extra: Add mod container with trait Deque

2 files changed, 41 insertions, 0 deletions

diff --git a/src/libextra/container.rs b/src/libextra/container.rs
new file mode 100644
index 00000000000..fe622289b29
--- /dev/null
+++ b/src/libextra/container.rs
@@ -0,0 +1,40 @@
+// Copyright 2013 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.
+
+//! Container traits for extra
+
+use std::container::Mutable;
+
+/// A double-ended sequence that allows querying, insertion and deletion at both ends.
+pub trait Deque<T> : Mutable {
+    /// Provide a reference to the front element, or None if the sequence is empty
+    fn front<'a>(&'a self) -> Option<&'a T>;
+
+    /// Provide a mutable reference to the front element, or None if the sequence is empty
+    fn front_mut<'a>(&'a mut self) -> Option<&'a mut T>;
+
+    /// Provide a reference to the back element, or None if the sequence is empty
+    fn back<'a>(&'a self) -> Option<&'a T>;
+
+    /// Provide a mutable reference to the back element, or None if the sequence is empty
+    fn back_mut<'a>(&'a mut self) -> Option<&'a mut T>;
+
+    /// Insert an element first in the sequence
+    fn push_front(&mut self, elt: T);
+
+    /// Insert an element last in the sequence
+    fn push_back(&mut self, elt: T);
+
+    /// Remove the last element and return it, or None if the sequence is empty
+    fn pop_back(&mut self) -> Option<T>;
+
+    /// Remove the first element and return it, or None if the sequence is empty
+    fn pop_front(&mut self) -> Option<T>;
+}
diff --git a/src/libextra/extra.rs b/src/libextra/extra.rs
index 7bec1d600b4..18322fcda59 100644
--- a/src/libextra/extra.rs
+++ b/src/libextra/extra.rs
@@ -67,6 +67,7 @@ pub mod flatpipes;
 
 // Collections
 
+pub mod container;
 pub mod bitv;
 pub mod deque;
 pub mod fun_treemap;