Source/core/css/DOMWindowCSS.cpp

/*
 * Copyright (C) 2012 Motorola Mobility Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above
 *    copyright notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the distribution.
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 *    contributors may be used to endorse or promote products derived from this
 *    software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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#include "config.h"
#include "core/css/DOMWindowCSS.h"

#include "core/css/CSSParser.h"
#include "core/css/StylePropertySet.h"
#include "core/page/RuntimeCSSEnabled.h"
#include "wtf/text/WTFString.h"

namespace WebCore {

PassRefPtr<DOMWindowCSS> DOMWindowCSS::create()
{
    return adoptRef(new DOMWindowCSS());
}

static String valueWithoutImportant(const String& value)
{
    if (!value.endsWith("important", false))
        return value;

    String newValue = value;
    int bangIndex = newValue.length() - 9 - 1;
    if (newValue[bangIndex] == ' ')
        bangIndex--;
    newValue = newValue.left(bangIndex);

    return newValue;
}

bool DOMWindowCSS::supports(const String& property, const String& value) const
{
    CSSPropertyID propertyID = cssPropertyID(property.stripWhiteSpace());
    if (propertyID == CSSPropertyInvalid)
        return false;

    if (!RuntimeCSSEnabled::isCSSPropertyEnabled(propertyID))
        return false;

    // CSSParser::parseValue() won't work correctly if !important is present,
    // so just get rid of it. It doesn't matter to supports() if it's actually
    // there or not, provided how it's specified in the value is correct.
    String normalizedValue = value.stripWhiteSpace().simplifyWhiteSpace();
    normalizedValue = valueWithoutImportant(normalizedValue);

    if (normalizedValue.isEmpty())
        return false;

    RefPtr<MutableStylePropertySet> dummyStyle = MutableStylePropertySet::create();
    return CSSParser::parseValue(dummyStyle.get(), propertyID, normalizedValue, false, CSSStrictMode, 0);
}

bool DOMWindowCSS::supports(const String& conditionText) const
{
    CSSParserContext context(CSSStrictMode);
    CSSParser parser(context);
    return parser.parseSupportsCondition(conditionText);
}

}