourceBase(&encoding);
-    if (LIKELY(!!resource)) {
-      WebCoreStringResourceBase* base;
-      if (encoding == v8::String::ONE_BYTE_ENCODING)
-        base = static_cast<WebCoreStringResource8*>(resource);
-      else
-        base = static_cast<WebCoreStringResource16*>(resource);
-      return StringTraits<StringType>::FromStringResource(base);
-    }
-  }
-
-  int length = v8_string->Length();
-  if (UNLIKELY(!length))
-    return StringType("");
-
-  bool one_byte = v8_string->ContainsOnlyOneByte();
-  StringType result(one_byte ? StringTraits<StringType>::template FromV8String<
-                                   V8StringOneByteTrait>(v8_string, length)
-                             : StringTraits<StringType>::template FromV8String<
-                                   V8StringTwoBytesTrait>(v8_string, length));
-
-  if (external != kExternalize || !v8_string->CanMakeExternal())
-    return result;
-
-  if (result.Is8Bit()) {
-    WebCoreStringResource8* string_resource =
-        new WebCoreStringResource8(result);
-    if (UNLIKELY(!v8_string->MakeExternal(string_resource)))
-      delete string_resource;
-  } else {
-    WebCoreStringResource16* string_resource =
-        new WebCoreStringResource16(result);
-    if (UNLIKELY(!v8_string->MakeExternal(string_resource)))
-      delete string_resource;
-  }
-  return result;
-}
-
-// Explicitly instantiate the above template with the expected
-// parameterizations, to ensure the compiler generates the code; otherwise link
-// errors can result in GCC 4.4.
-template String V8StringToWebCoreString<String>(v8::Local<v8::String>,
-                                                ExternalMode);
-template AtomicString V8StringToWebCoreString<AtomicString>(
-    v8::Local<v8::String>,
-    ExternalMode);
-
-// Fast but non thread-safe version.
-String Int32ToWebCoreStringFast(int value) {
-  // Caching of small strings below is not thread safe: newly constructed
-  // AtomicString are not safely published.
-  DCHECK(IsMainThread());
-
-  // Most numbers used are <= 100. Even if they aren't used there's very little
-  // cost in using the space.
-  const int kLowNumbers = 100;
-  DEFINE_STATIC_LOCAL(Vector<AtomicString>, low_numbers, (kLowNumbers + 1));
-  String web_core_string;
-  if (0 <= value && value <= kLowNumbers) {
-    web_core_string = low_numbers[value];
-    if (!web_core_string) {
-      AtomicString value_string = AtomicString::Number(value);
-      low_numbers[value] = value_string;
-      web_core_string = value_string;
-    }
-  } else {
-    web_core_string = String::Number(value);
-  }
-  return web_core_string;
-}
-
-String Int32ToWebCoreString(int value) {
-  // If we are on the main thread (this should always true for non-workers),
-  // call the faster one.
-  if (IsMainThread())
-    return Int32ToWebCoreStringFast(value);
-  return String::Number(value);
-}
-
-}  // namespace blink