src/libcollections/range.rs

   1 // Copyright 2015 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution and at
   3 // http://rust-lang.org/COPYRIGHT.
   4 //
   5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   8 // option. This file may not be copied, modified, or distributed
   9 // except according to those terms.
  10 #![unstable(feature = "collections_range", reason = "was just added")]
  11
  12 //! Range syntax.
  13
  14 use core::option::Option::{self, None, Some};
  15 use core::ops::{RangeFull, Range, RangeTo, RangeFrom};
  16
  17 /// **RangeArgument** is implemented by Rust's built-in range types, produced
  18 /// by range syntax like `..`, `a..`, `..b` or `c..d`.
  19 pub trait RangeArgument<T> {
  20     /// Start index (inclusive)
  21     ///
  22     /// Return start value if present, else `None`.
  23     fn start(&self) -> Option<&T> { None }
  24
  25     /// End index (exclusive)
  26     ///
  27     /// Return end value if present, else `None`.
  28     fn end(&self) -> Option<&T> { None }
  29 }
  30
  31
  32 impl<T> RangeArgument<T> for RangeFull {}
  33
  34 impl<T> RangeArgument<T> for RangeFrom<T> {
  35     fn start(&self) -> Option<&T> { Some(&self.start) }
  36 }
  37
  38 impl<T> RangeArgument<T> for RangeTo<T> {
  39     fn end(&self) -> Option<&T> { Some(&self.end) }
  40 }
  41
  42 impl<T> RangeArgument<T> for Range<T> {
  43     fn start(&self) -> Option<&T> { Some(&self.start) }
  44     fn end(&self) -> Option<&T> { Some(&self.end) }
  45 }