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Copy pathindexes.rs
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355 lines (323 loc) · 8.64 KB
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// 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::split_at::SplitAt;
use crate::zip::Offset;
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 = self.index.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 * b);
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! {}
fn raw_dim(&self) -> Self::Dim
{
self.dim
}
fn equal_dim(&self, dim: &Self::Dim) -> bool
{
self.dim.equal(dim)
}
fn as_ptr(&self) -> Self::Ptr
{
IndexPtr { index: self.start }
}
fn layout(&self) -> Layout
{
if self.dim.ndim() <= 1 {
Layout::one_dimensional()
} else {
Layout::none()
}
}
unsafe fn as_ref(&self, ptr: Self::Ptr) -> Self::Item
{
ptr.index.into_pattern()
}
unsafe fn uget_ptr(&self, i: &Self::Dim) -> Self::Ptr
{
let mut index = *i;
index += &self.start;
IndexPtr { index }
}
fn stride_of(&self, axis: Axis) -> Self::Stride
{
axis.index()
}
#[inline(always)]
fn contiguous_stride(&self) -> Self::Stride
{
0
}
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 * b);
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);
}
}