No_std support for ndarray (#864)

This pr enables ndarray to be used in the no_std environment, and maintains most of the functions. Fixes #708.
The `geomspace` `linspace` `logspace` `range` `var_axis` and `std_axis` methods are only available when `std` is enabled at current. And 'blas''rayon''serde' features are not available without std too.

Author: SparrowLii

Cargo.toml

@@ -28,19 +28,19 @@ bench = false
 test = true
 
 [dependencies]
-num-integer = "0.1.39"
+num-integer = { version = "0.1.39", default-features = false }
 num-traits = { version = "0.2", default-features = false }
 num-complex = { version = "0.3", default-features = false }
 
 rayon = { version = "1.0.3", optional = true }
 
-approx = { version = "0.4", optional = true }
+approx = { version = "0.4", optional = true , default-features = false }
 
 # Use via the `blas` crate feature!
 cblas-sys = { version = "0.1.4", optional = true, default-features = false }
 blas-src = { version = "0.6.1", optional = true, default-features = false }
 
-matrixmultiply = { version = "0.2.0" }
+matrixmultiply = { version = "0.2.0", default-features = false}
 serde = { version = "1.0", optional = true }
 rawpointer = { version = "0.2" }
 
@@ -52,6 +52,7 @@ itertools = { version = "0.9.0", default-features = false, features = ["use_std"
 
 [features]
 default = ["std"]
+
 # Enable blas usage
 # See README for more instructions
 blas = ["cblas-sys", "blas-src"]
@@ -66,7 +67,7 @@ test = ["test-blas-openblas-sys"]
 # This feature is used for docs
 docs = ["approx", "serde", "rayon"]
 
-std = ["num-traits/std"]
+std = ["num-traits/std", "matrixmultiply/std"]
 
 [profile.release]
 [profile.bench]

README.rst

@@ -48,6 +48,19 @@ Crate Feature Flags
 The following crate feature flags are available. They are configured in
 your `Cargo.toml`.
 
+- ``std``
+
+  - Rust Standard Library
+
+  - This crate can be used without the standard library by disabling the
+    default `std` feature. To do so, use this in your `Cargo.toml`:
+
+    [dependencies]
+    ndarray = { version = "0.x.y", default-features = false }
+
+  - The `geomspace` `linspace` `logspace` `range` `std` `var` `var_axis` and `std_axis`
+    methods are only available when `std` is enabled.
+
 - ``serde``
 
   - Optional, compatible with Rust stable
@@ -112,4 +125,3 @@ http://opensource.org/licenses/MIT, at your
 option. This file may not be copied, modified, or distributed
 except according to those terms.
 
-

examples/convo.rs

@@ -1,7 +1,7 @@
 #![allow(unused)]
 extern crate ndarray;
-extern crate num_traits;
 
+#[cfg(feature = "std")]
 use num_traits::Float;
 
 use ndarray::prelude::*;
@@ -13,6 +13,7 @@ const SHARPEN: [[f32; 3]; 3] = [[0., -1., 0.], [-1., 5., -1.], [0., -1., 0.]];
 type Kernel3x3<A> = [[A; 3]; 3];
 
 #[inline(never)]
+#[cfg(feature = "std")]
 fn conv_3x3<F>(a: &ArrayView2<'_, F>, out: &mut ArrayViewMut2<'_, F>, kernel: &Kernel3x3<F>)
 where
     F: Float,
@@ -41,6 +42,7 @@ where
     }
 }
 
+#[cfg(feature = "std")]
 fn main() {
     let n = 16;
     let mut a = Array::zeros((n, n));
@@ -61,3 +63,5 @@ fn main() {
     }
     println!("{:2}", res);
 }
+#[cfg(not(feature = "std"))]
+fn main() {}

examples/sort-axis.rs

@@ -129,7 +129,7 @@ where
         }
     }
 }
-
+#[cfg(feature = "std")]
 fn main() {
     let a = Array::linspace(0., 63., 64).into_shape((8, 8)).unwrap();
     let strings = a.map(|x| x.to_string());
@@ -143,3 +143,5 @@ fn main() {
     let c = strings.permute_axis(Axis(1), &perm);
     println!("{:?}", c);
 }
+#[cfg(not(feature = "std"))]
+fn main() {}

src/array_approx.rs

@@ -81,6 +81,7 @@ where
 #[cfg(test)]
 mod tests {
     use crate::prelude::*;
+    use alloc::vec;
     use approx::{
         assert_abs_diff_eq, assert_abs_diff_ne, assert_relative_eq, assert_relative_ne,
         assert_ulps_eq, assert_ulps_ne,

src/array_serde.rs

@@ -11,6 +11,8 @@ use serde::{Deserialize, Deserializer, Serialize, Serializer};
 
 use std::fmt;
 use std::marker::PhantomData;
+use alloc::format;
+use alloc::vec::Vec;
 
 use crate::imp_prelude::*;
 

src/arrayformat.rs

@@ -8,6 +8,9 @@
 use super::{ArrayBase, ArrayView, Axis, Data, Dimension, NdProducer};
 use crate::aliases::{Ix1, IxDyn};
 use std::fmt;
+use alloc::format;
+use alloc::string::String;
+use alloc::vec::Vec;
 
 /// Default threshold, below this element count, we don't ellipsize
 const ARRAY_MANY_ELEMENT_LIMIT: usize = 500;

src/arraytraits.rs

@@ -12,6 +12,7 @@ use std::iter::FromIterator;
 use std::iter::IntoIterator;
 use std::mem;
 use std::ops::{Index, IndexMut};
+use alloc::vec::Vec;
 
 use crate::imp_prelude::*;
 use crate::iter::{Iter, IterMut};

src/data_repr.rs

@@ -1,8 +1,9 @@
-
 use std::mem;
 use std::mem::ManuallyDrop;
 use std::ptr::NonNull;
-use std::slice;
+use alloc::slice;
+use alloc::borrow::ToOwned;
+use alloc::vec::Vec;
 use crate::extension::nonnull;
 
 /// Array's representation.

src/data_traits.rs

@@ -11,7 +11,8 @@
 use rawpointer::PointerExt;
 use std::mem::{self, size_of};
 use std::ptr::NonNull;
-use std::sync::Arc;
+use alloc::sync::Arc;
+use alloc::vec::Vec;
 
 use crate::{
     ArrayBase, CowRepr, Dimension, OwnedArcRepr, OwnedRepr, RawViewRepr, ViewRepr,