Reduce string copies in GURL creation

third_party/WebKit/Source/platform/exported/WebStringUTF8Adaptor.cpp

 /*
- * Copyright (C) 2013 Google Inc. All rights reserved.
+ * Copyright (C) 2016 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * 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.
  *     * Neither the name of Google Inc. nor the names of its
  * contributors may be used to endorse or promote products derived from
  * this software without specific prior written permission.
  *
  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND 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 THE COPYRIGHT
  * OWNER 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.
  */
 
-#ifndef WebMIDIAccessor_h
-#define WebMIDIAccessor_h
+#include "public/platform/WebStringUTF8Adaptor.h"
 
-#include "WebString.h"
+#include "public/platform/WebString.h"
+#include "wtf/text/CString.h"
+#include "wtf/text/WTFString.h"
 
 namespace blink {
 
-class WebMIDIAccessor {
-public:
-    virtual ~WebMIDIAccessor() { }
+WebStringUTF8Adaptor::WebStringUTF8Adaptor(const WebString& string)
+{
+    if (string.isEmpty())
+        return;
+    // 8-bit WTF::Strings are encoded in Latin-1. If |relative| is entirely
+    // ASCII, we luck out and can avoid mallocing a new buffer to hold the
+    // UTF-8 data because UTF-8 and Latin-1 use the same code units for ASCII
+    // code points.
+    const WTF::String& wtfString = string;
+    if (wtfString.is8Bit() && wtfString.containsOnlyASCII()) {
+        m_stringPiece = base::StringPiece(
+            reinterpret_cast<const char*>(wtfString.characters8()),
+            wtfString.length());

[michaeln, 2016/01/08 22:52:55]

drive by: Do you want the adapter to keep the WTF::String's internal buffer
alive for the lifetime of the adapter?

[brettw, 2016/01/08 23:11:21]

Maybe, I'm not sure what you mean. It's expected the string will outlive the
adaptor. What I do here is derived from the current StringUTF8Adaptor. What are
you suggesting doing?

+    } else {
+        m_utf8Buffer = wtfString.utf8().buffer();
+        m_stringPiece = base::StringPiece(m_utf8Buffer->data(), m_utf8Buffer->length());
+    }
+}
 
-    virtual void startSession() { }
-    virtual void open(unsigned portIndex) { }
-    // |timeStamp| is measured in milliseconds as Web MIDI spec defines.
-    virtual void sendMIDIData(unsigned portIndex, const unsigned char* data, size_t length, double timeStamp) { }
-    virtual void clear(unsigned portIndex) { }
-    virtual void close(unsigned portIndex) { }
-};
+WebStringUTF8Adaptor::~WebStringUTF8Adaptor()
+{
+    m_utf8Buffer.reset();
+}
 
 } // namespace blink
-
-#endif // WebMIDIAccessor_h