this_algorithm/words/build.rs

#![feature(slice_group_by)]
#![allow(unused_imports)]
use csv::ReaderBuilder;
use serde::{Deserialize, Deserializer, Serialize};
use std::collections::HashMap;
use std::env;
use std::fs::File;
use std::io::{BufRead, BufReader, BufWriter, Write};
use std::path::Path;

fn main() {
    let path = Path::new(&env::var("OUT_DIR").unwrap()).join("codegen.rs");
    let mut file = BufWriter::new(File::create(path).unwrap());
    let wordlist_path = "../data/wordlist-tmp.csv";

    println!("cargo:rerun-if-changed={}", wordlist_path);

    let rdr_builder = ReaderBuilder::new();

    // First get the actual wordlist
    let words: Vec<Word> = rdr_builder
        .from_reader(File::open(wordlist_path).unwrap())
        .deserialize()
        .collect::<Result<Vec<Word>, _>>()
        .unwrap();

    // Write it to an array containing all words
    write_words(&mut file, &words);

    // Make a mapping of all caps word to a reference to the `Word` entry
    write_word_map(&mut file, &words);

    // Make a mapping of numbers to `Word`s
    write_number_to_words(&mut file, &words);
}

fn write_words(mut file: impl Write, words: &[Word]) {
    let len = words.len();

    writeln!(
        &mut file,
        r#"/// Static array of `Word`
pub static WORDS: [Word; {len}] = ["#
    )
    .unwrap();

    for result in words.iter() {
        writeln!(&mut file, "\t{result:?},").unwrap();
    }
    writeln!(&mut file, "];\n").unwrap();
}

fn write_word_map(mut file: impl Write, words: &[Word]) {
    let mut word_map = phf_codegen::Map::new();
    for (idx, word) in words.iter().enumerate() {
        let idx_str = format!("&WORDS[{idx}]");
        word_map.entry(word.word.to_uppercase(), &idx_str);
    }
    writeln!(
        &mut file,
        r#"/// Mapping from all caps `&str` to `&'static Word`
pub static WORD_MAP: phf::Map<&'static str, &Word> = {};"#,
        word_map.build()
    )
    .unwrap();
}

fn write_number_to_words(mut file: impl Write, words: &[Word]) {
    let word_number_to_idx = words
        .iter()
        .enumerate()
        .map(|(idx, w)| (w.number, idx))
        .collect::<Vec<(u16, usize)>>();

    writeln!(
        &mut file,
        // "pub static NUMBER_TO_WORDS: &[&[usize]] = &["
        r#"/// Mapping from each number to its associated word
pub static NUMBER_TO_WORDS: &[&[&Word]] = &["#
    )
    .unwrap();

    for entry in word_number_to_idx
        .as_slice()
        .group_by(|(number1, _idx1), (number2, _idx2)| number1 == number2)
    {
        write!(&mut file, "\t&[",).unwrap();

        for idx in entry.iter().map(|(_w, idx)| idx) {
            // write!(&mut file, "{idx},").unwrap();
            write!(&mut file, "&WORDS[{idx}],").unwrap();
        }
        writeln!(&mut file, "], /* {} */", entry[0].0).unwrap();
    }
    writeln!(&mut file, "];\n").unwrap();
}

#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
pub struct Word {
    /// The word itself
    pub word: String,

    /// The binary representation of this number
    ///
    /// The words are responsible for 13 bits of data, so this is fine to fit in a u16
    pub number: u16,
}