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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
/* object that resolves CSS variables using specified and inherited variable
* values
*/
#ifndef mozilla_CSSVariableResolver_h
#define mozilla_CSSVariableResolver_h
#include "mozilla/DebugOnly.h"
#include "nsCSSParser.h"
#include "nsCSSScanner.h"
#include "nsDataHashtable.h"
#include "nsTArray.h"
namespace mozilla {
class CSSVariableDeclarations;
class CSSVariableValues;
class EnumerateVariableReferencesData;
class CSSVariableResolver
{
friend class CSSVariableDeclarations;
friend class CSSVariableValues;
friend class EnumerateVariableReferencesData;
public:
/**
* Creates a new CSSVariableResolver that will output a set of resolved,
* computed variables into aOutput.
*/
explicit CSSVariableResolver(CSSVariableValues* aOutput)
: mOutput(aOutput)
#ifdef DEBUG
, mResolved(false)
#endif
{
MOZ_ASSERT(aOutput);
}
/**
* Resolves the set of inherited variables from aInherited and the
* set of specified variables from aSpecified. The resolved variables
* are written into mOutput.
*/
void Resolve(const CSSVariableValues* aInherited,
const CSSVariableDeclarations* aSpecified);
private:
struct Variable
{
Variable(const nsAString& aVariableName,
nsString aValue,
nsCSSTokenSerializationType aFirstToken,
nsCSSTokenSerializationType aLastToken,
bool aWasInherited)
: mVariableName(aVariableName)
, mValue(aValue)
, mFirstToken(aFirstToken)
, mLastToken(aLastToken)
, mWasInherited(aWasInherited)
, mResolved(false)
, mReferencesNonExistentVariable(false)
, mInStack(false)
, mIndex(0)
, mLowLink(0) { }
nsString mVariableName;
nsString mValue;
nsCSSTokenSerializationType mFirstToken;
nsCSSTokenSerializationType mLastToken;
// Whether this variable came from the set of inherited variables.
bool mWasInherited;
// Whether this variable has been resolved yet.
bool mResolved;
// Whether this variables includes any references to non-existent variables.
bool mReferencesNonExistentVariable;
// Bookkeeping for the cycle remover algorithm.
bool mInStack;
size_t mIndex;
size_t mLowLink;
};
/**
* Adds or modifies an existing entry in the set of variables to be resolved.
* This is intended to be called by the AddVariablesToResolver functions on
* the CSSVariableDeclarations and CSSVariableValues objects passed in to
* Resolve.
*
* @param aName The variable name (not including any "--" prefix that would
* be part of the custom property name) whose value is to be set.
* @param aValue The variable value.
* @param aFirstToken The type of token at the start of the variable value.
* @param aLastToken The type of token at the en of the variable value.
* @param aWasInherited Whether this variable came from the set of inherited
* variables.
*/
void Put(const nsAString& aVariableName,
nsString aValue,
nsCSSTokenSerializationType aFirstToken,
nsCSSTokenSerializationType aLastToken,
bool aWasInherited);
// Helper functions for Resolve.
void RemoveCycles(size_t aID);
void ResolveVariable(size_t aID);
// A mapping of variable names to an ID that indexes into mVariables
// and mReferences.
nsDataHashtable<nsStringHashKey, size_t> mVariableIDs;
// The set of variables.
nsTArray<Variable> mVariables;
// The list of variables that each variable references.
nsTArray<nsTArray<size_t> > mReferences;
// The next index to assign to a variable found during the cycle removing
// algorithm's traversal of the variable reference graph.
size_t mNextIndex;
// Stack of variable IDs that we push to as we traverse the variable reference
// graph while looking for cycles. Variable::mInStack reflects whether a
// given variable has its ID in mStack.
nsTArray<size_t> mStack;
// CSS parser to use for parsing property values with variable references.
nsCSSParser mParser;
// The object to output the resolved variables into.
CSSVariableValues* mOutput;
#ifdef DEBUG
// Whether Resolve has been called.
bool mResolved;
#endif
};
} // namespace mozilla
#endif
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