Implement StringImpl sharing for StringView::toString().

third_party/WebKit/Source/wtf/text/StringView.cpp

 // Copyright 2016 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.
 
 #include "wtf/text/StringView.h"
 
 namespace WTF {
 
-StringView::StringView(const UChar* chars, unsigned length)
-    : m_length(length)
-    , m_is8Bit(false)
-{
-    m_data.characters16 = chars;
-}
-
 StringView::StringView(const UChar* chars)
     : StringView(chars, chars ? lengthOfNullTerminatedString(chars) : 0) {}
 
 #if DCHECK_IS_ON()
 StringView::~StringView()
 {
-    // StringView does not own the StringImpl, we must not be the last ref.
-    DCHECK(!m_impl || !m_impl->hasOneRef());
+    DCHECK(m_impl);
+    DCHECK(!m_impl->hasOneRef())
+        << "StringView does not own the StringImpl, it must not have the last ref.";
 }
 #endif
 
 String StringView::toString() const
 {
     if (isNull())
         return String();
     if (isEmpty())
         return emptyString();
+    if (StringImpl* impl = sharedImpl())
+        return impl;
     if (is8Bit())
-        return String(m_data.characters8, m_length);
-    return StringImpl::create8BitIfPossible(m_data.characters16, m_length);
+        return String(characters8(), m_length);
+    return StringImpl::create8BitIfPossible(characters16(), m_length);
 }
 
 AtomicString StringView::toAtomicString() const
 {
     if (isNull())
         return nullAtom;
     if (isEmpty())
         return emptyAtom;
+    if (StringImpl* impl = sharedImpl())
+        return AtomicString(impl);
     if (is8Bit())
-        return AtomicString(m_data.characters8, m_length);
-    return AtomicString(m_data.characters16, m_length);
+        return AtomicString(characters8(), m_length);
+    return AtomicString(characters16(), m_length);
 }
 
 bool equalStringView(const StringView& a, const StringView& b)
 {
     if (a.isNull() || b.isNull())
         return a.isNull() == b.isNull();
     if (a.length() != b.length())
         return false;
     if (a.is8Bit()) {
         if (b.is8Bit())
@@ skipping 15 matching lines @@
         if (b.is8Bit())
             return equalIgnoringASCIICase(a.characters8(), b.characters8(), a.length());
         return equalIgnoringASCIICase(a.characters8(), b.characters16(), a.length());
     }
     if (b.is8Bit())
         return equalIgnoringASCIICase(a.characters16(), b.characters8(), a.length());
     return equalIgnoringASCIICase(a.characters16(), b.characters16(), a.length());
 }
 
 } // namespace WTF