KickJava   Java API By Example, From Geeks To Geeks.

Java > Open Source Codes > polyglot > ext > jl > ast > While_c


1 package polyglot.ext.jl.ast;
2
3 import polyglot.ast.*;
4 import polyglot.types.*;
5 import polyglot.visit.*;
6 import polyglot.util.*;
7 import java.util.*;
8
9 /**
10  * An immutable representation of a Java language <code>while</code>
11  * statement. It contains a statement to be executed and an expression
12  * to be tested indicating whether to reexecute the statement.
13  */
14 public class While_c extends Loop_c implements While
15 {
16     protected Expr cond;
17     protected Stmt body;
18
19     public While_c(Position pos, Expr cond, Stmt body) {
20     super(pos);
21     this.cond = cond;
22     this.body = body;
23     }
24
25     /** Get the conditional of the statement. */
26     public Expr cond() {
27     return this.cond;
28     }
29
30     /** Set the conditional of the statement. */
31     public While cond(Expr cond) {
32     While_c n = (While_c) copy();
33     n.cond = cond;
34     return n;
35     }
36
37     /** Get the body of the statement. */
38     public Stmt body() {
39     return this.body;
40     }
41
42     /** Set the body of the statement. */
43     public While body(Stmt body) {
44     While_c n = (While_c) copy();
45     n.body = body;
46     return n;
47     }
48
49     /** Reconstruct the statement. */
50     protected While_c reconstruct(Expr cond, Stmt body) {
51     if (cond != this.cond || body != this.body) {
52         While_c n = (While_c) copy();
53         n.cond = cond;
54         n.body = body;
55         return n;
56     }
57
58     return this;
59     }
60
61     /** Visit the children of the statement. */
62     public Node visitChildren(NodeVisitor v) {
63     Expr cond = (Expr) visitChild(this.cond, v);
64     Stmt body = (Stmt) visitChild(this.body, v);
65     return reconstruct(cond, body);
66     }
67
68     /** Type check the statement. */
69     public Node typeCheck(TypeChecker tc) throws SemanticException {
70     TypeSystem ts = tc.typeSystem();
71     
72     if (! ts.equals(cond.type(), ts.Boolean())) {
73         throw new SemanticException(
74         "Condition of while statement must have boolean type.",
75         cond.position());
76     }
77     
78     return this;
79     }
80
81     public Type childExpectedType(Expr child, AscriptionVisitor av) {
82         TypeSystem ts = av.typeSystem();
83
84         if (child == cond) {
85             return ts.Boolean();
86         }
87
88         return child.type();
89     }
90
91     public String JavaDoc toString() {
92     return "while (" + cond + ") ...";
93     }
94
95     /** Write the statement to an output file. */
96     public void prettyPrint(CodeWriter w, PrettyPrinter tr) {
97     w.write("while (");
98     printBlock(cond, w, tr);
99     w.write(")");
100     printSubStmt(body, w, tr);
101     }
102
103     public Term entry() {
104         return cond.entry();
105     }
106
107     public List acceptCFG(CFGBuilder v, List succs) {
108         if (condIsConstantTrue()) {
109             v.visitCFG(cond, body.entry());
110         }
111         else {
112             v.visitCFG(cond, FlowGraph.EDGE_KEY_TRUE, body.entry(),
113                              FlowGraph.EDGE_KEY_FALSE, this);
114         }
115
116         v.push(this).visitCFG(body, cond.entry());
117
118         return succs;
119     }
120
121     public Term continueTarget() {
122         return cond.entry();
123     }
124 }
125
Popular Tags