src/main/java/org/codehaus/groovy/runtime/MethodClosure.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.runtime;

import groovy.lang.Closure;
import groovy.lang.MetaMethod;
import org.codehaus.groovy.reflection.CachedConstructor;
import org.codehaus.groovy.reflection.ReflectionCache;

import java.io.IOException;
import java.util.Arrays;
import java.util.List;

/**
 * Represents a method on an object using a closure which can be invoked
 * at any time
 */
public class MethodClosure extends Closure {
    public static final String NEW = "new";
    public static final String ANY_INSTANCE_METHOD_EXISTS = "anyInstanceMethodExists";

    private static final long serialVersionUID = -2491254866810955844L;
    public static boolean ALLOW_RESOLVE = false;

    private static final Class[] EMPTY_CLASS_ARRAY = new Class[0];
    private final String method;
    private final boolean anyInstanceMethodExists; // whether the method closure is related to instance method

    public MethodClosure(Object owner, String method) {
        super(owner);
        this.method = method;

        final Class clazz = owner.getClass() == Class.class ? (Class) owner : owner.getClass();

        this.maximumNumberOfParameters = 0;
        this.parameterTypes = EMPTY_CLASS_ARRAY;

        List<MetaMethod> methods = InvokerHelper.getMetaClass(clazz).respondsTo(owner, method);

        int instanceMethodCnt = 0;
        for (MetaMethod m : methods) {
            Class[] newParameterTypes = this.makeParameterTypes(owner, m);

            this.setParameterTypesAndNumber(newParameterTypes);

            if (!m.isStatic()) {
                instanceMethodCnt++;
            }
        }

        this.anyInstanceMethodExists = instanceMethodCnt > 0;

        if (NEW.equals(method)) {
            if (clazz.isArray()) {
                Class[] sizeTypes = new Class[ArrayTypeUtils.dimension(clazz)];
                Arrays.fill(sizeTypes, int.class);

                this.setParameterTypesAndNumber(sizeTypes);
            } else {
                for (CachedConstructor c : ReflectionCache.getCachedClass(clazz).getConstructors()) {
                    Class[] newParameterTypes = c.getNativeParameterTypes();

                    this.setParameterTypesAndNumber(newParameterTypes);
                }
            }
        }
    }

    private void setParameterTypesAndNumber(Class[] newParameterTypes) {
        if (!(newParameterTypes.length > this.maximumNumberOfParameters)) {
            return;
        }

        this.maximumNumberOfParameters = newParameterTypes.length;
        this.parameterTypes = newParameterTypes;
    }

    /*
     * Create a new array of parameter type.
     *
     * If the owner is a class instance(e.g. String) and the method is instance method,
     * we expand the original array of parameter type by inserting the owner at the first place of the expanded array
     */
    private Class[] makeParameterTypes(Object owner, MetaMethod m) {
        Class[] newParameterTypes;

        if (owner instanceof Class && !m.isStatic()) {
            Class[] nativeParameterTypes = m.getNativeParameterTypes();
            newParameterTypes = new Class[nativeParameterTypes.length + 1];

            System.arraycopy(nativeParameterTypes, 0, newParameterTypes, 1, nativeParameterTypes.length);
            newParameterTypes[0] = (Class) owner;
        } else {
            newParameterTypes = m.getNativeParameterTypes();
        }

        return newParameterTypes;
    }
    
    public String getMethod() {
        return method;
    }

    // TODO confirm: The "doCall" method seems to be never called..., because MetaClassImpl.invokeMethod will intercept calls and return the result
    protected Object doCall(Object arguments) {
        return InvokerHelper.invokeMethod(getOwner(), method, arguments);
    }

    private Object readResolve() {
        if (ALLOW_RESOLVE) {
            return this;
        }
        throw new UnsupportedOperationException();
    }

    private void readObject(java.io.ObjectInputStream stream) throws IOException, ClassNotFoundException {
        if (ALLOW_RESOLVE) {
            stream.defaultReadObject();
        }
        throw new UnsupportedOperationException();
    }
    
    public Object getProperty(String property) {
        if ("method".equals(property)) {
            return getMethod();
        } else if (ANY_INSTANCE_METHOD_EXISTS.equals(property)) {
            return this.anyInstanceMethodExists;
        } else return super.getProperty(property);
    }
}