323 lines
7.9 KiB
Rust
323 lines
7.9 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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//! A structure for holding a set of enum variants.
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//!
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//! This module defines a container which uses an efficient bit mask
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//! representation to hold C-like enum variants.
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use core::prelude::*;
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use core::fmt;
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#[deriving(Clone, PartialEq, Eq, Hash)]
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/// A specialized `Set` implementation to use enum types.
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pub struct EnumSet<E> {
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// We must maintain the invariant that no bits are set
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// for which no variant exists
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bits: uint
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}
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impl<E:CLike+fmt::Show> fmt::Show for EnumSet<E> {
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fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
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try!(write!(fmt, "{{"));
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let mut first = true;
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for e in self.iter() {
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if !first {
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try!(write!(fmt, ", "));
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}
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try!(write!(fmt, "{}", e));
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first = false;
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}
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write!(fmt, "}}")
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}
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}
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/// An interface for casting C-like enum to uint and back.
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pub trait CLike {
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/// Converts a C-like enum to a `uint`.
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fn to_uint(&self) -> uint;
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/// Converts a `uint` to a C-like enum.
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fn from_uint(uint) -> Self;
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}
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fn bit<E:CLike>(e: E) -> uint {
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1 << e.to_uint()
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}
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impl<E:CLike> EnumSet<E> {
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/// Returns an empty `EnumSet`.
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pub fn empty() -> EnumSet<E> {
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EnumSet {bits: 0}
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}
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/// Returns true if the `EnumSet` is empty.
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pub fn is_empty(&self) -> bool {
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self.bits == 0
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}
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/// Returns `true` if the `EnumSet` contains any enum of the given `EnumSet`.
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pub fn intersects(&self, e: EnumSet<E>) -> bool {
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(self.bits & e.bits) != 0
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}
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/// Returns the intersection of both `EnumSets`.
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pub fn intersection(&self, e: EnumSet<E>) -> EnumSet<E> {
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EnumSet {bits: self.bits & e.bits}
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}
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/// Returns `true` if a given `EnumSet` is included in an `EnumSet`.
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pub fn contains(&self, e: EnumSet<E>) -> bool {
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(self.bits & e.bits) == e.bits
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}
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/// Returns the union of both `EnumSets`.
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pub fn union(&self, e: EnumSet<E>) -> EnumSet<E> {
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EnumSet {bits: self.bits | e.bits}
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}
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/// Adds an enum to an `EnumSet`.
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pub fn add(&mut self, e: E) {
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self.bits |= bit(e);
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}
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/// Returns `true` if an `EnumSet` contains a given enum.
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pub fn contains_elem(&self, e: E) -> bool {
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(self.bits & bit(e)) != 0
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}
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/// Returns an iterator over an `EnumSet`.
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pub fn iter(&self) -> Items<E> {
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Items::new(self.bits)
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}
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}
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impl<E:CLike> Sub<EnumSet<E>, EnumSet<E>> for EnumSet<E> {
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fn sub(&self, e: &EnumSet<E>) -> EnumSet<E> {
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EnumSet {bits: self.bits & !e.bits}
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}
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}
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impl<E:CLike> BitOr<EnumSet<E>, EnumSet<E>> for EnumSet<E> {
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fn bitor(&self, e: &EnumSet<E>) -> EnumSet<E> {
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EnumSet {bits: self.bits | e.bits}
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}
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}
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impl<E:CLike> BitAnd<EnumSet<E>, EnumSet<E>> for EnumSet<E> {
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fn bitand(&self, e: &EnumSet<E>) -> EnumSet<E> {
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EnumSet {bits: self.bits & e.bits}
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}
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}
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/// An iterator over an EnumSet
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pub struct Items<E> {
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index: uint,
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bits: uint,
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}
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impl<E:CLike> Items<E> {
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fn new(bits: uint) -> Items<E> {
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Items { index: 0, bits: bits }
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}
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}
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impl<E:CLike> Iterator<E> for Items<E> {
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fn next(&mut self) -> Option<E> {
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if self.bits == 0 {
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return None;
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}
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while (self.bits & 1) == 0 {
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self.index += 1;
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self.bits >>= 1;
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}
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let elem = CLike::from_uint(self.index);
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self.index += 1;
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self.bits >>= 1;
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Some(elem)
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}
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fn size_hint(&self) -> (uint, Option<uint>) {
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let exact = self.bits.count_ones();
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(exact, Some(exact))
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}
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}
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#[cfg(test)]
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mod test {
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use std::prelude::*;
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use std::mem;
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use enum_set::{EnumSet, CLike};
