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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 org.codehaus.groovy.transform.trait;
import groovy.lang.GeneratedGroovyProxy;
import groovy.transform.SelfType;
import groovy.transform.Trait;
import org.codehaus.groovy.GroovyBugError;
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.InnerClassNode;
import org.codehaus.groovy.ast.MethodNode;
import org.codehaus.groovy.ast.expr.ClassExpression;
import org.codehaus.groovy.ast.expr.Expression;
import org.codehaus.groovy.ast.expr.ListExpression;
import org.codehaus.groovy.ast.tools.GenericsUtils;
import org.codehaus.groovy.classgen.asm.BytecodeHelper;
import org.codehaus.groovy.runtime.DefaultGroovyMethods;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
import java.lang.reflect.Method;
import java.util.Iterator;
import java.util.LinkedHashSet;
import java.util.List;
/**
* A collection of utility methods used to deal with traits.
*
* @author Cédric Champeau
* @since 2.3.0
*/
public abstract class Traits {
public static final ClassNode IMPLEMENTED_CLASSNODE = ClassHelper.make(Implemented.class);
public static final ClassNode TRAITBRIDGE_CLASSNODE = ClassHelper.make(TraitBridge.class);
public static final Class TRAIT_CLASS = Trait.class;
public static final ClassNode TRAIT_CLASSNODE = ClassHelper.make(TRAIT_CLASS);
public static final ClassNode GENERATED_PROXY_CLASSNODE = ClassHelper.make(GeneratedGroovyProxy.class);
public static final ClassNode SELFTYPE_CLASSNODE = ClassHelper.make(SelfType.class);
static final String TRAIT_TYPE_NAME = "@" + TRAIT_CLASSNODE.getNameWithoutPackage();
static final String TRAIT_HELPER = "$Trait$Helper";
static final String FIELD_HELPER = "$Trait$FieldHelper";
static final String DIRECT_SETTER_SUFFIX = "$set";
static final String DIRECT_GETTER_SUFFIX = "$get";
static final String INIT_METHOD = "$init$";
static final String STATIC_INIT_METHOD = "$static$init$";
public static final String THIS_OBJECT = "$self";
public static final String STATIC_THIS_OBJECT = "$static$self";
static final String STATIC_FIELD_PREFIX = "$static";
static final String FIELD_PREFIX = "$ins";
static final String PUBLIC_FIELD_PREFIX = "$0";
static final String PRIVATE_FIELD_PREFIX = "$1";
static final String SUPER_TRAIT_METHOD_PREFIX = "trait$super$";
static String fieldHelperClassName(final ClassNode traitNode) {
return traitNode.getName() + FIELD_HELPER;
}
static String helperGetterName(final FieldNode field) {
return remappedFieldName(unwrapOwner(field.getOwner()), field.getName()) + DIRECT_GETTER_SUFFIX;
}
static String helperSetterName(final FieldNode field) {
return remappedFieldName(unwrapOwner(field.getOwner()), field.getName()) + DIRECT_SETTER_SUFFIX;
}
static String helperClassName(final ClassNode traitNode) {
return traitNode.getName() + TRAIT_HELPER;
}
static String remappedFieldName(final ClassNode traitNode, final String name) {
return traitNode.getName().replace('.','_')+"__"+name;
}
private static ClassNode unwrapOwner(ClassNode owner) {
if (ClassHelper.CLASS_Type.equals(owner) && owner.getGenericsTypes()!=null && owner.getGenericsTypes().length==1) {
return owner.getGenericsTypes()[0].getType();
}
return owner;
}
public static ClassNode findHelper(final ClassNode trait) {
return findHelpers(trait).getHelper();
}
public static ClassNode findFieldHelper(final ClassNode trait) {
return findHelpers(trait).getFieldHelper();
}
static TraitHelpersTuple findHelpers(final ClassNode trait) {
ClassNode helperClassNode = null;
ClassNode fieldHelperClassNode = null;
Iterator innerClasses = trait.redirect().getInnerClasses();
if (innerClasses != null && innerClasses.hasNext()) {
// trait defined in same source unit
while (innerClasses.hasNext()) {
ClassNode icn = innerClasses.next();
if (icn.getName().endsWith(Traits.FIELD_HELPER)) {
fieldHelperClassNode = icn;
} else if (icn.getName().endsWith(Traits.TRAIT_HELPER)) {
helperClassNode = icn;
}
}
} else {
// precompiled trait
try {
final ClassLoader classLoader = trait.getTypeClass().getClassLoader();
String helperClassName = Traits.helperClassName(trait);
helperClassNode = ClassHelper.make(classLoader.loadClass(helperClassName));
try {
fieldHelperClassNode = ClassHelper.make(classLoader.loadClass(Traits.fieldHelperClassName(trait)));
} catch (ClassNotFoundException e) {
// not a problem, the field helper may be absent
}
} catch (ClassNotFoundException e) {
throw new GroovyBugError("Couldn't find trait helper classes on compile classpath!",e);
}
}
return new TraitHelpersTuple(helperClassNode, fieldHelperClassNode);
}
/**
* Returns true if the specified class node is a trait.
