C Simple Parser

The project aims to implement simple parser for sub-language of C with pattern-matching technique. The parser should recognize:

• Expression
• Assignement
• Int variable declaration
• Selection
• Block {}
• Loops

It produces an Abstract Syntax Tree (AST) as output.

Usage

The program should be compile with ghc and the executable takes two argument: the first one is the input file (.txt) and the second is the output file where the program will print the AST.

$ ghc c-parser.hs
$ ./c-parser input.txt output.txt

The input file shouldn't have main, but it should be wrapped between curly brackets. Check the input file 'input.txt' and try to run the program to see how it works.

Grammar

<program> ::= <compound>

<compound> ::= "{" <declaration_list> <statement_list> "}"

<declaration_list> ::= {<declaration>}

<declaration> ::= "int" string ";"

<statement_list> ::= {<statement>}

<statement> ::= <if_statement>
 |	<while_statement>
 |  <do_statement>
 |  <for_statement>
 |  <assignment_statement>
 |  <compound>

<if_statement> ::= "if" "(" <expression> ")" <statement> [<opt_else>]

<opt_else> ::= "else" <statement>

<while_statement> ::= "while" "(" <expression> ")" <statement>

<do_statement> ::= "do" "{" <statement> "}" "while" "(" <expression> ")" ";"

<for_statement> ::= "for" "(" <assignment_statement> ";" <expression> ";" <expression> ")" <statement>

<assignment_statement> ::= string "=" <expression>

<expression> ::= <equality>

<equality> ::= <comparison> { ("!="|"==") <comparison> }

<comparison> ::= <term> { (">"|">="|"<"|"<=") <term> }

<term> ::= <factor> { ("-"|"+") <factor> }

<factor> ::= <unary> { ("/"|"*") <unary> }

<unary> ::= ("!"|"-") <unary> | <primary>

<primary> ::= number | string | "(" <expression> ")"