CS301 Fall 1998

Project Part #1: The Scanner

Now it is the time to start applying all the neat tricks we learned in Chapter 2 of the text to implement the scanner. As usual, make a new directory called Scanner under your CS301 directory to place your work.

1. You will need to copy 6 of the TINY files plus Makefile into the new directory and modify them to be used as template for the Scanner.
2. In order to have consistent output, edit the main.c file to set TraceScan to TRUE, EchoSource to TRUE and NO_PARSE to TRUE. Before you move on, it makes sense to recompile and run the TINY compiler again on sample.tny. Verify that the tokens are written to the screen, and that no code is generated.
3. Meet with your teammate to design your scanner as a DFA on paper and persuade yourselves about its correctness.
4. Decide whether you want to implement the C- scanner using the technique used in TINY (the nested case-statements like in Figure 2.7) or the table-driven technique (described in page 63).
5. Decide whether you want to implement the lookup function using binary search or using a hash function. Sequential search implementation (like in TINY) is not an option here.
6. In the same meeting, discuss with your teammate whether you would like to work together through the implementation of this phase or if you would rather split the implementation into two pieces of roughly equal length and difficulty. This negotiation you should carry seriously and frankly. It is important that both of you understand what you agreed upon and that you feel it is fair.
7. Implement and test your code thoroughly. Write sample C- code to test your scanner on. Additional sample programs are on p. 496 of the book. For testing the scanner, the C- programs do not need to be syntactically or semantically correct. Demonstrate that you test the generation of every token and every error message you should produce. Remember that the C- source code file should have the .cm extension.
8. Make sure you have appropriate comments in your files including header comments describing the name(s) of the file creator/modifier, date of modifications and summary of the file contents and use. When needed, have in-line comments to explain elaborate coding that your instructor or your colleagues might have troubles understand.
9. Hand in the DFA, printouts of your code and your tests.
10. Party!

Happy programming!