|
1 package ro.infoiasi.donald.compiler.parser;
2
3 import ro.infoiasi.donald.compiler.cfg.*;
4 import java.io.*;
5 import java.util.*;
6
7 public abstract class AbstractLR1Parser extends AbstractParser {
8 public AbstractLR1Parser(ParserSpec spec) {
9 super(spec, true);
10 }
11
12 public AbstractLR1Parser(String  parserSpecPath)
13 throws IOException, SpecParseException {
14 super(parserSpecPath, true);
15 }
16
17 protected int stateNo;
18 protected ParseAction[][] actionTable;
19 protected Integer [][] gotoTable;
20 protected Integer startStateIndex;
21
22 public ParseAction getAction(int state, Terminal a) {
23 return actionTable[state][a.getIndex()];
24 }
25
26 public int getGoto(int state, NonTerminal x) {
27 Integer newState = gotoTable[state][x.getIndex()];
28 if (newState != null) {
29 return newState.intValue();
30 } else {
31 return -1;
32 }
33 }
34
35 public Production getStartProduction() {
36 return sp;
37 }
38
39 public int getStateNo() {
40 return stateNo;
41 }
42
43 public int getStartState() {
44 return startStateIndex.intValue();
45 }
46
47 public interface ParseAction {
48 boolean isShiftAction();
49 boolean isReduceAction();
50 }
51
52 public class ShiftAction implements ParseAction {
53 private Integer stateIndex;
54 public ShiftAction(Integer stateIndex) {
55 this.stateIndex = stateIndex;
56 }
57 public Integer getStateIndex() {
58 return stateIndex;
59 }
60 public boolean isShiftAction() {
61 return true;
62 }
63 public boolean isReduceAction() {
64 return false;
65 }
66 public String toString() {
67 return stateIndex.toString();
68 }
69 }
70
71 public class ReduceAction implements ParseAction {
72 private Production production;
73 public ReduceAction(Production production) {
74 this.production = production;
75 }
76 public Production getProduction() {
77 return production;
78 }
79 public boolean isShiftAction() {
80 return false;
81 }
82 public boolean isReduceAction() {
83 return true;
84 }
85 public String toString() {
86 return production.toString();
87 }
88 }
89
90 public List parse()
91 throws IOException, SyntaxError {
92 List pi = new LinkedList();
93 LinkedList stack = new LinkedList();
94 stack.add(startStateIndex);
95 Terminal a = lexer.nextToken().getSymbol();
96
97 while (true) {
98 if (DEBUG) {
99 System.out.print("Stack: ");
100 Iterator stackIt = stack.iterator();
101 while (stackIt.hasNext()) {
102 Integer stateIndex = (Integer )stackIt.next();
103 System.out.print(stateIndex.intValue()+" ");
104 }
105 System.out.println();
106 }
107
108 Integer stateIndex = (Integer )stack.getLast();
109 ParseAction pa = actionTable[stateIndex.intValue()][a.getIndex()];
110 if (pa == null) {
111 throw new SyntaxError(a);
112 }
113 if (pa.isShiftAction()) {
114 ShiftAction sa = (ShiftAction)pa;
115 stack.add(sa.getStateIndex());
116 a = lexer.nextToken().getSymbol();
117 } else {
118 ReduceAction ra = (ReduceAction)pa;
119 Production prod = ra.getProduction();
120 if (prod == sp) {
121 return pi; }
123 for (int i = 0; i<prod.getRHS().size(); i++) {
124 stack.removeLast();
125 }
126 stateIndex = (Integer )stack.getLast();
127 stack.addLast(gotoTable[stateIndex.intValue()][prod.getLHS().getIndex()]);
128 pi.add(prod);
129 }
130 }
131 }
132 }
133 |
Popular Tags |
Java API By Example, From Geeks To Geeks.