screwtape

In this assignment you will implement an interpreter for a simple programming language.

Wave 1

You will implement the constructor for the Node class that accepts a list of integers. It should have the Node under construction take the first value in the list. It should have its next point to a new Node that holds the second value in the list. That second node should point back to the first one, and so on for the 3rd, 4th, 5th, etc. nodes. In this way, the constructed node will be the head of a doubly linked list. You will NOT use the LinkedList java class. See the Javadoc for details.

As part of Wave 1, you will also implement additional unit tests. See NodeTest for details on what to implement.

Wave 2

You will implement to toList method of the Node class. This will take the given node to be the head of the list, and use its values to populate a new List of integers that it will return. You may use whichever type of Collections List you like (e.g. ArrayList, LinkedList, etc.)

As part of Wave 2 you will also implement additional unit tests. See NodeTest for details on what to implement.

Wave 3

You will implement the bracketMap method of ScrewtapeInterpreter. The input will be a Screwtape program, for example:

>[+>[+-]<]

Your map should have the location of the CLOSING bracket as the key and the corresponding OPENING bracket as the value. In this case, the map would be:

{
    9: 1,
    7: 4
}

Explanation: The closing bracket at index 9 is matched with the opening bracket at index 1. The closing brack at index 7 is matched with the opening bracket at index 4.

You will also implement additional tests for this wave, see ScrewtapeInterpreterTest for details.

Wave 4

You will implement the execute method of ScrewtapeInterpreter. I strongly reccommend taking this bit by bit!

Reccommended order:

1. Add functionality for addition and subtraction
2. Add functionality for left and right movement
3. Add functionality for outputting a value (hint: you can cast an int to a char)
4. Add functionality for loops

The different unit tests independently test these. It is possible to get some tests passing even if you have not completed the full functionality.

I strongly recommend looking at the comment at the top of the ScrewTapeInterpreter file for an explanation of how the language works.

Also remember when you're moving your tapePointer to add new nodes to the beginning or end of your tape if you run out of space.

Submitting

When finished, please make a PR and submit the link to the PR on Canvas. Nice job, this is a tough project!

Symbol	Description
>	Move the tape pointer to the next memory node.
<	Move the tape pointer to the previous memory node.
+	Increment the value in the current memory node.
-	Decrement the value in the current memory node.
.	Output the character represented by the value in the current memory node.
[	Do nothing
]	If the value in the current memory node is not 0, jump back to the matching [.