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1 package com.thaiopensource.relaxng.impl;
2
3 public class PatternBuilder {
4 private final EmptyPattern empty;
5 protected final NotAllowedPattern notAllowed;
6 protected final PatternInterner interner;
7
8 public PatternBuilder() {
9 empty = new EmptyPattern();
10 notAllowed = new NotAllowedPattern();
11 interner = new PatternInterner();
12 }
13
14 public PatternBuilder(PatternBuilder parent) {
15 empty = parent.empty;
16 notAllowed = parent.notAllowed;
17 interner = new PatternInterner(parent.interner);
18 }
19
20 Pattern makeEmpty() {
21 return empty;
22 }
23
24 Pattern makeNotAllowed() {
25 return notAllowed;
26 }
27
28 Pattern makeGroup(Pattern p1, Pattern p2) {
29 if (p1 == empty)
30 return p2;
31 if (p2 == empty)
32 return p1;
33 if (p1 == notAllowed || p2 == notAllowed)
34 return notAllowed;
35 if (false && p1 instanceof GroupPattern) {
36 GroupPattern sp = (GroupPattern)p1;
37 return makeGroup(sp.p1, makeGroup(sp.p2, p2));
38 }
39 Pattern p = new GroupPattern(p1, p2);
40 return interner.intern(p);
41 }
42
43 Pattern makeInterleave(Pattern p1, Pattern p2) {
44 if (p1 == empty)
45 return p2;
46 if (p2 == empty)
47 return p1;
48 if (p1 == notAllowed || p2 == notAllowed)
49 return notAllowed;
50 if (false && p1 instanceof InterleavePattern) {
51 InterleavePattern ip = (InterleavePattern)p1;
52 return makeInterleave(ip.p1, makeInterleave(ip.p2, p2));
53 }
54 if (false) {
55 if (p2 instanceof InterleavePattern) {
56 InterleavePattern ip = (InterleavePattern)p2;
57 if (p1.hashCode() > ip.p1.hashCode())
58 return makeInterleave(ip.p1, makeInterleave(p1, ip.p2));
59 }
60 else if (p1.hashCode() > p2.hashCode())
61 return makeInterleave(p2, p1);
62 }
63 Pattern p = new InterleavePattern(p1, p2);
64 return interner.intern(p);
65 }
66
67 Pattern makeChoice(Pattern p1, Pattern p2) {
68 if (p1 == empty && p2.isNullable())
69 return p2;
70 if (p2 == empty && p1.isNullable())
71 return p1;
72 Pattern p = new ChoicePattern(p1, p2);
73 return interner.intern(p);
74 }
75
76 Pattern makeOneOrMore(Pattern p) {
77 if (p == empty
78 || p == notAllowed
79 || p instanceof OneOrMorePattern)
80 return p;
81 Pattern p1 = new OneOrMorePattern(p);
82 return interner.intern(p1);
83 }
84
85 Pattern makeOptional(Pattern p) {
86 return makeChoice(p, empty);
87 }
88
89 Pattern makeZeroOrMore(Pattern p) {
90 return makeOptional(makeOneOrMore(p));
91 }
92 }
93 |
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