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Groovy example source code file (EqualsAndHashCodeASTTransformation.java)

This example Groovy source code file (EqualsAndHashCodeASTTransformation.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, blockstatement, blockstatement, classnode, emptystatement, expression, expression, list, list, my_type_name, parameter, staticmethodcallexpression, util, variableexpression, variableexpression

The Groovy EqualsAndHashCodeASTTransformation.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.EqualsAndHashCode;
import org.codehaus.groovy.ast.*;
import org.codehaus.groovy.ast.expr.*;
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.syntax.Token;
import org.codehaus.groovy.syntax.Types;
import org.codehaus.groovy.util.HashCodeHelper;

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

import static org.codehaus.groovy.transform.AbstractASTTransformUtil.*;

@GroovyASTTransformation(phase = CompilePhase.CANONICALIZATION)
public class EqualsAndHashCodeASTTransformation extends AbstractASTTransformation {
    static final Class MY_CLASS = EqualsAndHashCode.class;
    static final ClassNode MY_TYPE = ClassHelper.make(MY_CLASS);
    static final String MY_TYPE_NAME = "@" + MY_TYPE.getNameWithoutPackage();
    private static final ClassNode HASHUTIL_TYPE = ClassHelper.make(HashCodeHelper.class);
    private static final Token ASSIGN = Token.newSymbol(Types.ASSIGN, -1, -1);
    private static final ClassNode OBJECT_TYPE = new ClassNode(Object.class);

    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 callSuper = memberHasValue(anno, "callSuper", true);
            boolean useCanEqual = !memberHasValue(anno, "useCanEqual", false);
            if (callSuper && cNode.getSuperClass().getName().equals("java.lang.Object")) {
                addError("Error during " + MY_TYPE_NAME + " processing: callSuper=true but '" + cNode.getName() + "' has no super class.", anno);
            }
            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);
            }
            createHashCode(cNode, false, includeFields, callSuper, excludes, includes);
            createEquals(cNode, includeFields, callSuper, useCanEqual, excludes, includes);
        }
    }

    public static void createHashCode(ClassNode cNode, boolean cacheResult, boolean includeFields, boolean callSuper, List<String> excludes, List includes) {
        // make a public method if none exists otherwise try a private method with leading underscore
        boolean hasExistingHashCode = hasDeclaredMethod(cNode, "hashCode", 0);
        if (hasExistingHashCode && hasDeclaredMethod(cNode, "_hashCode", 0)) return;

        final BlockStatement body = new BlockStatement();
        // TODO use pList and fList
        if (cacheResult) {
            final FieldNode hashField = cNode.addField("$hash$code", ACC_PRIVATE | ACC_SYNTHETIC, ClassHelper.int_TYPE, null);
            final Expression hash = new VariableExpression(hashField);
            body.addStatement(new IfStatement(
                    isZeroExpr(hash),
                    calculateHashStatements(cNode, hash, includeFields, callSuper, excludes, includes),
                    new EmptyStatement()
            ));
            body.addStatement(new ReturnStatement(hash));
        } else {
            body.addStatement(calculateHashStatements(cNode, null, includeFields, callSuper, excludes, includes));
        }

        cNode.addMethod(new MethodNode(hasExistingHashCode ? "_hashCode" : "hashCode", hasExistingHashCode ? ACC_PRIVATE : ACC_PUBLIC,
                ClassHelper.int_TYPE, Parameter.EMPTY_ARRAY, ClassNode.EMPTY_ARRAY, body));
    }

    private static Statement calculateHashStatements(ClassNode cNode, Expression hash, boolean includeFields, boolean callSuper, List<String> excludes, List includes) {
        final List<PropertyNode> pList = getInstanceProperties(cNode);
        final List<FieldNode> fList = new ArrayList();
        if (includeFields) {
            fList.addAll(getInstanceNonPropertyFields(cNode));
        }
        final BlockStatement body = new BlockStatement();
        // def _result = HashCodeHelper.initHash()
        final Expression result = new VariableExpression("_result");
        final Expression init = new StaticMethodCallExpression(HASHUTIL_TYPE, "initHash", MethodCallExpression.NO_ARGUMENTS);
        body.addStatement(new ExpressionStatement(new DeclarationExpression(result, ASSIGN, init)));

        for (PropertyNode pNode : pList) {
            if (shouldSkip(pNode.getName(), excludes, includes)) continue;
            // _result = HashCodeHelper.updateHash(_result, getProperty())
            String getterName = "get" + Verifier.capitalize(pNode.getName());
            Expression getter = new MethodCallExpression(VariableExpression.THIS_EXPRESSION, getterName, MethodCallExpression.NO_ARGUMENTS);
            final Expression args = new TupleExpression(result, getter);
            final Expression current = new StaticMethodCallExpression(HASHUTIL_TYPE, "updateHash", args);
            body.addStatement(assignStatement(result, current));

