PL-0 Compiler

Introduction

This project is a compiler for the PL/0 programming language. It was written entirely in C.

This was a semester-long project for the COP 3402 (Systems Software) class at UCF taught by Dr. Euripides Montagne.

Function

This PL/0 compiler includes a lexical analyzer, parser (syntax analyzer), machine code generator. It also includes a PM/0 virtual machine that is designed to support features such as function calls, passing parameters, and recursion.

Given a program written in PL/0 programming language, the compiler will check the syntax, generate a symbol table, generate machine code, and finally run the machine code.

Usage

1. Download the project to your computer.
2. In the linux command line, navigate to the PL0-Compiler directory that you have downloaded (or cloned).
3. From there, navigate to the compiler directory using cd Compiler
4. To compile:
   • Run the following command: make
   • Alternatively use: gcc driver.c lex.c vm.c parser.c -lm
5. To run:
   • Run the following command: ./a.out ./Input\ Files/[Input File Name] [Directives]

Directives

The directives supported by the compiler are as follows:

  -l    Print out the generated lexeme list
  -a    Print out the generated assembly language code
  -v    Print out the stack trace of the virtual machine execuation
  -s    Print out the generated symbol table

How to Download

There are two ways this can be done:

1. Download the project from this link (Not yet available)
2. Use the command git clone https://github.com/NaimShaqqou/PL0-Compiler

More About PL/0

We are using the "tiny" PL/0 language for this compiler. It is a very simple programming language that is used for learning the details of constructing a compiler. The compiler functions as a recursive descent parser (this can be visualized by looking at the grammar below).

The compiler follows the EBNF shown as follows:

  program ::= block "." . 
  block ::= const-declaration  var-declaration  procedure-declaration statement.	
  const-declaration ::= ["const" ident ":=" number {"," ident ":=" number} ";"].	
  var-declaration  ::= [ "var "ident {"," ident} “;"].
  procedure-declaration ::= { "procedure" ident ";" block ";" }.
  statement   ::= [ ident ":=" expression
                  | "call" ident  
	      	        | "begin" statement { ";" statement } "end" 
	      	        | "if" condition "then" statement ["else" statement]
		              | "while" condition "do" statement
		              | "read" ident
		              | "write" expression
	      	        | ε ] .  
  condition ::= "odd" expression 
	  	          | expression  rel-op  expression.  
  rel-op ::= "=="|“!="|"<"|"<="|">"|">=“.
  expression ::= [ "+"|"-"] term { ("+"|"-") term}.
  term ::= factor {("*"|"/"|”%”) factor}. 
  factor ::= ident | number | "(" expression ")“ .
  number ::= digit {digit}.
  ident ::= letter {letter | digit}.
  digit ;;= "0" | "1" | "2" | "3" | "4" | "5" | "6" | "7" | "8" | "9“.
  letter ::= "a" | "b" | … | "y" | "z" | "A" | "B" | ... | "Y" | "Z".