Function parse_str

crates/literal/src/complex.rs:42–75

Parse a complex number from a string. Returns `Some((re, im))` on success.

(s: &str)

///
/// Returns `Some((re, im))` on success.
pub fn parse_str(s: &str) -> Option<(f64, f64)> {
    let s = s.trim();
    // Handle parentheses
    let s = match s.strip_prefix('(') {
        None => s,
        Some(s) => s.strip_suffix(')')?.trim(),
    };

    let value = match s.strip_suffix(|c| c == 'j' || c == 'J') {
        None => (float::parse_str(s)?, 0.0),
        Some(mut s) => {
            let mut real = 0.0;
            // Find the central +/- operator. If it exists, parse the real part.
            for (i, w) in s.as_bytes().windows(2).enumerate() {
                if (w[1] == b'+' || w[1] == b'-') && !(w[0] == b'e' || w[0] == b'E') {
                    real = float::parse_str(&s[..=i])?;
                    s = &s[i + 1..];
                    break;
                }
            }

            let imag = match s {
                // "j", "+j"
                "" | "+" => 1.0,
                // "-j"
                "-" => -1.0,
                s => float::parse_str(s)?,
            };

            (real, imag)
        }
    };
    Some(value)
}