/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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.apache.pdfbox.pdmodel.common.function.type4;
import java.util.List;
import java.util.Stack;
/**
* Represents an instruction sequence, a combination of values, operands and nested procedures.
*
*/
public class InstructionSequence
{
private final List<Object> instructions = new java.util.ArrayList<>();
/**
* Add a name (ex. an operator)
* @param name the name
*/
public void addName(String name)
{
this.instructions.add(name);
}
/**
* Adds an int value.
* @param value the value
*/
public void addInteger(int value)
{
this.instructions.add(value);
}
/**
* Adds a real value.
* @param value the value
*/
public void addReal(float value)
{
this.instructions.add(value);
}
/**
* Adds a bool value.
* @param value the value
*/
public void addBoolean(boolean value)
{
this.instructions.add(value);
}
/**
* Adds a proc (sub-sequence of instructions).
* @param child the child proc
*/
public void addProc(InstructionSequence child)
{
this.instructions.add(child);
}
/**
* Executes the instruction sequence.
* @param context the execution context
*/
public void execute(ExecutionContext context)
{
Stack<Object> stack = context.getStack();
for (Object o : instructions)
{
if (o instanceof String)
{
String name = (String)o;
Operator cmd = context.getOperators().getOperator(name);
if (cmd != null)
{
cmd.execute(context);
}
else
{
throw new UnsupportedOperationException("Unknown operator or name: " + name);
}
}
else
{
stack.push(o);
}
}
//Handles top-level procs that simply need to be executed
while (!stack.isEmpty() && stack.peek() instanceof InstructionSequence)
{
InstructionSequence nested = (InstructionSequence)stack.pop();
nested.execute(context);
}
}
}