Groovy example source code file (ToStringASTTransformation.java)

This example Groovy source code file (ToStringASTTransformation.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

acc_private, annotationnode, blockstatement, classnode, classnode, constantexpression, constantexpression, expression, expression, expressionstatement, list, list, my_type_name, string, util

The Groovy ToStringASTTransformation.java source code

/*
 * Copyright 2008-2011 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.ToString;
import org.codehaus.groovy.ast.ASTNode;
import org.codehaus.groovy.ast.AnnotatedNode;
import org.codehaus.groovy.ast.AnnotationNode;
import org.codehaus.groovy.ast.ClassHelper;
import org.codehaus.groovy.ast.ClassNode;
import org.codehaus.groovy.ast.FieldNode;
import org.codehaus.groovy.ast.MethodNode;
import org.codehaus.groovy.ast.Parameter;
import org.codehaus.groovy.ast.PropertyNode;
import org.codehaus.groovy.ast.expr.BooleanExpression;
import org.codehaus.groovy.ast.expr.ConstantExpression;
import org.codehaus.groovy.ast.expr.ConstructorCallExpression;
import org.codehaus.groovy.ast.expr.DeclarationExpression;
import org.codehaus.groovy.ast.expr.Expression;
import org.codehaus.groovy.ast.expr.MethodCallExpression;
import org.codehaus.groovy.ast.expr.StaticMethodCallExpression;
import org.codehaus.groovy.ast.expr.VariableExpression;
import org.codehaus.groovy.ast.stmt.BlockStatement;
import org.codehaus.groovy.ast.stmt.EmptyStatement;
import org.codehaus.groovy.ast.stmt.ExpressionStatement;
import org.codehaus.groovy.ast.stmt.IfStatement;
import org.codehaus.groovy.ast.stmt.ReturnStatement;
import org.codehaus.groovy.ast.stmt.Statement;
import org.codehaus.groovy.classgen.Verifier;
import org.codehaus.groovy.control.CompilePhase;
import org.codehaus.groovy.control.SourceUnit;
import org.codehaus.groovy.runtime.InvokerHelper;
import org.codehaus.groovy.syntax.Token;
import org.codehaus.groovy.syntax.Types;

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

import static org.codehaus.groovy.transform.AbstractASTTransformUtil.getInstanceNonPropertyFields;
import static org.codehaus.groovy.transform.AbstractASTTransformUtil.getInstanceProperties;
import static org.codehaus.groovy.transform.AbstractASTTransformUtil.hasDeclaredMethod;

/**
 * Handles generation of code for the @ToString annotation.
 *
 * @author Paul King
 */
@GroovyASTTransformation(phase = CompilePhase.CANONICALIZATION)
public class ToStringASTTransformation extends AbstractASTTransformation {

    static final Class MY_CLASS = ToString.class;
    static final ClassNode MY_TYPE = ClassHelper.make(MY_CLASS);
    static final String MY_TYPE_NAME = "@" + MY_TYPE.getNameWithoutPackage();
    private static final ClassNode STRINGBUFFER_TYPE = ClassHelper.make(StringBuffer.class);
    private static final ClassNode INVOKER_TYPE = ClassHelper.make(InvokerHelper.class);
    private static final Token ASSIGN = Token.newSymbol(Types.ASSIGN, -1, -1);

    public void visit(ASTNode[] nodes, SourceUnit source) {
        init(nodes, source);
        AnnotatedNode parent = (AnnotatedNode) nodes[1];
        AnnotationNode anno = (AnnotationNode) nodes[0];
        if (!MY_TYPE.equals(anno.getClassNode())) return;

        if (parent instanceof ClassNode) {
            ClassNode cNode = (ClassNode) parent;
            checkNotInterface(cNode, MY_TYPE_NAME);
            boolean includeSuper = memberHasValue(anno, "includeSuper", true);
            if (includeSuper && cNode.getSuperClass().getName().equals("java.lang.Object")) {
                addError("Error during " + MY_TYPE_NAME + " processing: includeSuper=true but '" + cNode.getName() + "' has no super class.", anno);
            }
            boolean includeNames = memberHasValue(anno, "includeNames", true);
            boolean includeFields = memberHasValue(anno, "includeFields", true);
            List<String> excludes = tokenize((String) getMemberValue(anno, "excludes"));
            List<String> includes = tokenize((String) getMemberValue(anno, "includes"));
            if (hasAnnotation(cNode, CanonicalASTTransformation.MY_TYPE)) {
                AnnotationNode canonical = cNode.getAnnotations(CanonicalASTTransformation.MY_TYPE).get(0);
                if (excludes == null || excludes.isEmpty()) excludes = tokenize((String) getMemberValue(canonical, "excludes"));
                if (includes == null || includes.isEmpty()) includes = tokenize((String) getMemberValue(canonical, "includes"));
            }
            if (includes != null && !includes.isEmpty() && excludes != null && !excludes.isEmpty()) {
                addError("Error during " + MY_TYPE_NAME + " processing: Only one of 'includes' and 'excludes' should be supplied not both.", anno);
            }
            toStringInit(cNode, new ConstantExpression(includeNames));
            createToString(cNode, includeSuper, includeFields, excludes, includes);
        }
    }

