1 // Copyright 2012 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.
11 //! A structure for holding a set of enum variants.
13 //! This module defines a container which uses an efficient bit mask
14 //! representation to hold C-like enum variants.
16 #![unstable(feature = "enumset",
17 reason
= "matches collection reform specification, \
18 waiting for dust to settle",
23 use core
::iter
::FromIterator
;
24 use core
::ops
::{Sub, BitOr, BitAnd, BitXor}
;
26 // FIXME(contentions): implement union family of methods? (general design may be
29 /// A specialized set implementation to use enum types.
31 /// It is a logic error for an item to be modified in such a way that the
32 /// transformation of the item to or from a `usize`, as determined by the
33 /// `CLike` trait, changes while the item is in the set. This is normally only
34 /// possible through `Cell`, `RefCell`, global state, I/O, or unsafe code.
35 #[derive(PartialEq, Eq, PartialOrd, Ord, Hash)]
36 pub struct EnumSet
<E
> {
37 // We must maintain the invariant that no bits are set
38 // for which no variant exists
40 marker
: marker
::PhantomData
<E
>,
43 impl<E
> Copy
for EnumSet
<E
> {}
45 impl<E
> Clone
for EnumSet
<E
> {
46 fn clone(&self) -> EnumSet
<E
> {
51 #[stable(feature = "rust1", since = "1.0.0")]
52 impl<E
: CLike
+ fmt
::Debug
> fmt
::Debug
for EnumSet
<E
> {
53 fn fmt(&self, fmt
: &mut fmt
::Formatter
) -> fmt
::Result
{
54 fmt
.debug_set().entries(self).finish()
58 /// An interface for casting C-like enum to usize and back.
59 /// A typically implementation is as below.
67 /// impl CLike for Foo {
68 /// fn to_usize(&self) -> usize {
72 /// fn from_usize(v: usize) -> Foo {
73 /// unsafe { mem::transmute(v) }
78 /// Converts a C-like enum to a `usize`.
79 fn to_usize(&self) -> usize;
80 /// Converts a `usize` to a C-like enum.
81 fn from_usize(usize) -> Self;
84 fn bit
<E
: CLike
>(e
: &E
) -> usize {
86 let value
= e
.to_usize();
87 let bits
= mem
::size_of
::<usize>() * 8;
89 "EnumSet only supports up to {} variants.",
94 impl<E
: CLike
> EnumSet
<E
> {
95 /// Returns an empty `EnumSet`.
96 pub fn new() -> EnumSet
<E
> {
99 marker
: marker
::PhantomData
,
103 /// Returns the number of elements in the given `EnumSet`.
104 pub fn len(&self) -> usize {
105 self.bits
.count_ones() as usize
108 /// Returns true if the `EnumSet` is empty.
109 pub fn is_empty(&self) -> bool
{
113 pub fn clear(&mut self) {
117 /// Returns `false` if the `EnumSet` contains any enum of the given `EnumSet`.
118 pub fn is_disjoint(&self, other
: &EnumSet
<E
>) -> bool
{
119 (self.bits
& other
.bits
) == 0
122 /// Returns `true` if a given `EnumSet` is included in this `EnumSet`.
123 pub fn is_superset(&self, other
: &EnumSet
<E
>) -> bool
{
124 (self.bits
& other
.bits
) == other
.bits
127 /// Returns `true` if this `EnumSet` is included in the given `EnumSet`.
128 pub fn is_subset(&self, other
: &EnumSet
<E
>) -> bool
{
129 other
.is_superset(self)
132 /// Returns the union of both `EnumSets`.
133 pub fn union(&self, e
: EnumSet
<E
>) -> EnumSet
<E
> {
135 bits
: self.bits
| e
.bits
,
136 marker
: marker
::PhantomData
,
140 /// Returns the intersection of both `EnumSets`.
