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1
6
7 package com.hp.hpl.jena.graph.query;
8
9 import com.hp.hpl.jena.graph.*;
10 import com.hp.hpl.jena.graph.query.Expression;
11 import com.hp.hpl.jena.util.CollectionFactory;
12 import com.hp.hpl.jena.util.iterator.*;
13
14 import java.util.*;
15
16
22
23 public class PatternStage extends Stage
24 {
25 protected Graph graph;
26 protected Pattern [] compiled;
27 protected ValuatorSet [] guards;
28 protected Set [] boundVariables;
29
30 public PatternStage( Graph graph, Mapping map, ExpressionSet constraints, Triple [] triples )
31 {
32 this.graph = graph;
33 this.compiled = compile( map, triples );
34 this.boundVariables = makeBoundVariables( triples );
35 this.guards = makeGuards( map, constraints, triples.length );
36 }
37
38
43 protected Set [] makeBoundVariables( Triple [] triples )
44 {
45 int length = triples.length;
46 Set [] result = new Set[length];
47 Set prev = CollectionFactory.createHashedSet();
48 for (int i = 0; i < length; i += 1)
49 prev = result[i] = Util.union( prev, Util.variablesOf( triples[i] ) );
50 return result;
51 }
52
53
66 protected ValuatorSet [] makeGuards( Mapping map, ExpressionSet constraints, int length )
67 {
68 ValuatorSet [] result = new ValuatorSet [length];
69 for (int i = 0; i < length; i += 1) result[i] = new ValuatorSet();
70 Iterator it = constraints.iterator();
71 while (it.hasNext())
72 plantWhereFullyBound( (Expression) it.next(), it, map, result );
73 return result;
74 }
75
76
81 protected void plantWhereFullyBound( Expression e, Iterator it, Mapping map, ValuatorSet [] es )
82 {
83 for (int i = 0; i < boundVariables.length; i += 1)
84 if (canEval( e, i ))
85 {
86 es[i].add( e.prepare( map ) );
87 it.remove();
88 return;
89 }
90 }
91
92
96 protected boolean canEval( Expression e, int index )
97 { return Expression.Util.containsAllVariablesOf( boundVariables[index], e ); }
98
99 protected Pattern [] compile( Mapping map, Triple [] triples )
100 { return compile( compiler, map, triples ); }
101
102 protected Pattern [] compile( PatternCompiler pc, Mapping map, Triple [] source )
103 { return PatternStageCompiler.compile( pc, map, source ); }
104
105 private static final PatternCompiler compiler = new PatternStageCompiler();
106
107 private static int count = 0;
108
109 public synchronized Pipe deliver( final Pipe result )
110 {
111 final Pipe stream = previous.deliver( new BufferPipe() );
112 new Thread  ( "PatternStage-" + ++count ) { public void run() { PatternStage.this.run( stream, result ); } } .start();
113 return result;
114 }
115
116 protected void run( Pipe source, Pipe sink )
117 {
118 try { while (stillOpen && source.hasNext()) nest( sink, source.get(), 0 ); }
119 catch (Exception e) { sink.close( e ); return; }
120 sink.close();
121 }
122
123 protected void nest( Pipe sink, Domain current, int index )
124 {
125 if (index == compiled.length)
126 sink.put( current.copy() );
127 else
128 {
129 Pattern p = compiled[index];
130 ValuatorSet guard = guards[index];
131 ClosableIterator it = graph.find( p.asTripleMatch( current ) );
132 while (stillOpen && it.hasNext())
133 if (p.match( current, (Triple) it.next()) && guard.evalBool( current ))
134 nest( sink, current, index + 1 );
135 it.close();
136 }
137 }
138 }
139
140
169 |
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