For this lab, you'll use the concepts of polymorphism to build an abstract syntax
tree for our simple calculator language, and implement a means to pretty-print
the program. Pretty-printing refers to outputting a "canonical", formatted
version of the code. One way to pretty-print a program is to extract it's AST, then
recursively output concrete syntax for each node. This is the approach that will be
taken by the project, and in this lab for the simple calculator language.
The calculator language has been enhanced
somewhat, as you'll see in the parser.yy file. The goal is to make it so that ASTs
in the language have a reasonable class hierarchy. How you do this is up to you,
but it should be the case that you can run the code in calc.cpp and get
calculate v 1+2*3
You should also be able to run the code:
IDNode * id = new IDNode("v");
NumNode * one = new NumNode(1);
NumNode * two = new NumNode(2);
NumNode * three = new NumNode(3);
MathNode * m = new MultNode(two, three);
MathNode * a = new MultNode(one, m);
OpNode * op1 = new CalculateNode(id, a);
OpNode * op2 = new OrateNode(id);
std::list nodes = new std::list();
ProgramNode * p = new ProgramNode(nodes);
and get the same output as above. This largely means that you should update ast.hpp in order to declare these node types. You'll also need to update the parser.yy file to set the translation types of the nonterminals.
Finally, you should use concepts from the video appropriately:
Subclass functions should override superclass functions. At the very least, all classes should have a virtual print function, and subclasses should override the superclass print
The OpNode class should be pure virtual (i.e. it cannot be instantiated)
Create a tarball consisting of a single directory with all of your work in it,
such as code or written answers.
If you have any auxiliary files (READMEs, Makefiles, etc.), be sure
to include those as well.
Name your work directory l5 and name
the tarball l5.tgz.
Upload your tarball to the L5 Canvas assignment.
Labs will be graded under one of following criteria:
You will automatically be given full credit for the labwork if the GTA
determines that your participation in the lab was meaningful - i.e. you
attended the lab session and used the time to make a good-faith attempt to
complete the work. It is the sole discretion of the GTA to determine
if you put in sufficient effort. Even if you expect an effort-based grade,
you should turn in your (possibly incomplete) work.
If you do not participant meaningfully in lab (i.e. you do not attend the
lab session), your grade will be assessed based on the correctness of your
Advice: How to Approach Labs
The two-criteria grading scheme above is designed to avoid wasting your time.
You should not feel obligated to attend the lab, and in fact should only
do so if you want help from the GTA on the labwork assignment
or whatever project is currently in progress. Here's a handy flowchart
for how I suggest you approach lab: