toolchest 0.1.0

//! URL encoding/decoding (percent-encoding for ASCII)

/// Percent-encode a string using ASCII-safe characters
pub fn url_encode(input: &str) -> String {
    let mut out = String::with_capacity(input.len());
    for b in input.bytes() {
        match b {
            b'-' | b'_' | b'.' | b'~' | b'0'..=b'9' | b'A'..=b'Z' | b'a'..=b'z' => {
                out.push(b as char)
            }
            b' ' => out.push_str("%20"),
            _ => out.push_str(&format!("%{b:02X}")),
        }
    }
    out
}

/// Decode percent-encoded sequences in a string
pub fn url_decode(input: &str) -> String {
    let mut out = String::with_capacity(input.len());
    let bytes = input.as_bytes();
    let mut i = 0;
    while i < bytes.len() {
        if bytes[i] == b'%' && i + 2 < bytes.len() {
            if let (Some(h), Some(l)) = (hex_val(bytes[i + 1]), hex_val(bytes[i + 2])) {
                out.push((h * 16 + l) as char);
                i += 3;
                continue;
            }
        }
        out.push(bytes[i] as char);
        i += 1;
    }
    out
}

fn hex_val(b: u8) -> Option<u8> {
    match b {
        b'0'..=b'9' => Some(b - b'0'),
        b'a'..=b'f' => Some(b - b'a' + 10),
        b'A'..=b'F' => Some(b - b'A' + 10),
        _ => None,
    }
}