labelverifier.java

大名鼎鼎的java动态脚本语言。已经通过了sun的认证

/*
 $Id: LabelVerifier.java,v 1.1 2006/01/19 00:07:02 blackdrag Exp $

 Copyright 2003 (C) James Strachan and Bob Mcwhirter. All Rights Reserved.

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 ("Software"), with or without modification, are permitted provided
 that the following conditions are met:

 1. Redistributions of source code must retain copyright
    statements and notices.  Redistributions must also contain a
    copy of this document.

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    above copyright notice, this list of conditions and the
    following disclaimer in the documentation and/or other
    materials provided with the distribution.

 3. The name "groovy" must not be used to endorse or promote
    products derived from this Software without prior written
    permission of The Codehaus.  For written permission,
    please contact [e-mail].

 4. Products derived from this Software may not be called "groovy"
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    trademark of The Codehaus.

 5. Due credit should be given to The Codehaus -
    http://groovy.codehaus.org/

 THIS SOFTWARE IS PROVIDED BY THE CODEHAUS AND CONTRIBUTORS
 ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT
 NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
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package org.codehaus.groovy.control;

import java.util.Iterator;
import java.util.LinkedList;

import org.codehaus.groovy.ast.ClassCodeVisitorSupport;
import org.codehaus.groovy.ast.stmt.BreakStatement;
import org.codehaus.groovy.ast.stmt.ContinueStatement;
import org.codehaus.groovy.ast.stmt.DoWhileStatement;
import org.codehaus.groovy.ast.stmt.ForStatement;
import org.codehaus.groovy.ast.stmt.Statement;
import org.codehaus.groovy.ast.stmt.SwitchStatement;
import org.codehaus.groovy.ast.stmt.WhileStatement;

/**
 * This class checks the handling of labels in the AST
 * 
 * @author Jochen Theodorou
 */
public class LabelVerifier extends ClassCodeVisitorSupport {

    private SourceUnit source;
    private LinkedList visitedLabels;
    private LinkedList continueLabels;
    private LinkedList breakLabels;
    boolean inLoop=false;
    boolean inSwitch=false;
    
    public LabelVerifier(SourceUnit src) {
        source = src;
    }
    
    protected SourceUnit getSourceUnit() {
        return source;
    }
    
    private void init(){
        visitedLabels = new LinkedList();
        continueLabels = new LinkedList();
        breakLabels = new LinkedList();
        inLoop=false;
        inSwitch=false;
    }
    
    protected void visitClassCodeContainer(Statement code) {
        init();
        super.visitClassCodeContainer(code);
        assertNoLabelsMissed();
    }
    
   public void visitStatement(Statement statement) {
       String label = statement.getStatementLabel();
       
       if (label!=null) {
           for (Iterator iter = breakLabels.iterator(); iter.hasNext();) {
               BreakStatement element = (BreakStatement) iter.next();
               if (element.getLabel().equals(label)) iter.remove();
           }
           
           for (Iterator iter = continueLabels.iterator(); iter.hasNext();) {
               ContinueStatement element = (ContinueStatement) iter.next();
               if (element.getLabel().equals(label)) iter.remove();
           }
           
           visitedLabels.add(label);
       }
       
       super.visitStatement(statement);
}
    
    public void visitForLoop(ForStatement forLoop) {
        boolean oldInLoop = inLoop;
        inLoop = true;
        super.visitForLoop(forLoop);
        inLoop = oldInLoop;
    }
    
    public void visitDoWhileLoop(DoWhileStatement loop) {
        boolean oldInLoop = inLoop;
        inLoop = true;
        super.visitDoWhileLoop(loop);
        inLoop = oldInLoop;
    }     
    
    public void visitWhileLoop(WhileStatement loop) {
        boolean oldInLoop = inLoop;
        inLoop = true;
        super.visitWhileLoop(loop);
        inLoop = oldInLoop;
    }
    
    public void visitBreakStatement(BreakStatement statement) {
        String label = statement.getLabel();
        boolean hasNamedLabel = label!=null;
        if (!hasNamedLabel && !inLoop && !inSwitch) {
            addError("the break statement is only allowed inside loops or switches",statement);
        } else if (hasNamedLabel && !inLoop) {
            addError("the break statement with named label is only allowed inside loops",statement);
        }
        if (label!=null) {
            boolean found=false;
            for (Iterator iter = visitedLabels.iterator(); iter.hasNext();) {
                String element = (String) iter.next();
                if (element.equals(label)) {
                    found = true;
                    break;
                }
            }
            if (!found) breakLabels.add(statement);
        }
        
        super.visitBreakStatement(statement);
    }
    
    public void visitContinueStatement(ContinueStatement statement) {
        String label = statement.getLabel();
        boolean hasNamedLabel = label!=null;
        if (!hasNamedLabel && !inLoop) {
            addError("the continue statement is only allowed inside loops",statement);
        } 
        if (label!=null) {
            boolean found=false;
            for (Iterator iter = visitedLabels.iterator(); iter.hasNext();) {
                String element = (String) iter.next();
                if (element.equals(label)) {
                    found = true;
                    break;
                }
            }
            if (!found) continueLabels.add(statement);
        }
        
        super.visitContinueStatement(statement);
    }
    
    protected void assertNoLabelsMissed() {
        //TODO: report multiple missing labels of the same name only once
        for (Iterator iter = continueLabels.iterator(); iter.hasNext();) {
            ContinueStatement element = (ContinueStatement) iter.next();
            addError("continue to missing label",element);
        }
        for (Iterator iter = breakLabels.iterator(); iter.hasNext();) {
            BreakStatement element = (BreakStatement) iter.next();
            addError("break to missing label",element);
        }
    }
    
    public void visitSwitch(SwitchStatement statement) {
        inSwitch=true;
        super.visitSwitch(statement);
    }

}