rust/src/libsyntax/opt_vec.rs

164 lines
3.8 KiB
Rust
Raw Normal View History

// 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()`.
*/
2013-07-05 20:38:56 -05:00
use std::vec::{VecIterator};
2013-07-02 14:47:32 -05:00
#[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> {
fn push(&mut self, t: T) {
match *self {
Vec(ref mut v) => {
v.push(t);
return;
}
Empty => {}
}
// FIXME(#5074): flow insensitive means we can't move
// assignment inside `match`
*self = Vec(~[t]);
}
fn map<U>(&self, op: &fn(&T) -> U) -> OptVec<U> {
match *self {
Empty => Empty,
Vec(ref v) => Vec(v.map(op))
}
}
fn map_move<U>(self, op: &fn(T) -> U) -> OptVec<U> {
2013-07-05 20:38:56 -05:00
match self {
Empty => Empty,
Vec(v) => Vec(v.move_iter().map(op).collect())
2013-07-05 20:38:56 -05:00
}
}
fn get<'a>(&'a self, i: uint) -> &'a T {
match *self {
Empty => fail!("Invalid index %u", i),
Vec(ref v) => &v[i]
}
}
fn is_empty(&self) -> bool {
self.len() == 0
}
fn len(&self) -> uint {
match *self {
Empty => 0,
Vec(ref v) => v.len()
}
}
#[inline]
fn iter<'r>(&'r self) -> OptVecIterator<'r, T> {
match *self {
Empty => OptVecIterator{iter: None},
Vec(ref v) => OptVecIterator{iter: Some(v.iter())}
}
}
#[inline]
fn map_to_vec<B>(&self, op: &fn(&T) -> B) -> ~[B] {
self.iter().map(op).collect()
}
fn mapi_to_vec<B>(&self, op: &fn(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
}
}
2013-07-02 14:47:32 -05:00
impl<T:Clone> OptVec<T> {
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)
}
}
pub struct OptVecIterator<'self, T> {
priv iter: Option<VecIterator<'self, T>>
}
impl<'self, T> Iterator<&'self T> for OptVecIterator<'self, T> {
#[inline]
fn next(&mut self) -> Option<&'self 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))
}
}
}