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Groovy example source code file (ClosureMetaMethod.java)

This example Groovy source code file (ClosureMetaMethod.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

cachedclass, cachedmethod, cachedmethod, class, class, closure, closure, closuremetamethod, metamethod, methodclosure, methodclosuremetamethod, object, object, reflection, string, util

The Groovy ClosureMetaMethod.java source code

/*
 * Copyright 2003-2007 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.metaclass;

import groovy.lang.Closure;
import groovy.lang.ClosureInvokingMethod;
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.GeneratedClosure;
import org.codehaus.groovy.runtime.InvokerHelper;
import org.codehaus.groovy.runtime.MethodClosure;

import java.lang.reflect.Modifier;
import java.util.ArrayList;
import java.util.List;

/**
 * A MetaMethod that accepts a closure in the constructor which is invoked when the MetaMethod is called.
 * The delegate of the closure is set to the instance that the MetaMethod is invoked on when called.
 *
 * @author Graeme Rocher
 * @since 1.5
 */
public class ClosureMetaMethod extends MetaMethod implements ClosureInvokingMethod {

    private final Closure callable;
    private final CachedMethod doCall;
    private final String name;
    private final CachedClass declaringClass;

    public ClosureMetaMethod(String name, Closure c, CachedMethod doCall) {
        this(name, c.getOwner().getClass(), c, doCall);
    }

    public ClosureMetaMethod(String name, Class declaringClass, Closure c, CachedMethod doCall) {
        super (doCall.getNativeParameterTypes());
        this.name = name;
        callable = c;
        this.doCall = doCall;
        this.declaringClass = ReflectionCache.getCachedClass(declaringClass);
    }


    public int getModifiers() {
        return Modifier.PUBLIC;
    }

    public String getName() {
        return name;
    }

    public Class getReturnType() {
        return Object.class;
    }

    public CachedClass getDeclaringClass() {
        return declaringClass;
    }

    public Object invoke(final Object object, Object[] arguments) {
        Closure cloned = (Closure) callable.clone();
        cloned.setDelegate(object);

        arguments = coerceArgumentsToClasses(arguments);
        return doCall.invoke(cloned, arguments);
    }

  /**
     * Retrieves the closure that is invoked by this MetaMethod
     *
     * @return The closure
     */
    public Closure getClosure() {
        return callable;
    }

    public static List<MetaMethod> createMethodList(final String name, final Class declaringClass, final Closure closure) {
        List<MetaMethod> res = new ArrayList();
        if (closure instanceof MethodClosure) {
            MethodClosure methodClosure = (MethodClosure) closure;
            Object owner = closure.getOwner();
            Class ownerClass = (Class) (owner instanceof Class ? owner : owner.getClass());
            for (CachedMethod method : ReflectionCache.getCachedClass(ownerClass).getMethods() ) {
                if (method.getName().equals(methodClosure.getMethod())) {
                    MetaMethod metaMethod = new MethodClosureMetaMethod(name, declaringClass, closure, method); 
                    res.add(adjustParamTypesForStdMethods(metaMethod, name));
                }
            }
        }
        else {
            if (closure instanceof GeneratedClosure) {
                for (CachedMethod method : ReflectionCache.getCachedClass(closure.getClass()).getMethods() ) {
                    if (method.getName().equals("doCall")) {
                        MetaMethod metaMethod = new ClosureMetaMethod(name, declaringClass, closure, method);
                        res.add(adjustParamTypesForStdMethods(metaMethod, name));
                    }
                }
            }
            else {
                MetaMethod metaMethod = new AnonymousMetaMethod(closure, name, declaringClass);
                res.add(adjustParamTypesForStdMethods(metaMethod, name));
            }
        }
        return res;
    }
    
    private static MetaMethod adjustParamTypesForStdMethods(MetaMethod metaMethod, String methodName) {
        Class[] nativeParamTypes = metaMethod.getNativeParameterTypes();
        nativeParamTypes = (nativeParamTypes != null) ? nativeParamTypes : new Class[0];
        // for methodMissing, first parameter should be String type - to allow overriding of this method without
        // type String explicitly specified for first parameter (missing method name) - GROOVY-2951
        if("methodMissing".equals(methodName) && nativeParamTypes.length == 2 && nativeParamTypes[0] != String.class) {
            nativeParamTypes[0] = String.class;
        }
        return metaMethod;
    }
    public CachedMethod getDoCall() {
        return doCall;
    }

    public static ClosureMetaMethod copy(ClosureMetaMethod closureMethod) {
        if (closureMethod instanceof MethodClosureMetaMethod)
          return new MethodClosureMetaMethod(closureMethod.getName(), closureMethod.getDeclaringClass().getTheClass(), closureMethod.getClosure(), closureMethod.getDoCall());
        else
          return new ClosureMetaMethod(closureMethod.getName(), closureMethod.getDeclaringClass().getTheClass(), closureMethod.getClosure(), closureMethod.getDoCall());
    }

    private static class MethodClosureMetaMethod extends ClosureMetaMethod {
        public MethodClosureMetaMethod(String name, Class declaringClass, Closure closure, CachedMethod method) {
            super(name, declaringClass, closure, method);
        }

        public Object invoke(Object object, Object[] arguments) {
            return getDoCall().invoke(getClosure().getOwner(), arguments);
        }
    }

    static class AnonymousMetaMethod extends MetaMethod {
        private final Closure closure;
        private final String name;
        private final Class declaringClass;

        public AnonymousMetaMethod(Closure closure, String name, Class declaringClass) {
            super(closure.getParameterTypes());
            this.closure = closure;
            this.name = name;
            this.declaringClass = declaringClass;
        }

        public int getModifiers() {
            return Modifier.PUBLIC;
        }

        public String getName() {
            return name;
        }

        public Class getReturnType() {
            return Object.class;
        }

        public CachedClass getDeclaringClass() {
            return ReflectionCache.getCachedClass(declaringClass);
        }

        public Object invoke(Object object, Object[] arguments) {
            Closure cloned = (Closure) closure.clone();
            cloned.setDelegate(object);
            arguments = coerceArgumentsToClasses(arguments);
            return InvokerHelper.invokeMethod(cloned, "call", arguments);
        }
    }
}

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