Project 4: Semantic Analysis

Due date: 2003 Oct 27th(Wednesday), 12:00 Noon

Description

In this project, you need to do semantic analysis for type-checking as described in Chapter 5 of the text. Basically, you will read in and traverse the Abstract Syntax Tree (that was generated by the parser in Project 3), and check for various type compatibilities.

This project is to be completed in pairs.

Directions

• Read Chapter 5 of Appel.
• Observe the reference implementation of the semantic analyzer. It can be run with the command:
      /homes/cs352/bin/p3 inputfile.java | /homes/cs352/bin/p4
  This means that your semantic analyzer will accept the abstract syntax tree from the standard input (System.in).
• You must create a class called 'Table' in package 'Symbol' as your symbol table class, which will have atleast the following public methods:
          void Table()
          void put(Symbol key, Object value)
          Object get(Symbol key)
          void beginScope()
          void endScope()
  Note that we'll be testing for these functionalities. It is important that you get these right to get full credit.
• Information on error messages and grading are available at: Error Messages
.
• Your Semantic Analyzer will be graded with automated scripts. Make certain that your project submission can be executed using the following commands:
   
  cd Project4; make; /homes/cs352/bin/p3 inputfile.java | java Semant.Main
   
  where "inputfile.java" is the MiniJava file to be analyzed. Failure to follow this simple directory and package naming scheme will result in a zero on the project. If you have not created a Makefile or Java packages before, consult your TA.
• The javacc binary is installed on the lab machines under /p/java2/tools/JavaCC/bin/javacc, and we recommend using the newer version of Java installed under /p/java2/bin/ for this and all remaining projects. Run the setup script /homes/cs352/bin/setup-352 to create a bin directory in your path that points to the new tools and the reference implementation.
• Some hints are available at: Hints
.
• Debug your program until your output matches the reference implementation.

Resources

If you have questions please ask either Dr. Brylow or a TA, or post a message to the class news group at purdue.class.cs352.

Hints

The symbol table will have  functions to put an object for an associated symbol( put(Symbol, Object) ) and get the Object stored for a particular symbol( get(Symbol) ). In addition, it will have methods to begin a new scope ( beginScope( ) ) and end the scope( endScope( ) ). Endscope will basically delete all the entries added after the beginScope( ), so that the information for those entries is not retained after the scope has ended. You will neeed to use two symbol tables: classEnv (used to store all the information of various classes, including their fields and functions), and varEnv (used to store information of various variables with the function declarations).

You may want to create various classes for each type. Each of these classes will have coerceTo( ) method to check if two types are compatible. For example, if you have two objects X and Y, and you want to check if these two objects are compatible, then you have to invoke either X.coerceTo(Y) or Y.coerceTo(X), which will return true or false.

Error Messages

All the possible error messages can be found here. You must generate the same error messages and also the same number of error messages for the particular testcase as the solution program provided(though the messages may differ with respect to number of spaces), else you will receive zero points for the test case. You cannot come later and claim any partial credit claiming that the meaning of the error message is same, or that there is a spelling mistake, etc. There won't be any change in policy regarding this. Also you must match the other standard output generated regarding the types exactly.

Errors must be printed on StdErr. So while using diff to compare the outputs, use the following commands:

% /homes/cs352/bin/p3 inputfile.java | java Semant.Main >& out1

% /homes/cs352/bin/p3 inputfile.java | /homes/cs352/bin/p4 >& out2

% diff -w out1 out2

Turnin

Note: Late submissions will not be graded. Please see the course website for more info.

• Submit a directory named Project4 with the required programs and a Makefile. Do not submit any binaries or compiled class files.
• Submit using
   
  /homes/cs352/bin/turnin -c cs352=0X01 -p project4 Project4
   
  on a machine in the CS undergraduate "Lore" domain, where "Project4" is the name of your project 4 directory, and "0X01" is your division number.

Useful Links

• Java Language Specification
• Textbook Website
• MiniJava BNF
• Error Messages
• Newsgroup

Credits

This has been adapted from Dr. Hosking and Dr. Brylow's previous course projects.