Compiler generation (TeaC Compiler)

Source-to-source compiler (trans-compiler or transpiler) using FLEX & BISON.

Table of contents

• General Info
• Installation
• Execution
• Acknowledgements

General Information

The input files (file .tc) is written in the fictional TeaC programming language and the generated code is in C. Each TeaC program is a set of word units, which are arranged according to syntax rules of a fictional language. We generate a compiler that recognizes .tc archives and generate the equivalent C code. The implementation is split to two parts:

• Lexical Analyzer
• Parser Generator
  • Convertion fictional code to C code using bison actions.

Flex

General form of description of a language programming. Scans words in text files in token format and corresponds them to grammatical rules (declared in .l file).
We specify the categories of rules:

• Keywords
• Identifiers
• Constants
  • Boolean
  • Real positive
  • Strings
• Operators
• Delimiters
• Specials (white space, comments)

In this version, we have set some specific words for TeaC as keywords:

Keywords
int	real	bool
string	true	false
if	then	else
fi	while	loop
pool	const	let
return	not	end
or	start

The other categories have basic common programming language content (possibly with some shortcomings, check .l for clarifications).

For more information about Flex, see https://www.geeksforgeeks.org/flex-fast-lexical-analyzer-generator/.

Bison

Syntactic rules of a language define the correct syntax of its word units. Here, we have:

• Main
  • Declarations
  • Functions
  • Body
• Data Types
• Array (one dimension)
• Variables
• Functions
• Expressions
• Commands
• Constants

It builds <parser_name>.tab.c, <parser_name>.tab.h files.

For more information https://www.geeksforgeeks.org/bison-command-in-linux-with-examples/

Installation

• In linux terminal, run commands to install tools.

$ sudo apt-get install flex
$ sudo apt update
$ sudo apt install bison

For any help, see

$ bison --help

• GCC install to converter parser rules to a recognized programming language (C in this case)

$ sudo apt install build-essential
$ sudo apt-get update

• Verify correctly installation with the version of the GCC

 gcc --version

Execution

• Syntax analysis from parser

bison -d -v -r  <parser_name>.y

• Lexical analysis from lexer

flex <analyzer name>.l

• Build compiler using the extracted rules

gcc -o teac <parser_name>.tab.c <analyzer name>.yy.c cgen.c -lfl

• Convert the fictional input to a .c file

./teac < <TeaC_input>.tc> output.c

• Build and run

gcc -Wall -std=c99 -o out output.c
./out

In \scripts, there are a few script for testing code for different sample inputs. correct1.tc is a sample of source code of TeaC language.

Prerequisites

cgen.c contains function for lex to handle string. In other words, uses buffers to handle the parser's tokens.
Error in stream => Error in syntax => No executable

Acknowledgements

• This project was created for the requirements of the lesson Theory of Computation