range.rs.html -- source
Description: Source to the Rust file `src/liballoc/range.rs`.
Keywords: rust, rustlang, rust-lang

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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::ops::{RangeFull, Range, RangeTo, RangeFrom, RangeInclusive, RangeToInclusive};
    use Bound::{self, Excluded, Included, Unbounded};

    /// `RangeArgument` is implemented by Rust's built-in range types, produced
    /// by range syntax like `..`, `a..`, `..b` or `c..d`.
    pub trait RangeArgument<T: ?Sized> {
        /// Start index bound.
        ///
        /// Returns the start value as a `Bound`.
        ///
        /// # Examples
        ///
        /// ```
        /// #![feature(alloc)]
        /// #![feature(collections_range)]
        ///
        /// extern crate alloc;
        ///
        /// # fn main() {
        /// use alloc::range::RangeArgument;
        /// use alloc::Bound::*;
        ///
        /// assert_eq!((..10).start(), Unbounded);
        /// assert_eq!((3..10).start(), Included(&3));
        /// # }
        /// ```
        fn start(&self) -> Bound<&T>;

        /// End index bound.
        ///
        /// Returns the end value as a `Bound`.
        ///
        /// # Examples
        ///
        /// ```
        /// #![feature(alloc)]
        /// #![feature(collections_range)]
        ///
        /// extern crate alloc;
        ///
        /// # fn main() {
        /// use alloc::range::RangeArgument;
        /// use alloc::Bound::*;
        ///
        /// assert_eq!((3..).end(), Unbounded);
        /// assert_eq!((3..10).end(), Excluded(&10));
        /// # }
        /// ```
        fn end(&self) -> Bound<&T>;
    }

    // FIXME add inclusive ranges to RangeArgument

    impl<T: ?Sized> RangeArgument<T> for RangeFull {
        fn start(&self) -> Bound<&T> {
            Unbounded
        }
        fn end(&self) -> Bound<&T> {
            Unbounded
        }
    }

    impl<T> RangeArgument<T> for RangeFrom<T> {
        fn start(&self) -> Bound<&T> {
            Included(&self.start)
        }
        fn end(&self) -> Bound<&T> {
            Unbounded
        }
    }

    impl<T> RangeArgument<T> for RangeTo<T> {
        fn start(&self) -> Bound<&T> {
            Unbounded
        }
        fn end(&self) -> Bound<&T> {
            Excluded(&self.end)
        }
    }

    impl<T> RangeArgument<T> for Range<T> {
        fn start(&self) -> Bound<&T> {
            Included(&self.start)
        }
        fn end(&self) -> Bound<&T> {
            Excluded(&self.end)
        }
    }

    #[unstable(feature = "inclusive_range", reason = "recently added, follows RFC", issue = "28237")]
    impl<T> RangeArgument<T> for RangeInclusive<T> {
        fn start(&self) -> Bound<&T> {
            Included(&self.start)
        }
        fn end(&self) -> Bound<&T> {
            Included(&self.end)
        }
    }

    #[unstable(feature = "inclusive_range", reason = "recently added, follows RFC", issue = "28237")]
    impl<T> RangeArgument<T> for RangeToInclusive<T> {
        fn start(&self) -> Bound<&T> {
            Unbounded
        }
        fn end(&self) -> Bound<&T> {
            Included(&self.end)
        }
    }

    impl<T> RangeArgument<T> for (Bound<T>, Bound<T>) {
        fn start(&self) -> Bound<&T> {
            match *self {
                (Included(ref start), _) => Included(start),
                (Excluded(ref start), _) => Excluded(start),
                (Unbounded, _)           => Unbounded,
            }
        }

        fn end(&self) -> Bound<&T> {
            match *self {
                (_, Included(ref end)) => Included(end),
                (_, Excluded(ref end)) => Excluded(end),
                (_, Unbounded)         => Unbounded,
            }
        }
    }

    impl<'a, T: ?Sized + 'a> RangeArgument<T> for (Bound<&'a T>, Bound<&'a T>) {
        fn start(&self) -> Bound<&T> {
            self.0
        }

        fn end(&self) -> Bound<&T> {
            self.1
        }
    }

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