Groovy example source code file (Expando.java)

This example Groovy source code file (Expando.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

boolean, closure, closure, entry, expando, expando, groovyruntimeexception, integer, list, map, map, metaexpandoproperty, object, object, util

The Groovy Expando.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 groovy.util;

import groovy.lang.Closure;
import groovy.lang.GroovyObjectSupport;
import groovy.lang.GroovyRuntimeException;
import groovy.lang.MetaExpandoProperty;
import groovy.lang.MissingPropertyException;

import java.util.HashMap;
import java.util.Map;
import java.util.Map.Entry;
import java.util.List;
import java.util.ArrayList;


/**
 * Represents a dynamically expandable bean.
 *
 * @author <a href="mailto:james@coredevelopers.net">James Strachan
 * @author Hein Meling
 * @author Pilho Kim
 * @version $Revision: 20583 $
 */
public class Expando extends GroovyObjectSupport {

    private Map expandoProperties;

    public Expando() {
    }

    public Expando(Map expandoProperties) {
        this.expandoProperties = expandoProperties;
    }

    /**
     * @return the dynamically expanded properties
     */
    public Map getProperties() {
        if (expandoProperties == null) {
            expandoProperties = createMap();
        }
        return expandoProperties;
    }

    public List getMetaPropertyValues() {
        // run through all our current properties and create MetaProperty objects
        List ret = new ArrayList();
        for (Object o : getProperties().entrySet()) {
            Entry entry = (Entry) o;
            ret.add(new MetaExpandoProperty(entry));
        }

        return ret;
    }

    public Object getProperty(String property) {
        // always use the expando properties first
        Object result = getProperties().get(property);
        if (result != null) return result;
        try {
            return super.getProperty(property);
        }
        catch (MissingPropertyException e) {
            // IGNORE
        }
        return null;
    }

    public void setProperty(String property, Object newValue) {
        // always use the expando properties
        getProperties().put(property, newValue);
    }

    public Object invokeMethod(String name, Object args) {
        try {
            return super.invokeMethod(name, args);
        }
        catch (GroovyRuntimeException e) {
            // br should get a "native" property match first. getProperty includes such fall-back logic
            Object value = this.getProperty(name);
            if (value instanceof Closure) {
                Closure closure = (Closure) value;
                closure = (Closure) closure.clone();
                closure.setDelegate(this);
                return closure.call((Object[]) args);
            } else {
                throw e;
            }
        }

    }

    /**
     * This allows toString to be overridden by a closure <i>field method attached
     * to the expando object.
     *
     * @see java.lang.Object#toString()
     */
    public String toString() {
        Object method = getProperties().get("toString");
        if (method != null && method instanceof Closure) {
            // invoke overridden toString closure method
            Closure closure = (Closure) method;
            closure.setDelegate(this);
            return closure.call().toString();
        } else {
            return expandoProperties.toString();
        }
    }

    /**
     * This allows equals to be overridden by a closure <i>field method attached
     * to the expando object.
     *
     * @see java.lang.Object#equals(java.lang.Object)
     */
    public boolean equals(Object obj) {
        Object method = getProperties().get("equals");
        if (method != null && method instanceof Closure) {
            // invoke overridden equals closure method
            Closure closure = (Closure) method;
            closure.setDelegate(this);
            Boolean ret = (Boolean) closure.call(obj);
            return ret.booleanValue();
        } else {
            return super.equals(obj);
        }
    }

    /**
     * This allows hashCode to be overridden by a closure <i>field method attached
     * to the expando object.
     *
     * @see java.lang.Object#hashCode()
     */
    public int hashCode() {
        Object method = getProperties().get("hashCode");
        if (method != null && method instanceof Closure) {
            // invoke overridden hashCode closure method
            Closure closure = (Closure) method;
            closure.setDelegate(this);
            Integer ret = (Integer) closure.call();
            return ret.intValue();
        } else {
            return super.hashCode();
        }
    }

    /**
     * Factory method to create a new Map used to store the expando properties map
     *
     * @return a newly created Map implementation
     */
    protected Map createMap() {
        return new HashMap();
    }

}