Expand WTF::StringView's API to be more like StringPiece.

third_party/WebKit/Source/wtf/text/StringImpl.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010, 2013 Apple Inc. All rights reserved.
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
@@ skipping 11 matching lines @@
 
 #ifndef StringImpl_h
 #define StringImpl_h
 
 #include "wtf/ASCIICType.h"
 #include "wtf/Forward.h"
 #include "wtf/HashMap.h"
 #include "wtf/StringHasher.h"
 #include "wtf/Vector.h"
 #include "wtf/WTFExport.h"
+#include "wtf/text/StringView.h"
 #include "wtf/text/Unicode.h"
 #include <limits.h>
 
 #if OS(MACOSX)
 typedef const struct __CFString * CFStringRef;
 #endif
 
 #ifdef __OBJC__
 @class NSString;
 #endif
@@ skipping 694 matching lines @@
     return c <= 0x7F ? WTF::isASCIISpace(c) : WTF::Unicode::direction(c) == WTF::Unicode::WhiteSpaceNeutral;
 }
 
 inline PassRefPtr<StringImpl> StringImpl::isolatedCopy() const
 {
     if (is8Bit())
         return create(characters8(), m_length);
     return create(characters16(), m_length);
 }
 
+inline void StringView::set(StringImpl& impl, unsigned offset, unsigned length)
+{
+    SECURITY_DCHECK(offset + length <= impl.length());
+    m_length = length;
+    m_is8Bit = impl.is8Bit();
+    if (m_is8Bit)
+        m_data.characters8 = impl.characters8() + offset;
+    else
+        m_data.characters16 = impl.characters16() + offset;
+}
+
+inline StringView::StringView(StringImpl* impl)
+{
+    impl ? set(*impl, 0, impl->length()) : clear();
+}
+
+inline StringView::StringView(StringImpl* impl, unsigned offset)
+{
+    impl ? set(*impl, offset, impl->length()) : clear();
+}
+
+inline StringView::StringView(StringImpl* impl, unsigned offset, unsigned length)
+{
+    impl ? set(*impl, offset, length) : clear();
+}
+
 // TODO(rob.buis) possibly find a better place for this method.
 // Turns a UChar32 to uppercase based on localeIdentifier.
 WTF_EXPORT UChar32 toUpper(UChar32, const AtomicString& localeIdentifier);
 
 struct StringHash;
 
 // StringHash is the default hash for StringImpl* and RefPtr<StringImpl>
 template<typename T> struct DefaultHash;
 template<> struct DefaultHash<StringImpl*> {
     typedef StringHash Hash;
 };
 template<> struct DefaultHash<RefPtr<StringImpl>> {
     typedef StringHash Hash;
 };
 
 } // namespace WTF
 
 using WTF::StringImpl;
 using WTF::equal;
 using WTF::equalNonNull;
 using WTF::TextCaseSensitivity;
 using WTF::TextCaseSensitive;
 using WTF::TextCaseASCIIInsensitive;
 using WTF::TextCaseInsensitive;
 
 #endif