libcollections

1 files changed, 61 insertions, 0 deletions

diff --git a/libcollections/range.rs b/libcollections/range.rs
new file mode 100644
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--- /dev/null
+++ b/libcollections/range.rs
@@ -0,0 +1,61 @@
+// Copyright 2015 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.
+
+#![unstable(feature = "collections_range",
+            reason = "waiting for dust to settle on inclusive ranges",
+            issue = "30877")]
+
+//! Range syntax.
+
+use core::option::Option::{self, None, Some};
+use core::ops::{RangeFull, Range, RangeTo, RangeFrom};
+
+/// **RangeArgument** is implemented by Rust's built-in range types, produced
+/// by range syntax like `..`, `a..`, `..b` or `c..d`.
+pub trait RangeArgument<T> {
+    /// Start index (inclusive)
+    ///
+    /// Return start value if present, else `None`.
+    fn start(&self) -> Option<&T> {
+        None
+    }
+
+    /// End index (exclusive)
+    ///
+    /// Return end value if present, else `None`.
+    fn end(&self) -> Option<&T> {
+        None
+    }
+}
+
+// FIXME add inclusive ranges to RangeArgument
+
+impl<T> RangeArgument<T> for RangeFull {}
+
+impl<T> RangeArgument<T> for RangeFrom<T> {
+    fn start(&self) -> Option<&T> {
+        Some(&self.start)
+    }
+}
+
+impl<T> RangeArgument<T> for RangeTo<T> {
+    fn end(&self) -> Option<&T> {
+        Some(&self.end)
+    }
+}
+
+impl<T> RangeArgument<T> for Range<T> {
+    fn start(&self) -> Option<&T> {
+        Some(&self.start)
+    }
+    fn end(&self) -> Option<&T> {
+        Some(&self.end)
+    }
+}