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Groovy: A powerful, dynamic language for the JVM
/*
* 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 groovy.transform.builder;
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.FieldNode;
import org.codehaus.groovy.ast.InnerClassNode;
import org.codehaus.groovy.ast.MethodNode;
import org.codehaus.groovy.ast.Parameter;
import org.codehaus.groovy.ast.expr.Expression;
import org.codehaus.groovy.ast.stmt.BlockStatement;
import org.codehaus.groovy.transform.BuilderASTTransformation;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import static org.codehaus.groovy.ast.ClassHelper.OBJECT_TYPE;
import static org.codehaus.groovy.ast.tools.GeneralUtils.args;
import static org.codehaus.groovy.ast.tools.GeneralUtils.assignX;
import static org.codehaus.groovy.ast.tools.GeneralUtils.block;
import static org.codehaus.groovy.ast.tools.GeneralUtils.callX;
import static org.codehaus.groovy.ast.tools.GeneralUtils.constX;
import static org.codehaus.groovy.ast.tools.GeneralUtils.ctorX;
import static org.codehaus.groovy.ast.tools.GeneralUtils.declS;
import static org.codehaus.groovy.ast.tools.GeneralUtils.getInstancePropertyFields;
import static org.codehaus.groovy.ast.tools.GeneralUtils.param;
import static org.codehaus.groovy.ast.tools.GeneralUtils.params;
import static org.codehaus.groovy.ast.tools.GeneralUtils.propX;
import static org.codehaus.groovy.ast.tools.GeneralUtils.returnS;
import static org.codehaus.groovy.ast.tools.GeneralUtils.stmt;
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;
import static org.codehaus.groovy.ast.tools.GenericsUtils.newClass;
import static org.codehaus.groovy.transform.AbstractASTTransformation.getMemberStringValue;
import static org.codehaus.groovy.transform.AbstractASTTransformation.shouldSkip;
import static org.codehaus.groovy.transform.BuilderASTTransformation.NO_EXCEPTIONS;
import static org.codehaus.groovy.transform.BuilderASTTransformation.NO_PARAMS;
import static org.objectweb.asm.Opcodes.ACC_PRIVATE;
import static org.objectweb.asm.Opcodes.ACC_PUBLIC;
import static org.objectweb.asm.Opcodes.ACC_STATIC;
/**
* This strategy is used with the {@link Builder} AST transform to create a builder helper class
* for the fluent creation of instances of a specified class. It can be used at the class,
* static method or constructor levels.
*
* You use it as follows:
*
* import groovy.transform.builder.*
*
* {@code @Builder}
* class Person {
* String firstName
* String lastName
* int age
* }
* def person = Person.builder().firstName("Robert").lastName("Lewandowski").age(21)
* assert person.firstName == "Robert"
* assert person.lastName == "Lewandowski"
* assert person.age == 21
*
* The {@code prefix} annotation attribute can be used to create setters with a different naming convention. The default is the
* empty string but you could change that to "set" as follows:
*
* {@code @groovy.transform.builder.Builder}(prefix='set')
* class Person {
* String firstName
* String lastName
* int age
* }
* def p2 = Person.builder().setFirstName("Robert").setLastName("Lewandowski").setAge(21)
*
* or using a prefix of 'with' would result in usage like this:
*
* def p3 = Person.builder().withFirstName("Robert").withLastName("Lewandowski").withAge(21)
*
*
* You can also use the {@code @Builder} annotation in combination with this strategy on one or more constructor or
* static method instead of or in addition to using it at the class level. An example with a constructor follows:
*
* import groovy.transform.ToString
* import groovy.transform.builder.Builder
*
* {@code @ToString}
* class Person {
* String first, last
* int born
*
* {@code @Builder}
* Person(String roleName) {
* if (roleName == 'Jack Sparrow') {
* first = 'Johnny'; last = 'Depp'; born = 1963
* }
* }
* }
* assert Person.builder().roleName("Jack Sparrow").build().toString() == 'Person(Johnny, Depp, 1963)'
*
* In this case, the parameter(s) for the constructor or static method become the properties available
* in the builder. For the case of a static method, the return type of the static method becomes the
* class of the instance being created. For static factory methods, this is normally the class containing the
* static method but in general it can be any class.
