FEAT: Add internal array builder methods from_data_ptr and with_strides_dim

These methods will be used instead of the ArrayBase struct constructor
expression.

Author: bluss

src/impl_internal_constructors.rs

@@ -0,0 +1,65 @@
+// Copyright 2021 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 std::ptr::NonNull;
+
+use crate::imp_prelude::*;
+
+// internal "builder-like" methods
+impl<A, S> ArrayBase<S, Ix1>
+where
+    S: RawData<Elem = A>,
+{
+    /// Create an (initially) empty one-dimensional array from the given data and array head
+    /// pointer
+    ///
+    /// ## Safety
+    ///
+    /// The caller must ensure that the data storage and pointer is valid.
+    /// 
+    /// See ArrayView::from_shape_ptr for general pointer validity documentation.
+    pub(crate) unsafe fn from_data_ptr(data: S, ptr: NonNull<A>) -> Self {
+        let array = ArrayBase {
+            data: data,
+            ptr: ptr,
+            dim: Ix1(0),
+            strides: Ix1(1),
+        };
+        debug_assert!(array.pointer_is_inbounds());
+        array
+    }
+}
+
+// internal "builder-like" methods
+impl<A, S, D> ArrayBase<S, D>
+where
+    S: RawData<Elem = A>,
+    D: Dimension,
+{
+
+    /// Set strides and dimension of the array to the new values
+    ///
+    /// The argument order with strides before dimensions is used because strides are often
+    /// computed as derived from the dimension.
+    ///
+    /// ## Safety
+    ///
+    /// The caller needs to ensure that the new strides and dimensions are correct
+    /// for the array data.
+    pub(crate) unsafe fn with_strides_dim<E>(self, strides: E, dim: E) -> ArrayBase<S, E>
+    where
+        E: Dimension
+    {
+        ArrayBase {
+            data: self.data,
+            ptr: self.ptr,
+            dim,
+            strides,
+        }
+    }
+}

src/impl_methods.rs

@@ -1942,7 +1942,7 @@ where
         self.index_axis_move(axis, 0)
     }
 
-    fn pointer_is_inbounds(&self) -> bool {
+    pub(crate) fn pointer_is_inbounds(&self) -> bool {
         match self.data._data_slice() {
             None => {
                 // special case for non-owned views

src/lib.rs

@@ -1488,6 +1488,7 @@ impl<'a, A> CowRepr<'a, A> {
 
 mod impl_clone;
 
+mod impl_internal_constructors;
 mod impl_constructors;
 
 mod impl_methods;