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// Mode: -*- C++ -*- |
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// GiSTcursor.cpp |
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// |
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// Copyright (c) 1996, Regents of the University of California |
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// $Header: /usr/local/devel/GiST/libGiST/libGiST/GiSTcursor.cpp,v 1.1.1.1 1996/08/06 23:47:20 jmh Exp $ |
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#include "GiST.h" |
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GiSTcursor::GiSTcursor(const GiST& gist, const GiSTpredicate& query): gist(gist) |
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{ |
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this->query=(GiSTpredicate*) query.Copy(); |
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first=1; |
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lastlevel=-1; |
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} |
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GiSTentry* |
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GiSTcursor::Next() |
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{ |
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GiSTpage page; |
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while(first||!stack.IsEmpty()) { |
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if(first) { |
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page=GiSTRootPage; |
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first=0; |
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} |
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else { |
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assert(lastlevel>=0); |
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GiSTentry *entry=stack.RemoveFront(); |
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if(entry->IsLeaf()) return entry; |
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// Pop off the stack |
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for(int i=0; i<entry->Level()-lastlevel; i++) path.MakeParent(); |
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page=entry->Ptr(); |
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delete entry; |
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} |
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// Entry was a pointer to another node |
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path.MakeChild(page); |
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GiSTnode *node=gist.ReadNode(path); |
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lastlevel=node->Level(); |
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GiSTlist<GiSTentry*> list=node->Search(*query); |
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while(!list.IsEmpty()) { |
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GiSTentry *entry=list.RemoveRear(); |
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stack.Prepend(entry); |
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} |
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delete node; |
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} |
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// The search is over... |
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return NULL; |
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} |
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GiSTcursor::~GiSTcursor() |
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{ |
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if(query!=NULL) delete query; |
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while(!stack.IsEmpty()) delete stack.RemoveFront(); |
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} |
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const GiSTpath& |
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GiSTcursor::Path() const |
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{ |
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return path; |
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} |
