Source/WebCore/css/CSSVariableReferenceValue.cpp

// Copyright 2015 The Chromium Authors. All rights reserved.
// Copyright (C) 2016 Apple Inc. All rights reserved.
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#include "config.h"
#include "CSSVariableReferenceValue.h"

#include "RenderStyle.h"
#include "StyleBuilder.h"
#include "StyleResolver.h"

namespace WebCore {

String CSSVariableReferenceValue::customCSSText() const
{
    if (!m_serialized) {
        m_serialized = true;
        m_stringValue = m_data->tokenRange().serialize();
    }
    return m_stringValue;
}

static bool resolveTokenRange(CSSParserTokenRange, Vector<CSSParserToken>&, Style::BuilderState&);

static bool resolveVariableFallback(CSSParserTokenRange range, Vector<CSSParserToken>& result, Style::BuilderState& builderState)
{
    if (range.atEnd())
        return false;
    ASSERT(range.peek().type() == CommaToken);
    range.consume();
    return resolveTokenRange(range, result, builderState);
}

static bool resolveVariableReference(CSSParserTokenRange range, Vector<CSSParserToken>& result, Style::BuilderState& builderState)
{
    auto& registeredProperties = builderState.document().getCSSRegisteredCustomPropertySet();
    auto& style = builderState.style();

    range.consumeWhitespace();
    ASSERT(range.peek().type() == IdentToken);
    String variableName = range.consumeIncludingWhitespace().value().toString();
    ASSERT(range.atEnd() || (range.peek().type() == CommaToken));

    // Apply this variable first, in case it is still unresolved
    builderState.builder().applyCustomProperty(variableName);

    // Apply fallback to detect cycles
    Vector<CSSParserToken> fallbackResult;
    bool fallbackReturn = resolveVariableFallback(CSSParserTokenRange(range), fallbackResult, builderState);

    auto* property = style.getCustomProperty(variableName);

    if (!property || property->isUnset()) {
        auto* registered = registeredProperties.get(variableName);
        if (registered && registered->initialValue())
            property = registered->initialValue();
    }

    if (!property || property->isInvalid()) {
        if (fallbackReturn)
            result.appendVector(fallbackResult);
        return fallbackReturn;
    }

    ASSERT(property->isResolved());
    result.appendVector(property->tokens());

    return true;
}

static bool resolveTokenRange(CSSParserTokenRange range, Vector<CSSParserToken>& result, Style::BuilderState& builderState)
{
    bool success = true;
    while (!range.atEnd()) {
        if (range.peek().functionId() == CSSValueVar || range.peek().functionId() == CSSValueEnv)
            success &= resolveVariableReference(range.consumeBlock(), result, builderState);
        else
            result.append(range.consume());
    }
    return success;
}

RefPtr<CSSVariableData> CSSVariableReferenceValue::resolveVariableReferences(Style::BuilderState& builderState) const
{
    Vector<CSSParserToken> resolvedTokens;
    CSSParserTokenRange range = m_data->tokenRange();

    if (!resolveTokenRange(range, resolvedTokens, builderState))
        return nullptr;

    return CSSVariableData::create(resolvedTokens);
}

} // namespace WebCore