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1
3 package ro.infoiasi.donald.compiler.cfg;
4
5 import java.util.*;
6
7 public class Productions {
8 private List prodByIndex = new ArrayList();
9
10 private Map prodByLHS = new LinkedHashMap();
11 private Map prodByRHS = new HashMap();
12
13 private Production addToMaps(Production prod) {
14 NonTerminal lhs = prod.getLHS();
15 Word rhs = prod.getRHS();
16
17 LinkedList right;
18 if (prodByLHS.containsKey(lhs)) {
19 right = (LinkedList)prodByLHS.get(lhs);
20 } else {
21 right = new LinkedList();
22 }
23 Iterator it = right.iterator();
25 while (it.hasNext()) {
26 Production oldProd = (Production)it.next();
27 if (lhs.equals(oldProd.getLHS()) && rhs.equals(oldProd.getRHS())) {
28 return oldProd;
29 }
30 }
31 right.add(prod);
32 prodByLHS.put(lhs, right);
33
34
35 LinkedList left;
36 if (prodByRHS.containsKey(rhs)) {
37 left = (LinkedList)prodByRHS.get(rhs);
38 } else {
39 left = new LinkedList();
40 }
41 left.add(prod);
42 prodByRHS.put(rhs, left);
43 return prod;
44 }
45
46 private void clearMaps() {
47 prodByLHS.clear();
48 prodByRHS.clear();
49 }
50
51 public Production addNew(NonTerminal lhs, Word rhs,
52 int precedence, SemanticAction action) {
53 Production prod = new Production(lhs, rhs, precedence, action, count());
54 prod = addToMaps(prod);
55 prodByIndex.add(prod);
56 return prod;
57 }
58
59 public Production addNew(NonTerminal lhs, Word rhs, int precedence) {
60 return addNew(lhs, rhs, precedence, null);
61
62 }
63
64 public Production addNew(NonTerminal lhs, Word rhs, SemanticAction action) {
65 return addNew(lhs, rhs, Production.LAST_TERMINAL_PRECEDENCE, action);
66 }
67
68 public Production addNew(NonTerminal lhs, Word rhs) {
69 return addNew(lhs, rhs, Production.LAST_TERMINAL_PRECEDENCE, null);
70 }
71
72 public void addNew(NonTerminal lhs, List rhsList,
73 int precedence, SemanticAction action) {
74 Iterator it = rhsList.iterator();
75 while (it.hasNext()) {
76 Word rhs = (Word)it.next();
77 addNew(lhs, rhs, precedence, action);
78 }
79 }
80
81 public void addNew(NonTerminal lhs, List rhsList, int precedence) {
82 addNew(lhs, rhsList, precedence, null);
83 }
84
85 public void addNew(NonTerminal lhs, List rhsList, SemanticAction action) {
86 addNew(lhs, rhsList, Production.LAST_TERMINAL_PRECEDENCE, action);
87 }
88
89 public void addNew(NonTerminal lhs, List rhsList) {
90 addNew(lhs, rhsList, Production.LAST_TERMINAL_PRECEDENCE, null);
91 }
92
93 public int count() {
94 return prodByIndex.size();
95 }
96
97 public Iterator iterator() {
98 return Collections.unmodifiableList(prodByIndex).iterator();
99 }
100
101 public Iterator iterator(NonTerminal a) {
102 List prodList = find(a);
103 if (prodList == null) {
104 return new Iterator() {
106 public boolean hasNext() { return false; }
107 public Object  next() { throw new NoSuchElementException(); }
108 public void remove() { throw new UnsupportedOperationException (); }
109 };
110 } else {
111 return Collections.unmodifiableList(prodList).iterator();
112 }
113 }
114
115 public Production find(int index) {
116 if (index < 0 || index >= count()) {
117 return null;
118 } else {
119 return (Production)prodByIndex.get(index);
120 }
121 }
122
123 public LinkedList find(NonTerminal a) {
124 return (LinkedList)prodByLHS.get(a);
126 }
127
128 public LinkedList find(Word w) {
129 return (LinkedList)prodByRHS.get(w);
131 }
132
133 public void clear() {
134 prodByIndex.clear();
135 clearMaps();
136 }
137
138
139 void removeUseless(List s) {
140 clearMaps();
141 List tmp = new ArrayList();
142 for (int i = 0; i<prodByIndex.size(); i++) {
143 Production p = find(i);
144 boolean useful = true;
145 if (s.contains(p.getLHS())) {
146 useful = false;
147 } else {
148 Word w = p.getRHS();
149 WordIterator itW = w.iterator();
150 while (itW.hasNextNonTerminal()) {
151 NonTerminal a = itW.nextNonTerminal();
152 if (s.contains(a)) {
153 useful = false;
154 break;
155 }
156 }
157 }
158 if (useful) {
159 p.setIndex(tmp.size());
160 tmp.add(p);
161 addToMaps(p);
162 }
163 }
164 prodByIndex = tmp;
165 }
166
167 public boolean isInvertible() {
168 Iterator it = prodByRHS.keySet().iterator();
169 while (it.hasNext()) {
170 List rhsList = find((Word)it.next());
171 switch (rhsList.size()) {
172 case 0: throw new RuntimeException ("Null value in prodByRHS");
173 case 1: break;
174 default: return false;
175 }
176 }
177 return true;
178 }
179
180 public String toString() {
181 StringBuffer sb = new StringBuffer ();
182 Set keySet = prodByLHS.keySet();
183 Iterator it = keySet.iterator();
184 while (it.hasNext()) {
185 NonTerminal var = (NonTerminal)it.next();
186 sb.append(var+" ::= ");
187 List rhsList = (List)prodByLHS.get(var);
188 Iterator itL = rhsList.iterator();
189 while (itL.hasNext()) {
190 sb.append(((Production)itL.next()).getRHS());
191 if (itL.hasNext()) {
192 sb.append(" | ");
193 }
194 }
195 sb.append(";\n");
196 }
197 return sb.toString();
198 }
199 }
200 |
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