/*
* Copyright 2003-2013 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.runtime.m12n;
import groovy.lang.MetaMethod;
import org.codehaus.groovy.reflection.CachedClass;
import org.codehaus.groovy.reflection.CachedMethod;
import org.codehaus.groovy.reflection.ReflectionCache;
import org.codehaus.groovy.runtime.metaclass.NewInstanceMetaMethod;
import org.codehaus.groovy.runtime.metaclass.NewStaticMetaMethod;
import java.util.LinkedList;
import java.util.List;
import java.util.logging.Logger;
/**
* An extension module which provides extension methods using a {@link org.codehaus.groovy.runtime.DefaultGroovyMethods}-like implementation, that
* is to say using static methods defined in an "extension class".
* <p>
* For commodity, multiple extension classes may be defined in a single module, including classes used to define new
* static methods.
* <p>
* Modules are required to implement the {@link #getInstanceMethodsExtensionClasses} for classes defining new instance
* methods, and {@link #getStaticMethodsExtensionClasses()} for classes defining static methods.
* <p>
* For example, to define a module adding methods to the {@link String} class, you can write a helper class:
* <pre>
* class StringExtension {
* public static int count(String self, char c) {
* int result = 0;
* for (int i=0;i<self.length(); i++) {
* if (self.charAt(i)==c) result++;
* }
* return result;
* }
* }
* </pre>
* <p>
* This class defines a single static method taking the string instance as first argument, allowing to define
* a new instance method on the String class: <pre>String#count(char c)</pre>.
* <p>
* To define a new static method on a class, as the static modifier is already used for instance methods, you must use
* another helper class, for example:
* <p>
* <pre>
* class StaticStringExtension {
* public static void foo(String self) { System.out.println("foo"); }
* }
* </pre>
* <p>
* The first argument of the method is only used to tell the class for which we add a static method. You can now define
* an extension module:
* <p>
* <pre>
* class MyStringModule extends SimpleExtensionModule {
* // ...
*
* public List<Class> getInstanceMethodsExtensionClasses() {
* return Collections.singletonList(StringExtension.class);
* }
*
* public List<Class> getStaticMethodsExtensionClasses() {
* return Collections.singletonList(StaticStringExtension.class);
* }
* }
* </pre>
*
* @author Cedric Champeau
* @since 2.0.0
*/
public abstract class SimpleExtensionModule extends ExtensionModule {
private static final Logger LOG = Logger.getLogger(SimpleExtensionModule.class.getName());
public SimpleExtensionModule(final String moduleName, final String moduleVersion) {
super(moduleName, moduleVersion);
}
@Override
public List<MetaMethod> getMetaMethods() {
List<MetaMethod> metaMethods = new LinkedList<MetaMethod>();
List<Class> extensionClasses = getInstanceMethodsExtensionClasses();
for (Class extensionClass : extensionClasses) {
try {
createMetaMethods(extensionClass, metaMethods, false);
} catch (LinkageError e) {
LOG.warning("Module ["+getName()+"] - Unable to load extension class ["+extensionClass+"] due to ["+e.getMessage()+"]. Maybe this module is not supported by your JVM version.");
}
}
extensionClasses = getStaticMethodsExtensionClasses();
for (Class extensionClass : extensionClasses) {
try {
createMetaMethods(extensionClass, metaMethods, true);
} catch (LinkageError e) {
LOG.warning("Module ["+getName()+"] - Unable to load extension class ["+extensionClass+"] due to ["+e.getMessage()+"]. Maybe this module is not supported by your JVM version.");
}
}
return metaMethods;
}
private void createMetaMethods(final Class extensionClass, final List<MetaMethod> metaMethods, final boolean isStatic) {
CachedClass cachedClass = ReflectionCache.getCachedClass(extensionClass);
CachedMethod[] methods = cachedClass.getMethods();
for (CachedMethod method : methods) {
if (method.isStatic() && method.isPublic() && method.getParamsCount() > 0) {
// an extension method is found
metaMethods.add(isStatic?new NewStaticMetaMethod(method) : new NewInstanceMetaMethod(method));
}
}
}
/**
* @return the list of classes defining new instance methods.
*/
public abstract List<Class> getInstanceMethodsExtensionClasses();
/**
* @return the list of classes defining new static methods.
*/
public abstract List<Class> getStaticMethodsExtensionClasses();
}