brainfuck/
brainfuck.rs

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//! This is a simple [brainfuck](https://en.wikipedia.org/wiki/Brainfuck) tokenizer.
//! This is intended to show how to use a [TokenizerContext] at the very, very basic level.

#![allow(dead_code)]

use alkale::{TokenizerContext, TokenizerResult};

/// Represents the eight brainfuck tokens
#[derive(Debug, Clone, Copy)]
enum BFTokenType {
    Increment,
    Decrement,
    MoveRight,
    MoveLeft,
    BeginWhile,
    EndWhile,
    ReadIO,
    WriteIO,
}

/// Tokenizes a string according to brainfuck grammar.
fn tokenize(source: &str) -> TokenizerResult<BFTokenType> {
    use BFTokenType::*;

    // Create the reader context
    let mut context = TokenizerContext::new(source.chars());

    // Repeat this code while there are more characters in the source code.
    while context.has_next() {
        // Attempt to map these characters to their respective tokens.
        let pushed_token = context.map_single_char_token(|char| match char {
            '+' => Some(Increment),
            '-' => Some(Decrement),
            '>' => Some(MoveRight),
            '<' => Some(MoveLeft),
            '[' => Some(BeginWhile),
            ']' => Some(EndWhile),
            '.' => Some(WriteIO),
            ',' => Some(ReadIO),
            _ => None,
        });

        // If a token was NOT pushed above— i.e. it was a different character, just skip it and move on.
        if !pushed_token {
            context.skip();
        }
    }

    // Return the result
    context.result()
}

fn main() {
    let program = r#"
    ++++++++[>++++[>
    ++>+++>+++>+<<<<
    -]>+>+>->>+[<]<-
    ]>>.>---.+++++++
    ..+++.>>.<-.<.++
    +.------.-------
    -.>>+.>++.
    "#;

    let result = tokenize(program);

    println!("{:#?}", result);
}