KickJava   Java API By Example, From Geeks To Geeks.

Java > Open Source Codes > polyglot > visit > ConstructorCallChecker


1 package polyglot.visit;
2
3 import java.util.HashMap JavaDoc;
4 import java.util.Map JavaDoc;
5
6 import polyglot.ast.ConstructorCall;
7 import polyglot.ast.Node;
8 import polyglot.ast.NodeFactory;
9 import polyglot.frontend.Job;
10 import polyglot.types.ConstructorInstance;
11 import polyglot.types.Context;
12 import polyglot.types.SemanticException;
13 import polyglot.types.TypeSystem;
14 import polyglot.util.InternalCompilerError;
15
16 /** Visitor which ensures that constructor calls are not recursive. */
17 public class ConstructorCallChecker extends ContextVisitor
18 {
19     public ConstructorCallChecker(Job job, TypeSystem ts, NodeFactory nf) {
20     super(job, ts, nf);
21     }
22
23     protected Map JavaDoc constructorInvocations = new HashMap JavaDoc();
24     
25     protected NodeVisitor enterCall(Node n) throws SemanticException {
26         if (n instanceof ConstructorCall) {
27             ConstructorCall cc = (ConstructorCall)n;
28             if (cc.kind() == ConstructorCall.THIS) {
29                 // the constructor calls another constructor in the same class
30 Context ctxt = context();
31
32                 if (!(ctxt.currentCode() instanceof ConstructorInstance)) {
33                     throw new InternalCompilerError("Constructor call " +
34                         "occurring in a non-constructor.", cc.position());
35                 }
36                 ConstructorInstance srcCI = (ConstructorInstance)ctxt.currentCode();
37                 ConstructorInstance destCI = cc.constructorInstance();
38                 
39                 constructorInvocations.put(srcCI, destCI);
40                 while (destCI != null) {
41                     destCI = (ConstructorInstance)constructorInvocations.get(destCI);
42                     if (destCI != null && srcCI.equals(destCI)) {
43                         // loop in the constructor invocations!
44 throw new SemanticException("Recursive constructor " +
45                             "invocation.", cc.position());
46                     }
47                 }
48             }
49         }
50         return this;
51     }
52 }
53
54
Popular Tags