src/libcore/array.rs

   1 // Copyright 2014 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
  11 //! Implementations of things like `Eq` for fixed-length arrays
  12 //! up to a certain length. Eventually we should able to generalize
  13 //! to all lengths.
  14 //!
  15 //! *[See also the array primitive type](../../std/primitive.array.html).*
  16
  17 #![unstable(feature = "fixed_size_array",
  18             reason = "traits and impls are better expressed through generic \
  19                       integer constants",
  20             issue = "27778")]
  21
  22 use borrow::{Borrow, BorrowMut};
  23 use clone::Clone;
  24 use cmp::{PartialEq, Eq, PartialOrd, Ord, Ordering};
  25 use convert::{AsRef, AsMut};
  26 use default::Default;
  27 use fmt;
  28 use hash::{Hash, self};
  29 use iter::IntoIterator;
  30 use marker::{Copy, Sized, Unsize};
  31 use option::Option;
  32 use slice::{Iter, IterMut, SliceExt};
  33
  34 /// Utility trait implemented only on arrays of fixed size
  35 ///
  36 /// This trait can be used to implement other traits on fixed-size arrays
  37 /// without causing much metadata bloat.
  38 ///
  39 /// The trait is marked unsafe in order to restrict implementors to fixed-size
  40 /// arrays. User of this trait can assume that implementors have the exact
  41 /// layout in memory of a fixed size array (for example, for unsafe
  42 /// initialization).
  43 ///
  44 /// Note that the traits AsRef and AsMut provide similar methods for types that
  45 /// may not be fixed-size arrays. Implementors should prefer those traits
  46 /// instead.
  47 pub unsafe trait FixedSizeArray<T> {
  48     /// Converts the array to immutable slice
  49     fn as_slice(&self) -> &[T];
  50     /// Converts the array to mutable slice
  51     fn as_mut_slice(&mut self) -> &mut [T];
  52 }
  53
  54 unsafe impl<T, A: Unsize<[T]>> FixedSizeArray<T> for A {
  55     #[inline]
  56     fn as_slice(&self) -> &[T] {
  57         self
  58     }
  59     #[inline]
  60     fn as_mut_slice(&mut self) -> &mut [T] {
  61         self
  62     }
  63 }
  64
  65 macro_rules! __impl_slice_eq1 {
  66     ($Lhs: ty, $Rhs: ty) => {
  67         __impl_slice_eq1! { $Lhs, $Rhs, Sized }
  68     };
  69     ($Lhs: ty, $Rhs: ty, $Bound: ident) => {
  70         #[stable(feature = "rust1", since = "1.0.0")]
  71         impl<'a, 'b, A: $Bound, B> PartialEq<$Rhs> for $Lhs where A: PartialEq<B> {
  72             #[inline]
  73             fn eq(&self, other: &$Rhs) -> bool { self[..] == other[..] }
  74             #[inline]
  75             fn ne(&self, other: &$Rhs) -> bool { self[..] != other[..] }
  76         }
  77     }
  78 }
  79
  80 macro_rules! __impl_slice_eq2 {
  81     ($Lhs: ty, $Rhs: ty) => {
  82         __impl_slice_eq2! { $Lhs, $Rhs, Sized }
  83     };
  84     ($Lhs: ty, $Rhs: ty, $Bound: ident) => {
  85         __impl_slice_eq1!($Lhs, $Rhs, $Bound);
  86
  87         #[stable(feature = "rust1", since = "1.0.0")]
  88         impl<'a, 'b, A: $Bound, B> PartialEq<$Lhs> for $Rhs where B: PartialEq<A> {
  89             #[inline]
  90             fn eq(&self, other: &$Lhs) -> bool { self[..] == other[..] }
  91             #[inline]
  92             fn ne(&self, other: &$Lhs) -> bool { self[..] != other[..] }
  93         }
  94     }
  95 }
  96
  97 // macro for implementing n-ary tuple functions and operations
  98 macro_rules! array_impls {
  99     ($($N:expr)+) => {
 100         $(
 101             impl<T> AsRef<[T]> for [T; $N] {
 102                 #[inline]
 103                 fn as_ref(&self) -> &[T] {
 104                     &self[..]
 105                 }
 106             }
 107
 108             impl<T> AsMut<[T]> for [T; $N] {
 109                 #[inline]
 110                 fn as_mut(&mut self) -> &mut [T] {
 111                     &mut self[..]
