move enum_set to libcollections. #8784

2 files changed, 296 insertions, 0 deletions

diff --git a/src/libcollections/enum_set.rs b/src/libcollections/enum_set.rs
new file mode 100644
index 00000000000..94d378b9dc4
--- /dev/null
+++ b/src/libcollections/enum_set.rs
@@ -0,0 +1,294 @@
+// 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.
+
+//! A structure for holding a set of enum variants
+//!
+//! This module defines a container which uses an efficient bit mask
+//! representation to hold C-like enum variants.
+
+use std::num::Bitwise;
+
+#[deriving(Clone, Eq, IterBytes, ToStr, Encodable, Decodable)]
+/// A specialized Set implementation to use enum types.
+pub struct EnumSet<E> {
+    // We must maintain the invariant that no bits are set
+    // for which no variant exists
+    priv bits: uint
+}
+
+/// An interface for casting C-like enum to uint and back.
+pub trait CLike {
+    /// Converts C-like enum to uint.
+    fn to_uint(&self) -> uint;
+    /// Converts uint to C-like enum.
+    fn from_uint(uint) -> Self;
+}
+
+fn bit<E:CLike>(e: E) -> uint {
+    1 << e.to_uint()
+}
+
+impl<E:CLike> EnumSet<E> {
+    /// Returns an empty EnumSet.
+    pub fn empty() -> EnumSet<E> {
+        EnumSet {bits: 0}
+    }
+
+    /// Returns true if an EnumSet is empty.
+    pub fn is_empty(&self) -> bool {
+        self.bits == 0
+    }
+
+    /// Returns true if an EnumSet contains any enum of a given EnumSet
+    pub fn intersects(&self, e: EnumSet<E>) -> bool {
+        (self.bits & e.bits) != 0
+    }
+
+    /// Returns an intersection of both EnumSets.
+    pub fn intersection(&self, e: EnumSet<E>) -> EnumSet<E> {
+        EnumSet {bits: self.bits & e.bits}
+    }
+
+    /// Returns true if a given EnumSet is included in an EnumSet.
+    pub fn contains(&self, e: EnumSet<E>) -> bool {
+        (self.bits & e.bits) == e.bits
+    }
+
+    /// Returns a union of both EnumSets.
+    pub fn union(&self, e: EnumSet<E>) -> EnumSet<E> {
+        EnumSet {bits: self.bits | e.bits}
+    }
+
+    /// Add an enum to an EnumSet
+    pub fn add(&mut self, e: E) {
+        self.bits |= bit(e);
+    }
+
+    /// Returns true if an EnumSet contains a given enum
+    pub fn contains_elem(&self, e: E) -> bool {
+        (self.bits & bit(e)) != 0
+    }
+
+    /// Returns an iterator over an EnumSet
+    pub fn iter(&self) -> Items<E> {
+        Items::new(self.bits)
+    }
+}
+
+impl<E:CLike> Sub<EnumSet<E>, EnumSet<E>> for EnumSet<E> {
+    fn sub(&self, e: &EnumSet<E>) -> EnumSet<E> {
+        EnumSet {bits: self.bits & !e.bits}
+    }
+}
+
+impl<E:CLike> BitOr<EnumSet<E>, EnumSet<E>> for EnumSet<E> {
+    fn bitor(&self, e: &EnumSet<E>) -> EnumSet<E> {
+        EnumSet {bits: self.bits | e.bits}
+    }
+}
+
+impl<E:CLike> BitAnd<EnumSet<E>, EnumSet<E>> for EnumSet<E> {
+    fn bitand(&self, e: &EnumSet<E>) -> EnumSet<E> {
+        EnumSet {bits: self.bits & e.bits}
+    }
+}
+
+/// An iterator over an EnumSet
+pub struct Items<E> {
+    priv index: uint,
+    priv bits: uint,
+}
+
+impl<E:CLike> Items<E> {
+    fn new(bits: uint) -> Items<E> {
+        Items { index: 0, bits: bits }
+    }
+}
+
+impl<E:CLike> Iterator<E> for Items<E> {
+    fn next(&mut self) -> Option<E> {
+        if self.bits == 0 {
+            return None;
+        }
+
+        while (self.bits & 1) == 0 {
+            self.index += 1;
+            self.bits >>= 1;
+        }
+        let elem = CLike::from_uint(self.index);
+        self.index += 1;
+        self.bits >>= 1;
+        Some(elem)
+    }
+
+    fn size_hint(&self) -> (uint, Option<uint>) {
+        let exact = self.bits.count_ones();
+        (exact, Some(exact))
+    }
+}
+
+#[cfg(test)]
+mod test {
+
+    use std::cast;
+
+    use enum_set::{EnumSet, CLike};
+
+    #[deriving(Eq)]
+    #[repr(uint)]
+    enum Foo {
+        A, B, C
+    }
+
+    impl CLike for Foo {
+        fn to_uint(&self) -> uint {
+            *self as uint
+        }
+
+        fn from_uint(v: uint) -> Foo {
+            unsafe { cast::transmute(v) }
+        }
+    }
+