* @param cNode a class node to test
* @return true if the classnode represents a trait
*/
public static boolean isTrait(final ClassNode cNode) {
return cNode!=null
&& ((cNode.isInterface() && !cNode.getAnnotations(TRAIT_CLASSNODE).isEmpty())
|| isAnnotatedWithTrait(cNode));
}
/**
* Returns true if the specified class is a trait.
* @param clazz a class to test
* @return true if the classnode represents a trait
*/
public static boolean isTrait(final Class clazz) {
return clazz!=null && clazz.getAnnotation(Trait.class)!=null;
}
/**
* Returns true if the specified class node is annotated with the {@link Trait} interface.
* @param cNode a class node
* @return true if the specified class node is annotated with the {@link Trait} interface.
*/
public static boolean isAnnotatedWithTrait(final ClassNode cNode) {
List traitAnn = cNode.getAnnotations(Traits.TRAIT_CLASSNODE);
return traitAnn != null && !traitAnn.isEmpty();
}
/**
* Indicates whether a method in a trait interface has a default implementation.
* @param method a method node
* @return true if the method has a default implementation in the trait
*/
public static boolean hasDefaultImplementation(final MethodNode method) {
return !method.getAnnotations(IMPLEMENTED_CLASSNODE).isEmpty();
}
/**
* Indicates whether a method in a trait interface has a default implementation.
* @param method a method node
* @return true if the method has a default implementation in the trait
*/
public static boolean hasDefaultImplementation(final Method method) {
return method.getAnnotation(Implemented.class)!=null;
}
/**
* Reflection API to indicate whether some method is a bridge method to the default implementation
* of a trait.
* @param someMethod a method node
* @return null if it is not a method implemented in a trait. If it is, returns the method from the trait class.
*/
public static boolean isBridgeMethod(Method someMethod) {
TraitBridge annotation = someMethod.getAnnotation(TraitBridge.class);
return annotation!=null;
}
/**
* Reflection API to find the method corresponding to the default implementation of a trait, given a bridge method.
* @param someMethod a method node
* @return null if it is not a method implemented in a trait. If it is, returns the method from the trait class.
*/
public static Method getBridgeMethodTarget(Method someMethod) {
TraitBridge annotation = someMethod.getAnnotation(TraitBridge.class);
if (annotation==null) {
return null;
}
Class aClass = annotation.traitClass();
String desc = annotation.desc();
for (Method method : aClass.getDeclaredMethods()) {
String methodDescriptor = BytecodeHelper.getMethodDescriptor(method.getReturnType(), method.getParameterTypes());
if (desc.equals(methodDescriptor)) {
return method;
}
}
return null;
}
/**
* Converts a class implementing some trait into a target class. If the trait is a dynamic proxy and
* that the target class is assignable to the target object of the proxy, then the target object is
* returned. Otherwise, falls back to {@link org.codehaus.groovy.runtime.DefaultGroovyMethods#asType(java.lang.Object, Class)}
* @param self an object to be coerced to some class
* @param clazz the class to be coerced to
* @return the object coerced to the target class, or the proxy instance if it is compatible with the target class.
*/
@SuppressWarnings("unchecked")
public static T getAsType(Object self, Class clazz) {
if (self instanceof GeneratedGroovyProxy) {
Object proxyTarget = ((GeneratedGroovyProxy)self).getProxyTarget();
if (clazz.isAssignableFrom(proxyTarget.getClass())) {
return (T) proxyTarget;
}
}
return DefaultGroovyMethods.asType(self, clazz);
}
/**
* Returns the name of a method without the super trait specific prefix. If the method name
* doesn't correspond to a super trait method call, the result will be null.
