A thread-safe Media Query Parser

Source/core/css/CSSValueIDHelper.cpp

+// Copyright 2014 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 "config.h"
+#include "core/css/CSSValueIDHelper.h"
+
+#include "core/css/CSSParserValues.h"
+#include "core/css/HashTools.h"
+
+namespace WebCore {
+
+template <typename CharacterType>
+static CSSValueID cssValueKeywordID(const CharacterType* valueKeyword, unsigned length)
+{
+    char buffer[maxCSSValueKeywordLength + 1]; // 1 for null character
+
+    for (unsigned i = 0; i != length; ++i) {
+        CharacterType c = valueKeyword[i];
+        if (!c || c >= 0x7F)
+            return CSSValueInvalid; // illegal character
+        buffer[i] = WTF::toASCIILower(c);
+    }
+    buffer[length] = '\0';
+
+    const Value* hashTableEntry = findValue(buffer, length);
+    return hashTableEntry ? static_cast<CSSValueID>(hashTableEntry->id) : CSSValueInvalid;
+}
+
+CSSValueID cssValueKeywordID(const CSSParserString& string)
+{
+    unsigned length = string.length();
+    if (!length)
+        return CSSValueInvalid;
+    if (length > maxCSSValueKeywordLength)
+        return CSSValueInvalid;
+
+    return string.is8Bit() ? cssValueKeywordID(string.characters8(), length) : cssValueKeywordID(string.characters16(), length);
+}
+
+}