*
* Note: if using more than one {@code @Builder} annotation, which is only possible when using static method
* or constructor variants, it is up to you to ensure that any generated helper classes or builder methods
* have unique names. E.g. we can modify the previous example to have three builders. At least two of the builders
* in our case will need to set the 'builderClassName' and 'builderMethodName' annotation attributes to ensure
* we have unique names. This is shown in the following example:
*
* import groovy.transform.builder.*
* import groovy.transform.*
*
* {@code @ToString}
* {@code @Builder}
* class Person {
* String first, last
* int born
*
* Person(){} // required to retain no-arg constructor
*
* {@code @Builder}(builderClassName='MovieBuilder', builderMethodName='byRoleBuilder')
* Person(String roleName) {
* if (roleName == 'Jack Sparrow') {
* this.first = 'Johnny'; this.last = 'Depp'; this.born = 1963
* }
* }
*
* {@code @Builder}(builderClassName='SplitBuilder', builderMethodName='splitBuilder')
* static Person split(String name, int year) {
* def parts = name.split(' ')
* new Person(first: parts[0], last: parts[1], born: year)
* }
* }
*
* assert Person.splitBuilder().name("Johnny Depp").year(1963).build().toString() == 'Person(Johnny, Depp, 1963)'
* assert Person.byRoleBuilder().roleName("Jack Sparrow").build().toString() == 'Person(Johnny, Depp, 1963)'
* assert Person.builder().first("Johnny").last('Depp').born(1963).build().toString() == 'Person(Johnny, Depp, 1963)'
*
*
* The 'forClass' annotation attribute for the {@code @Builder} transform isn't applicable for this strategy.
*
* @author Paul King
*/
public class DefaultStrategy extends BuilderASTTransformation.AbstractBuilderStrategy {
private static final Expression DEFAULT_INITIAL_VALUE = null;
private static final int PUBLIC_STATIC = ACC_PUBLIC | ACC_STATIC;
public void build(BuilderASTTransformation transform, AnnotatedNode annotatedNode, AnnotationNode anno) {
if (unsupportedAttribute(transform, anno, "forClass")) return;
if (annotatedNode instanceof ClassNode) {
buildClass(transform, (ClassNode) annotatedNode, anno);
} else if (annotatedNode instanceof MethodNode) {
buildMethod(transform, (MethodNode) annotatedNode, anno);
}
}
public void buildMethod(BuilderASTTransformation transform, MethodNode mNode, AnnotationNode anno) {
if (transform.getMemberValue(anno, "includes") != null || transform.getMemberValue(anno, "excludes") != null) {
transform.addError("Error during " + BuilderASTTransformation.MY_TYPE_NAME +
" processing: includes/excludes only allowed on classes", anno);
}
ClassNode buildee = mNode.getDeclaringClass();
ClassNode builder = createBuilder(anno, buildee);
createBuilderFactoryMethod(anno, buildee, builder);
for (Parameter parameter : mNode.getParameters()) {
builder.addField(createFieldCopy(buildee, parameter));
builder.addMethod(createBuilderMethodForProp(builder, new PropertyInfo(parameter.getName(), parameter.getType()), getPrefix(anno)));
}
builder.addMethod(createBuildMethodForMethod(anno, buildee, mNode, mNode.getParameters()));
}
public void buildClass(BuilderASTTransformation transform, ClassNode buildee, AnnotationNode anno) {
List excludes = new ArrayList();
List includes = new ArrayList();
if (!getIncludeExclude(transform, anno, buildee, excludes, includes)) return;
ClassNode builder = createBuilder(anno, buildee);
createBuilderFactoryMethod(anno, buildee, builder);
List fields = getInstancePropertyFields(buildee);
List filteredFields = selectFieldsFromExistingClass(fields, includes, excludes);
for (FieldNode fieldNode : filteredFields) {
ClassNode correctedType = getCorrectedType(buildee, fieldNode);
String fieldName = fieldNode.getName();
builder.addField(createFieldCopy(buildee, fieldName, correctedType));
builder.addMethod(createBuilderMethodForProp(builder, new PropertyInfo(fieldName, correctedType), getPrefix(anno)));
}
builder.addMethod(createBuildMethod(anno, buildee, filteredFields));
}
private static ClassNode getCorrectedType(ClassNode buildee, FieldNode fieldNode) {
