tinycalc

Tinycalc is a quick and dirty calculator REPL written in C99. It features a recursive-descent parser and tree-walk interpeter for math expressions.

Built mostly for educational purposes, and as a ground to build more complex interpreters.

Features

• Binary operators (+, -, *, /, ^)
• Bit manipulation (<<, >>, &, |, ~)
• Parentheses "(", ")"
• Standard functions (sin, abs, etc.)
• Type-checking against integers and floating-point expressions
• Follows C operator precedence

Example usage

> 1 - 2
-1
> (1+2)*4 + 10
22
> -1 * (-1 + 5)
-4

Grammar

<expr>         = <bitor> 
<bitor>        = <bitand> { "|" <bitand> }*
<bitand>       = <shifts> { "&" <shifts> }*
<shifts>       = <add_sub> { ("<<" | ">>") <add_sub> }*
<add_sub>      = <mult_div> { ("+" | "-") <mult_div> }*
<mult_div>     = <power> { ("*" | "/") <power> }*
<power>        = <unary> { "^" <unary> }*
<unary>        = ("-" | "~" | <func> ) <unary> | <primary>
<primary>      = "(" <expr> ")" | <number>