+    #[test]
+    fn test_empty() {
+        let e: EnumSet<Foo> = EnumSet::empty();
+        assert!(e.is_empty());
+    }
+
+    ///////////////////////////////////////////////////////////////////////////
+    // intersect
+
+    #[test]
+    fn test_two_empties_do_not_intersect() {
+        let e1: EnumSet<Foo> = EnumSet::empty();
+        let e2: EnumSet<Foo> = EnumSet::empty();
+        assert!(!e1.intersects(e2));
+    }
+
+    #[test]
+    fn test_empty_does_not_intersect_with_full() {
+        let e1: EnumSet<Foo> = EnumSet::empty();
+
+        let mut e2: EnumSet<Foo> = EnumSet::empty();
+        e2.add(A);
+        e2.add(B);
+        e2.add(C);
+
+        assert!(!e1.intersects(e2));
+    }
+
+    #[test]
+    fn test_disjoint_intersects() {
+        let mut e1: EnumSet<Foo> = EnumSet::empty();
+        e1.add(A);
+
+        let mut e2: EnumSet<Foo> = EnumSet::empty();
+        e2.add(B);
+
+        assert!(!e1.intersects(e2));
+    }
+
+    #[test]
+    fn test_overlapping_intersects() {
+        let mut e1: EnumSet<Foo> = EnumSet::empty();
+        e1.add(A);
+
+        let mut e2: EnumSet<Foo> = EnumSet::empty();
+        e2.add(A);
+        e2.add(B);
+
+        assert!(e1.intersects(e2));
+    }
+
+    ///////////////////////////////////////////////////////////////////////////
+    // contains and contains_elem
+
+    #[test]
+    fn test_contains() {
+        let mut e1: EnumSet<Foo> = EnumSet::empty();
+        e1.add(A);
+
+        let mut e2: EnumSet<Foo> = EnumSet::empty();
+        e2.add(A);
+        e2.add(B);
+
+        assert!(!e1.contains(e2));
+        assert!(e2.contains(e1));
+    }
+
+    #[test]
+    fn test_contains_elem() {
+        let mut e1: EnumSet<Foo> = EnumSet::empty();
+        e1.add(A);
+        assert!(e1.contains_elem(A));
+        assert!(!e1.contains_elem(B));
+        assert!(!e1.contains_elem(C));
+
+        e1.add(A);
+        e1.add(B);
+        assert!(e1.contains_elem(A));
+        assert!(e1.contains_elem(B));
+        assert!(!e1.contains_elem(C));
+    }
+
+    ///////////////////////////////////////////////////////////////////////////
+    // iter
+
+    #[test]
+    fn test_iterator() {
+        let mut e1: EnumSet<Foo> = EnumSet::empty();
+
+        let elems: ~[Foo] = e1.iter().collect();
+        assert_eq!(~[], elems)
+
+        e1.add(A);
+        let elems: ~[Foo] = e1.iter().collect();
+        assert_eq!(~[A], elems)
+
+        e1.add(C);
+        let elems: ~[Foo] = e1.iter().collect();
+        assert_eq!(~[A,C], elems)
+
+        e1.add(C);
+        let elems: ~[Foo] = e1.iter().collect();
+        assert_eq!(~[A,C], elems)
+
+        e1.add(B);
+        let elems: ~[Foo] = e1.iter().collect();
+        assert_eq!(~[A,B,C], elems)
+    }
+
+    ///////////////////////////////////////////////////////////////////////////
+    // operators
+
+    #[test]
+    fn test_operators() {
+        let mut e1: EnumSet<Foo> = EnumSet::empty();
+        e1.add(A);
+        e1.add(C);
+
+        let mut e2: EnumSet<Foo> = EnumSet::empty();
+        e2.add(B);
+        e2.add(C);
+
+        let e_union = e1 | e2;
+        let elems: ~[Foo] = e_union.iter().collect();
+        assert_eq!(~[A,B,C], elems)
+
+        let e_intersection = e1 & e2;
+        let elems: ~[Foo] = e_intersection.iter().collect();
+        assert_eq!(~[C], elems)
+
+        let e_subtract = e1 - e2;
+        let elems: ~[Foo] = e_subtract.iter().collect();
+        assert_eq!(~[A], elems)
+    }
+}
diff --git a/src/libcollections/lib.rs b/src/libcollections/lib.rs
index e97eeac4f66..4eeabc38905 100644
--- a/src/libcollections/lib.rs
+++ b/src/libcollections/lib.rs
@@ -26,6 +26,7 @@ pub use bitv::Bitv;
 pub use btree::BTree;
 pub use deque::Deque;
 pub use dlist::DList;
+pub use enum_set::EnumSet;
 pub use list::List;
 pub use lru_cache::LruCache;
 pub use priority_queue::PriorityQueue;
@@ -37,6 +38,7 @@ pub mod bitv;
 pub mod btree;
 pub mod deque;
 pub mod dlist;
+pub mod enum_set;
 pub mod list;
 pub mod lru_cache;
 pub mod priority_queue;