nix-configs/programs/flip-bool/src/main.rs

#![feature(iter_array_chunks)]
#![feature(round_char_boundary)]
#![feature(iter_collect_into)]
#![feature(pattern)]

use std::{
    io::{Read, Write},
    str::pattern::Pattern,
};

const BOOL_COUNT: usize = BOOLS.len();
const BOOLS: &[[&str; 2]] = &[
    ["false", "true"],
    ["False", "True"],
    ["FALSE", "TRUE"],
    ["0", "1"],
    ["no", "yes"],
];

fn main() {
    let mut input = String::new();
    let mut stdin = std::io::stdin();
    let mut stdout = std::io::stdout();

    stdin.read_to_string(&mut input).unwrap();

    let bool_locs = find_bools(&input);
    stdout
        .write_all(replace_bools(&mut input, bool_locs).as_bytes())
        .unwrap();
}

type BoolLocs = [[Vec<usize>; 2]; BOOL_COUNT];

// you thought [`find_bools`] was stupid? this is *so* much worse!!!
fn replace_bools(input: &str, mut bool_locs: BoolLocs) -> String {
    let mut result = String::with_capacity(input.len());
    let mut intermediate = input;
    let mut flattened = bool_locs
        .iter_mut()
        .flatten()
        .map(|vec| {
            vec.reverse();
            vec
        })
        .enumerate()
        .collect::<Vec<_>>();

    let mut smallest = || {
        let min_idx = flattened
            .iter()
            .min_by(|va, vb| {
                va.1.last()
                    .unwrap_or(&usize::MAX)
                    .cmp(vb.1.last().unwrap_or(&usize::MAX))
            })?
            .0;

        Some((min_idx, flattened[min_idx].1.pop()?))
    };

    let mut input_idx = 0;
    while let Some(item) = smallest() {
        let (a, b) = intermediate.split_at(item.1 - input_idx);
        input_idx += a.len();
        result += a;
        let bool_ = &BOOLS[item.0 / 2];
        input_idx += bool_[item.0 % 2].len();
        result += bool_[if item.0 % 2 == 0 { 1 } else { 0 }];
        let (_, b) = b.split_at(bool_[item.0 % 2].len());
        intermediate = b;
    }

    result + intermediate
}

// this is so fucking stupid
// it also would've been way easier using a regex crate lmao
fn find_bools(input: &str) -> [[Vec<usize>; 2]; BOOL_COUNT] {
    let mut res = Vec::with_capacity(BOOL_COUNT);
    BOOLS
        .iter()
        .flatten()
        .map(|it| {
            input
                .match_indices(it)
                .filter_map(|it| {
                    fn char_guard(c: char) -> bool {
                        !(c.is_alphanumeric() || c.is_contained_in("-_"))
                    }

                    let last_idx = it.0 + it.1.len();

                    (it.0 > 0
                        && last_idx < input.len()
                        && char_guard(
                            input[it.1.floor_char_boundary(it.0 - 1)..it.0]
                                .chars()
                                .last()
                                .unwrap(),
                        )
                        && char_guard(
                            input[(last_idx)..(input.ceil_char_boundary(last_idx + 1))]
                                .chars()
                                .last()
                                .unwrap(),
                        ))
                    .then_some(it.0)
                })
                .collect()
        })
        .array_chunks::<2>()
        .collect_into(&mut res);

    res.try_into().unwrap()
}