third_party/WebKit/Source/core/css/resolver/CSSVariableResolver.h

// Copyright 2015 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.

#ifndef CSSVariableResolver_h
#define CSSVariableResolver_h

#include "core/CSSPropertyNames.h"
#include "core/css/parser/CSSParserToken.h"
#include "wtf/HashSet.h"
#include "wtf/text/AtomicString.h"
#include "wtf/text/AtomicStringHash.h"

namespace blink {

class CSSParserTokenRange;
class CSSPendingSubstitutionValue;
class CSSVariableData;
class CSSVariableReferenceValue;
class PropertyRegistry;
class StyleResolverState;
class StyleInheritedVariables;
class StyleNonInheritedVariables;

class CSSVariableResolver {
  STACK_ALLOCATED();

 public:
  static void resolveVariableDefinitions(const StyleResolverState&);

  // Shorthand properties are not supported.
  static const CSSValue* resolveVariableReferences(const StyleResolverState&,
                                                   CSSPropertyID,
                                                   const CSSValue&);

  DECLARE_TRACE();

 private:
  CSSVariableResolver(const StyleResolverState&);

  static const CSSValue* resolvePendingSubstitutions(
      const StyleResolverState&,
      CSSPropertyID,
      const CSSPendingSubstitutionValue&);
  static const CSSValue* resolveVariableReferences(
      const StyleResolverState&,
      CSSPropertyID,
      const CSSVariableReferenceValue&);

  // These return false if we encounter a reference to an invalid variable with
  // no fallback.

  // Resolves a range which may contain var() references or @apply rules.
  bool resolveTokenRange(CSSParserTokenRange, Vector<CSSParserToken>& result);
  // Resolves the fallback (if present) of a var() reference, starting from the
  // comma.
  bool resolveFallback(CSSParserTokenRange, Vector<CSSParserToken>& result);
  // Resolves the contents of a var() reference.
  bool resolveVariableReference(CSSParserTokenRange,
                                Vector<CSSParserToken>& result);
  // Consumes and resolves an @apply rule.
  void resolveApplyAtRule(CSSParserTokenRange&, Vector<CSSParserToken>& result);

  // These return null if the custom property is invalid.

  // Returns the CSSVariableData for a custom property, resolving and storing it
  // if necessary.
  CSSVariableData* valueForCustomProperty(AtomicString name);
  // Resolves the CSSVariableData from a custom property declaration.
  PassRefPtr<CSSVariableData> resolveCustomProperty(AtomicString name,
                                                    const CSSVariableData&);

  const StyleResolverState& m_styleResolverState;
  StyleInheritedVariables* m_inheritedVariables;
  StyleNonInheritedVariables* m_nonInheritedVariables;
  Member<const PropertyRegistry> m_registry;
  HashSet<AtomicString> m_variablesSeen;
  // Resolution doesn't finish when a cycle is detected. Fallbacks still
  // need to be tracked for additional cycles, and invalidation only
  // applies back to cycle starts.
  HashSet<AtomicString> m_cycleStartPoints;
};

}  // namespace blink

#endif  // CSSVariableResolver