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
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
// Copyright 2014-2016 bluss and ndarray developers.
//
// 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.
use super::Dimension;
use crate::dimension::IntoDimension;
use crate::zip::Offset;
use crate::split_at::SplitAt;
use crate::Axis;
use crate::Layout;
use crate::NdProducer;
use crate::{ArrayBase, Data};

/// An iterator over the indexes of an array shape.
///
/// Iterator element type is `D`.
#[derive(Clone)]
pub struct IndicesIter<D> {
    dim: D,
    index: Option<D>,
}

/// Create an iterable of the array shape `shape`.
///
/// *Note:* prefer higher order methods, arithmetic operations and
/// non-indexed iteration before using indices.
pub fn indices<E>(shape: E) -> Indices<E::Dim>
where
    E: IntoDimension,
{
    let dim = shape.into_dimension();
    Indices {
        start: E::Dim::zeros(dim.ndim()),
        dim,
    }
}

/// Return an iterable of the indices of the passed-in array.
///
/// *Note:* prefer higher order methods, arithmetic operations and
/// non-indexed iteration before using indices.
pub fn indices_of<S, D>(array: &ArrayBase<S, D>) -> Indices<D>
where
    S: Data,
    D: Dimension,
{
    indices(array.dim())
}

impl<D> Iterator for IndicesIter<D>
where
    D: Dimension,
{
    type Item = D::Pattern;
    #[inline]
    fn next(&mut self) -> Option<Self::Item> {
        let index = match self.index {
            None => return None,
            Some(ref ix) => ix.clone(),
        };
        self.index = self.dim.next_for(index.clone());
        Some(index.into_pattern())
    }

    fn size_hint(&self) -> (usize, Option<usize>) {
        let l = match self.index {
            None => 0,
            Some(ref ix) => {
                let gone = self
                    .dim
                    .default_strides()
                    .slice()
                    .iter()
                    .zip(ix.slice().iter())
                    .fold(0, |s, (&a, &b)| s + a as usize * b as usize);
                self.dim.size() - gone
            }
        };
        (l, Some(l))
    }

    fn fold<B, F>(self, init: B, mut f: F) -> B
    where
        F: FnMut(B, D::Pattern) -> B,
    {
        let IndicesIter { mut index, dim } = self;
        let ndim = dim.ndim();
        if ndim == 0 {
            return match index {
                Some(ix) => f(init, ix.into_pattern()),
                None => init,
            };
        }
        let inner_axis = ndim - 1;
        let inner_len = dim[inner_axis];
        let mut acc = init;
        while let Some(mut ix) = index {
            // unroll innermost axis
            for i in ix[inner_axis]..inner_len {
                ix[inner_axis] = i;
                acc = f(acc, ix.clone().into_pattern());
            }
            index = dim.next_for(ix);
        }
        acc
    }
}

impl<D> ExactSizeIterator for IndicesIter<D> where D: Dimension {}

impl<D> IntoIterator for Indices<D>
where
    D: Dimension,
{
    type Item = D::Pattern;
    type IntoIter = IndicesIter<D>;
    fn into_iter(self) -> Self::IntoIter {
        let sz = self.dim.size();
        let index = if sz != 0 { Some(self.start) } else { None };
        IndicesIter {
            index,
            dim: self.dim,
        }
    }
}

/// Indices producer and iterable.
///
/// `Indices` is an `NdProducer` that produces the indices of an array shape.
#[derive(Copy, Clone, Debug)]
pub struct Indices<D>
where
    D: Dimension,
{
    start: D,
    dim: D,
}

#[derive(Copy, Clone, Debug)]
pub struct IndexPtr<D> {
    index: D,
}

impl<D> Offset for IndexPtr<D>
where
    D: Dimension + Copy,
{
    // stride: The axis to increment
    type Stride = usize;

    unsafe fn stride_offset(mut self, stride: Self::Stride, index: usize) -> Self {
        self.index[stride] += index;
        self
    }
    private_impl! {}
}

// How the NdProducer for Indices works.
//
// NdProducer allows for raw pointers (Ptr), strides (Stride) and the produced
// item (Item).
//
// Instead of Ptr, there is `IndexPtr<D>` which is an index value, like [0, 0, 0]
// for the three dimensional case.
//
// The stride is simply which axis is currently being incremented. The stride for axis 1, is 1.
//
// .stride_offset(stride, index) simply computes the new index along that axis, for example:
// [0, 0, 0].stride_offset(1, 10) => [0, 10, 0]  axis 1 is incremented by 10.
//
// .as_ref() converts the Ptr value to an Item. For example [0, 10, 0] => (0, 10, 0)
impl<D: Dimension + Copy> NdProducer for Indices<D> {
    type Item = D::Pattern;
    type Dim = D;
    type Ptr = IndexPtr<D>;
    type Stride = usize;

    private_impl! {}

    #[doc(hidden)]
    fn raw_dim(&self) -> Self::Dim {
        self.dim
    }

    #[doc(hidden)]
    fn equal_dim(&self, dim: &Self::Dim) -> bool {
        self.dim.equal(dim)
    }

