Popo 🍑 Compiler

Popo is a simple compiler only for educational purposes written in Python, it compiles a basic lang to C.

🚀 Fire it up!

You need to have Python3 installed, then run the command below:

python3 index.py hello.popo

index.py takes any file that ends with .popo as an input and compiles it out to C.

How does it work?

The compiler will work in three stages: (1) lexing, which breaks the input code up into small pieces called tokens, (2) parsing, which verifies that the tokens are in an order that our language allows, and (3) emitting, which produces the appropriate C code.

If you want to know more, please check Resources section.

Grammers

program ::= {statement}
statement ::= "PRINT" (expression | string) nl
            | "IF" comparison "THEN" nl {statement} "ENDIF" nl
            | "WHILE" comparison "REPEAT" nl {statement} "ENDWHILE" nl
            | "LABEL" ident nl
            | "GOTO" ident nl
            | "LET" ident "=" expression nl
            | "INPUT" ident nl
comparison ::= expression (("==" | "!=" | ">" | ">=" | "<" | "<=") expression)+
expression ::= term {( "-" | "+" ) term}
term ::= unary {( "/" | "*" ) unary}
unary ::= ["+" | "-"] primary
primary ::= number | ident
nl ::= '\n'+

What it doesn't support

There are no functions, no arrays, no way to read/write from a file, and no else statement.

Operators

Popo supports the following operators:

+ - \* / = == != > < >= <=

Strings

Double quotation followed by zero or more characters and a double quotation. Such as:

"Hello, world!"

Numbers

Currently, decimals are not supported.

Identifiers

An alphabetical character followed by zero or more alphanumeric characters.

Keywords

Exact text match of:

LABEL, GOTO, PRINT, INPUT, LET, IF, THEN, ENDIF, WHILE, REPEAT, ENDWHILE

Resources

Thanks to Austin Henley for his great article

Don't miss James Kyle's Super Tiny Compiler