Map genericsSpec = createGenericsSpec(fieldNode.getDeclaringClass());
extractSuperClassGenerics(fieldNode.getType(), buildee, genericsSpec);
return correctToGenericsSpecRecurse(genericsSpec, fieldNode.getType());
}
private static void createBuilderFactoryMethod(AnnotationNode anno, ClassNode buildee, ClassNode builder) {
buildee.getModule().addClass(builder);
buildee.addMethod(createBuilderMethod(anno, builder));
}
private static ClassNode createBuilder(AnnotationNode anno, ClassNode buildee) {
return new InnerClassNode(buildee, getFullName(anno, buildee), PUBLIC_STATIC, OBJECT_TYPE);
}
private static String getFullName(AnnotationNode anno, ClassNode buildee) {
String builderClassName = getMemberStringValue(anno, "builderClassName", buildee.getNameWithoutPackage() + "Builder");
return buildee.getName() + "$" + builderClassName;
}
private static String getPrefix(AnnotationNode anno) {
return getMemberStringValue(anno, "prefix", "");
}
private static MethodNode createBuildMethodForMethod(AnnotationNode anno, ClassNode buildee, MethodNode mNode, Parameter[] params) {
String buildMethodName = getMemberStringValue(anno, "buildMethodName", "build");
final BlockStatement body = new BlockStatement();
ClassNode returnType;
if (mNode instanceof ConstructorNode) {
returnType = newClass(buildee);
body.addStatement(returnS(ctorX(newClass(mNode.getDeclaringClass()), args(params))));
} else {
body.addStatement(returnS(callX(newClass(mNode.getDeclaringClass()), mNode.getName(), args(params))));
returnType = newClass(mNode.getReturnType());
}
return new MethodNode(buildMethodName, ACC_PUBLIC, returnType, NO_PARAMS, NO_EXCEPTIONS, body);
}
private static MethodNode createBuilderMethod(AnnotationNode anno, ClassNode builder) {
String builderMethodName = getMemberStringValue(anno, "builderMethodName", "builder");
final BlockStatement body = new BlockStatement();
body.addStatement(returnS(ctorX(builder)));
return new MethodNode(builderMethodName, PUBLIC_STATIC, builder, NO_PARAMS, NO_EXCEPTIONS, body);
}
private static MethodNode createBuildMethod(AnnotationNode anno, ClassNode buildee, List fields) {
String buildMethodName = getMemberStringValue(anno, "buildMethodName", "build");
final BlockStatement body = new BlockStatement();
body.addStatement(returnS(initializeInstance(buildee, fields, body)));
return new MethodNode(buildMethodName, ACC_PUBLIC, newClass(buildee), NO_PARAMS, NO_EXCEPTIONS, body);
}
private MethodNode createBuilderMethodForProp(ClassNode builder, PropertyInfo pinfo, String prefix) {
ClassNode fieldType = pinfo.getType();
String fieldName = pinfo.getName();
String setterName = getSetterName(prefix, fieldName);
return new MethodNode(setterName, ACC_PUBLIC, newClass(builder), params(param(fieldType, fieldName)), NO_EXCEPTIONS, block(
stmt(assignX(propX(varX("this"), constX(fieldName)), varX(fieldName, fieldType))),
returnS(varX("this", builder))
));
}
private static FieldNode createFieldCopy(ClassNode buildee, Parameter param) {
Map genericsSpec = createGenericsSpec(buildee);
extractSuperClassGenerics(param.getType(), buildee, genericsSpec);
ClassNode correctedParamType = correctToGenericsSpecRecurse(genericsSpec, param.getType());
return new FieldNode(param.getName(), ACC_PRIVATE, correctedParamType, buildee, param.getInitialExpression());
}
private static FieldNode createFieldCopy(ClassNode buildee, String fieldName, ClassNode fieldType) {
return new FieldNode(fieldName, ACC_PRIVATE, fieldType, buildee, DEFAULT_INITIAL_VALUE);
}
private static List selectFieldsFromExistingClass(List fieldNodes, List includes, List excludes) {
List fields = new ArrayList();
for (FieldNode fNode : fieldNodes) {
if (shouldSkip(fNode.getName(), excludes, includes)) continue;
fields.add(fNode);
}
return fields;
}
private static Expression initializeInstance(ClassNode buildee, List fields, BlockStatement body) {
Expression instance = varX("_the" + buildee.getNameWithoutPackage(), buildee);
body.addStatement(declS(instance, ctorX(buildee)));
for (FieldNode field : fields) {
body.addStatement(stmt(assignX(propX(instance, field.getName()), varX(field))));
}
return instance;
}
}