1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/layout/style/CSSVariableResolver.h Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,144 @@
1.4 +/* vim: set shiftwidth=2 tabstop=8 autoindent cindent expandtab: */
1.5 +/* This Source Code Form is subject to the terms of the Mozilla Public
1.6 + * License, v. 2.0. If a copy of the MPL was not distributed with this
1.7 + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
1.8 +
1.9 +/* object that resolves CSS variables using specified and inherited variable
1.10 + * values
1.11 + */
1.12 +
1.13 +#ifndef mozilla_CSSVariableResolver_h
1.14 +#define mozilla_CSSVariableResolver_h
1.15 +
1.16 +#include "mozilla/DebugOnly.h"
1.17 +#include "nsCSSParser.h"
1.18 +#include "nsCSSScanner.h"
1.19 +#include "nsDataHashtable.h"
1.20 +#include "nsTArray.h"
1.21 +
1.22 +namespace mozilla {
1.23 +
1.24 +class CSSVariableDeclarations;
1.25 +class CSSVariableValues;
1.26 +class EnumerateVariableReferencesData;
1.27 +
1.28 +class CSSVariableResolver
1.29 +{
1.30 + friend class CSSVariableDeclarations;
1.31 + friend class CSSVariableValues;
1.32 + friend class EnumerateVariableReferencesData;
1.33 +public:
1.34 + /**
1.35 + * Creates a new CSSVariableResolver that will output a set of resolved,
1.36 + * computed variables into aOutput.
1.37 + */
1.38 + CSSVariableResolver(CSSVariableValues* aOutput)
1.39 + : mOutput(aOutput)
1.40 + , mResolved(false)
1.41 + {
1.42 + MOZ_ASSERT(aOutput);
1.43 + }
1.44 +
1.45 + /**
1.46 + * Resolves the set of inherited variables from aInherited and the
1.47 + * set of specified variables from aSpecified. The resoled variables
1.48 + * are written in to mOutput.
1.49 + */
1.50 + void Resolve(const CSSVariableValues* aInherited,
1.51 + const CSSVariableDeclarations* aSpecified);
1.52 +
1.53 +private:
1.54 + struct Variable
1.55 + {
1.56 + Variable(const nsAString& aVariableName,
1.57 + nsString aValue,
1.58 + nsCSSTokenSerializationType aFirstToken,
1.59 + nsCSSTokenSerializationType aLastToken,
1.60 + bool aWasInherited)
1.61 + : mVariableName(aVariableName)
1.62 + , mValue(aValue)
1.63 + , mFirstToken(aFirstToken)
1.64 + , mLastToken(aLastToken)
1.65 + , mWasInherited(aWasInherited)
1.66 + , mResolved(false)
1.67 + , mReferencesNonExistentVariable(false)
1.68 + , mInStack(false)
1.69 + , mIndex(0)
1.70 + , mLowLink(0) { }
1.71 +
1.72 + nsString mVariableName;
1.73 + nsString mValue;
1.74 + nsCSSTokenSerializationType mFirstToken;
1.75 + nsCSSTokenSerializationType mLastToken;
1.76 +
1.77 + // Whether this variable came from the set of inherited variables.
1.78 + bool mWasInherited;
1.79 +
1.80 + // Whether this variable has been resolved yet.
1.81 + bool mResolved;
1.82 +
1.83 + // Whether this variables includes any references to non-existent variables.
1.84 + bool mReferencesNonExistentVariable;
1.85 +
1.86 + // Bookkeeping for the cycle remover algorithm.
1.87 + bool mInStack;
1.88 + size_t mIndex;
1.89 + size_t mLowLink;
1.90 + };
1.91 +
1.92 + /**
1.93 + * Adds or modifies an existing entry in the set of variables to be resolved.
1.94 + * This is intended to be called by the AddVariablesToResolver functions on
1.95 + * the CSSVariableDeclarations and CSSVariableValues objects passed in to
1.96 + * Resolve.
1.97 + *
1.98 + * @param aName The variable name (not including any "--" prefix that would
1.99 + * be part of the custom property name) whose value is to be set.
1.100 + * @param aValue The variable value.
1.101 + * @param aFirstToken The type of token at the start of the variable value.
1.102 + * @param aLastToken The type of token at the en of the variable value.
1.103 + * @param aWasInherited Whether this variable came from the set of inherited
1.104 + * variables.
1.105 + */
1.106 + void Put(const nsAString& aVariableName,
1.107 + nsString aValue,
1.108 + nsCSSTokenSerializationType aFirstToken,
1.109 + nsCSSTokenSerializationType aLastToken,
1.110 + bool aWasInherited);
1.111 +
1.112 + // Helper functions for Resolve.
1.113 + void RemoveCycles(size_t aID);
1.114 + void ResolveVariable(size_t aID);
1.115 +
1.116 + // A mapping of variable names to an ID that indexes into mVariables
1.117 + // and mReferences.
1.118 + nsDataHashtable<nsStringHashKey, size_t> mVariableIDs;
1.119 +
1.120 + // The set of variables.
1.121 + nsTArray<Variable> mVariables;
1.122 +
1.123 + // The list of variables that each variable references.
1.124 + nsTArray<nsTArray<size_t> > mReferences;
1.125 +
1.126 + // The next index to assign to a variable found during the cycle removing
1.127 + // algorithm's traversal of the variable reference graph.
1.128 + size_t mNextIndex;
1.129 +
1.130 + // Stack of variable IDs that we push to as we traverse the variable reference
1.131 + // graph while looking for cycles. Variable::mInStack reflects whether a
1.132 + // given variable has its ID in mStack.
1.133 + nsTArray<size_t> mStack;
1.134 +
1.135 + // CSS parser to use for parsing property values with variable references.
1.136 + nsCSSParser mParser;
1.137 +
1.138 + // The object to output the resolved variables into.
1.139 + CSSVariableValues* mOutput;
1.140 +
1.141 + // Whether Resolve has been called.
1.142 + DebugOnly<bool> mResolved;
1.143 +};
1.144 +
1.145 +}
1.146 +
1.147 +#endif
