loadcmd.java

Hecl编程语言是一个高层次的脚本语言的Java实现。其用意是要小

/* Copyright 2005 David N. Welton

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.hecl.load;

import org.hecl.Command;
import org.hecl.HeclException;
import org.hecl.Interp;
import org.hecl.ListThing;
import org.hecl.Thing;

import org.hecl.files.HeclFile;
import org.hecl.HeclModule;

import java.net.URI;
import java.net.URLClassLoader;
import java.net.URL;

import java.util.Vector;

/**
 * <code>LoadCmd</code> implements the "load" command.
 *
 * @author <a href="mailto:[e-mail]">David N. Welton </a>
 * @version 1.0
 */

public class LoadCmd implements Command {
    private LoadCmd() {}
    
    /**
     * The <code>cmdCode</code> method implements the 'load' command.
     *
     * @param interp an <code>Interp</code> value
     * @param argv a <code>Thing[]</code> value
     * @exception HeclException if an error occurs
     */
    public Thing cmdCode(Interp interp, Thing[] argv) throws HeclException {
	try {
	    /* The the list of URI's where code might be located. */
	    Vector urlv = ListThing.get(argv[2]);
	    int sz = urlv.size();
	    URL[] urls = new URL[sz];

	    for (int i = 0; i < sz; i++ ) {
		/* Apparently the URI's must be absolute. */
		URI uri = new URI(((Thing)urlv.elementAt(i)).toString());
		if (!uri.isAbsolute()) {
		    URI current = new URI("file://" + HeclFile.currentFile);
		    uri = current.resolve(uri.normalize());
		}
		urls[i] = uri.toURL();
	    }

	    /* Actually load the module. */
	    URLClassLoader ucl = new URLClassLoader(urls);
	    Class c = ucl.loadClass (argv[1].toString());
	    HeclModule module = (HeclModule) c.newInstance();
	    module.loadModule(interp);
	} catch (Exception e) {
	    throw new HeclException(e.toString());
	}
	return null;
    }

    public static void load(Interp interp) throws HeclException {
	interp.addCommand("load", cmd);
    }

    /**
     * The <code>unloadModule</code> method unloads the module.
     *
     * @param interp an <code>Interp</code> value
     * @exception HeclException if an error occurs
     */
    public static void unload(Interp interp) throws HeclException {
        interp.removeCommand("load");
    }
    

    private static LoadCmd cmd = new LoadCmd();
}