PostScriptStack.java

// Copyright 2001, FreeHEP.
package org.freehep.postscript;

import java.util.Stack;



/**
 * PostScript Abstract Stack for PostScript Processor
 *
 * @author Mark Donszelmann
 * @version $Id: PostScriptStack.java 10178 2006-12-08 09:03:07Z duns $
 */
public class PostScriptStack extends Stack {

    protected int marker = -1;

    public Object push(Object o) {
        if (o == null) 
            throw new IllegalArgumentException("PostScript Stack cannot contain 'null'");
      
        if (!(o instanceof PSObject)) 
            throw new IllegalArgumentException("PostScript Stack can only contain PSObjects, not: "+o);
        
        return super.push(o);
    }

    public Object push(String s) {
        return super.push(new PSName(s));
    }
    
    public PSObject peekObject() {
        return (PSObject)peek();
    }
    
    public PSObject peekObject(int i) {
        if (i > elementCount) {
            return null;
        }
        return (PSObject)elementData[elementCount-i-1];
    }
    
    // do not remove elements, just lower the top of the stack
    public Object pop() {
        if (elementCount == 0) return null;
        
        elementCount--;
        return elementData[elementCount];
    }
    
    public PSObject popObject() {
        return (PSObject)pop();
    }

    // mark and counttomark needed for making procedure objects    
    public int countToMark() {
        int count = 0;
        int i = elementCount-1;
        while (i > 0 && !(elementData[i] instanceof PSMark)) {
            i--;
            count++;
        }
        return (elementData[i] instanceof PSMark) ? count : -1;       
    }

    public PSMark popMark() {
        return (PSMark)super.pop();
    }
    
    // sets the marker, and cleans up what is above
    public void mark() {
        marker = elementCount;
        setSize(marker);
    }
    
    // resets the stack to the marker level, and cleans above
    public void reset() {
        if (marker >= 0) {
            setSize(marker);
            marker = -1;
        }
    }    
    
    public void copyInto(PSArray a) {
        for (int i=0; i<a.size(); i++) {
            a.set(i, (PSObject)elementData[i]);
        }
    }   

    public void printStack() {
        for (int i=elementCount-1; i>=0; i--) {
            System.out.println(i+": "+elementData[i].getClass().getName()+": "+elementData[i].toString());
        }
    }
}