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
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
//! Useful traits for manipulating sequences of data stored in `GenericArray`s

use super::*;
use core::ops::{Add, Sub};
use core::{mem, ptr};
use typenum::operator_aliases::*;

/// Defines some sequence with an associated length and iteration capabilities.
///
/// This is useful for passing N-length generic arrays as generics.
pub unsafe trait GenericSequence<T>: Sized + IntoIterator {
    /// `GenericArray` associated length
    type Length: ArrayLength<T>;

    /// Concrete sequence type used in conjuction with reference implementations of `GenericSequence`
    type Sequence: GenericSequence<T, Length = Self::Length> + FromIterator<T>;

    /// Initializes a new sequence instance using the given function.
    ///
    /// If the generator function panics while initializing the sequence,
    /// any already initialized elements will be dropped.
    fn generate<F>(f: F) -> Self::Sequence
    where
        F: FnMut(usize) -> T;

    #[doc(hidden)]
    fn inverted_zip<B, U, F>(
        self,
        lhs: GenericArray<B, Self::Length>,
        mut f: F,
    ) -> MappedSequence<GenericArray<B, Self::Length>, B, U>
    where
        GenericArray<B, Self::Length>: GenericSequence<B, Length = Self::Length>
            + MappedGenericSequence<B, U>,
        Self: MappedGenericSequence<T, U>,
        Self::Length: ArrayLength<B> + ArrayLength<U>,
        F: FnMut(B, Self::Item) -> U,
    {
        unsafe {
            let mut left = ArrayConsumer::new(lhs);

            let (left_array_iter, left_position) = left.iter_position();

            FromIterator::from_iter(left_array_iter.zip(self.into_iter()).map(
                |(l, right_value)| {
                        let left_value = ptr::read(l);

                        *left_position += 1;

                        f(left_value, right_value)
                },
            ))
        }
    }

    #[doc(hidden)]
    fn inverted_zip2<B, Lhs, U, F>(self, lhs: Lhs, mut f: F) -> MappedSequence<Lhs, B, U>
    where
        Lhs: GenericSequence<B, Length = Self::Length> + MappedGenericSequence<B, U>,
        Self: MappedGenericSequence<T, U>,
        Self::Length: ArrayLength<B> + ArrayLength<U>,
        F: FnMut(Lhs::Item, Self::Item) -> U,
    {
        FromIterator::from_iter(lhs.into_iter().zip(self.into_iter()).map(|(l, r)| f(l, r)))
    }
}

/// Accessor for `GenericSequence` item type, which is really `IntoIterator::Item`
///
/// For deeply nested generic mapped sequence types, like shown in `tests/generics.rs`,
/// this can be useful for keeping things organized.
pub type SequenceItem<T> = <T as IntoIterator>::Item;

unsafe impl<'a, T: 'a, S: GenericSequence<T>> GenericSequence<T> for &'a S
where
    &'a S: IntoIterator,
{
    type Length = S::Length;
    type Sequence = S::Sequence;

    #[inline]
    fn generate<F>(f: F) -> Self::Sequence
    where
        F: FnMut(usize) -> T,
    {
        S::generate(f)
    }
}

unsafe impl<'a, T: 'a, S: GenericSequence<T>> GenericSequence<T> for &'a mut S
where
    &'a mut S: IntoIterator,
{
    type Length = S::Length;
    type Sequence = S::Sequence;

    #[inline]
    fn generate<F>(f: F) -> Self::Sequence
    where
        F: FnMut(usize) -> T,
    {
        S::generate(f)
    }
}

/// Defines any `GenericSequence` which can be lengthened or extended by appending
/// or prepending an element to it.
///
/// Any lengthened sequence can be shortened back to the original using `pop_front` or `pop_back`
pub unsafe trait Lengthen<T>: Sized + GenericSequence<T> {
    /// `GenericSequence` that has one more element than `Self`
    type Longer: Shorten<T, Shorter = Self>;

    /// Returns a new array with the given element appended to the end of it.
    ///
    /// Example:
    ///
    /// ```ignore
    /// let a = arr![i32; 1, 2, 3];
    ///
    /// let b = a.append(4);
    ///
    /// assert_eq!(b, arr![i32; 1, 2, 3, 4]);
    /// ```
    fn append(self, last: T) -> Self::Longer;

    /// Returns a new array with the given element prepended to the front of it.
    ///
    /// Example:
    ///
    /// ```ignore
    /// let a = arr![i32; 1, 2, 3];
    ///
    /// let b = a.prepend(4);
    ///
    /// assert_eq!(b, arr![i32; 4, 1, 2, 3]);
    /// ```
    fn prepend(self, first: T) -> Self::Longer;
}

/// Defines a `GenericSequence` which can be shortened by removing the first or last element from it.
///
/// Additionally, any shortened sequence can be lengthened by
/// appending or prepending an element to it.
pub unsafe trait Shorten<T>: Sized + GenericSequence<T> {
    /// `GenericSequence` that has one less element than `Self`
    type Shorter: Lengthen<T, Longer = Self>;

