home | career | drupal | java | mac | mysql | perl | scala | uml | unix

Groovy example source code file (PreJava2GroovyConverter.java)

This example Groovy source code file (PreJava2GroovyConverter.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Groovy tags/keywords

groovysourceast, groovysourceast, java2groovyconvertor, list_constructor, object, object, opening_visit, prejava2groovyconverter, prejava2groovyconverter, stack, stack, string, util, visitoradapter

The Groovy PreJava2GroovyConverter.java source code

/*
 * Copyright 2003-2007 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.codehaus.groovy.antlr.java;

import java.util.Stack;

import org.codehaus.groovy.antlr.GroovySourceAST;
import org.codehaus.groovy.antlr.treewalker.VisitorAdapter;

/** This class mutates the Java AST, whilst it is still a Java AST, in readiness for conversion to Groovy, yippee-ky-a ! */
public class PreJava2GroovyConverter extends VisitorAdapter{
    private String[] tokenNames;
    private Stack stack;

	public PreJava2GroovyConverter(String[] tokenNames) {
		this.tokenNames = tokenNames;
		this.stack = new Stack();
	}
	
    public void visitDefault(GroovySourceAST t,int visit) {
        if (visit == OPENING_VISIT) {
        	if (t.getType() == JavaTokenTypes.LITERAL_do) {
        		visitJavaLiteralDo(t);        		
        	} else if (t.getType() == JavaTokenTypes.ARRAY_INIT) {
        		visitJavaArrayInit(t);
        	}
        }
    }
    
    private void visitJavaLiteralDo(GroovySourceAST t) {
    	// todo - incomplete, as body of do...while... should be executed at least once, which this doesn't provide.
    	swapTwoChildren(t);        		    	
    }

    /**
     * Handle Arrays. Examples:
     *
     * <pre>
     * String[] myArray = new String[] {"a","b","c"};
     * 
     * becomes
     * 
     * String[] myArray = ["a", "b", "c"]
     * 
     * ---
     * 
     * To convert node (t) and surrounding nodes into the right structure for List Constructor
     * 
     * (a) java/EXPR
     *  |
     *  +- (b) java/new
     *      |
     *      + (t) java/ARRAY_INIT
     *    
     *  becomes
     *  
     * (a) groovy/LIST_CONSTRUCTOR (via ARRAY_INIT as temporary marker type)
     *  |
     *  +- (t) groovy/ELIST
     *  
     *  * note: node (b) is thrown away...
     * </pre>
     */
	private void visitJavaArrayInit(GroovySourceAST t) {
		// given that we might have a grandParent...
		if (stack.size() > 2) {
			GroovySourceAST grandParent = getGrandParentNode();
			if (grandParent.getType() == JavaTokenTypes.EXPR) {
				grandParent.setType(JavaTokenTypes.ARRAY_INIT); //set type as indicator for Java2GroovyConvertor to turn into LIST_CONSTRUCTOR
				grandParent.setFirstChild(t);
				t.setType(JavaTokenTypes.ELIST);
			}
		}
	}

	/** To swap two children of node t...
	 * 
	 *<pre>
	 *   (t)
	 *    |
	 *    |
	 *   (a) -- (b)
	 * 
	 * t.down = firstNode
	 * a.right = b
	 * b.right = null
	 *</pre> 
	 * becomes
	 *<pre>
	 *   (t)
	 *    |
	 *    |
	 *   (b) -- (a)
	 *   
	 * t.down = b
	 * a.right = null
	 * b.right = a
	 *</pre>
	 *
	 * todo - build API of basic tree mutations like this method.
	 */
    public void swapTwoChildren(GroovySourceAST t) {
		// this swaps the two child nodes, see javadoc above for explanation of implementation
		GroovySourceAST a = (GroovySourceAST) t.getFirstChild();
		GroovySourceAST b = (GroovySourceAST) a.getNextSibling();

		t.setFirstChild(b);
		a.setNextSibling(null);
		b.setNextSibling(a);
    }
    
    
    
    
    public void push(GroovySourceAST t) {
        stack.push(t);
    }
    public GroovySourceAST pop() {
        if (!stack.empty()) {
            return (GroovySourceAST) stack.pop();
        }
        return null;
    }

    private GroovySourceAST getParentNode() {
        Object currentNode = stack.pop();
        Object parentNode = stack.peek();
        stack.push(currentNode);
        return (GroovySourceAST) parentNode;
    }

    private GroovySourceAST getGrandParentNode() {
        Object currentNode = stack.pop();
        Object parentNode = stack.pop();
        Object grandParentNode = stack.peek();
        stack.push(parentNode);
        stack.push(currentNode);
        return (GroovySourceAST) grandParentNode;
    }
}

Other Groovy examples (source code examples)

Here is a short list of links related to this Groovy PreJava2GroovyConverter.java source code file:

new blog posts

 

Copyright 1998-2013 Alvin Alexander, alvinalexander.com
All Rights Reserved.