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Diffstat (limited to 'geom_bottleneck/bottleneck/include/ANN/pr_queue.h')
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1 files changed, 127 insertions, 0 deletions
diff --git a/geom_bottleneck/bottleneck/include/ANN/pr_queue.h b/geom_bottleneck/bottleneck/include/ANN/pr_queue.h new file mode 100644 index 0000000..f938a73 --- /dev/null +++ b/geom_bottleneck/bottleneck/include/ANN/pr_queue.h @@ -0,0 +1,127 @@ +//---------------------------------------------------------------------- +// File: pr_queue.h +// Programmer: Sunil Arya and David Mount +// Description: Include file for priority queue and related +// structures. +// Last modified: 01/04/05 (Version 1.0) +//---------------------------------------------------------------------- +// Copyright (c) 1997-2005 University of Maryland and Sunil Arya and +// David Mount. All Rights Reserved. +// +// This software and related documentation is part of the Approximate +// Nearest Neighbor Library (ANN). This software is provided under +// the provisions of the Lesser GNU Public License (LGPL). See the +// file ../ReadMe.txt for further information. +// +// The University of Maryland (U.M.) and the authors make no +// representations about the suitability or fitness of this software for +// any purpose. It is provided "as is" without express or implied +// warranty. +//---------------------------------------------------------------------- +// History: +// Revision 0.1 03/04/98 +// Initial release +//---------------------------------------------------------------------- + +#ifndef PR_QUEUE_H +#define PR_QUEUE_H + +#include <ANN/ANNx.h> // all ANN includes +#include <ANN/ANNperf.h> // performance evaluation + +namespace geom_bt { +//---------------------------------------------------------------------- +// Basic types. +//---------------------------------------------------------------------- +typedef void *PQinfo; // info field is generic pointer +typedef ANNdist PQkey; // key field is distance + +//---------------------------------------------------------------------- +// Priority queue +// A priority queue is a list of items, along with associated +// priorities. The basic operations are insert and extract_minimum. +// +// The priority queue is maintained using a standard binary heap. +// (Implementation note: Indexing is performed from [1..max] rather +// than the C standard of [0..max-1]. This simplifies parent/child +// computations.) User information consists of a void pointer, +// and the user is responsible for casting this quantity into whatever +// useful form is desired. +// +// Because the priority queue is so central to the efficiency of +// query processing, all the code is inline. +//---------------------------------------------------------------------- + +class ANNpr_queue { + + struct pq_node { // node in priority queue + PQkey key; // key value + PQinfo info; // info field + }; + int n; // number of items in queue + int max_size; // maximum queue size + pq_node *pq; // the priority queue (array of nodes) + +public: + ANNpr_queue(int max) // constructor (given max size) + { + n = 0; // initially empty + max_size = max; // maximum number of items + pq = new pq_node[max+1]; // queue is array [1..max] of nodes + } + + ~ANNpr_queue() // destructor + { delete [] pq; } + + ANNbool empty() // is queue empty? + { if (n==0) return ANNtrue; else return ANNfalse; } + + ANNbool non_empty() // is queue nonempty? + { if (n==0) return ANNfalse; else return ANNtrue; } + + void reset() // make existing queue empty + { n = 0; } + + inline void insert( // insert item (inlined for speed) + PQkey kv, // key value + PQinfo inf) // item info + { + if (++n > max_size) annError("Priority queue overflow.", ANNabort); + register int r = n; + while (r > 1) { // sift up new item + register int p = r/2; + ANN_FLOP(1) // increment floating ops + if (pq[p].key <= kv) // in proper order + break; + pq[r] = pq[p]; // else swap with parent + r = p; + } + pq[r].key = kv; // insert new item at final location + pq[r].info = inf; + } + + inline void extr_min( // extract minimum (inlined for speed) + PQkey &kv, // key (returned) + PQinfo &inf) // item info (returned) + { + kv = pq[1].key; // key of min item + inf = pq[1].info; // information of min item + register PQkey kn = pq[n--].key;// last item in queue + register int p = 1; // p points to item out of position + register int r = p<<1; // left child of p + while (r <= n) { // while r is still within the heap + ANN_FLOP(2) // increment floating ops + // set r to smaller child of p + if (r < n && pq[r].key > pq[r+1].key) r++; + if (kn <= pq[r].key) // in proper order + break; + pq[p] = pq[r]; // else swap with child + p = r; // advance pointers + r = p<<1; + } + pq[p] = pq[n+1]; // insert last item in proper place + } +}; + +} +#endif
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