/*
 * LrangeCmd.java
 *
 * Copyright (c) 1997 Cornell University.
 * Copyright (c) 1997 Sun Microsystems, Inc.
 *
 * See the file "license.terms" for information on usage and
 * redistribution of this file, and for a DISCLAIMER OF ALL
 * WARRANTIES.
 * 
 * RCS: @(#) $Id: LrangeCmd.java,v 1.1.1.1 1998/10/14 21:09:20 cvsadmin Exp $
 *
 */

package tcl.lang;

/**
 * This class implements the built-in "lrange" command in Tcl.
 */

class LrangeCmd implements Command {
    /**
     * See Tcl user documentation for details.
     * @exception TclException If incorrect number of arguments.
     */

    public void cmdProc(Interp interp, TclObject argv[])
	    throws TclException {
	if (argv.length != 4) {
	    throw new TclNumArgsException(interp, 1, argv, 
                    "list first last");
        }

	int size = TclList.getLength(interp, argv[1]);
	int first;
	int last;

	first = TclInteger.getForIndex(interp, argv[2], size-1);
	last  = TclInteger.getForIndex(interp, argv[3], size-1);

	if (last < 0) {
	    interp.resetResult();
	    return;
	}
	if (first >= size) {
	    interp.resetResult();
	    return;
	}
	if (first <= 0 && last >= size) {
	    interp.setResult(argv[1]);
	    return;
	} 

	if (first < 0) {
	    first = 0;
	}
	if (first >= size) {
	    first = size - 1;
	}
	if (last < 0) {
	    last = 0;
	}
	if (last >= size) {
	    last = size - 1;

	}
	if (first > last) {
	    interp.resetResult();
	    return;
	}

	TclObject list = TclList.newInstance();

	list.preserve();
	try {
	    for (int i=first; i<=last; i++) {
		TclList.append(interp, list, TclList.index(interp, argv[1],i));
	    }
	    interp.setResult(list);
	} finally {
	    list.release();
	}
    }
}