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1 package net.sf.saxon.sort;
2
3 import net.sf.saxon.expr.Expression;
4 import net.sf.saxon.expr.XPathContext;
5 import net.sf.saxon.om.Item;
6 import net.sf.saxon.om.ListIterator;
7 import net.sf.saxon.om.LookaheadIterator;
8 import net.sf.saxon.om.SequenceIterator;
9 import net.sf.saxon.trans.DynamicError;
10 import net.sf.saxon.trans.XPathException;
11 import net.sf.saxon.value.AtomicValue;
12
13 import java.util.ArrayList  ;
14 import java.util.Comparator ;
15 import java.util.List ;
16
17
22
23 public class GroupAdjacentIterator implements GroupIterator, LookaheadIterator {
24
25 private SequenceIterator population;
26 private Expression keyExpression;
27 private Comparator collator;
28 private AtomicSortComparer comparer;
29 private AtomicSortComparer.ComparisonKey currentComparisonKey;
30 private XPathContext baseContext;
31 private XPathContext runningContext;
32 private AtomicValue currentKey = null;
33 private List currentMembers;
34 private AtomicValue nextKey = null;
35 private Item next;
36 private Item current = null;
37 private int position = 0;
38
39 public GroupAdjacentIterator(SequenceIterator population, Expression keyExpression,
40 XPathContext baseContext, Comparator collator)
41 throws XPathException {
42 this.population = population;
43 this.keyExpression = keyExpression;
44 this.baseContext = baseContext;
45 this.runningContext = baseContext.newMinorContext();
46 runningContext.setCurrentIterator(population);
48 this.collator = collator;
49 this.comparer = new AtomicSortComparer(collator, baseContext);
50 next = population.next();
51 if (next != null) {
52 nextKey = (AtomicValue)keyExpression.evaluateItem(runningContext);
53 }
54 }
55
56 private void advance() throws XPathException {
57 currentMembers = new ArrayList (20);
58 currentMembers.add(current);
59 while (true) {
60 Item nextCandidate = population.next();
61 if (nextCandidate == null) {
62 break;
63 }
64 AtomicValue candidateKey =
65 (AtomicValue)keyExpression.evaluateItem(runningContext);
66 try {
67 if (currentComparisonKey.equals(comparer.getComparisonKey(candidateKey))) {
68 currentMembers.add(nextCandidate);
69 } else {
70 next = nextCandidate;
71 nextKey = candidateKey;
72 return;
73 }
74 } catch (ClassCastException e) {
75 DynamicError err = new DynamicError("Grouping key values are of non-comparable types (" +
76 currentKey.getItemType() +
77 " and " +
78 candidateKey.getItemType() + ')');
79 err.setIsTypeError(true);
80 err.setXPathContext(runningContext);
81 throw err;
82 }
83 }
84 next = null;
85 nextKey = null;
86 }
87
88 public AtomicValue getCurrentGroupingKey() {
89 return currentKey;
90 }
91
92 public SequenceIterator iterateCurrentGroup() {
93 return new ListIterator(currentMembers);
94 }
95
96 public boolean hasNext() {
97 return next != null;
98 }
99
100 public Item next() throws XPathException {
101 if (next == null) {
102 current = null;
103 position = -1;
104 return null;
105 }
106 current = next;
107 currentKey = nextKey;
108 currentComparisonKey = comparer.getComparisonKey(currentKey);
109 position++;
110 advance();
111 return current;
112 }
113
114 public Item current() {
115 return current;
116 }
117
118 public int position() {
119 return position;
120 }
121
122 public SequenceIterator getAnother() throws XPathException {
123 return new GroupAdjacentIterator(population.getAnother(), keyExpression, baseContext, collator);
124 }
125
126
135
136 public int getProperties() {
137 return LOOKAHEAD;
138 }
139
140
141 }
142
143
144 |
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