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

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

Index: third_party/WebKit/Source/wtf/text/StringView.cpp
diff --git a/third_party/WebKit/Source/wtf/text/StringView.cpp b/third_party/WebKit/Source/wtf/text/StringView.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..ae69b3178d03a2ef5800f1d68426df6b9c449495
--- /dev/null
+++ b/third_party/WebKit/Source/wtf/text/StringView.cpp
@@ -0,0 +1,48 @@
+// 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"
+
+#include "wtf/text/StringImpl.h"
+#include "wtf/text/WTFString.h"
+
+namespace WTF {
+
+StringView::StringView(const UChar* chars, unsigned length)
+    : m_length(length)
+    , m_is8Bit(false)
+{
+    SECURITY_DCHECK(!chars || length <= lengthOfNullTerminatedString(chars));
+    m_data.characters16 = chars;
+}
+
+StringView::StringView(const UChar* chars)
+    : StringView(chars, chars ? lengthOfNullTerminatedString(chars) : 0) {}
+
+String StringView::toString() const
+{
+    if (!m_data.bytes)

[haraken, 2016/05/26 22:27:22]

isNull()

[esprehn, 2016/05/26 22:40:21]

done, also added a case for empty strings.

+        return String();
+    if (is8Bit())
+        return String(m_data.characters8, m_length);
+    return String(m_data.characters16, m_length);
+}
+
+bool equalStringView(const StringView& a, const StringView& b)
+{
+    if (a.length() != b.length())
+        return false;
+    if (a.isNull() || b.isNull())
+        return a.isNull() == b.isNull();

[haraken, 2016/05/26 22:27:22]

A better check would be:

  if (a.length() == 0 || b.length() == 0)
    return a.length() == b.length();

?

Then we can cover empty strings.

[esprehn, 2016/05/26 22:40:21]

Yeah, checking isEmpty() works here.

+    if (a.is8Bit()) {
+        if (b.is8Bit())
+            return WTF::equal(a.characters8(), b.characters8(), a.length());
+        return WTF::equal(a.characters8(), b.characters16(), a.length());
+    }
+    if (b.is8Bit())
+        return WTF::equal(a.characters16(), b.characters8(), a.length());
+    return WTF::equal(a.characters16(), b.characters16(), a.length());
+}
+
+} // namespace WTF