/*
* Copyright 2006-2017 ICEsoft Technologies Canada Corp.
*
* 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.icepdf.core.pobjects.functions.postscript;
import java.util.Stack;
/**
* Procedure represents a groups of operands enclosed by braces. For example
* {dup 0 lt {pop 0 }{dup 1 gt {pop 1 } if } ifelse is defined as:
* {operand... {proc} {proc {proc}}operand} operand}
* <br>
* This structures aids in the handling of ifelse and if statements.
*
* @since 5.1.0
*/
public class Procedure extends Operator {
private Stack<Object> stack;
private Procedure previousProcedure;
@SuppressWarnings("unchecked")
public Procedure(Procedure previousProcedure) {
super(OperatorNames.OP_PROC);
stack = new Stack<Object>();
if (previousProcedure != null) {
previousProcedure.getProc().push(this);
}
this.previousProcedure = previousProcedure;
}
public Procedure getPrevious() {
return previousProcedure;
}
public Stack<Object> getProc() {
return stack;
}
@Override
@SuppressWarnings("unchecked")
public void eval(Stack stack) {
// iterate over the stack objects and update the eval stack
// we need to to this in revers...
for (Object tmp : this.stack) {
if (tmp instanceof Operator && !(tmp instanceof Procedure)) {
((Operator) tmp).eval(stack);
} else {
stack.push(tmp);
}
}
}
}