fasthash 0.3.0

A suite of non-cryptographic hash functions for Rust.
Documentation 
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use std::env;
use std::fs::File;
use std::io::Write;
use std::path::Path;

fn snake_case_name(name: &str) -> String {
    name.chars()
        .enumerate()
        .map(|(i, c)| {
            if c.is_uppercase() {
                format!(
                    "{}{}",
                    if i == 0 { "" } else { "_" },
                    c.to_lowercase().next().unwrap()
                )
            } else {
                format!("{}", c)
            }
        })
        .collect::<Vec<String>>()
        .join("")
}

fn bench_hash<W: Write>(w: &mut W, hashes: Vec<(&str, Vec<&str>)>) {
    for (module, methods) in hashes {
        for method in methods {
            for shift in 4..10 {
                let bench = format!(
                    "
#[bench]
fn bench_{name}_key_{keysize}(b: &mut Bencher) {{
    bench_fasthash::<{module}::{method}>(b, {keysize});
}}",
                    module = module,
                    name = snake_case_name(method),
                    method = method,
                    keysize = 1 << shift
                );

                w.write_all(bench.as_str().as_bytes()).unwrap();
            }
        }
    }
}

fn bench_hasher<W: Write>(w: &mut W, hashers: Vec<&str>) {
    for hasher in hashers {
        let name = snake_case_name(hasher);

        for shift in 4..10 {
            let bench = format!(
                "
#[bench]
fn bench_{name}_key_{keysize}(b: &mut \
                                 Bencher) {{
    bench_hasher::<{hasher}>(b, {keysize});
}}",
                name = name,
                hasher = hasher,
                keysize = 1 << shift
            );

            w.write_all(bench.as_str().as_bytes()).unwrap();
        }
    }
}

fn bench_buf_hasher<W: Write>(w: &mut W, hashers: Vec<&str>) {
    for hasher in hashers {
        let name = snake_case_name(hasher);

        for shift in 4..10 {
            let bench = format!(
                "
#[bench]
fn bench_{name}_key_{keysize}(b: &mut \
                                 Bencher) {{
    bench_buf_hasher::<{hasher}>(b, {keysize});
}}",
                name = name,
                hasher = hasher,
                keysize = 1 << shift
            );

            w.write_all(bench.as_str().as_bytes()).unwrap();
        }
    }
}

fn main() {
    let out_dir = env::var("OUT_DIR").unwrap();
    let dest_path = Path::new(&out_dir).join("benches.rs");
    let mut f = File::create(&dest_path).unwrap();

    bench_hash(
        &mut f,
        vec![
            (
                "city",
                vec!["CityHash32", "CityHash64", "CityHash128", "CityHashCrc128"],
            ),
            ("farm", vec!["FarmHash32", "FarmHash64", "FarmHash128"]),
            ("lookup3", vec!["Lookup3"]),
            (
                "metro",
                vec![
                    "MetroHash64_1",
                    "MetroHash64_2",
                    "MetroHash128_1",
                    "MetroHash128_2",
                    "MetroHash64Crc_1",
                    "MetroHash64Crc_2",
                    "MetroHash128Crc_1",
                    "MetroHash128Crc_2",
                ],
            ),
            ("mum", vec!["MumHash"]),
            ("murmur", vec!["Murmur", "MurmurAligned"]),
            (
                "murmur2",
                vec![
                    "Murmur2",
                    "Murmur2A",
                    "MurmurNeutral2",
                    "MurmurAligned2",
                    "Murmur2_x64_64",
                    "Murmur2_x86_64",
                ],
            ),
            (
                "murmur3",
                vec!["Murmur3_x86_32", "Murmur3_x86_128", "Murmur3_x64_128"],
            ),
            ("sea", vec!["SeaHash"]),
            (
                "spooky",
                vec!["SpookyHash32", "SpookyHash64", "SpookyHash128"],
            ),
            (
                "t1ha",
                vec![
                    "T1ha0_32Le",
                    "T1ha0_32Be",
                    "T1ha1_64Le",
                    "T1ha1_64Be",
                    "T1ha2_64",
                ],
            ),
            ("xx", vec!["XXHash32", "XXHash64"]),
        ],
    );

    bench_hasher(
        &mut f,
        vec![
            "SipHasher",
            "FnvHasher",
            "SeaHasher",
            "SpookyHasher",
            "SpookyHasherExt",
            "T1haHasher",
            "XXHasher",
        ],
    );

    bench_buf_hasher(
        &mut f,
        vec![
            "CityHasher",
            "CityHasherExt",
            "FarmHasher",
            "FarmHasherExt",
            "Lookup3Hasher",
            "MetroHasher",
            "MetroHasherExt",
            "MumHasher",
            "MurmurHasher",
            "Murmur2Hasher",
            "Murmur3Hasher",
            "Murmur3HasherExt",
        ],
    );
}