Groovy example source code file (InheritConstructorsASTTransformation.java)

This example Groovy source code file (InheritConstructorsASTTransformation.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, annotatednode, annotationnode, annotationnode, argumentlistexpression, blockstatement, classnode, classnode, constructornode, groovybugerror, my_type_name, parameter, parameter, sourceunit, util

The Groovy InheritConstructorsASTTransformation.java source code

/*
 * Copyright 2008-2010 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.transform;

import groovy.transform.InheritConstructors;
import org.codehaus.groovy.GroovyBugError;
import org.codehaus.groovy.ast.*;
import org.codehaus.groovy.ast.expr.ArgumentListExpression;
import org.codehaus.groovy.ast.expr.ConstructorCallExpression;
import org.codehaus.groovy.ast.expr.Expression;
import org.codehaus.groovy.ast.expr.VariableExpression;
import org.codehaus.groovy.ast.stmt.BlockStatement;
import org.codehaus.groovy.ast.stmt.ExpressionStatement;
import org.codehaus.groovy.control.CompilePhase;
import org.codehaus.groovy.control.SourceUnit;
import org.codehaus.groovy.control.messages.SyntaxErrorMessage;
import org.codehaus.groovy.syntax.SyntaxException;
import org.objectweb.asm.Opcodes;

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


/**
 * Handles generation of code for the {@code @}InheritConstructors annotation.
 *
 * @author Paul King
 */
@GroovyASTTransformation(phase = CompilePhase.CANONICALIZATION)
public class InheritConstructorsASTTransformation implements ASTTransformation, Opcodes {

    private static final Class MY_CLASS = InheritConstructors.class;
    private static final ClassNode MY_TYPE = ClassHelper.make(MY_CLASS);
    private static final String MY_TYPE_NAME = "@" + MY_TYPE.getNameWithoutPackage();

    public void visit(ASTNode[] nodes, SourceUnit source) {
        if (nodes.length != 2 || !(nodes[0] instanceof AnnotationNode) || !(nodes[1] instanceof AnnotatedNode)) {
            throw new GroovyBugError("Internal error: expecting [AnnotationNode, AnnotatedNode] but got: " + Arrays.asList(nodes));
        }

        AnnotatedNode parent = (AnnotatedNode) nodes[1];
        AnnotationNode node = (AnnotationNode) nodes[0];
        if (!MY_TYPE.equals(node.getClassNode())) return;

        if (parent instanceof ClassNode) {
            ClassNode cNode = (ClassNode) parent;
            if (cNode.isInterface()) {
                addError("Error processing interface '" + cNode.getName() +
                        "'. " + MY_TYPE_NAME + " only allowed for classes.", cNode, source);
                return;
            }
            ClassNode sNode = cNode.getSuperClass();
            for (ConstructorNode cn : sNode.getDeclaredConstructors()) {
                Parameter[] params = cn.getParameters();
                if (cn.isPrivate()) continue;
                Parameter[] pcopy = new Parameter[params.length];
                List<Expression> args = new ArrayList();
                for (int i = 0; i < params.length; i++) {
                    Parameter p = params[i];
                    pcopy[i] = p.hasInitialExpression() ?
                            new Parameter(p.getType(), p.getName(), p.getInitialExpression()) :
                            new Parameter(p.getType(), p.getName());
                    args.add(new VariableExpression(p.getName(), p.getType()));
                }
                if (isClashing(cNode, pcopy)) continue;
                BlockStatement body = new BlockStatement();
                body.addStatement(new ExpressionStatement(new ConstructorCallExpression(ClassNode.SUPER, new ArgumentListExpression(args))));
                cNode.addConstructor(cn.getModifiers(), pcopy, cn.getExceptions(), body);
            }
        }
    }

    private boolean isClashing(ClassNode cNode, Parameter[] pcopy) {
        for (ConstructorNode cn : cNode.getDeclaredConstructors()) {
            if (conflictingTypes(pcopy, cn.getParameters())) {
                return true;
            }
        }
        return false;
    }

    private boolean conflictingTypes(Parameter[] pcopy, Parameter[] parameters) {
        if (pcopy.length != parameters.length) return false;
        for (int i = 0; i < pcopy.length; i++) {
            if (!pcopy[i].getType().equals(parameters[i].getType())) {
                return false;
            }
        }
        return true;
    }

    private void addError(String msg, ASTNode expr, SourceUnit source) {
        int line = expr.getLineNumber();
        int col = expr.getColumnNumber();
        source.getErrorCollector().addErrorAndContinue(
                new SyntaxErrorMessage(new SyntaxException(msg + '\n', line, col), source)
        );
    }

}