* @param origName the name of a method
* @return null if the name doesn't start with the super trait prefix, otherwise the name without the prefix
*/
public static String[] decomposeSuperCallName(String origName) {
if (origName.contains(SUPER_TRAIT_METHOD_PREFIX)) {
int endIndex = origName.indexOf(SUPER_TRAIT_METHOD_PREFIX);
String tName = origName.substring(0, endIndex).replace('_','.').replace("..","_");
String fName = origName.substring(endIndex+SUPER_TRAIT_METHOD_PREFIX.length());
return new String[]{tName, fName};
}
return null;
}
/**
* Collects all interfaces of a class node, but reverses the order of the declaration of direct interfaces
* of this class node. This is used to make sure a trait implementing A,B where both A and B have the same
* method will take the method from B (latest), aligning the behavior with categories.
* @param cNode a class node
* @param interfaces ordered set of interfaces
*/
public static LinkedHashSet collectAllInterfacesReverseOrder(ClassNode cNode, LinkedHashSet interfaces) {
if (cNode.isInterface())
interfaces.add(cNode);
ClassNode[] directInterfaces = cNode.getInterfaces();
for (int i = directInterfaces.length-1; i >=0 ; i--) {
final ClassNode anInterface = directInterfaces[i];
interfaces.add(GenericsUtils.parameterizeType(cNode,anInterface));
collectAllInterfacesReverseOrder(anInterface, interfaces);
}
return interfaces;
}
/**
* Collects all the self types that a type should extend or implement, given
* the traits is implements. Collects from interfaces and superclasses too.
* @param receiver a class node that may implement a trait
* @param selfTypes a collection where the list of self types will be written
* @return the selfTypes collection itself
* @since 2.4.0
*/
public static LinkedHashSet collectSelfTypes(
ClassNode receiver,
LinkedHashSet selfTypes) {
return collectSelfTypes(receiver, selfTypes, true, true);
}
/**
* Collects all the self types that a type should extend or implement, given
* the traits is implements.
* @param receiver a class node that may implement a trait
* @param selfTypes a collection where the list of self types will be written
* @param checkInterfaces should the interfaces that the node implements be collected too
* @param checkSuper should we collect from the superclass too
* @return the selfTypes collection itself
* @since 2.4.0
*/
public static LinkedHashSet collectSelfTypes(
ClassNode receiver,
LinkedHashSet selfTypes,
boolean checkInterfaces,
boolean checkSuper) {
if (Traits.isTrait(receiver)) {
List annotations = receiver.getAnnotations(SELFTYPE_CLASSNODE);
for (AnnotationNode annotation : annotations) {
Expression value = annotation.getMember("value");
if (value instanceof ClassExpression) {
selfTypes.add(value.getType());
} else if (value instanceof ListExpression) {
List expressions = ((ListExpression) value).getExpressions();
for (Expression expression : expressions) {
if (expression instanceof ClassExpression) {
selfTypes.add(expression.getType());
}
}
}
}
}
if (checkInterfaces) {
ClassNode[] interfaces = receiver.getInterfaces();
for (ClassNode anInterface : interfaces) {
collectSelfTypes(anInterface, selfTypes, true, checkSuper);
}
}
if (checkSuper) {
ClassNode superClass = receiver.getSuperClass();
if (superClass != null) {
collectSelfTypes(superClass, selfTypes, checkInterfaces, true);
}
}
return selfTypes;
}
static String getSuperTraitMethodName(ClassNode trait, String method) {
return trait.getName().replace("_","__").replace('.','_')+SUPER_TRAIT_METHOD_PREFIX+method;
}
/**
* Internal annotation used to indicate which methods in a trait interface have a
* default implementation.
*/
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.METHOD)
public static @interface Implemented {}
/**
* Internal annotation used to indicate that a method is a bridge method to a trait
* default implementation.
*/
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.METHOD)
public static @interface TraitBridge {
/**
* @return the trait class
*/
Class traitClass();
/**
* @return The method descriptor of the method from the trait
*/
String desc();
}
}