150 lines
3.5 KiB
Rust
150 lines
3.5 KiB
Rust
// Copyright 2012 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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/*!
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*
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* Defines a type OptVec<T> that can be used in place of ~[T].
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* OptVec avoids the need for allocation for empty vectors.
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* OptVec implements the iterable interface as well as
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* other useful things like `push()` and `len()`.
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*/
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use std::vec::VecIterator;
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#[deriving(Encodable, Decodable)]
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pub enum OptVec<T> {
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Empty,
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Vec(~[T])
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}
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pub fn with<T>(t: T) -> OptVec<T> {
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Vec(~[t])
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}
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pub fn from<T>(t: ~[T]) -> OptVec<T> {
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if t.len() == 0 {
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Empty
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} else {
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Vec(t)
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}
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}
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impl<T> OptVec<T> {
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fn push(&mut self, t: T) {
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match *self {
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Vec(ref mut v) => {
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v.push(t);
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return;
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}
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Empty => {}
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}
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// FIXME(#5074): flow insensitive means we can't move
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// assignment inside `match`
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*self = Vec(~[t]);
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}
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fn map<U>(&self, op: &fn(&T) -> U) -> OptVec<U> {
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match *self {
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Empty => Empty,
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Vec(ref v) => Vec(v.map(op))
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}
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}
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fn get<'a>(&'a self, i: uint) -> &'a T {
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match *self {
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Empty => fail!("Invalid index %u", i),
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Vec(ref v) => &v[i]
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}
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}
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fn is_empty(&self) -> bool {
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self.len() == 0
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}
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fn len(&self) -> uint {
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match *self {
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Empty => 0,
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Vec(ref v) => v.len()
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}
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}
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#[inline]
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fn iter<'r>(&'r self) -> OptVecIterator<'r, T> {
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match *self {
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Empty => OptVecIterator{iter: None},
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Vec(ref v) => OptVecIterator{iter: Some(v.iter())}
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}
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}
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#[inline]
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fn map_to_vec<B>(&self, op: &fn(&T) -> B) -> ~[B] {
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self.iter().transform(op).collect()
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}
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fn mapi_to_vec<B>(&self, op: &fn(uint, &T) -> B) -> ~[B] {
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let mut index = 0;
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self.map_to_vec(|a| {
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let i = index;
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index += 1;
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op(i, a)
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})
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}
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}
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pub fn take_vec<T>(v: OptVec<T>) -> ~[T] {
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match v {
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Empty => ~[],
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Vec(v) => v
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}
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}
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impl<T:Copy> OptVec<T> {
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fn prepend(&self, t: T) -> OptVec<T> {
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let mut v0 = ~[t];
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match *self {
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Empty => {}
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Vec(ref v1) => { v0.push_all(*v1); }
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}
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return Vec(v0);
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}
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}
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impl<A:Eq> Eq for OptVec<A> {
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fn eq(&self, other: &OptVec<A>) -> bool {
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// Note: cannot use #[deriving(Eq)] here because
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// (Empty, Vec(~[])) ought to be equal.
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match (self, other) {
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(&Empty, &Empty) => true,
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(&Empty, &Vec(ref v)) => v.is_empty(),
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(&Vec(ref v), &Empty) => v.is_empty(),
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(&Vec(ref v1), &Vec(ref v2)) => *v1 == *v2
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}
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}
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fn ne(&self, other: &OptVec<A>) -> bool {
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!self.eq(other)
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}
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}
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pub struct OptVecIterator<'self, T> {
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priv iter: Option<VecIterator<'self, T>>
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}
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impl<'self, T> Iterator<&'self T> for OptVecIterator<'self, T> {
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#[inline]
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fn next(&mut self) -> Option<&'self T> {
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match self.iter {
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Some(ref mut x) => x.next(),
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None => None
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}
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}
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}
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