array.rs

// Copyright 2014 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.

//! Implementations of things like `Eq` for fixed-length arrays
//! up to a certain length. Eventually we should able to generalize
//! to all lengths.

#![doc(primitive = "array")]
#![unstable(feature = "fixed_size_array",
            reason = "traits and impls are better expressed through generic \
                      integer constants")]

use clone::Clone;
use cmp::{PartialEq, Eq, PartialOrd, Ord, Ordering};
use convert::{AsRef, AsMut};
use fmt;
use hash::{Hash, self};
use iter::IntoIterator;
use marker::{Copy, Sized};
use option::Option;
use slice::{Iter, IterMut, SliceExt};

/// Utility trait implemented only on arrays of fixed size
///
/// This trait can be used to implement other traits on fixed-size arrays
/// without causing much metadata bloat.
pub trait FixedSizeArray<T> {
    /// Converts the array to immutable slice
    fn as_slice(&self) -> &[T];
    /// Converts the array to mutable slice
    fn as_mut_slice(&mut self) -> &mut [T];
}

// macro for implementing n-ary tuple functions and operations
macro_rules! array_impls {
    ($($N:expr)+) => {
        $(
            impl<T> FixedSizeArray<T> for [T; $N] {
                #[inline]
                fn as_slice(&self) -> &[T] {
                    &self[..]
                }
                #[inline]
                fn as_mut_slice(&mut self) -> &mut [T] {
                    &mut self[..]
                }
            }

            impl<T> AsRef<[T]> for [T; $N] {
                #[inline]
                fn as_ref(&self) -> &[T] {
                    &self[..]
                }
            }

            impl<T> AsMut<[T]> for [T; $N] {
                #[inline]
                fn as_mut(&mut self) -> &mut [T] {
                    &mut self[..]
                }
            }

            #[stable(feature = "rust1", since = "1.0.0")]
            impl<T:Copy> Clone for [T; $N] {
                fn clone(&self) -> [T; $N] {
                    *self
                }
            }

            #[stable(feature = "rust1", since = "1.0.0")]
            impl<T: Hash> Hash for [T; $N] {
                fn hash<H: hash::Hasher>(&self, state: &mut H) {
                    Hash::hash(&self[..], state)
                }
            }

            #[stable(feature = "rust1", since = "1.0.0")]
            impl<T: fmt::Debug> fmt::Debug for [T; $N] {
                fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
                    fmt::Debug::fmt(&&self[..], f)
                }
            }

            #[stable(feature = "rust1", since = "1.0.0")]
            impl<'a, T> IntoIterator for &'a [T; $N] {
                type Item = &'a T;
                type IntoIter = Iter<'a, T>;

                fn into_iter(self) -> Iter<'a, T> {
                    self.iter()
                }
            }

            #[stable(feature = "rust1", since = "1.0.0")]
            impl<'a, T> IntoIterator for &'a mut [T; $N] {
                type Item = &'a mut T;
                type IntoIter = IterMut<'a, T>;

                fn into_iter(self) -> IterMut<'a, T> {
                    self.iter_mut()
                }
            }

            // NOTE: some less important impls are omitted to reduce code bloat
            __impl_slice_eq1! { [A; $N], [B; $N] }
            __impl_slice_eq2! { [A; $N], [B] }
            __impl_slice_eq2! { [A; $N], &'b [B] }
            __impl_slice_eq2! { [A; $N], &'b mut [B] }
            // __impl_slice_eq2! { [A; $N], &'b [B; $N] }
            // __impl_slice_eq2! { [A; $N], &'b mut [B; $N] }

            #[stable(feature = "rust1", since = "1.0.0")]
            impl<T:Eq> Eq for [T; $N] { }

            #[stable(feature = "rust1", since = "1.0.0")]
            impl<T:PartialOrd> PartialOrd for [T; $N] {
                #[inline]
                fn partial_cmp(&self, other: &[T; $N]) -> Option<Ordering> {
                    PartialOrd::partial_cmp(&&self[..], &&other[..])
                }
                #[inline]
                fn lt(&self, other: &[T; $N]) -> bool {
                    PartialOrd::lt(&&self[..], &&other[..])
                }
                #[inline]
                fn le(&self, other: &[T; $N]) -> bool {
                    PartialOrd::le(&&self[..], &&other[..])
                }
                #[inline]
                fn ge(&self, other: &[T; $N]) -> bool {
                    PartialOrd::ge(&&self[..], &&other[..])
                }
                #[inline]
                fn gt(&self, other: &[T; $N]) -> bool {
                    PartialOrd::gt(&&self[..], &&other[..])
                }
            }

            #[stable(feature = "rust1", since = "1.0.0")]
            impl<T:Ord> Ord for [T; $N] {
                #[inline]
                fn cmp(&self, other: &[T; $N]) -> Ordering {
                    Ord::cmp(&&self[..], &&other[..])
                }
            }
        )+
    }
}

array_impls! {
     0  1  2  3  4  5  6  7  8  9
    10 11 12 13 14 15 16 17 18 19
    20 21 22 23 24 25 26 27 28 29
    30 31 32
}