rust/src/lib/smallintmap.rs

/// A simple map based on a vector for small integer keys. Space requirements
/// are O(highest integer key).
import option::{some, none};

// FIXME: Should not be @; there's a bug somewhere in rustc that requires this
// to be.
type smallintmap<T> = @{mutable v: [mutable option::t<T>]};

fn mk<T>() -> smallintmap<T> {
    let v: [mutable option::t<T>] = [mutable];
    ret @{mutable v: v};
}

fn insert<T>(m: smallintmap<T>, key: uint, val: T) {
    vec::grow_set::<option::t<T>>(m.v, key, none::<T>, some::<T>(val));
}

fn find<T>(m: smallintmap<T>, key: uint) -> option::t<T> {
    if key < vec::len::<option::t<T>>(m.v) { ret m.v[key]; }
    ret none::<T>;
}

fn get<T>(m: smallintmap<T>, key: uint) -> T {
    alt find::<T>(m, key) {
      none::<T>. { log_err "smallintmap::get(): key not present"; fail; }
      some::<T>(v) { ret v; }
    }
}

fn contains_key<T>(m: smallintmap<T>, key: uint) -> bool {
    ret !option::is_none(find::<T>(m, key));
}

fn truncate<T>(m: smallintmap<T>, len: uint) {
    m.v = vec::slice_mut::<option::t<T>>(m.v, 0u, len);
}

fn max_key<T>(m: smallintmap<T>) -> uint {
    ret vec::len::<option::t<T>>(m.v);
}