auto merge of #17334 : Gankro/rust/btree-vec, r=huonw

Replaces BTree with BTreeMap and BTreeSet, which are completely new implementations.
BTreeMap's internal Node representation is particularly inefficient at the moment to
make this first implementation easy to reason about and fairly safe. Both collections
are also currently missing some of the tooling specific to sorted collections, which
is planned as future work pending reform of these APIs. General implementation issues
are discussed with TODOs internally

[breaking-change]

Still waiting on compilation/test/bench stuff locally, but the edit-distance on any errors should be very small at this point. This is ready to be reviewed.

Author: bors

src/libcollections/btree.rs

@@ -0,0 +1,32 @@
+// Copyright 2014 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.
+
+pub use self::map::BTreeMap;
+pub use self::map::Entries;
+pub use self::map::MutEntries;
+pub use self::map::MoveEntries;
+pub use self::map::Keys;
+pub use self::map::Values;
+pub use self::map::Entry;
+pub use self::map::OccupiedEntry;
+pub use self::map::VacantEntry;
+
+pub use self::set::BTreeSet;
+pub use self::set::Items;
+pub use self::set::MoveItems;
+pub use self::set::DifferenceItems;
+pub use self::set::UnionItems;
+pub use self::set::SymDifferenceItems;
+pub use self::set::IntersectionItems;
+
+
+mod node;
+mod map;
+mod set;

src/libcollections/btree/map.rs

@@ -37,7 +37,7 @@ extern crate alloc;
 use core::prelude::Option;
 
 pub use bitv::{Bitv, BitvSet};
-pub use btree::BTree;
+pub use btree::{BTreeMap, BTreeSet};
 pub use core::prelude::Collection;
 pub use dlist::DList;
 pub use enum_set::EnumSet;

src/libcollections/btree/mod.rs

@@ -16,7 +16,7 @@
 
 pub use core_collections::{Collection, Mutable, Map, MutableMap};
 pub use core_collections::{Set, MutableSet, Deque, MutableSeq};
-pub use core_collections::{Bitv, BitvSet, BTree, DList, EnumSet};
+pub use core_collections::{Bitv, BitvSet, BTreeMap, BTreeSet, DList, EnumSet};
 pub use core_collections::{PriorityQueue, RingBuf, SmallIntMap};
 pub use core_collections::{TreeMap, TreeSet, TrieMap, TrieSet};
 pub use core_collections::{bitv, btree, dlist, enum_set};