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1 package ro.infoiasi.donald.compiler.parser;
2
3 import ro.infoiasi.donald.compiler.cfg.*;
4 import java.util.*;
5
6 public class LR0State {
7 private int index;
8 private Set kernel = new LinkedHashSet();
9 private Set closure = new LinkedHashSet();
10 private Map itemsByNext = new LinkedHashMap();
11
12
13 public boolean equals(Object  o) {
14 return (o instanceof LR0State &&
15 kernel.equals(((LR0State)o).kernel) &&
16 closure.equals(((LR0State)o).closure));
17 }
18
19 public int hashCode() {
20 return 17+kernel.hashCode()*37+closure.hashCode();
21 }
22
23 public boolean isEmpty() {
24 return kernel.isEmpty();
25 }
26
27 private void addToItemsByNext(LR0Item item) {
28 if (!item.isComplete()) {
29 Symbol sym = item.getNextSymbol();
30 LinkedList itemList;
31 if (itemsByNext.containsKey(sym)) {
32 itemList = (LinkedList)itemsByNext.get(sym);
33 } else {
34 itemList = new LinkedList();
35 }
36 itemList.add(item);
37 itemsByNext.put(sym, itemList);
38 }
39 }
40
41 public boolean addKernelItem(LR0Item item) {
42 if (kernel.add(item)) {
43 addToItemsByNext(item);
44 return true;
45 } else {
46 return false;
47 }
48 }
49
50 public Iterator iterator() {
51 return new Iterator() {
52 Iterator it = kernel.iterator();
53 boolean inKernel = true;
54
55 public boolean hasNext() {
56 if (it.hasNext() || (inKernel && !closure.isEmpty())) {
57 return true;
58 } else {
59 return false;
60 }
61 }
62
63 public Object next() {
64 if (inKernel && !it.hasNext()) {
65 it = closure.iterator();
66 inKernel = false;
67 }
68 return it.next();
69 }
70
71 public void remove() {
72 throw new UnsupportedOperationException ();
73 }
74 };
75 }
76
77 public LinkedList find(Symbol x) {
78 return (LinkedList)itemsByNext.get(x);
79 }
80
81 public Iterator iterator(Symbol x) {
82 List itemList = find(x);
83 if (itemList == null) {
84 return new Iterator() {
86 public boolean hasNext() { return false; }
87 public Object next() { throw new NoSuchElementException(); }
88 public void remove() { throw new UnsupportedOperationException (); }
89 };
90 } else {
91 return Collections.unmodifiableList(itemList).iterator();
92 }
93 }
94
95 public boolean contains(LR0Item item) {
96 return kernel.contains(item) || closure.contains(item);
97 }
98
99 public void closure(Productions p) {
100 LinkedList queue = new LinkedList();
101 queue.addAll(kernel);
102
103 while (!queue.isEmpty()) {
104 LR0Item item = (LR0Item)queue.removeFirst();
105 if (!item.isComplete()) {
106 Symbol sym = (Symbol)item.getNextSymbol();
107 if (!sym.isTerminal()) {
108 List prodList = p.find((NonTerminal)sym);
109 Iterator pIt = prodList.iterator();
110 while (pIt.hasNext()) {
111 Production prod = (Production)pIt.next();
112 LR0Item newItem = new LR0Item(prod);
113 if (closure.add(newItem)) {
114 addToItemsByNext(newItem);
115 queue.addLast(newItem);
116 }
117 }
118 }
119 }
120 }
121 }
122
123 void setIndex(int index) {
124 this.index = index;
125 }
126
127 public int getIndex() {
128 return index;
129 }
130
131 public Collection getKernelItems() {
132 return kernel;
133 }
134
135 public Collection getClosureItems() {
136 return closure;
137 }
138
139 public String toString() {
140 StringBuffer sb = new StringBuffer ();
141 sb.append("{");
142 Iterator it = kernel.iterator();
143 while (it.hasNext()) {
144 sb.append(it.next());
145 if (it.hasNext()) {
146 sb.append(", ");
147 }
148 }
149 sb.append("; ");
150 it = closure.iterator();
151 while (it.hasNext()) {
152 sb.append(it.next());
153 if (it.hasNext()) {
154 sb.append(", ");
155 }
156 }
157 sb.append("}");
158 return new String (sb);
159 }
160 }
161 |
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