 112                 }
 113             }
 114
 115             #[stable(feature = "array_borrow", since = "1.4.0")]
 116             impl<T> Borrow<[T]> for [T; $N] {
 117                 fn borrow(&self) -> &[T] {
 118                     self
 119                 }
 120             }
 121
 122             #[stable(feature = "array_borrow", since = "1.4.0")]
 123             impl<T> BorrowMut<[T]> for [T; $N] {
 124                 fn borrow_mut(&mut self) -> &mut [T] {
 125                     self
 126                 }
 127             }
 128
 129             #[stable(feature = "rust1", since = "1.0.0")]
 130             impl<T:Copy> Clone for [T; $N] {
 131                 fn clone(&self) -> [T; $N] {
 132                     *self
 133                 }
 134             }
 135
 136             #[stable(feature = "rust1", since = "1.0.0")]
 137             impl<T: Hash> Hash for [T; $N] {
 138                 fn hash<H: hash::Hasher>(&self, state: &mut H) {
 139                     Hash::hash(&self[..], state)
 140                 }
 141             }
 142
 143             #[stable(feature = "rust1", since = "1.0.0")]
 144             impl<T: fmt::Debug> fmt::Debug for [T; $N] {
 145                 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 146                     fmt::Debug::fmt(&&self[..], f)
 147                 }
 148             }
 149
 150             #[stable(feature = "rust1", since = "1.0.0")]
 151             impl<'a, T> IntoIterator for &'a [T; $N] {
 152                 type Item = &'a T;
 153                 type IntoIter = Iter<'a, T>;
 154
 155                 fn into_iter(self) -> Iter<'a, T> {
 156                     self.iter()
 157                 }
 158             }
 159
 160             #[stable(feature = "rust1", since = "1.0.0")]
 161             impl<'a, T> IntoIterator for &'a mut [T; $N] {
 162                 type Item = &'a mut T;
 163                 type IntoIter = IterMut<'a, T>;
 164
 165                 fn into_iter(self) -> IterMut<'a, T> {
 166                     self.iter_mut()
 167                 }
 168             }
 169
 170             // NOTE: some less important impls are omitted to reduce code bloat
 171             __impl_slice_eq1! { [A; $N], [B; $N] }
 172             __impl_slice_eq2! { [A; $N], [B] }
 173             __impl_slice_eq2! { [A; $N], &'b [B] }
 174             __impl_slice_eq2! { [A; $N], &'b mut [B] }
 175             // __impl_slice_eq2! { [A; $N], &'b [B; $N] }
 176             // __impl_slice_eq2! { [A; $N], &'b mut [B; $N] }
 177
 178             #[stable(feature = "rust1", since = "1.0.0")]
 179             impl<T:Eq> Eq for [T; $N] { }
 180
 181             #[stable(feature = "rust1", since = "1.0.0")]
 182             impl<T:PartialOrd> PartialOrd for [T; $N] {
 183                 #[inline]
 184                 fn partial_cmp(&self, other: &[T; $N]) -> Option<Ordering> {
 185                     PartialOrd::partial_cmp(&&self[..], &&other[..])
 186                 }
 187                 #[inline]
 188                 fn lt(&self, other: &[T; $N]) -> bool {
 189                     PartialOrd::lt(&&self[..], &&other[..])
 190                 }
 191                 #[inline]
 192                 fn le(&self, other: &[T; $N]) -> bool {
 193                     PartialOrd::le(&&self[..], &&other[..])
 194                 }
 195                 #[inline]
 196                 fn ge(&self, other: &[T; $N]) -> bool {
 197                     PartialOrd::ge(&&self[..], &&other[..])
 198                 }
 199                 #[inline]
 200                 fn gt(&self, other: &[T; $N]) -> bool {
 201                     PartialOrd::gt(&&self[..], &&other[..])
 202                 }
 203             }
 204
 205             #[stable(feature = "rust1", since = "1.0.0")]
 206             impl<T:Ord> Ord for [T; $N] {
 207                 #[inline]
 208                 fn cmp(&self, other: &[T; $N]) -> Ordering {
 209                     Ord::cmp(&&self[..], &&other[..])
 210                 }
 211             }
 212         )+
 213     }
 214 }
 215
 216 array_impls! {
 217      0  1  2  3  4  5  6  7  8  9
 218     10 11 12 13 14 15 16 17 18 19
 219     20 21 22 23 24 25 26 27 28 29
 220     30 31 32
 221 }
 222
 223 // The Default impls cannot be generated using the array_impls! macro because
 224 // they require array literals.
 225
 226 macro_rules! array_impl_default {
 227     {$n:expr, $t:ident $($ts:ident)*} => {
 228         #[stable(since = "1.4.0", feature = "array_default")]
 229         impl<T> Default for [T; $n] where T: Default {
 230             fn default() -> [T; $n] {
 231                 [$t::default(), $($ts::default()),*]
 232             }
 233         }
 234         array_impl_default!{($n - 1), $($ts)*}
 235     };
 236     {$n:expr,} => {
 237         #[stable(since = "1.4.0", feature = "array_default")]
 238         impl<T> Default for [T; $n] {
 239             fn default() -> [T; $n] { [] }
 240         }
 241     };
 242 }
 243
 244 array_impl_default!{32, T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T}