mirror of
https://github.com/classilla/tenfourfox.git
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218 lines
6.3 KiB
C++
218 lines
6.3 KiB
C++
/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef nsRDFBinding_h__
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#define nsRDFBinding_h__
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#include "nsAutoPtr.h"
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#include "nsIAtom.h"
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#include "nsIRDFResource.h"
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#include "nsISupportsImpl.h"
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class nsXULTemplateResultRDF;
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class nsBindingValues;
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/*
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* Classes related to storing bindings for RDF handling.
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*/
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/*
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* a <binding> descriptors
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*/
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class RDFBinding {
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public:
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nsCOMPtr<nsIAtom> mSubjectVariable;
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nsCOMPtr<nsIRDFResource> mPredicate;
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nsCOMPtr<nsIAtom> mTargetVariable;
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// indicates whether a binding is dependant on the result from a
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// previous binding
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bool mHasDependency;
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RDFBinding* mNext;
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private:
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friend class RDFBindingSet;
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RDFBinding(nsIAtom* aSubjectVariable,
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nsIRDFResource* aPredicate,
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nsIAtom* aTargetVariable)
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: mSubjectVariable(aSubjectVariable),
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mPredicate(aPredicate),
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mTargetVariable(aTargetVariable),
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mHasDependency(false),
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mNext(nullptr)
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{
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MOZ_COUNT_CTOR(RDFBinding);
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}
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~RDFBinding()
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{
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MOZ_COUNT_DTOR(RDFBinding);
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}
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};
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/*
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* a collection of <binding> descriptors. This object is refcounted by
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* nsBindingValues objects and the query processor.
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*/
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class RDFBindingSet final
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{
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private:
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// Private destructor, to discourage deletion outside of Release():
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~RDFBindingSet();
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// the number of bindings
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int32_t mCount;
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// pointer to the first binding in a linked list
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RDFBinding* mFirst;
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public:
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RDFBindingSet()
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: mCount(0),
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mFirst(nullptr)
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{
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MOZ_COUNT_CTOR(RDFBindingSet);
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}
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NS_INLINE_DECL_REFCOUNTING(RDFBindingSet)
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int32_t Count() const { return mCount; }
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/*
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* Add a binding (aRef -> aPredicate -> aVar) to the set
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*/
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nsresult
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AddBinding(nsIAtom* aVar, nsIAtom* aRef, nsIRDFResource* aPredicate);
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/*
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* Return true if the binding set contains a binding which would cause
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* the result to need resynchronizing for an RDF triple. The member
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* variable may be supplied as an optimization since bindings most
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* commonly use the member variable as the subject. If aMemberVariable
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* is set, aSubject must be the value of the member variable for the
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* result. The supplied binding values aBindingValues must be values
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* using this binding set (that is aBindingValues->GetBindingSet() == this)
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*
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* @param aSubject subject of the RDF triple
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* @param aPredicate predicate of the RDF triple
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* @param aTarget target of the RDF triple
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* @param aMemberVariable member variable for the query for the binding
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* @param aResult result to synchronize
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* @param aBindingValues the values for the bindings for the result
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*/
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bool
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SyncAssignments(nsIRDFResource* aSubject,
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nsIRDFResource* aPredicate,
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nsIRDFNode* aTarget,
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nsIAtom* aMemberVariable,
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nsXULTemplateResultRDF* aResult,
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nsBindingValues& aBindingValues);
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/*
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* The query processor maintains a map of subjects to an array of results.
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* This is used such that when a new assertion is added to the RDF graph,
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* the results associated with the subject of that triple may be checked
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* to see if their bindings have changed. The AddDependencies method adds
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* these subject dependencies to the map.
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*/
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void
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AddDependencies(nsIRDFResource* aSubject,
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nsXULTemplateResultRDF* aResult);
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/*
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* Remove the results from the dependencies map when results are deleted.
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*/
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void
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RemoveDependencies(nsIRDFResource* aSubject,
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nsXULTemplateResultRDF* aResult);
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/*
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* The nsBindingValues classes stores an array of values, one for each
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* target symbol that could be set by the bindings in the set.
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* LookupTargetIndex determines the index into the array for a given
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* target symbol.
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*/
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int32_t
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LookupTargetIndex(nsIAtom* aTargetVariable, RDFBinding** aBinding);
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};
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/*
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* A set of values of bindings. This object is used once per result.
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* This stores a reference to the binding set and an array of node values.
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* Since the binding set is used once per query and the values are
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* used once per result, we reduce size by only storing the value array's
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* length in the binding set. This is possible since the array is always
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* a fixed length for a particular binding set.
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*
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* XXX ndeakin We may want to revisit this later since it makes the code
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* more complicated.
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*/
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class nsBindingValues
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{
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protected:
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// the binding set
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RefPtr<RDFBindingSet> mBindings;
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/*
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* A set of values for variable bindings. To look up a binding value,
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* scan through the binding set in mBindings for the right target atom.
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* Its index will correspond to the index in this array. The size of this
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* array is determined by the RDFBindingSet's Count().
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*/
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nsCOMPtr<nsIRDFNode>* mValues;
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public:
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nsBindingValues()
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: mBindings(nullptr),
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mValues(nullptr)
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{
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MOZ_COUNT_CTOR(nsBindingValues);
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}
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~nsBindingValues();
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/**
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* Clear the binding set, to be called when the nsBindingValues is deleted
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* or a new binding set is being set.
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*/
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void ClearBindingSet();
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RDFBindingSet* GetBindingSet() { return mBindings; }
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/**
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* Set the binding set to use. This needs to be called once a rule matches
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* since it is then known which bindings will apply.
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*/
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nsresult SetBindingSet(RDFBindingSet* aBindings);
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nsCOMPtr<nsIRDFNode>* ValuesArray() { return mValues; }
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/*
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* Retrieve the assignment for a particular variable
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*/
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void
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GetAssignmentFor(nsXULTemplateResultRDF* aResult,
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nsIAtom* aVar,
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nsIRDFNode** aValue);
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/*
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* Remove depenedencies the bindings have on particular resources
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*/
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void
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RemoveDependencies(nsIRDFResource* aSubject,
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nsXULTemplateResultRDF* aResult);
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};
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#endif // nsRDFBinding_h__
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