    /// Returns a new array without the last element, and the last element.
    ///
    /// Example:
    ///
    /// ```ignore
    /// let a = arr![i32; 1, 2, 3, 4];
    ///
    /// let (init, last) = a.pop_back();
    ///
    /// assert_eq!(init, arr![i32; 1, 2, 3]);
    /// assert_eq!(last, 4);
    /// ```
    fn pop_back(self) -> (Self::Shorter, T);

    /// Returns a new array without the first element, and the first element.
    /// Example:
    ///
    /// ```ignore
    /// let a = arr![i32; 1, 2, 3, 4];
    ///
    /// let (head, tail) = a.pop_front();
    ///
    /// assert_eq!(head, 1);
    /// assert_eq!(tail, arr![i32; 2, 3, 4]);
    /// ```
    fn pop_front(self) -> (T, Self::Shorter);
}

unsafe impl<T, N: ArrayLength<T>> Lengthen<T> for GenericArray<T, N>
where
    N: Add<B1>,
    Add1<N>: ArrayLength<T>,
    Add1<N>: Sub<B1, Output = N>,
    Sub1<Add1<N>>: ArrayLength<T>,
{
    type Longer = GenericArray<T, Add1<N>>;

    fn append(self, last: T) -> Self::Longer {
        let mut longer: Self::Longer = unsafe { mem::uninitialized() };

        unsafe {
            ptr::write(longer.as_mut_ptr() as *mut _, self);
            ptr::write(&mut longer[N::to_usize()], last);
        }

        longer
    }

    fn prepend(self, first: T) -> Self::Longer {
        let mut longer: Self::Longer = unsafe { mem::uninitialized() };

        let longer_ptr = longer.as_mut_ptr();

        unsafe {
            ptr::write(longer_ptr as *mut _, first);
            ptr::write(longer_ptr.offset(1) as *mut _, self);
        }

        longer
    }
}

unsafe impl<T, N: ArrayLength<T>> Shorten<T> for GenericArray<T, N>
where
    N: Sub<B1>,
    Sub1<N>: ArrayLength<T>,
    Sub1<N>: Add<B1, Output = N>,
    Add1<Sub1<N>>: ArrayLength<T>,
{
    type Shorter = GenericArray<T, Sub1<N>>;

    fn pop_back(self) -> (Self::Shorter, T) {
        let init_ptr = self.as_ptr();
        let last_ptr = unsafe { init_ptr.add(Sub1::<N>::to_usize()) };

        let init = unsafe { ptr::read(init_ptr as _) };
        let last = unsafe { ptr::read(last_ptr as _) };

        mem::forget(self);

        (init, last)
    }

    fn pop_front(self) -> (T, Self::Shorter) {
        let head_ptr = self.as_ptr();
        let tail_ptr = unsafe { head_ptr.offset(1) };

        let head = unsafe { ptr::read(head_ptr as _) };
        let tail = unsafe { ptr::read(tail_ptr as _) };

        mem::forget(self);

        (head, tail)
    }
}

/// Defines a `GenericSequence` that can be split into two parts at a given pivot index.
pub unsafe trait Split<T, K>: GenericSequence<T>
where
    K: ArrayLength<T>,
{
    /// First part of the resulting split array
    type First: GenericSequence<T>;
    /// Second part of the resulting split array
    type Second: GenericSequence<T>;

    /// Splits an array at the given index, returning the separate parts of the array.
    fn split(self) -> (Self::First, Self::Second);
}

unsafe impl<T, N, K> Split<T, K> for GenericArray<T, N>
where
    N: ArrayLength<T>,
    K: ArrayLength<T>,
    N: Sub<K>,
    Diff<N, K>: ArrayLength<T>,
{
    type First = GenericArray<T, K>;
    type Second = GenericArray<T, Diff<N, K>>;

    fn split(self) -> (Self::First, Self::Second) {
        let head_ptr = self.as_ptr();
        let tail_ptr = unsafe { head_ptr.add(K::to_usize()) };

        let head = unsafe { ptr::read(head_ptr as _) };
        let tail = unsafe { ptr::read(tail_ptr as _) };

        mem::forget(self);

        (head, tail)
    }
}

/// Defines `GenericSequence`s which can be joined together, forming a larger array.
pub unsafe trait Concat<T, M>: GenericSequence<T>
where
    M: ArrayLength<T>,
{
    /// Sequence to be concatenated with `self`
    type Rest: GenericSequence<T, Length = M>;

    /// Resulting sequence formed by the concatenation.
    type Output: GenericSequence<T>;

    /// Concatenate, or join, two sequences.
    fn concat(self, rest: Self::Rest) -> Self::Output;
}

unsafe impl<T, N, M> Concat<T, M> for GenericArray<T, N>
where
    N: ArrayLength<T> + Add<M>,
    M: ArrayLength<T>,
    Sum<N, M>: ArrayLength<T>,
{
    type Rest = GenericArray<T, M>;
    type Output = GenericArray<T, Sum<N, M>>;

    fn concat(self, rest: Self::Rest) -> Self::Output {
        let mut output: Self::Output = unsafe { mem::uninitialized() };

        let output_ptr = output.as_mut_ptr();

        unsafe {
            ptr::write(output_ptr as *mut _, self);
            ptr::write(output_ptr.add(N::to_usize()) as *mut _, rest);
        }

        output
    }
}