1 // Copyright 2013-2014 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
15 /// A vector type optimized for cases where the size is almost always 0 or 1
16 pub struct SmallVector<T> {
17 repr: SmallVectorRepr<T>,
20 enum SmallVectorRepr<T> {
26 impl<T> Collection for SmallVector<T> {
27 fn len(&self) -> uint {
31 Many(ref vals) => vals.len()
36 impl<T> FromIterator<T> for SmallVector<T> {
37 fn from_iter<I: Iterator<T>>(iter: I) -> SmallVector<T> {
38 let mut v = SmallVector::zero();
44 impl<T> Extendable<T> for SmallVector<T> {
45 fn extend<I: Iterator<T>>(&mut self, mut iter: I) {
52 impl<T> SmallVector<T> {
53 pub fn zero() -> SmallVector<T> {
54 SmallVector { repr: Zero }
57 pub fn one(v: T) -> SmallVector<T> {
58 SmallVector { repr: One(v) }
61 pub fn many(vs: Vec<T>) -> SmallVector<T> {
62 SmallVector { repr: Many(vs) }
65 pub fn as_slice<'a>(&'a self) -> &'a [T] {
68 One(ref v) => slice::ref_slice(v),
69 Many(ref vs) => vs.as_slice()
73 pub fn push(&mut self, v: T) {
75 Zero => self.repr = One(v),
77 let one = mem::replace(&mut self.repr, Zero);
79 One(v1) => mem::replace(&mut self.repr, Many(vec!(v1, v))),
83 Many(ref mut vs) => vs.push(v)
87 pub fn push_all(&mut self, other: SmallVector<T>) {
88 for v in other.move_iter() {
93 pub fn get<'a>(&'a self, idx: uint) -> &'a T {
95 One(ref v) if idx == 0 => v,
96 Many(ref vs) => vs.get(idx),
97 _ => fail!("out of bounds access")
101 pub fn expect_one(self, err: &'static str) -> T {
106 v.move_iter().next().unwrap()
115 pub fn move_iter(self) -> MoveItems<T> {
116 let repr = match self.repr {
117 Zero => ZeroIterator,
118 One(v) => OneIterator(v),
119 Many(vs) => ManyIterator(vs.move_iter())
121 MoveItems { repr: repr }
125 pub struct MoveItems<T> {
126 repr: MoveItemsRepr<T>,
129 enum MoveItemsRepr<T> {
132 ManyIterator(vec::MoveItems<T>),
135 impl<T> Iterator<T> for MoveItems<T> {
136 fn next(&mut self) -> Option<T> {
138 ZeroIterator => None,
140 let mut replacement = ZeroIterator;
141 mem::swap(&mut self.repr, &mut replacement);
143 OneIterator(v) => Some(v),
147 ManyIterator(ref mut inner) => inner.next()
151 fn size_hint(&self) -> (uint, Option<uint>) {
153 ZeroIterator => (0, Some(0)),
154 OneIterator(..) => (1, Some(1)),
155 ManyIterator(ref inner) => inner.size_hint()
166 let v: SmallVector<int> = SmallVector::zero();
167 assert_eq!(0, v.len());
169 assert_eq!(1, SmallVector::one(1).len());
170 assert_eq!(5, SmallVector::many(vec!(1, 2, 3, 4, 5)).len());
175 let mut v = SmallVector::zero();
177 assert_eq!(1, v.len());
178 assert_eq!(&1, v.get(0));
180 assert_eq!(2, v.len());
181 assert_eq!(&2, v.get(1));
183 assert_eq!(3, v.len());
184 assert_eq!(&3, v.get(2));
188 fn test_from_iter() {
189 let v: SmallVector<int> = (vec!(1, 2, 3)).move_iter().collect();
190 assert_eq!(3, v.len());
191 assert_eq!(&1, v.get(0));
192 assert_eq!(&2, v.get(1));
193 assert_eq!(&3, v.get(2));
197 fn test_move_iter() {
198 let v = SmallVector::zero();
199 let v: Vec<int> = v.move_iter().collect();
200 assert_eq!(Vec::new(), v);
202 let v = SmallVector::one(1);
203 assert_eq!(vec!(1), v.move_iter().collect());
205 let v = SmallVector::many(vec!(1, 2, 3));
206 assert_eq!(vec!(1, 2, 3), v.move_iter().collect());
211 fn test_expect_one_zero() {
212 let _: int = SmallVector::zero().expect_one("");
217 fn test_expect_one_many() {
218 SmallVector::many(vec!(1, 2)).expect_one("");
222 fn test_expect_one_one() {
223 assert_eq!(1, SmallVector::one(1).expect_one(""));
224 assert_eq!(1, SmallVector::many(vec!(1)).expect_one(""));