bluss
f5290c1eea
Raw pointer taking should go through the MaybeUninit wrappers around the arrays anyway, when it is partially uninitialized, which it often is. The remaining .as_ptr() and .as_slice() methods on Array is only used on a fully initialized array in ArrayString::from_byte_string
153 lines
4.7 KiB
Rust
153 lines
4.7 KiB
Rust
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/// Trait for fixed size arrays.
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///
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/// This trait is implemented for some specific array sizes, see
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/// the implementor list below. At the current state of Rust we can't
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/// make this fully general for every array size.
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///
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/// The following crate features add more array sizes (and they are not
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/// enabled by default due to their impact on compliation speed).
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///
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/// - `array-sizes-33-128`: All sizes 33 to 128 are implemented
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/// (a few in this range are included by default).
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/// - `array-sizes-129-255`: All sizes 129 to 255 are implemented
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/// (a few in this range are included by default).
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pub unsafe trait Array {
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/// The array’s element type
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type Item;
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/// The smallest type that can index and tell the length of the array.
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#[doc(hidden)]
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type Index: Index;
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/// The array's element capacity
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const CAPACITY: usize;
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#[doc(hidden)]
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fn as_ptr(&self) -> *const Self::Item;
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#[doc(hidden)]
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fn capacity() -> usize;
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}
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pub trait Index : PartialEq + Copy {
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fn to_usize(self) -> usize;
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fn from(usize) -> Self;
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}
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use std::slice::{from_raw_parts};
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pub trait ArrayExt : Array {
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#[inline(always)]
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fn as_slice(&self) -> &[Self::Item] {
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unsafe {
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from_raw_parts(self.as_ptr(), Self::capacity())
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}
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}
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}
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impl<A> ArrayExt for A where A: Array { }
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impl Index for () {
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#[inline(always)]
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fn to_usize(self) -> usize { 0 }
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#[inline(always)]
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fn from(_ix: usize) -> Self { () }
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}
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impl Index for bool {
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#[inline(always)]
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fn to_usize(self) -> usize { self as usize }
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#[inline(always)]
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fn from(ix: usize) -> Self { ix != 0 }
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}
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impl Index for u8 {
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#[inline(always)]
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fn to_usize(self) -> usize { self as usize }
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#[inline(always)]
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fn from(ix: usize) -> Self { ix as u8 }
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}
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impl Index for u16 {
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#[inline(always)]
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fn to_usize(self) -> usize { self as usize }
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#[inline(always)]
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fn from(ix: usize) -> Self { ix as u16 }
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}
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impl Index for u32 {
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#[inline(always)]
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fn to_usize(self) -> usize { self as usize }
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#[inline(always)]
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fn from(ix: usize) -> Self { ix as u32 }
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}
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impl Index for usize {
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#[inline(always)]
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fn to_usize(self) -> usize { self }
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#[inline(always)]
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fn from(ix: usize) -> Self { ix }
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}
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macro_rules! fix_array_impl {
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($index_type:ty, $len:expr ) => (
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unsafe impl<T> Array for [T; $len] {
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type Item = T;
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type Index = $index_type;
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const CAPACITY: usize = $len;
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#[doc(hidden)]
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#[inline(always)]
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fn as_ptr(&self) -> *const T { self as *const _ as *const _ }
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#[doc(hidden)]
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#[inline(always)]
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fn capacity() -> usize { $len }
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}
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)
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}
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macro_rules! fix_array_impl_recursive {
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($index_type:ty, ) => ();
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($index_type:ty, $($len:expr,)*) => (
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$(fix_array_impl!($index_type, $len);)*
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);
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}
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fix_array_impl_recursive!((), 0,);
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fix_array_impl_recursive!(bool, 1,);
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fix_array_impl_recursive!(u8, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,
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15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27,
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28, 29, 30, 31, );
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#[cfg(not(feature="array-sizes-33-128"))]
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fix_array_impl_recursive!(u8, 32, 40, 48, 50, 56, 64, 72, 96, 100, 128, );
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#[cfg(feature="array-sizes-33-128")]
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fix_array_impl_recursive!(u8,
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32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51,
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52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71,
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72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91,
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92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108,
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109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124,
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125, 126, 127, 128,
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);
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#[cfg(not(feature="array-sizes-129-255"))]
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fix_array_impl_recursive!(u8, 160, 192, 200, 224,);
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#[cfg(feature="array-sizes-129-255")]
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fix_array_impl_recursive!(u8,
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129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140,
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141, 142, 143, 144, 145, 146, 147, 148, 149, 150, 151, 152, 153, 154, 155, 156,
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157, 158, 159, 160, 161, 162, 163, 164, 165, 166, 167, 168, 169, 170, 171, 172,
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173, 174, 175, 176, 177, 178, 179, 180, 181, 182, 183, 184, 185, 186, 187, 188,
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189, 190, 191, 192, 193, 194, 195, 196, 197, 198, 199, 200, 201, 202, 203, 204,
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205, 206, 207, 208, 209, 210, 211, 212, 213, 214, 215, 216, 217, 218, 219, 220,
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221, 222, 223, 224, 225, 226, 227, 228, 229, 230, 231, 232, 233, 234, 235, 236,
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237, 238, 239, 240, 241, 242, 243, 244, 245, 246, 247, 248, 249, 250, 251, 252,
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253, 254, 255,
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);
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fix_array_impl_recursive!(u16, 256, 384, 512, 768, 1024, 2048, 4096, 8192, 16384, 32768,);
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// This array size doesn't exist on 16-bit
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#[cfg(any(target_pointer_width="32", target_pointer_width="64"))]
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fix_array_impl_recursive!(u32, 1 << 16,);
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