CSE 423 Lab #1: Flex

Turnin: a .zip on Canvas.

Group Work

For each team:

Find and Introduce yourselves, then spend 15 minutes on the following
- Assign one person to build a list of integer codes (#define or enum names) for all of the Kotlin operators
- Assign one person to build a list of integer codes (#define or enum names) for all of the Kotlin reserved words
- [If your team has three members] Assign one person to build a list of integer codes (#define or enum names) for all other Kotlin tokens (literal constants, identifiers, etc.)
It is recommended that you use the mnemonic names given in the Kotlin official lexical grammar when such are available.
Some of these are longer/harder than others, just do the best you can in 15 minutes.
After 15 minutes, report to your teammates what your list consists of, and what questions or obstacles you have. Exchange your lists with each other. Discuss any corrections/refinements needed, and make changes if you can see things to fix.
End result of group section of lab: each group member has a .h file with all the integer categories/tokens needed for lexical analysis of Kotlin
Turnin this .h file within the .zip for your individual lab efforts. Include a README file that rates your teammates as 2=full participation, 1=partial participation, or 0= not present or did not contribute

Individual Work

1. Flex Basics

Use Flex to compile and run the "word counter" flex program from the Flex manual page, or flex-wc.l (HTML, raw .l: flex-wc.l), a version of the word counter that comes from github. In your .zip submission, you can include your final versions of source code files used here, plus a file lab1.1_answers.txt

When you run flex flex-wc.l, what output file does flex write?
When you run gcc on Flex's output .c file, what is the executable file named?
Run your program on itself with ./a.out <flex-wc.l
Fix your program to take the name of the file as a command line argument, instead of using < to redirect standard input.
Convert to separate compilation! move main() into a separate main.c and write a makefile that compiles main.c and lex.yy.c separately and then links them.

2. Flex (Most of) your HW#2 Away

Well, you can save the "allocate tokens and build a linked list of them" part for later, but if you complete this lab, you should have your regular expressions identified, and have integer codes for each category. We should also get a good idea of how to handle some of Kotlin's more quirky rules.

Let's walk through Kotlin's description of Kotlin's lexical analysis, its so-called lexical grammar. Then we proceed as follows.

Copy flex-wc.l to a file named kotlex.l
Modify kotlex.l to discard whitespace, but otherwise count chars/words
Modify kotlex.l to discard comments, but otherwise count chars/words
Modify kotlex.l to return a 257 on each word, and modify the main() to call yylex() in a while loop. Print chars and words at the end.
Change the while loop to print out a line showing each word after yylex() returns it. Print the return code as well as yytext
Add regular expressions to recognize reserved words and return different integers for each one. Fail and stop with an error message if a Kotlin reserved word not in k0 appears.
Add regular expressions for operators and punctuation and return different integers for each one.
Add regular expressions for integer, float and string literals. Return a different integer code for each kind of literal.
Figure out what to do about Kotlin's less obvious tokens. You may work on this part collaboratively.
Ask questions about anything fishy in Kotlin that we haven't specified yet. We will have to get all decisions written down and shared.