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Diffstat (limited to 'dom/xul/templates/nsRDFBinding.h')
| -rw-r--r-- | dom/xul/templates/nsRDFBinding.h | 216 |
1 files changed, 216 insertions, 0 deletions
diff --git a/dom/xul/templates/nsRDFBinding.h b/dom/xul/templates/nsRDFBinding.h new file mode 100644 index 000000000..92c8b16ca --- /dev/null +++ b/dom/xul/templates/nsRDFBinding.h @@ -0,0 +1,216 @@ +/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */ +/* 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/. */ + +#ifndef nsRDFBinding_h__ +#define nsRDFBinding_h__ + +#include "nsIAtom.h" +#include "nsIRDFResource.h" +#include "nsISupportsImpl.h" + +class nsXULTemplateResultRDF; +class nsBindingValues; + +/* + * Classes related to storing bindings for RDF handling. + */ + +/* + * a <binding> descriptors + */ +class RDFBinding { + +public: + + nsCOMPtr<nsIAtom> mSubjectVariable; + nsCOMPtr<nsIRDFResource> mPredicate; + nsCOMPtr<nsIAtom> mTargetVariable; + + // indicates whether a binding is dependant on the result from a + // previous binding + bool mHasDependency; + + RDFBinding* mNext; + +private: + + friend class RDFBindingSet; + + RDFBinding(nsIAtom* aSubjectVariable, + nsIRDFResource* aPredicate, + nsIAtom* aTargetVariable) + : mSubjectVariable(aSubjectVariable), + mPredicate(aPredicate), + mTargetVariable(aTargetVariable), + mHasDependency(false), + mNext(nullptr) + { + MOZ_COUNT_CTOR(RDFBinding); + } + + ~RDFBinding() + { + MOZ_COUNT_DTOR(RDFBinding); + } +}; + +/* + * a collection of <binding> descriptors. This object is refcounted by + * nsBindingValues objects and the query processor. + */ +class RDFBindingSet final +{ +private: + // Private destructor, to discourage deletion outside of Release(): + ~RDFBindingSet(); + + // the number of bindings + int32_t mCount; + + // pointer to the first binding in a linked list + RDFBinding* mFirst; + +public: + + RDFBindingSet() + : mCount(0), + mFirst(nullptr) + { + MOZ_COUNT_CTOR(RDFBindingSet); + } + + NS_INLINE_DECL_REFCOUNTING(RDFBindingSet) + + int32_t Count() const { return mCount; } + + /* + * Add a binding (aRef -> aPredicate -> aVar) to the set + */ + nsresult + AddBinding(nsIAtom* aVar, nsIAtom* aRef, nsIRDFResource* aPredicate); + + /* + * Return true if the binding set contains a binding which would cause + * the result to need resynchronizing for an RDF triple. The member + * variable may be supplied as an optimization since bindings most + * commonly use the member variable as the subject. If aMemberVariable + * is set, aSubject must be the value of the member variable for the + * result. The supplied binding values aBindingValues must be values + * using this binding set (that is aBindingValues->GetBindingSet() == this) + * + * @param aSubject subject of the RDF triple + * @param aPredicate predicate of the RDF triple + * @param aTarget target of the RDF triple + * @param aMemberVariable member variable for the query for the binding + * @param aResult result to synchronize + * @param aBindingValues the values for the bindings for the result + */ + bool + SyncAssignments(nsIRDFResource* aSubject, + nsIRDFResource* aPredicate, + nsIRDFNode* aTarget, + nsIAtom* aMemberVariable, + nsXULTemplateResultRDF* aResult, + nsBindingValues& aBindingValues); + + /* + * The query processor maintains a map of subjects to an array of results. + * This is used such that when a new assertion is added to the RDF graph, + * the results associated with the subject of that triple may be checked + * to see if their bindings have changed. The AddDependencies method adds + * these subject dependencies to the map. + */ + void + AddDependencies(nsIRDFResource* aSubject, + nsXULTemplateResultRDF* aResult); + + /* + * Remove the results from the dependencies map when results are deleted. + */ + void + RemoveDependencies(nsIRDFResource* aSubject, + nsXULTemplateResultRDF* aResult); + + /* + * The nsBindingValues classes stores an array of values, one for each + * target symbol that could be set by the bindings in the set. + * LookupTargetIndex determines the index into the array for a given + * target symbol. + */ + int32_t + LookupTargetIndex(nsIAtom* aTargetVariable, RDFBinding** aBinding); +}; + +/* + * A set of values of bindings. This object is used once per result. + * This stores a reference to the binding set and an array of node values. + * Since the binding set is used once per query and the values are + * used once per result, we reduce size by only storing the value array's + * length in the binding set. This is possible since the array is always + * a fixed length for a particular binding set. + * + * XXX ndeakin We may want to revisit this later since it makes the code + * more complicated. + */ +class nsBindingValues +{ +protected: + + // the binding set + RefPtr<RDFBindingSet> mBindings; + + /* + * A set of values for variable bindings. To look up a binding value, + * scan through the binding set in mBindings for the right target atom. + * Its index will correspond to the index in this array. The size of this + * array is determined by the RDFBindingSet's Count(). + */ + nsCOMPtr<nsIRDFNode>* mValues; + +public: + + nsBindingValues() + : mBindings(nullptr), + mValues(nullptr) + { + MOZ_COUNT_CTOR(nsBindingValues); + } + + ~nsBindingValues(); + + + /** + * Clear the binding set, to be called when the nsBindingValues is deleted + * or a new binding set is being set. + */ + void ClearBindingSet(); + + RDFBindingSet* GetBindingSet() { return mBindings; } + + /** + * Set the binding set to use. This needs to be called once a rule matches + * since it is then known which bindings will apply. + */ + nsresult SetBindingSet(RDFBindingSet* aBindings); + + nsCOMPtr<nsIRDFNode>* ValuesArray() { return mValues; } + + /* + * Retrieve the assignment for a particular variable + */ + void + GetAssignmentFor(nsXULTemplateResultRDF* aResult, + nsIAtom* aVar, + nsIRDFNode** aValue); + + /* + * Remove depenedencies the bindings have on particular resources + */ + void + RemoveDependencies(nsIRDFResource* aSubject, + nsXULTemplateResultRDF* aResult); +}; + +#endif // nsRDFBinding_h__ |