Interpreter

A simple interpreter and IDE built using python

Integrated Development Environment

IDE is built using Python's GUI Tkinter

You can visit the documentation site for the current programming language by clicking on help in the ide and then selecting Document

Click here to visit the documentation page

Grammar

program : PROGRAM variable SEMI block DOT

block : declarations compound_statement

declarations : VAR (variable_declaration SEMI)+ | empty

variable_declaration : ID (COMMA ID)* COLON type_spec

type_spec : INTEGER | REAL | BOOLEAN | STRING

compound_statement : BEGIN statement_list END

statement_list : statement | statement SEMI statement_list

statement : compound_statement | assignment_statement | if_statement | loop_statement | break | continue | empty

assignment_statement : variable ASSIGN expr

if_statement : IF expr THEN statement_list (ELSEIF expr THEN statement_list)* (ELSE statement_list)? ENDIF

loop_statement : LOOP IF expr statement_list (ELSE statement_list)? ENDLOOP

break : BREAK

continue : CONTINUE

empty :

expr : level_1 (OR level_1)*

level_1 : level_2 (AND level_2)*

level_2 : level_3 ((E|NE|GT|LT|GTE|LTE) level_3)*

level_3 : level_4 ((PLUS|MINUS) level_4)*

level_4 : level_5 ((MUL|FLOAT_DIV|INTEGER_DIV) level_5)*

level_5 : level_6 (DOLLAR level_6)*

level_6 : PLUS level_6 | MINUS level_6 | INTEGER_CONST | REAL_CONST | BOOLEAN | STRING | LPAREN expr RPAREN | variable

variable: ID

Code Examples

program helloWorld;
var 
    greeting : string;
    
begin
    greeting := 'Hello World';
    display(greeting);
end.

{Displaying numbers from 1 to 20}
program main;
var 
	range : integer;
	count : integer;

begin
	range := 20;
	count := 0;
	loop if (count < range)
		count := count + 1;
		display('Number is :', count);
	endloop;
end.

program continueStatement;
var
	a : integer;

begin 
	a := 0;
	loop if (a < 5)
		a := a + 1;
		if a = 4 then
			continue;
		elseif a = 2 then
			continue;
		endif;
		display('current value of a:', a);
	endloop;
end.

program breakStatement;
var
	a : integer;

begin 
	a := 0;
	loop if (a < 5)
		a := a + 1;
		if a = 3 then
			break;
		endif;
		display('current value of a:', a);
	endloop;
	display('hurray');
end.

{Factorial}
program factorial;
var 
	counter, fact : integer;

begin
	counter := 1;
	fact := 1;
	loop if (counter < 10)
		fact := fact * counter;
		counter := counter + 1;
	endloop;
	display('factorial of 10 :',fact);
end.

Referrences

Ruslan's Blog: Let’s Build A Simple Interpreter