org.armedbear.lisp.LispStackFrame Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of abcl Show documentation
Common Lisp implementation running on the JVM
There is a newer version: 1.9.2
/*
 * LispStackFrame.java
 *
 * Copyright (C) 2009 Mark Evenson
 * $Id: LispStackFrame.java 14572 2013-08-10 08:24:46Z mevenson $
 *
 * 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.
 *
 * As a special exception, the copyright holders of this library give you
 * permission to link this library with independent modules to produce an
 * executable, regardless of the license terms of these independent
 * modules, and to copy and distribute the resulting executable under
 * terms of your choice, provided that you also meet, for each linked
 * independent module, the terms and conditions of the license of that
 * module.  An independent module is a module which is not derived from
 * or based on this library.  If you modify this library, you may extend
 * this exception to your version of the library, but you are not
 * obligated to do so.  If you do not wish to do so, delete this
 * exception statement from your version.
 */

package org.armedbear.lisp;

import static org.armedbear.lisp.Lisp.*;

public class LispStackFrame 
  extends StackFrame
{
  public final LispObject operator;
  private final LispObject[] args;

  private final static class UnavailableArgument extends LispObject 
  {
    public UnavailableArgument () { }
    @Override
    public String printObject() { 
      return unreadableString("unavailable arg", false); 
    }
  }

  private final static LispObject UNAVAILABLE_ARG = new UnavailableArgument();

  public LispStackFrame(Object[] stack, int framePos, int numArgs)
  {
    operator = (LispObject) stack[framePos];
    args = new LispObject[numArgs];
    for (int i = 0; i < numArgs; i++) 
    {
      args[i] = (LispObject) stack[framePos + 1 + i];
    }
  }

   @Override
   public LispObject typeOf() { 
     return Symbol.LISP_STACK_FRAME; 
   }
  
   @Override
   public LispObject classOf() { 
     return BuiltInClass.LISP_STACK_FRAME; 
   }

   @Override
   public String printObject() 
   { 
     String result = "";
     final String LISP_STACK_FRAME = "LISP-STACK-FRAME";
     try {
       result = unreadableString(LISP_STACK_FRAME + " " + toLispList().printObject());
     } catch (Throwable t) { // error while printing stack
       Debug.trace("Serious printing error: ");
       Debug.trace(t);
       result = unreadableString(LISP_STACK_FRAME);
     }
     return result;
   }

  @Override
  public LispObject typep(LispObject typeSpecifier) 

  {
    if (typeSpecifier == Symbol.LISP_STACK_FRAME)
      return T;
    if (typeSpecifier == BuiltInClass.LISP_STACK_FRAME)
      return T;
    return super.typep(typeSpecifier);
   }

  public LispObject toLispList() 

  {
    LispObject result = argsToLispList();
    if (operator instanceof Operator) {
      LispObject lambdaName = ((Operator)operator).getLambdaName();
      if (lambdaName != null && lambdaName != Lisp.NIL)
	return result.push(lambdaName);
    }
    return result.push(operator);
  }

  private LispObject argsToLispList()

  {
    LispObject result = Lisp.NIL;
    for (int i = 0; i < args.length; i++)
      // `args' come here from LispThread.execute. I don't know
      // how it comes that some callers pass NULL ptrs around but
      // we better do not create conses with their CAR being NULL;
      // it'll horribly break printing such a cons; and probably
      // other bad things may happen, too. --TCR, 2009-09-17.
      if (args[i] == null)
        result = result.push(UNAVAILABLE_ARG);
      else
        result = result.push(args[i]);
    return result.nreverse();
  }

  public SimpleString toLispString() 

  {
    String result;
    try {
      result = this.toLispList().printObject();
    } catch (Throwable t) { // error while printing stack
      Debug.trace("Serious printing error: ");
      Debug.trace(t);
      result = unreadableString("LISP-STACK-FRAME");
    }
    return new SimpleString(result);
  }

  public int getNumArgs()
  {
    return args.length;
  }

  public LispObject getOperator() {
    return operator;
  }

  @Override 
  public LispObject getParts() 

  {
    LispObject result = NIL;
    result = result.push(new Cons("OPERATOR", getOperator()));
    LispObject args = argsToLispList();
    if (args != NIL) {
      result = result.push(new Cons("ARGS", args));
    }
			 
    return result.nreverse();
  }
}