    public static void createToString(ClassNode cNode, boolean includeSuper, boolean includeFields, List<String> excludes, List includes) {
        // make a public method if none exists otherwise try a private method with leading underscore
        boolean hasExistingToString = hasDeclaredMethod(cNode, "toString", 0);
        if (hasExistingToString && hasDeclaredMethod(cNode, "_toString", 0)) return;

        final BlockStatement body = new BlockStatement();
        // def _result = new StringBuffer()
        final Expression result = new VariableExpression("_result");
        final Expression init = new ConstructorCallExpression(STRINGBUFFER_TYPE, MethodCallExpression.NO_ARGUMENTS);
        body.addStatement(new ExpressionStatement(new DeclarationExpression(result, ASSIGN, init)));

        body.addStatement(append(result, new ConstantExpression(cNode.getName())));
        body.addStatement(append(result, new ConstantExpression("(")));
        boolean first = true;
        List<PropertyNode> pList = getInstanceProperties(cNode);
        for (PropertyNode pNode : pList) {
            if (shouldSkip(pNode.getName(), excludes, includes)) continue;
            first = appendPrefix(cNode, body, result, first, pNode.getName());
            String getterName = "get" + Verifier.capitalize(pNode.getName());
            Expression getter = new MethodCallExpression(VariableExpression.THIS_EXPRESSION, getterName, MethodCallExpression.NO_ARGUMENTS);
            body.addStatement(append(result, new StaticMethodCallExpression(INVOKER_TYPE, "toString", getter)));
        }
        List<FieldNode> fList = new ArrayList();
        if (includeFields) {
            fList.addAll(getInstanceNonPropertyFields(cNode));
        }
        for (FieldNode fNode : fList) {
            if (shouldSkip(fNode.getName(), excludes, includes)) continue;
            first = appendPrefix(cNode, body, result, first, fNode.getName());
            body.addStatement(append(result, new StaticMethodCallExpression(INVOKER_TYPE, "toString", new VariableExpression(fNode))));
        }
        if (includeSuper) {
            appendPrefix(cNode, body, result, first, "super");
            // not through MOP to avoid infinite recursion
            body.addStatement(append(result, new MethodCallExpression(VariableExpression.SUPER_EXPRESSION, "toString", MethodCallExpression.NO_ARGUMENTS)));
        }
        body.addStatement(append(result, new ConstantExpression(")")));
        body.addStatement(new ReturnStatement(new MethodCallExpression(result, "toString", MethodCallExpression.NO_ARGUMENTS)));
        cNode.addMethod(new MethodNode(hasExistingToString ? "_toString" : "toString", hasExistingToString ? ACC_PRIVATE : ACC_PUBLIC,
                ClassHelper.STRING_TYPE, Parameter.EMPTY_ARRAY, ClassNode.EMPTY_ARRAY, body));
    }

    private static boolean appendPrefix(ClassNode cNode, BlockStatement body, Expression result, boolean first, String name) {
        if (first) {
            first = false;
        } else {
            body.addStatement(append(result, new ConstantExpression(", ")));
        }
        body.addStatement(new IfStatement(
                new BooleanExpression(new VariableExpression(cNode.getField("$print$names"))),
                toStringPropertyName(result, name),
                new EmptyStatement()
        ));
        return first;
    }

    private static Statement toStringPropertyName(Expression result, String fName) {
        final BlockStatement body = new BlockStatement();
        body.addStatement(append(result, new ConstantExpression(fName)));
        body.addStatement(append(result, new ConstantExpression(":")));
        return body;
    }

    private static ExpressionStatement append(Expression result, Expression expr) {
        return new ExpressionStatement(new MethodCallExpression(result, "append", expr));
    }

    private static boolean shouldSkip(String name, List<String> excludes, List includes) {
        return (excludes != null && excludes.contains(name)) || name.contains("$") || (includes != null && !includes.isEmpty() && !includes.contains(name));
    }

    public static void toStringInit(ClassNode cNode, ConstantExpression fieldValue) {
        cNode.addField("$print$names", ACC_PRIVATE | ACC_SYNTHETIC, ClassHelper.boolean_TYPE, fieldValue);
    }

}