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// 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`.
///
/// # Examples
///
/// ```
/// #![feature(collections)]
/// #![feature(collections_range)]
///
/// extern crate collections;
///
/// # fn main() {
/// use collections::range::RangeArgument;
///
/// assert_eq!((..10).start(), None);
/// assert_eq!((3..10).start(), Some(&3));
/// # }
/// ```
fn start(&self) -> Option<&T> {
None
}
/// End index (exclusive)
///
/// Return end value if present, else `None`.
///
/// # Examples
///
/// ```
/// #![feature(collections)]
/// #![feature(collections_range)]
///
/// extern crate collections;
///
/// # fn main() {
/// use collections::range::RangeArgument;
///
/// assert_eq!((3..).end(), None);
/// assert_eq!((3..10).end(), Some(&10));
/// # }
/// ```
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)
}
}
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