rust/src/lib/smallintmap.rs

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