Function geohash_decode

nodedb-spatial/src/geohash.rs:102–145

Decode a geohash string to its bounding box. Returns `None` if the geohash contains invalid characters or is empty.

(hash: &str)

///
/// Returns `None` if the geohash contains invalid characters or is empty.
pub fn geohash_decode(hash: &str) -> Option<BoundingBox> {
    if hash.is_empty() {
        return None;
    }

    let mut min_lng = -180.0_f64;
    let mut max_lng = 180.0_f64;
    let mut min_lat = -90.0_f64;
    let mut max_lat = 90.0_f64;
    let mut is_lng = true;

    for byte in hash.bytes() {
        if byte >= 128 {
            return None;
        }
        let idx = DECODE_TABLE[byte as usize];
        if idx == 255 {
            return None;
        }

        // Each character encodes 5 bits, MSB first.
        for bit in (0..5).rev() {
            let on = (idx >> bit) & 1 == 1;
            if is_lng {
                let mid = (min_lng + max_lng) / 2.0;
                if on {
                    min_lng = mid;
                } else {
                    max_lng = mid;
                }
            } else {
                let mid = (min_lat + max_lat) / 2.0;
                if on {
                    min_lat = mid;
                } else {
                    max_lat = mid;
                }
            }
            is_lng = !is_lng;
        }
    }

    Some(BoundingBox::new(min_lng, min_lat, max_lng, max_lat))
}

/// Decode a geohash to its center point (longitude, latitude).
pub fn geohash_decode_center(hash: &str) -> Option<(f64, f64)> {