141 pub fn intersection(&self, e
: EnumSet
<E
>) -> EnumSet
<E
> {
143 bits
: self.bits
& e
.bits
,
144 marker
: marker
::PhantomData
,
148 /// Adds an enum to the `EnumSet`, and returns `true` if it wasn't there before
149 pub fn insert(&mut self, e
: E
) -> bool
{
150 let result
= !self.contains(&e
);
151 self.bits
|= bit(&e
);
155 /// Removes an enum from the EnumSet
156 pub fn remove(&mut self, e
: &E
) -> bool
{
157 let result
= self.contains(e
);
158 self.bits
&= !bit(e
);
162 /// Returns `true` if an `EnumSet` contains a given enum.
163 pub fn contains(&self, e
: &E
) -> bool
{
164 (self.bits
& bit(e
)) != 0
167 /// Returns an iterator over an `EnumSet`.
168 pub fn iter(&self) -> Iter
<E
> {
173 impl<E
: CLike
> Sub
for EnumSet
<E
> {
174 type Output
= EnumSet
<E
>;
176 fn sub(self, e
: EnumSet
<E
>) -> EnumSet
<E
> {
178 bits
: self.bits
& !e
.bits
,
179 marker
: marker
::PhantomData
,
184 impl<E
: CLike
> BitOr
for EnumSet
<E
> {
185 type Output
= EnumSet
<E
>;
187 fn bitor(self, e
: EnumSet
<E
>) -> EnumSet
<E
> {
189 bits
: self.bits
| e
.bits
,
190 marker
: marker
::PhantomData
,
195 impl<E
: CLike
> BitAnd
for EnumSet
<E
> {
196 type Output
= EnumSet
<E
>;
198 fn bitand(self, e
: EnumSet
<E
>) -> EnumSet
<E
> {
200 bits
: self.bits
& e
.bits
,
201 marker
: marker
::PhantomData
,
206 impl<E
: CLike
> BitXor
for EnumSet
<E
> {
207 type Output
= EnumSet
<E
>;
209 fn bitxor(self, e
: EnumSet
<E
>) -> EnumSet
<E
> {
211 bits
: self.bits ^ e
.bits
,
212 marker
: marker
::PhantomData
,
217 /// An iterator over an EnumSet
221 marker
: marker
::PhantomData
<E
>,
224 // FIXME(#19839) Remove in favor of `#[derive(Clone)]`
225 impl<E
> Clone
for Iter
<E
> {
226 fn clone(&self) -> Iter
<E
> {
230 marker
: marker
::PhantomData
,
235 impl<E
: CLike
> Iter
<E
> {
236 fn new(bits
: usize) -> Iter
<E
> {
240 marker
: marker
::PhantomData
,
245 impl<E
: CLike
> Iterator
for Iter
<E
> {
248 fn next(&mut self) -> Option
<E
> {
253 while (self.bits
& 1) == 0 {
257 let elem
= CLike
::from_usize(self.index
);
263 fn size_hint(&self) -> (usize, Option
<usize>) {
264 let exact
= self.bits
.count_ones() as usize;
269 impl<E
: CLike
> FromIterator
<E
> for EnumSet
<E
> {
270 fn from_iter
<I
: IntoIterator
<Item
= E
>>(iter
: I
) -> EnumSet
<E
> {
271 let mut ret
= EnumSet
::new();
277 #[stable(feature = "rust1", since = "1.0.0")]
278 impl<'a
, E
> IntoIterator
for &'a EnumSet
<E
> where E
: CLike
281 type IntoIter
= Iter
<E
>;
283 fn into_iter(self) -> Iter
<E
> {
288 impl<E
: CLike
> Extend
<E
> for EnumSet
<E
> {
289 fn extend
<I
: IntoIterator
<Item
= E
>>(&mut self, iter
: I
) {
290 for element
in iter
{
291 self.insert(element
);
296 #[stable(feature = "extend_ref", since = "1.2.0")]
297 impl<'a
, E
: 'a
+ CLike
+ Copy
> Extend
<&'a E
> for EnumSet
<E
> {
298 fn extend
<I
: IntoIterator
<Item
= &'a E
>>(&mut self, iter
: I
) {
299 self.extend(iter
.into_iter().cloned());