rust/src/libsyntax/opt_vec.rs

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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()`.
*/
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use core::prelude::*;
use core::old_iter;
use core::old_iter::BaseIter;
#[auto_encode]
#[auto_decode]
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 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()
}
}
}
pub fn take_vec<T>(v: OptVec<T>) -> ~[T] {
match v {
Empty => ~[],
Vec(v) => v
}
}
impl<T:Copy> 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);
}
fn push_all<I: BaseIter<T>>(&mut self, from: &I) {
for from.each |e| {
self.push(copy *e);
}
}
#[inline(always)]
fn mapi_to_vec<B>(&self, op: &fn(uint, &T) -> B) -> ~[B] {
let mut index = 0;
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old_iter::map_to_vec(self, |a| {
let i = index;
index += 1;
op(i, a)
})
}
}
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<A> BaseIter<A> for OptVec<A> {
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#[cfg(stage0)]
fn each(&self, blk: &fn(v: &A) -> bool) {
match *self {
Empty => {}
Vec(ref v) => v.each(blk)
}
}
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#[cfg(not(stage0))]
fn each(&self, blk: &fn(v: &A) -> bool) -> bool {
match *self {
Empty => true,
Vec(ref v) => v.each(blk)
}
}
fn size_hint(&self) -> Option<uint> {
Some(self.len())
}
}
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impl<A> old_iter::ExtendedIter<A> for OptVec<A> {
#[inline(always)]
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#[cfg(stage0)]
fn eachi(&self, blk: &fn(v: uint, v: &A) -> bool) {
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old_iter::eachi(self, blk)
}
#[inline(always)]
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#[cfg(not(stage0))]
fn eachi(&self, blk: &fn(v: uint, v: &A) -> bool) -> bool {
old_iter::eachi(self, blk)
}
#[inline(always)]
fn all(&self, blk: &fn(&A) -> bool) -> bool {
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old_iter::all(self, blk)
}
#[inline(always)]
fn any(&self, blk: &fn(&A) -> bool) -> bool {
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old_iter::any(self, blk)
}
#[inline(always)]
fn foldl<B>(&self, b0: B, blk: &fn(&B, &A) -> B) -> B {
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old_iter::foldl(self, b0, blk)
}
#[inline(always)]
fn position(&self, f: &fn(&A) -> bool) -> Option<uint> {
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old_iter::position(self, f)
}
#[inline(always)]
fn map_to_vec<B>(&self, op: &fn(&A) -> B) -> ~[B] {
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old_iter::map_to_vec(self, op)
}
#[inline(always)]
fn flat_map_to_vec<B,IB:BaseIter<B>>(&self, op: &fn(&A) -> IB)
-> ~[B] {
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old_iter::flat_map_to_vec(self, op)
}
}
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impl<A: Eq> old_iter::EqIter<A> for OptVec<A> {
#[inline(always)]
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fn contains(&self, x: &A) -> bool { old_iter::contains(self, x) }
#[inline(always)]
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fn count(&self, x: &A) -> uint { old_iter::count(self, x) }
}
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impl<A: Copy> old_iter::CopyableIter<A> for OptVec<A> {
#[inline(always)]
fn filter_to_vec(&self, pred: &fn(&A) -> bool) -> ~[A] {
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old_iter::filter_to_vec(self, pred)
}
#[inline(always)]
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fn to_vec(&self) -> ~[A] { old_iter::to_vec(self) }
#[inline(always)]
fn find(&self, f: &fn(&A) -> bool) -> Option<A> {
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old_iter::find(self, f)
}
}
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impl<A: Copy+Ord> old_iter::CopyableOrderedIter<A> for OptVec<A> {
#[inline(always)]
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fn min(&self) -> A { old_iter::min(self) }
#[inline(always)]
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fn max(&self) -> A { old_iter::max(self) }
}