src/main/java/org/codehaus/groovy/transform/InheritConstructorsASTTransformation.java

/*
 *  Licensed to the Apache Software Foundation (ASF) under one
 *  or more contributor license agreements.  See the NOTICE file
 *  distributed with this work for additional information
 *  regarding copyright ownership.  The ASF licenses this file
 *  to you 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.ast.ASTNode;
import org.codehaus.groovy.ast.AnnotatedNode;
import org.codehaus.groovy.ast.AnnotationNode;
import org.codehaus.groovy.ast.ClassNode;
import org.codehaus.groovy.ast.ConstructorNode;
import org.codehaus.groovy.ast.Parameter;
import org.codehaus.groovy.ast.expr.Expression;
import org.codehaus.groovy.ast.tools.ParameterUtils;
import org.codehaus.groovy.control.CompilePhase;
import org.codehaus.groovy.control.SourceUnit;

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

import static org.apache.groovy.ast.tools.ClassNodeUtils.addGeneratedConstructor;
import static org.codehaus.groovy.ast.ClassHelper.make;
import static org.codehaus.groovy.ast.tools.GeneralUtils.args;
import static org.codehaus.groovy.ast.tools.GeneralUtils.block;
import static org.codehaus.groovy.ast.tools.GeneralUtils.castX;
import static org.codehaus.groovy.ast.tools.GeneralUtils.ctorSuperS;
import static org.codehaus.groovy.ast.tools.GeneralUtils.param;
import static org.codehaus.groovy.ast.tools.GeneralUtils.varX;
import static org.codehaus.groovy.ast.tools.GenericsUtils.correctToGenericsSpecRecurse;
import static org.codehaus.groovy.ast.tools.GenericsUtils.createGenericsSpec;
import static org.codehaus.groovy.ast.tools.GenericsUtils.extractSuperClassGenerics;

/**
 * Handles generation of code for the {@code @}InheritConstructors annotation.
 */
@GroovyASTTransformation(phase = CompilePhase.CANONICALIZATION)
public class InheritConstructorsASTTransformation extends AbstractASTTransformation {

    private static final ClassNode INHERIT_CONSTRUCTORS_TYPE = make(InheritConstructors.class);
    private static final String ANNOTATION = "@" + INHERIT_CONSTRUCTORS_TYPE.getNameWithoutPackage();

    public void visit(ASTNode[] nodes, SourceUnit source) {
        init(nodes, source);
        AnnotationNode anno = (AnnotationNode) nodes[0];
        AnnotatedNode target = (AnnotatedNode) nodes[1];
        if (INHERIT_CONSTRUCTORS_TYPE.equals(anno.getClassNode()) && target instanceof ClassNode) {
            processClass((ClassNode) target, anno);
        }
    }

    private void processClass(ClassNode cNode, AnnotationNode node) {
        if (cNode.isInterface()) {
            addError("Error processing interface '" + cNode.getName() +
                    "'. " + ANNOTATION + " only allowed for classes.", cNode);
            return;
        }
        boolean copyConstructorAnnotations = memberHasValue(node, "constructorAnnotations", true);
        boolean copyParameterAnnotations = memberHasValue(node, "parameterAnnotations", true);
        ClassNode sNode = cNode.getSuperClass();
        List<AnnotationNode> superAnnotations = sNode.getAnnotations(INHERIT_CONSTRUCTORS_TYPE);
        if (superAnnotations.size() == 1) {
            // We need @InheritConstructors from parent classes processed first
            // so force that order here. The transformation is benign on an already
            // processed node so processing twice in any order won't matter bar
            // a very small time penalty.
            processClass(sNode, node);
        }
        for (ConstructorNode cn : sNode.getDeclaredConstructors()) {
            addConstructorUnlessAlreadyExisting(cNode, cn, copyConstructorAnnotations, copyParameterAnnotations);
        }
    }

    private void addConstructorUnlessAlreadyExisting(ClassNode classNode, ConstructorNode consNode, boolean copyConstructorAnnotations, boolean copyParameterAnnotations) {
        Parameter[] origParams = consNode.getParameters();
        if (consNode.isPrivate()) return;
        Parameter[] params = new Parameter[origParams.length];
        Map<String, ClassNode> genericsSpec = createGenericsSpec(classNode);
        extractSuperClassGenerics(classNode, classNode.getSuperClass(), genericsSpec);
        List<Expression> theArgs = buildParams(origParams, params, genericsSpec, copyParameterAnnotations);
        if (isExisting(classNode, params)) return;
        ConstructorNode added = addGeneratedConstructor(classNode, consNode.getModifiers(), params, consNode.getExceptions(), block(ctorSuperS(args(theArgs))));
        if (copyConstructorAnnotations) {
            added.addAnnotations(copyAnnotatedNodeAnnotations(consNode, ANNOTATION, false));
        }
    }

    private List<Expression> buildParams(Parameter[] origParams, Parameter[] params, Map<String, ClassNode> genericsSpec, boolean copyParameterAnnotations) {
        List<Expression> theArgs = new ArrayList<>();
        for (int i = 0, n = origParams.length; i < n; i += 1) {
            Parameter p = origParams[i];
            ClassNode newType = correctToGenericsSpecRecurse(genericsSpec, p.getType());
            params[i] = p.hasInitialExpression() ? param(newType, p.getName(), p.getInitialExpression()) : param(newType, p.getName());
            if (copyParameterAnnotations) {
                params[i].addAnnotations(copyAnnotatedNodeAnnotations(origParams[i], ANNOTATION));
            }
            // cast argument to parameter type in case the value is null
            theArgs.add(castX(p.getType(), varX(p.getName(), newType)));
        }
        return theArgs;
    }

    private static boolean isExisting(ClassNode classNode, Parameter[] params) {
        return classNode.getDeclaredConstructors().stream().anyMatch(ctor -> matchingTypes(params, ctor.getParameters()));
    }

    private static boolean matchingTypes(Parameter[] params, Parameter[] existingParams) {
        return ParameterUtils.parametersEqual(params, existingParams);
    }
}