RandomFilter.java

/**********************************************************************
Copyright (c) 2009 Asfun Net.

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 net.asfun.jangod.lib.filter;

import java.lang.reflect.Array;
import java.math.BigDecimal;
import java.util.Collection;
import java.util.Iterator;
import java.util.Map;

import net.asfun.jangod.interpret.InterpretException;
import net.asfun.jangod.interpret.JangodInterpreter;
import net.asfun.jangod.lib.Filter;

public class RandomFilter implements Filter {

    @Override
    public Object filter(Object object, JangodInterpreter interpreter,
	    String... arg) throws InterpretException {
	if (object == null) {
	    return null;
	}
	// collection
	if (object instanceof Collection) {
	    Collection<?> clt = (Collection<?>) object;
	    Iterator<?> it = clt.iterator();
	    int size = clt.size();
	    if (size == 0) {
		return null;
	    }
	    int index = Double.valueOf(Math.random() * size).intValue();
	    if (index == size)
		index = 0;
	    while (index-- > 0) {
		it.next();
	    }
	    return it.next();
	}
	// array
	if (object.getClass().isArray()) {
	    int size = Array.getLength(object);
	    if (size == 0) {
		return null;
	    }
	    int index = Double.valueOf(Math.random() * size).intValue();
	    if (index == size)
		index = 0;
	    return Array.get(object, index);
	}
	// map
	if (object instanceof Map) {
	    Map<?, ?> map = (Map<?, ?>) object;
	    Iterator<?> it = map.values().iterator();
	    int size = map.size();
	    if (size == 0) {
		return null;
	    }
	    int index = Double.valueOf(Math.random() * size).intValue();
	    if (index == size)
		index = 0;
	    while (index-- > 0) {
		it.next();
	    }
	    return it.next();
	}
	// number
	if (object instanceof Number) {
	    return BigDecimal.valueOf(
		    ((Number) object).doubleValue() * Math.random())
		    .longValue();
	}
	// string
	if (object instanceof String) {
	    try {
		return BigDecimal.valueOf(
			Double.valueOf((String) object).doubleValue()
				* Math.random()).longValue();
	    } catch (Exception e) {
		return 0;
	    }
	}
	// TODO iterable
	// TODO iterator
	return object;
    }

    @Override
    public String getName() {
	return "filter";
    }

}