Function encode

nodedb-fts/src/codec/delta.rs:13–23

Delta encoding/decoding for sorted `u32` sequences. Posting lists are sorted by doc ID. Delta encoding stores the first ID absolute and subsequent IDs as `current - previous`. Typical deltas are much smaller than absolute IDs, enabling tighter bitpacking. Delta-encode a sorted slice of u32 values in place. After encoding: `out[0] = values[0]`, `out[i] = values[i] - values[i-1]`. The input MUST b

(values: &[u32])

/// After encoding: `out[0] = values[0]`, `out[i] = values[i] - values[i-1]`.
/// The input MUST be sorted ascending. Unsorted input produces garbage.
pub fn encode(values: &[u32]) -> Vec<u32> {
    if values.is_empty() {
        return Vec::new();
    }
    let mut deltas = Vec::with_capacity(values.len());
    deltas.push(values[0]);
    for i in 1..values.len() {
        deltas.push(values[i] - values[i - 1]);
    }
    deltas
}

/// Decode delta-encoded values back to absolute sorted values.
///