content/xul/templates/src/nsRDFQuery.h

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   5  * The contents of this file are subject to the Mozilla Public License Version
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  15  * The Original Code is mozilla.org code.
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  17  * The Initial Developer of the Original Code is Neil Deakin
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  36
  37 #ifndef nsRDFQuery_h__
  38 #define nsRDFQuery_h__
  39
  40 #include "nsAutoPtr.h"
  41 #include "nsISimpleEnumerator.h"
  42 #include "nsCycleCollectionParticipant.h"
  43
  44 #define NS_ITEMPLATERDFQUERY_IID \
  45   {0x8929ff60, 0x1c9c, 0x4d87, \
  46     { 0xac, 0x02, 0x09, 0x14, 0x15, 0x3b, 0x48, 0xc4 }}
  47
  48 /**
  49  * A compiled query in the RDF query processor. This interface should not be
  50  * used directly outside of the RDF query processor.
  51  */
  52 class nsITemplateRDFQuery : public nsISupports
  53 {
  54 public:
  55     NS_DECLARE_STATIC_IID_ACCESSOR(NS_ITEMPLATERDFQUERY_IID)
  56
  57     // return the processor the query was created from
  58     virtual nsXULTemplateQueryProcessorRDF* Processor() = 0;  // not addrefed
  59
  60     // return the member variable for the query
  61     virtual nsIAtom* GetMemberVariable() = 0; // not addrefed
  62
  63     // return the <query> node the query was compiled from
  64     virtual void GetQueryNode(nsIDOMNode** aQueryNode) = 0;
  65
  66     // remove any results that are cached by the query
  67     virtual void ClearCachedResults() = 0;
  68 };
  69
  70 class nsRDFQuery : public nsITemplateRDFQuery
  71 {
  72 public:
  73
  74     nsRDFQuery(nsXULTemplateQueryProcessorRDF* aProcessor)
  75       : mProcessor(aProcessor),
  76         mSimple(PR_FALSE),
  77         mRoot(nsnull),
  78         mCachedResults(nsnull)
  79     { }
  80
  81     ~nsRDFQuery() { Finish(); }
  82
  83     NS_DECL_CYCLE_COLLECTING_ISUPPORTS
  84     NS_DECL_CYCLE_COLLECTION_CLASS(nsRDFQuery)
  85
  86     /**
  87      * Retrieve the root node in the rule network
  88      * @return the root node in the rule network
  89      */
  90     TestNode* GetRoot() { return mRoot; }
  91
  92     void SetRoot(TestNode* aRoot) { mRoot = aRoot; }
  93
  94     void GetQueryNode(nsIDOMNode** aQueryNode)
  95     {
  96        *aQueryNode = mQueryNode;
  97        NS_IF_ADDREF(*aQueryNode);
  98     }
  99
 100     void SetQueryNode(nsIDOMNode* aQueryNode)
 101     {
 102        mQueryNode = aQueryNode;
 103     }
 104
 105     // an optimization is used when several queries all use the simple query
 106     // syntax. Since simple queries can only generate one possible set of
 107     // results, they only need to be calculated once and reused for every
 108     // simple query. The results may be cached in the query for this purpose.
 109     // If successful, this method takes ownership of aInstantiations.
 110     nsresult SetCachedResults(nsXULTemplateQueryProcessorRDF* aProcessor,
 111                               const InstantiationSet& aInstantiations);
 112
 113     // grab the cached results, if any, causing the caller to take ownership
 114     // of them. This also has the effect of setting the cached results in this
 115     // nsRDFQuery to null.
 116     void UseCachedResults(nsISimpleEnumerator** aResults);
 117
 118     // clear the cached results
 119     void ClearCachedResults()
 120     {
 121         mCachedResults = nsnull;
 122     }
 123
 124     nsXULTemplateQueryProcessorRDF* Processor() { return mProcessor; }
 125
 126     nsIAtom* GetMemberVariable() { return mMemberVariable; }
 127
 128     PRBool IsSimple() { return mSimple; }
 129
 130     void SetSimple() { mSimple = PR_TRUE; }
 131
 132     // the reference and member variables for the query
 133     nsCOMPtr<nsIAtom> mRefVariable;
 134     nsCOMPtr<nsIAtom> mMemberVariable;
 135
 136 protected:
 137
 138     nsXULTemplateQueryProcessorRDF* mProcessor;
 139
 140     // true if the query is a simple rule (one with a default query)
 141     PRBool mSimple;
 142
 143     /**
 144      * The root node in the network for this query
 145      */
 146     TestNode *mRoot;
 147
 148     // the <query> node
 149     nsCOMPtr<nsIDOMNode> mQueryNode;
 150
 151     // used for simple rules since their results are all determined in one step
 152     nsCOMPtr<nsISimpleEnumerator> mCachedResults;
 153
 154     void Finish();
 155 };
 156
 157 NS_DEFINE_STATIC_IID_ACCESSOR(nsRDFQuery, NS_ITEMPLATERDFQUERY_IID)
 158
 159 #endif // nsRDFQuery_h__