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Groovy example source code file (Expression.java)

This example Groovy source code file (Expression.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

annotatednode, class, classnode, classnode, expression, expression, expressiontransformer, expressiontransformer, list, list, t, transformed, util

The Groovy Expression.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.ast.expr;

import java.util.ArrayList;
import java.util.List;

import org.codehaus.groovy.ast.ClassHelper;
import org.codehaus.groovy.ast.ClassNode;
import org.codehaus.groovy.ast.AnnotatedNode;
import org.codehaus.groovy.GroovyBugError;

/**
 * Represents a base class for expressions which evaluate as an object
 * 
 * @author <a href="mailto:james@coredevelopers.net">James Strachan
 * @version $Revision: 17114 $
 */
public abstract class Expression extends AnnotatedNode {

    private ClassNode type=ClassHelper.DYNAMIC_TYPE;
    
    /**
     * Return a copy of the expression calling the transformer on any nested expressions 
     * @param transformer
     */
    public abstract Expression transformExpression(ExpressionTransformer transformer);

    /**
     * Transforms the list of expressions
     * @return a new list of transformed expressions
     */
    protected List<Expression> transformExpressions(List expressions, ExpressionTransformer transformer) {
        List<Expression> list = new ArrayList(expressions.size());
        for (Expression expr : expressions ) {
            list.add(transformer.transform(expr));
        }
        return list;
    }

    /**
     * Transforms the list of expressions, and checks that all transformed expressions have the given type.
     *
     * @return a new list of transformed expressions
     */
    protected <T extends Expression> List transformExpressions(List expressions,
            ExpressionTransformer transformer, Class<T> transformedType) {
        List<T> list = new ArrayList(expressions.size());
        for (Expression expr : expressions) {
            Expression transformed = transformer.transform(expr);
            if (!transformedType.isInstance(transformed))
                throw new GroovyBugError(String.format("Transformed expression should have type %s but has type %s",
                    transformedType, transformed.getClass()));
            list.add(transformedType.cast(transformed));
        }
        return list;
    }
    
    public ClassNode getType() {
        return type;
    }
    
    public void setType(ClassNode t) {
        type=t;
    }
}

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