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use MutableSeq;
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#[deriving(PartialEq, Show)]
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#[repr(uint)]
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enum Foo {
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A, B, C
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}
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impl CLike for Foo {
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fn to_uint(&self) -> uint {
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*self as uint
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}
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fn from_uint(v: uint) -> Foo {
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unsafe { mem::transmute(v) }
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}
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}
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#[test]
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fn test_empty() {
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let e: EnumSet<Foo> = EnumSet::empty();
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assert!(e.is_empty());
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}
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#[test]
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fn test_show() {
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let mut e = EnumSet::empty();
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assert_eq!("{}", e.to_string().as_slice());
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e.add(A);
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assert_eq!("{A}", e.to_string().as_slice());
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e.add(C);
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assert_eq!("{A, C}", e.to_string().as_slice());
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}
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///////////////////////////////////////////////////////////////////////////
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// intersect
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#[test]
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fn test_two_empties_do_not_intersect() {
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let e1: EnumSet<Foo> = EnumSet::empty();
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let e2: EnumSet<Foo> = EnumSet::empty();
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assert!(!e1.intersects(e2));
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}
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#[test]
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fn test_empty_does_not_intersect_with_full() {
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let e1: EnumSet<Foo> = EnumSet::empty();
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let mut e2: EnumSet<Foo> = EnumSet::empty();
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e2.add(A);
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e2.add(B);
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e2.add(C);
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assert!(!e1.intersects(e2));
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}
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#[test]
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fn test_disjoint_intersects() {
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let mut e1: EnumSet<Foo> = EnumSet::empty();
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e1.add(A);
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let mut e2: EnumSet<Foo> = EnumSet::empty();
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e2.add(B);
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assert!(!e1.intersects(e2));
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}
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#[test]
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fn test_overlapping_intersects() {
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let mut e1: EnumSet<Foo> = EnumSet::empty();
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e1.add(A);
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let mut e2: EnumSet<Foo> = EnumSet::empty();
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e2.add(A);
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e2.add(B);
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assert!(e1.intersects(e2));
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}
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///////////////////////////////////////////////////////////////////////////
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// contains and contains_elem
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#[test]
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fn test_contains() {
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let mut e1: EnumSet<Foo> = EnumSet::empty();
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e1.add(A);
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let mut e2: EnumSet<Foo> = EnumSet::empty();
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e2.add(A);
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e2.add(B);
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assert!(!e1.contains(e2));
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assert!(e2.contains(e1));
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}
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#[test]
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fn test_contains_elem() {
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let mut e1: EnumSet<Foo> = EnumSet::empty();
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e1.add(A);
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assert!(e1.contains_elem(A));
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assert!(!e1.contains_elem(B));
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assert!(!e1.contains_elem(C));
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e1.add(A);
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e1.add(B);
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assert!(e1.contains_elem(A));
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assert!(e1.contains_elem(B));
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assert!(!e1.contains_elem(C));
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}
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///////////////////////////////////////////////////////////////////////////
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// iter
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#[test]
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fn test_iterator() {
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let mut e1: EnumSet<Foo> = EnumSet::empty();
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let elems: Vec<Foo> = e1.iter().collect();
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assert!(elems.is_empty())
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e1.add(A);
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let elems = e1.iter().collect();
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assert_eq!(vec![A], elems)
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e1.add(C);
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let elems = e1.iter().collect();
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assert_eq!(vec![A,C], elems)
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e1.add(C);
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let elems = e1.iter().collect();
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assert_eq!(vec![A,C], elems)
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e1.add(B);
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let elems = e1.iter().collect();
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assert_eq!(vec![A,B,C], elems)
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}
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///////////////////////////////////////////////////////////////////////////
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// operators
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#[test]
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fn test_operators() {
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let mut e1: EnumSet<Foo> = EnumSet::empty();
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e1.add(A);
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e1.add(C);
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let mut e2: EnumSet<Foo> = EnumSet::empty();
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e2.add(B);
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e2.add(C);
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let e_union = e1 | e2;
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let elems = e_union.iter().collect();
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assert_eq!(vec![A,B,C], elems)
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let e_intersection = e1 & e2;
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let elems = e_intersection.iter().collect();
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assert_eq!(vec![C], elems)
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let e_subtract = e1 - e2;
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let elems = e_subtract.iter().collect();
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assert_eq!(vec![A], elems)
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}
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}
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