    #[doc(hidden)]
    fn as_ptr(&self) -> Self::Ptr {
        IndexPtr { index: self.start }
    }

    #[doc(hidden)]
    fn layout(&self) -> Layout {
        if self.dim.ndim() <= 1 {
            Layout::one_dimensional()
        } else {
            Layout::none()
        }
    }

    #[doc(hidden)]
    unsafe fn as_ref(&self, ptr: Self::Ptr) -> Self::Item {
        ptr.index.into_pattern()
    }

    #[doc(hidden)]
    unsafe fn uget_ptr(&self, i: &Self::Dim) -> Self::Ptr {
        let mut index = *i;
        index += &self.start;
        IndexPtr { index }
    }

    #[doc(hidden)]
    fn stride_of(&self, axis: Axis) -> Self::Stride {
        axis.index()
    }

    #[inline(always)]
    fn contiguous_stride(&self) -> Self::Stride {
        0
    }

    #[doc(hidden)]
    fn split_at(self, axis: Axis, index: usize) -> (Self, Self) {
        let start_a = self.start;
        let mut start_b = start_a;
        let (a, b) = self.dim.split_at(axis, index);
        start_b[axis.index()] += index;
        (
            Indices {
                start: start_a,
                dim: a,
            },
            Indices {
                start: start_b,
                dim: b,
            },
        )
    }
}

/// An iterator over the indexes of an array shape.
///
/// Iterator element type is `D`.
#[derive(Clone)]
pub struct IndicesIterF<D> {
    dim: D,
    index: D,
    has_remaining: bool,
}

pub fn indices_iter_f<E>(shape: E) -> IndicesIterF<E::Dim>
where
    E: IntoDimension,
{
    let dim = shape.into_dimension();
    let zero = E::Dim::zeros(dim.ndim());
    IndicesIterF {
        has_remaining: dim.size_checked() != Some(0),
        index: zero,
        dim,
    }
}

impl<D> Iterator for IndicesIterF<D>
where
    D: Dimension,
{
    type Item = D::Pattern;
    #[inline]
    fn next(&mut self) -> Option<Self::Item> {
        if !self.has_remaining {
            None
        } else {
            let elt = self.index.clone().into_pattern();
            self.has_remaining = self.dim.next_for_f(&mut self.index);
            Some(elt)
        }
    }

    fn size_hint(&self) -> (usize, Option<usize>) {
        if !self.has_remaining {
            return (0, Some(0));
        }
        let gone = self
            .dim
            .fortran_strides()
            .slice()
            .iter()
            .zip(self.index.slice().iter())
            .fold(0, |s, (&a, &b)| s + a as usize * b as usize);
        let l = self.dim.size() - gone;
        (l, Some(l))
    }
}

impl<D> ExactSizeIterator for IndicesIterF<D> where D: Dimension {}

#[cfg(test)]
mod tests {
    use super::indices;
    use super::indices_iter_f;

    #[test]
    fn test_indices_iter_c_size_hint() {
        let dim = (3, 4);
        let mut it = indices(dim).into_iter();
        let mut len = dim.0 * dim.1;
        assert_eq!(it.len(), len);
        while let Some(_) = it.next() {
            len -= 1;
            assert_eq!(it.len(), len);
        }
        assert_eq!(len, 0);
    }

    #[test]
    fn test_indices_iter_c_fold() {
        macro_rules! run_test {
            ($dim:expr) => {
                for num_consume in 0..3 {
                    let mut it = indices($dim).into_iter();
                    for _ in 0..num_consume {
                        it.next();
                    }
                    let clone = it.clone();
                    let len = it.len();
                    let acc = clone.fold(0, |acc, ix| {
                        assert_eq!(ix, it.next().unwrap());
                        acc + 1
                    });
                    assert_eq!(acc, len);
                    assert!(it.next().is_none());
                }
            };
        }
        run_test!(());
        run_test!((2,));
        run_test!((2, 3));
        run_test!((2, 0, 3));
        run_test!((2, 3, 4));
        run_test!((2, 3, 4, 2));
    }

    #[test]
    fn test_indices_iter_f_size_hint() {
        let dim = (3, 4);
        let mut it = indices_iter_f(dim);
        let mut len = dim.0 * dim.1;
        assert_eq!(it.len(), len);
        while let Some(_) = it.next() {
            len -= 1;
            assert_eq!(it.len(), len);
        }
        assert_eq!(len, 0);
    }
}