Replace CSSParserString with StringView.

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)
@@ skipping 33 matching lines @@
     if (a.is8Bit()) {
         if (b.is8Bit())
             return equal(a.characters8(), b.characters8(), a.length());
         return equal(a.characters8(), b.characters16(), a.length());
     }
     if (b.is8Bit())
         return equal(a.characters16(), b.characters8(), a.length());
     return equal(a.characters16(), b.characters16(), a.length());
 }
 
+bool equalIgnoringASCIICase(StringView a, StringView b)
+{
+    if (a.length() != b.length())
+        return false;
+    if (a.isEmpty() || b.isEmpty())

[Timothy Loh, 2016/06/01 05:51:32]

How about:

if (a.isEmpty())
    return true;

Or just remove the branch, I can't imagine this early-out being particularly
common.

[esprehn, 2016/06/01 06:19:04]

I see that the method in StringImpl.h does accept strings, the libc things like
memcmp don't even if the length is 0.

I was actually trying to match the semantics of String and StringImpl. I see now
that they make it so null strings are only ever equal to other null strings. I
changed this to do that too and added tests. I want to make StringView a drop in
replacement wherever possible without having subtle differences.

+        return a.isEmpty() == b.isEmpty();
+    if (a.is8Bit()) {
+        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