The Tor Browser: layout/style/CSSVariableResolver.h@925c144e1f1f

     1 /* vim: set shiftwidth=2 tabstop=8 autoindent cindent expandtab: */

     2 /* This Source Code Form is subject to the terms of the Mozilla Public

     3  * License, v. 2.0. If a copy of the MPL was not distributed with this

     4  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

     6 /* object that resolves CSS variables using specified and inherited variable

     7  * values

     8  */

    10 #ifndef mozilla_CSSVariableResolver_h

    11 #define mozilla_CSSVariableResolver_h

    13 #include "mozilla/DebugOnly.h"

    14 #include "nsCSSParser.h"

    15 #include "nsCSSScanner.h"

    16 #include "nsDataHashtable.h"

    17 #include "nsTArray.h"

    19 namespace mozilla {

    21 class CSSVariableDeclarations;

    22 class CSSVariableValues;

    23 class EnumerateVariableReferencesData;

    25 class CSSVariableResolver

    26 {

    27   friend class CSSVariableDeclarations;

    28   friend class CSSVariableValues;

    29   friend class EnumerateVariableReferencesData;

    30 public:

    31   /**

    32    * Creates a new CSSVariableResolver that will output a set of resolved,

    33    * computed variables into aOutput.

    34    */

    35   CSSVariableResolver(CSSVariableValues* aOutput)

    36     : mOutput(aOutput)

    37     , mResolved(false)

    38   {

    39     MOZ_ASSERT(aOutput);

    40   }

    42   /**

    43    * Resolves the set of inherited variables from aInherited and the

    44    * set of specified variables from aSpecified.  The resoled variables

    45    * are written in to mOutput.

    46    */

    47   void Resolve(const CSSVariableValues* aInherited,

    48                const CSSVariableDeclarations* aSpecified);

    50 private:

    51   struct Variable

    52   {

    53     Variable(const nsAString& aVariableName,

    54              nsString aValue,

    55              nsCSSTokenSerializationType aFirstToken,

    56              nsCSSTokenSerializationType aLastToken,

    57              bool aWasInherited)

    58       : mVariableName(aVariableName)

    59       , mValue(aValue)

    60       , mFirstToken(aFirstToken)

    61       , mLastToken(aLastToken)

    62       , mWasInherited(aWasInherited)

    63       , mResolved(false)

    64       , mReferencesNonExistentVariable(false)

    65       , mInStack(false)

    66       , mIndex(0)

    67       , mLowLink(0) { }

    69     nsString mVariableName;

    70     nsString mValue;

    71     nsCSSTokenSerializationType mFirstToken;

    72     nsCSSTokenSerializationType mLastToken;

    74     // Whether this variable came from the set of inherited variables.

    75     bool mWasInherited;

    77     // Whether this variable has been resolved yet.

    78     bool mResolved;

    80     // Whether this variables includes any references to non-existent variables.

    81     bool mReferencesNonExistentVariable;

    83     // Bookkeeping for the cycle remover algorithm.

    84     bool mInStack;

    85     size_t mIndex;

    86     size_t mLowLink;

    87   };

    89   /**

    90    * Adds or modifies an existing entry in the set of variables to be resolved.

    91    * This is intended to be called by the AddVariablesToResolver functions on

    92    * the CSSVariableDeclarations and CSSVariableValues objects passed in to

    93    * Resolve.

    94    *

    95    * @param aName The variable name (not including any "--" prefix that would

    96    *   be part of the custom property name) whose value is to be set.

    97    * @param aValue The variable value.

    98    * @param aFirstToken The type of token at the start of the variable value.

    99    * @param aLastToken The type of token at the en of the variable value.

   100    * @param aWasInherited Whether this variable came from the set of inherited

   101    *   variables.

   102    */

   103   void Put(const nsAString& aVariableName,

   104            nsString aValue,

   105            nsCSSTokenSerializationType aFirstToken,

   106            nsCSSTokenSerializationType aLastToken,

   107            bool aWasInherited);

   109   // Helper functions for Resolve.

   110   void RemoveCycles(size_t aID);

   111   void ResolveVariable(size_t aID);

   113   // A mapping of variable names to an ID that indexes into mVariables

   114   // and mReferences.

   115   nsDataHashtable<nsStringHashKey, size_t> mVariableIDs;

   117   // The set of variables.

   118   nsTArray<Variable> mVariables;

   120   // The list of variables that each variable references.

   121   nsTArray<nsTArray<size_t> > mReferences;

   123   // The next index to assign to a variable found during the cycle removing

   124   // algorithm's traversal of the variable reference graph.

   125   size_t mNextIndex;

   127   // Stack of variable IDs that we push to as we traverse the variable reference

   128   // graph while looking for cycles.  Variable::mInStack reflects whether a

   129   // given variable has its ID in mStack.

   130   nsTArray<size_t> mStack;

   132   // CSS parser to use for parsing property values with variable references.

   133   nsCSSParser mParser;

   135   // The object to output the resolved variables into.

   136   CSSVariableValues* mOutput;

   138   // Whether Resolve has been called.

   139   DebugOnly<bool> mResolved;

   140 };

   142 }

   144 #endif

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