        }
        for (FieldNode fNode : fList) {
            if (shouldSkip(fNode.getName(), excludes, includes)) continue;
            // _result = HashCodeHelper.updateHash(_result, field)
            final Expression fieldExpr = new VariableExpression(fNode);
            final Expression args = new TupleExpression(result, fieldExpr);
            final Expression current = new StaticMethodCallExpression(HASHUTIL_TYPE, "updateHash", args);
            body.addStatement(assignStatement(result, current));
        }
        if (callSuper) {
            // _result = HashCodeHelper.updateHash(_result, super.hashCode())
            final Expression args = new TupleExpression(result, new MethodCallExpression(VariableExpression.SUPER_EXPRESSION, "hashCode", MethodCallExpression.NO_ARGUMENTS));
            final Expression current = new StaticMethodCallExpression(HASHUTIL_TYPE, "updateHash", args);
            body.addStatement(assignStatement(result, current));
        }
        // $hash$code = _result
        if (hash != null) {
            body.addStatement(assignStatement(hash, result));
        } else {
            body.addStatement(new ReturnStatement(result));
        }
        return body;
    }

    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));
    }

    private static void createCanEqual(ClassNode cNode) {
        boolean hasExistingCanEqual = hasDeclaredMethod(cNode, "canEqual", 1);
        if (hasExistingCanEqual && hasDeclaredMethod(cNode, "_canEqual", 1)) return;

        final BlockStatement body = new BlockStatement();
        VariableExpression other = new VariableExpression("other");
        body.addStatement(new ReturnStatement(isInstanceof(cNode, other)));
        Parameter[] params = {new Parameter(OBJECT_TYPE, other.getName())};
        cNode.addMethod(new MethodNode(hasExistingCanEqual ? "_canEqual" : "canEqual", hasExistingCanEqual ? ACC_PRIVATE : ACC_PUBLIC,
                ClassHelper.boolean_TYPE, params, ClassNode.EMPTY_ARRAY, body));

    }

    public static void createEquals(ClassNode cNode, boolean includeFields, boolean callSuper, boolean useCanEqual, List<String> excludes, List includes) {
        if (useCanEqual) createCanEqual(cNode);
        // make a public method if none exists otherwise try a private method with leading underscore
        boolean hasExistingEquals = hasDeclaredMethod(cNode, "equals", 1);
        if (hasExistingEquals && hasDeclaredMethod(cNode, "_equals", 1)) return;

        final BlockStatement body = new BlockStatement();
        VariableExpression other = new VariableExpression("other");

        // some short circuit cases for efficiency
        body.addStatement(returnFalseIfNull(other));
        body.addStatement(returnTrueIfIdentical(VariableExpression.THIS_EXPRESSION, other));

        if (useCanEqual) {
            body.addStatement(returnFalseIfNotInstanceof(cNode, other));
            body.addStatement(new IfStatement(
                    new BooleanExpression(new MethodCallExpression(other, "canEqual", VariableExpression.THIS_EXPRESSION)),
                    new EmptyStatement(),
                    new ReturnStatement(ConstantExpression.FALSE)
            ));
        } else {
            body.addStatement(returnFalseIfWrongType(cNode, other));
        }
//        body.addStatement(new ExpressionStatement(new BinaryExpression(other, ASSIGN, new CastExpression(cNode, other))));

        List<PropertyNode> pList = getInstanceProperties(cNode);
        for (PropertyNode pNode : pList) {
            if (shouldSkip(pNode.getName(), excludes, includes)) continue;
            body.addStatement(returnFalseIfPropertyNotEqual(pNode, other));
        }
        List<FieldNode> fList = new ArrayList();
        if (includeFields) {
            fList.addAll(getInstanceNonPropertyFields(cNode));
        }
        for (FieldNode fNode : fList) {
            if (shouldSkip(fNode.getName(), excludes, includes)) continue;
            body.addStatement(returnFalseIfFieldNotEqual(fNode, other));
        }
        if (callSuper) {
            body.addStatement(new IfStatement(
                    isTrueExpr(new MethodCallExpression(VariableExpression.SUPER_EXPRESSION, "equals", other)),
                    new EmptyStatement(),
                    new ReturnStatement(ConstantExpression.FALSE)
            ));
        }

        // default
        body.addStatement(new ReturnStatement(ConstantExpression.TRUE));

        Parameter[] params = {new Parameter(OBJECT_TYPE, other.getName())};
        cNode.addMethod(new MethodNode(hasExistingEquals ? "_equals" : "equals", hasExistingEquals ? ACC_PRIVATE : ACC_PUBLIC,
                ClassHelper.boolean_TYPE, params, ClassNode.EMPTY_ARRAY, body));
    }
}

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