userfunction.java

类似于Windows上的Excel

/*
 * MC2 -- j2me spreadsheet
 *
 * Copyright (c) 2004-2006 Michael Zemljanukha ([e-mail])
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the Free
 * Software Foundation; either version 2 of the License, or (at your option)
 * any later version.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */

package com.wapindustrial.calc;
/**
 *  Description of the Class
 *
 *@author     mixa
 *@created    May 21, 2003
 */
public class UserFunction extends FunctionObject {
    private final NameObjectBase name;
    private final QuotedList args;
    private final LispObject body;
    
    /**
     * True for (defmacro) - arguments not evaluated on function call
     */
    private final boolean isMacro;

    /**
     * Creates User Functor on (defun) or (defmacro)
     * @param isMacro (defun) / (defmacro) selector
     * @param name user functor
     * @param args arguments list
     * @param body function body
     */
    public UserFunction(boolean isMacro, NameObjectBase name, QuotedList args, LispObject body) {
        this.isMacro = isMacro;
        this.name = name;
        this.args = args;
        this.body = body;
        try {
            name.setMappedObject(this);
        }
        catch (EvaluateException e) {
            debug("cannot set name "+name);        
        }
    }

    public LispObject evaluate(FunctorList sexp) throws EvaluateException {
        
        LispObject shadowed[] = new LispObject[ args.value.length ];

	// evaluate args
        for (int i = 0; i < args.value.length; i++) {
            shadowed[i] = isMacro ? sexp.getArgumentN(i+1) : sexp.evaluateArgN(i+1);
        }

        // shadow this variables
        for (int i = 0; i < args.value.length; i++) {
            NameObjectBase nm = (NameObjectBase) args.value[i];
	    LispObject temp = nm.getMappedObject();
            nm.setMappedObject(shadowed[i]);
            shadowed[i] = temp;
        }

        // evaluate the sexps that constitute this function
        LispObject result = body.interpret();

        // copy the values of the shadowed variables back into the environment
        for (int i = 0; i < args.value.length; i++) {
            NameObjectBase nm = (NameObjectBase) args.value[i];
            nm.setMappedObject(shadowed[i]);
        }
        
        return result;
    }

}