devmuzaky/Arithmetic-Expression-Scanner-and-Parser-Compiler-Design

Arithmetic Expression Scanner and Parser

This project is part of compiler design course.

It support four arithmitic operations:

• Addition '+'
• Substration '-'
• Multiplication '*'
• Division '/'

Tools used in the project

• FLEX:

  FLEX (Fast LEXical analyzer generator) is a tool for generating scanners. In stead of writing a scanner from scratch, you only need to identify the vocabulary of a certain language (e.g. Simple), write a specification of patterns using regular expressions (e.g. DIGIT [0-9]), and FLEX will construct a scanner for you. FLEX is generally used in the manner depicted here:

• Bison:

  Bison is a general-purpose parser generator that converts a grammar description (Bison Grammar Files) for an LALR(1) context-free grammar into a C program to parse that grammar. The Bison parser is a bottom-up parser. It tries, by shifts and reductions, to reduce the entire input down to a single grouping whose symbol is the grammar's start-symbol.

how Flex and Bison work together

Yacc generates a parser in file y.tab.c and an include file y.tab.h. Lex includes this file (y.tab.h) and uses the definitions for token values found in this file for the returned tokens.

How to run the Scanner and the parser

1. Install bison from link
2. Install flex from link
3. in the terminal type bison -d parser.y to genrate the definiation and the grammer
4. then type flex parser.l to run the lexical analzer
5. then type gcc lex.yy.c parser.tab.c -o parser to compile into c language
6. then type ./parser to run the app

ScreenShot for example