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// Copyright 2012 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
/*!
* Defines a type OptVec<T> that can be used in place of ~[T].
* OptVec avoids the need for allocation for empty vectors.
* OptVec implements the iterable interface as well as
* other useful things like `push()` and `len()`.
*/
use std::vec;
#[deriving(Clone, Encodable, Decodable, IterBytes)]
pub enum OptVec<T> {
Empty,
Vec(~[T])
}
pub fn with<T>(t: T) -> OptVec<T> {
Vec(~[t])
}
pub fn from<T>(t: ~[T]) -> OptVec<T> {
if t.len() == 0 {
Empty
} else {
Vec(t)
}
}
impl<T> OptVec<T> {
pub fn push(&mut self, t: T) {
match *self {
Vec(ref mut v) => {
v.push(t);
return;
}
Empty => {
*self = Vec(~[t]);
}
}
}
pub fn pop(&mut self) -> Option<T> {
match *self {
Vec(ref mut v) => v.pop(),
Empty => None
}
}
pub fn last<'a>(&'a self) -> Option<&'a T> {
match *self {
Vec(ref v) => v.last(),
Empty => None
}
}
pub fn mut_last<'a>(&'a mut self) -> Option<&'a mut T> {
match *self {
Vec(ref mut v) => v.mut_last(),
Empty => None
}
}
pub fn map<U>(&self, op: |&T| -> U) -> OptVec<U> {
match *self {
Empty => Empty,
Vec(ref v) => Vec(v.map(op))
}
}
pub fn map_move<U>(self, op: |T| -> U) -> OptVec<U> {
match self {
Empty => Empty,
Vec(v) => Vec(v.move_iter().map(op).collect())
}
}
pub fn get<'a>(&'a self, i: uint) -> &'a T {
match *self {
Empty => fail!("invalid index {}", i),
Vec(ref v) => &v[i]
}
}
pub fn is_empty(&self) -> bool {
self.len() == 0
}
pub fn len(&self) -> uint {
match *self {
Empty => 0,
Vec(ref v) => v.len()
}
}
pub fn swap_remove(&mut self, index: uint) {
match *self {
Empty => { fail!("index out of bounds"); }
Vec(ref mut v) => {
assert!(index < v.len());
v.swap_remove(index);
}
}
}
#[inline]
pub fn iter<'r>(&'r self) -> Items<'r, T> {
match *self {
Empty => Items{iter: None},
Vec(ref v) => Items{iter: Some(v.iter())}
}
}
#[inline]
pub fn map_to_vec<B>(&self, op: |&T| -> B) -> ~[B] {
self.iter().map(op).collect()
}
pub fn mapi_to_vec<B>(&self, op: |uint, &T| -> B) -> ~[B] {
let mut index = 0;
self.map_to_vec(|a| {
let i = index;
index += 1;
op(i, a)
})
}
}
pub fn take_vec<T>(v: OptVec<T>) -> ~[T] {
match v {
Empty => ~[],
Vec(v) => v
}
}
impl<T:Clone> OptVec<T> {
pub fn prepend(&self, t: T) -> OptVec<T> {
let mut v0 = ~[t];
match *self {
Empty => {}
Vec(ref v1) => { v0.push_all(*v1); }
}
return Vec(v0);
}
}
impl<A:Eq> Eq for OptVec<A> {
fn eq(&self, other: &OptVec<A>) -> bool {
// Note: cannot use #[deriving(Eq)] here because
// (Empty, Vec(~[])) ought to be equal.
match (self, other) {
(&Empty, &Empty) => true,
(&Empty, &Vec(ref v)) => v.is_empty(),
(&Vec(ref v), &Empty) => v.is_empty(),
(&Vec(ref v1), &Vec(ref v2)) => *v1 == *v2
}
}
fn ne(&self, other: &OptVec<A>) -> bool {
!self.eq(other)
}
}
impl<T> Default for OptVec<T> {
fn default() -> OptVec<T> { Empty }
}
pub struct Items<'a, T> {
priv iter: Option<vec::Items<'a, T>>
}
impl<'a, T> Iterator<&'a T> for Items<'a, T> {
#[inline]
fn next(&mut self) -> Option<&'a T> {
match self.iter {
Some(ref mut x) => x.next(),
None => None
}
}
#[inline]
fn size_hint(&self) -> (uint, Option<uint>) {
match self.iter {
Some(ref x) => x.size_hint(),
None => (0, Some(0))
}
}
}
impl<'a, T> DoubleEndedIterator<&'a T> for Items<'a, T> {
#[inline]
fn next_back(&mut self) -> Option<&'a T> {
match self.iter {
Some(ref mut x) => x.next_back(),
None => None
}
}
}
impl<A> FromIterator<A> for OptVec<A> {
fn from_iterator<T: Iterator<A>>(iterator: &mut T) -> OptVec<A> {
let mut r = Empty;
for x in *iterator {
r.push(x);
}
r
}
}
|
