Programming Assignment 3: Syntactic Analysis (Parsing)

Using ml-yacc

1. Make a new directory as3 for this assignment.
2. Copy the files /u/cos320/chap3/*.sml and /u/cos320/chap3/*.cm into as3.
3. Please, familiarize yourself with the code that is already there.
4. Copy your working tiger.lex from assignment 2 into as3. If your lexer is not working, then do NOT copy it into as3 and skip the next step. In this case, CM.make(); will automatically use the file tiger.lex.sml that is provided.
5. Edit your tiger.lex to make sure it contains the following code:
   • In the first section:

           type svalue = Tokens.svalue
           type pos = int
           type ('a,'b) token = ('a,'b) Tokens.token
           type lexresult = (svalue, pos) token
           

   • After the first %%:

           %header (functor TigerLexFun (structure Tokens: Tiger_TOKENS));
           

   Make sure you delete the old definiton of type lexresult.
6. Edit tiger.grm until it specifies a parser for the Tiger language (See Appendix A of Modern Compiler Implelmentation in ML).
7. Compile using CM.make(); This will automatically run ml-lex and ml-yacc as necessary.
8. Test your parser by invoking Parse.parse "filename". Debug, edit, recompile, test. Repeat.
9. Write a README file with a detailed description of any shift/reduce conflict that your parser might have. Explain why it is not harmful. You must eliminate all reduce/reduce conflicts, though. (By the way, my parser has no conflicts. However, shift/reduce conflicts are ok as long as they correspond to phenomena, such as "dangling else", that are well understood.)
10. Submit your solution with submit 3 README tiger.grm.