Use Traits in V8StringResource to avoid code duplication

Source/bindings/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
@@ skipping 34 matching lines @@
 
 void WebCoreStringResourceBase::visitStrings(ExternalStringVisitor* visitor)
 {
     visitor->visitJSExternalString(m_plainString.impl());
     if (m_plainString.impl() != m_atomicString.impl() && !m_atomicString.isNull())
         visitor->visitJSExternalString(m_atomicString.impl());
 }
 
 template<class StringClass> struct StringTraits {
     static const StringClass& fromStringResource(WebCoreStringResourceBase*);
-    template<bool oneByte>
+    template <typename V8StringTrait>
     static StringClass fromV8String(v8::Handle<v8::String>, int);
 };
 
 template<>
 struct StringTraits<String> {
     static const String& fromStringResource(WebCoreStringResourceBase* resource)
     {
         return resource->webcoreString();
     }
-    template<bool oneByte>
+    template <typename V8StringTrait>
     static String fromV8String(v8::Handle<v8::String>, int);
 };
 
 template<>
 struct StringTraits<AtomicString> {
     static const AtomicString& fromStringResource(WebCoreStringResourceBase* resource)
     {
         return resource->atomicString();
     }
-    template<bool oneByte>
+    template <typename V8StringTrait>
     static AtomicString fromV8String(v8::Handle<v8::String>, int);
 };
 
-template<>
-String StringTraits<String>::fromV8String<false>(v8::Handle<v8::String> v8String, int length)
+struct V8StringTwoBytesTrait {
+    typedef UChar CharType;
+    ALWAYS_INLINE static void write(v8::Handle<v8::String> v8String, CharType* buffer, int length)
+    {
+        v8String->Write(reinterpret_cast<uint16_t*>(buffer), 0, length);
+    }
+};
+
+struct V8StringOneByteTrait {
+    typedef LChar CharType;
+    ALWAYS_INLINE static void write(v8::Handle<v8::String> v8String, CharType* buffer, int length)
+    {
+        v8String->WriteOneByte(buffer, 0, length);
+    }
+};
+
+template <typename V8StringTrait>
+String StringTraits<String>::fromV8String(v8::Handle<v8::String> v8String, int length)
 {
     ASSERT(v8String->Length() == length);
-    UChar* buffer;
+    typename V8StringTrait::CharType* buffer;
     String result = String::createUninitialized(length, buffer);
-    v8String->Write(reinterpret_cast<uint16_t*>(buffer), 0, length);
+    V8StringTrait::write(v8String, buffer, length);
     return result;
 }
 
-template<>
-AtomicString StringTraits<AtomicString>::fromV8String<false>(v8::Handle<v8::String> v8String, int length)
+template <typename V8StringTrait>
+AtomicString StringTraits<AtomicString>::fromV8String(v8::Handle<v8::String> v8String, int length)
 {
     ASSERT(v8String->Length() == length);
-    static const int inlineBufferSize = 16;
+    static const int inlineBufferSize = 32 / sizeof(typename V8StringTrait::CharType);
     if (length <= inlineBufferSize) {
-        UChar inlineBuffer[inlineBufferSize];
-        v8String->Write(reinterpret_cast<uint16_t*>(inlineBuffer), 0, length);
+        typename V8StringTrait::CharType inlineBuffer[inlineBufferSize];
+        V8StringTrait::write(v8String, inlineBuffer, length);
         return AtomicString(inlineBuffer, length);
     }
-    UChar* buffer;
-    String result = String::createUninitialized(length, buffer);
-    v8String->Write(reinterpret_cast<uint16_t*>(buffer), 0, length);
-    return AtomicString(result);
-}
-
-template<>
-String StringTraits<String>::fromV8String<true>(v8::Handle<v8::String> v8String, int length)
-{
-    ASSERT(v8String->Length() == length);
-    LChar* buffer;
-    String result = String::createUninitialized(length, buffer);
-    v8String->WriteOneByte(buffer, 0, length);
-    return result;
-}
-
-template<>
-AtomicString StringTraits<AtomicString>::fromV8String<true>(v8::Handle<v8::String> v8String, int length)
-{
-    ASSERT(v8String->Length() == length);
-    static const int inlineBufferSize = 32;
-    if (length <= inlineBufferSize) {
-        LChar inlineBuffer[inlineBufferSize];
-        v8String->WriteOneByte(inlineBuffer, 0, length);
-        return AtomicString(inlineBuffer, length);
-    }
-    LChar* buffer;
+    typename V8StringTrait::CharType* buffer;
     String string = String::createUninitialized(length, buffer);
-    v8String->WriteOneByte(buffer, 0, length);
+    V8StringTrait::write(v8String, buffer, length);
     return AtomicString(string);
 }
 
 template<typename StringType>
 StringType v8StringToWebCoreString(v8::Handle<v8::String> v8String, ExternalMode external)
 {
     {
         // A lot of WebCoreStringResourceBase::toWebCoreStringResourceBase is copied here by hand for performance reasons.
         // This portion of this function is very hot in certain Dromeao benchmarks.
         v8::String::Encoding encoding;
         v8::String::ExternalStringResourceBase* resource = v8String->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 = v8String->Length();
     if (UNLIKELY(!length))
         return StringType("");
 
     bool oneByte = v8String->ContainsOnlyOneByte();
-    StringType result(oneByte ? StringTraits<StringType>::template fromV8String<true>(v8String, length) : StringTraits<StringType>::template fromV8String<false>(v8String, length));
+    StringType result(oneByte ? StringTraits<StringType>::template fromV8String<V8StringOneByteTrait>(v8String, length) : StringTraits<StringType>::template fromV8String<V8StringTwoBytesTrait>(v8String, length));
 
     if (external != Externalize || !v8String->CanMakeExternal())
         return result;
 
     if (result.is8Bit()) {
         WebCoreStringResource8* stringResource = new WebCoreStringResource8(result);
         if (UNLIKELY(!v8String->MakeExternal(stringResource)))
             delete stringResource;
     } else {
         WebCoreStringResource16* stringResource = new WebCoreStringResource16(result);
@@ skipping 33 matching lines @@
 
 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 WebCore