build.rs

use std::env;
use std::fs::File;
use std::io;
use std::io::{BufWriter, Write};
use std::path::Path;

fn main() {
    let sources = [
        ("data/resources/assets/xkcd.txt", "XKCD", "XKCD_VALUES"),
        ("data/resources/assets/basic.txt", "BASIC", "BASIC_VALUES"),
        ("data/resources/assets/svg.txt", "SVG", "SVG_VALUES"),
        ("data/resources/assets/gnome.txt", "GNOME", "GNOME_VALUES"),
    ];

    let out_dir = env::var_os("OUT_DIR").unwrap();
    let path = Path::new(&out_dir).join("codegen.rs");
    let mut file = BufWriter::new(File::create(path).expect("Failed to create map file"));

    sources.iter().for_each(|(path, name, rev_name)| {
        println!("cargo:rerun-if-changed={}", path);
        generate_map(&mut file, path, name, rev_name).expect("Failed to write map")
    });

    println!("cargo:rerun-if-changed=build.rs");
}

fn generate_map<T: AsRef<Path>>(
    file: &mut BufWriter<File>,
    path: T,
    name: &str,
    rev_name: &str,
) -> Result<(), io::Error> {
    // the resulting map must have unique key
    // some colors have multiple names, so they need to be removed
    // these should (hopefully) be the less used ones
    const DUPLICATED_COLORS: [&str; 10] = [
        "aqua",           //conflicts with cyan
        "darkgray",       //conflicts with darkgrey
        "darkslategray",  //conflicts with darkslategrey
        "dimgray",        //conflicts with dimgrey
        "gray",           //conflicts with grey
        "olive",          //conflicts with grey
        "lightgray",      //conflicts with lightgrey
        "lightslategray", //conflicts with lightslategrey
        "fuchsia",        //conflicts with magenta
        "slategray",      //conflicts with slategrey
    ];

    let input_file = std::fs::read_to_string(path)?;
    let mut map = phf_codegen::Map::new();
    let mut reverse_map = phf_codegen::Map::new();

    input_file
        .lines()
        .filter(|line| !line.trim().is_empty() && !line.starts_with('#'))
        .filter_map(|line| line.split_once(','))
        .map(|(name, val)| (name.trim(), val.trim()))
        .for_each(|(name, hex)| {
            map.entry(name.to_ascii_lowercase(), &format!("\"{}ff\"", hex));

            if !DUPLICATED_COLORS.contains(&name) {
                reverse_map.entry(
                    format!("{}ff", hex.to_ascii_lowercase()),
                    &format!("\"{}\"", name),
                );
            }
        });

    write_map(file, name, map)?;
    write_map(file, rev_name, reverse_map)
}

fn write_map(
    file: &mut BufWriter<File>,
    name: &str,
    map: phf_codegen::Map<String>,
) -> Result<(), io::Error> {
    write!(
        file,
        "const {}: phf::Map<&'static str, &'static str> = {}",
        name,
        map.build()
    )?;
    writeln!(file, ";")
}