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/* -*- 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__
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