#[doc = "
A simple map based on a vector for small integer keys. Space requirements
are O(highest integer key).
"];
import core::option;
import core::option::{some, none};
import dvec::{dvec, extensions};

// FIXME: Should not be @; there's a bug somewhere in rustc that requires this
// to be. (#2347)
type smallintmap<T: copy> = @{v: dvec<option<T>>};

#[doc = "Create a smallintmap"]
fn mk<T: copy>() -> smallintmap<T> {
    ret @{v: dvec()};
}

#[doc = "
Add a value to the map. If the map already contains a value for
the specified key then the original value is replaced.
"]
fn insert<T: copy>(self: smallintmap<T>, key: uint, val: T) {
    self.v.grow_set_elt(key, none, some(val));
}

#[doc = "
Get the value for the specified key. If the key does not exist
in the map then returns none
"]
fn find<T: copy>(self: smallintmap<T>, key: uint) -> option<T> {
    if key < self.v.len() { ret self.v.get_elt(key); }
    ret none::<T>;
}

#[doc = "
Get the value for the specified key

# Failure

If the key does not exist in the map
"]
fn get<T: copy>(self: smallintmap<T>, key: uint) -> T {
    alt find(self, key) {
      none { #error("smallintmap::get(): key not present"); fail; }
      some(v) { ret v; }
    }
}

#[doc = "
Returns true if the map contains a value for the specified key
"]
fn contains_key<T: copy>(self: smallintmap<T>, key: uint) -> bool {
    ret !option::is_none(find(self, key));
}

#[doc = "Implements the map::map interface for smallintmap"]
impl <V: copy> of map::map<uint, V> for smallintmap<V> {
    fn size() -> uint {
        let mut sz = 0u;
        for self.v.each {|item|
            alt item { some(_) { sz += 1u; } _ {} }
        }
        sz
    }
    fn insert(&&key: uint, value: V) -> bool {
        let exists = contains_key(self, key);
        insert(self, key, value);
        ret !exists;
    }
    fn remove(&&key: uint) -> option<V> {
        if key >= self.v.len() { ret none; }
        let old = self.v.get_elt(key);
        self.v.set_elt(key, none);
        old
    }
    fn contains_key(&&key: uint) -> bool {
        contains_key(self, key)
    }
    fn get(&&key: uint) -> V { get(self, key) }
    fn find(&&key: uint) -> option<V> { find(self, key) }
    fn rehash() { fail }
    fn each(it: fn(&&uint, V) -> bool) {
        let mut idx = 0u, l = self.v.len();
        while idx < l {
            alt self.v.get_elt(idx) {
              some(elt) {
                if !it(idx, elt) { break; }
              }
              none { }
            }
            idx += 1u;
        }
    }
    fn each_key(it: fn(&&uint) -> bool) {
        let mut idx = 0u, l = self.v.len();
        while idx < l {
            if self.v.get_elt(idx) != none && !it(idx) { ret; }
            idx += 1u;
        }
    }
    fn each_value(it: fn(V) -> bool) {
        self.each {|_i, v| it(v)}
    }
}

#[doc = "Cast the given smallintmap to a map::map"]
fn as_map<V: copy>(s: smallintmap<V>) -> map::map<uint, V> {
    s as map::map::<uint, V>
}