Add all possible ctors for py::array

include/pybind11/numpy.h

@@ -211,12 +211,16 @@ public:
         forcecast = detail::npy_api::NPY_ARRAY_FORCECAST_
     };
 
-    template <typename Type> array(size_t size, const Type *ptr) {
+    array(const pybind11::dtype& dt, const std::vector<size_t>& shape,
+          void *ptr, const std::vector<size_t>& strides) {
         auto& api = detail::npy_api::get();
-        auto descr = pybind11::dtype::of<Type>().release().ptr();
-        Py_intptr_t shape = (Py_intptr_t) size;
-        object tmp = object(api.PyArray_NewFromDescr_(
-            api.PyArray_Type_, descr, 1, &shape, nullptr, (void *) ptr, 0, nullptr), false);
+        auto ndim = shape.size();
+        if (shape.size() != strides.size())
+            pybind11_fail("NumPy: shape ndim doesn't match strides ndim");
+        auto descr = dt;
+        object tmp(api.PyArray_NewFromDescr_(
+            api.PyArray_Type_, descr.release().ptr(), (int) ndim, (Py_intptr_t *) shape.data(),
+            (Py_intptr_t *) strides.data(), ptr, 0, nullptr), false);
         if (!tmp)
             pybind11_fail("NumPy: unable to create array!");
         if (ptr)
@@ -224,18 +228,30 @@ public:
         m_ptr = tmp.release().ptr();
     }
 
-    array(const buffer_info &info) {
-        auto& api = detail::npy_api::get();
-        auto descr = pybind11::dtype(info).release().ptr();
-        object tmp(api.PyArray_NewFromDescr_(
-            api.PyArray_Type_, descr, (int) info.ndim, (Py_intptr_t *) &info.shape[0],
-            (Py_intptr_t *) &info.strides[0], info.ptr, 0, nullptr), false);
-        if (!tmp)
-            pybind11_fail("NumPy: unable to create array!");
-        if (info.ptr)
-            tmp = object(api.PyArray_NewCopy_(tmp.ptr(), -1 /* any order */), false);
-        m_ptr = tmp.release().ptr();
-    }
+    array(const pybind11::dtype& dt, const std::vector<size_t>& shape, void *ptr)
+    : array(dt, shape, ptr, default_strides(shape, dt.itemsize()))
+    { }
+
+    array(const pybind11::dtype& dt, size_t size, void *ptr)
+    : array(dt, std::vector<size_t> { size }, ptr)
+    { }
+
+    template<typename T> array(const std::vector<size_t>& shape,
+                               T* ptr, const std::vector<size_t>& strides)
+    : array(pybind11::dtype::of<T>(), shape, (void *) ptr, strides)
+    { }
+
+    template<typename T> array(const std::vector<size_t>& shape, T* ptr)
+    : array(shape, ptr, default_strides(shape, sizeof(T)))
+    { }
+
+    template<typename T> array(size_t size, T* ptr)
+    : array(std::vector<size_t> { size }, ptr)
+    { }
+
+    array(const buffer_info &info)
+    : array(pybind11::dtype(info), info.shape, info.ptr, info.strides)
+    { }
 
     pybind11::dtype dtype() {
         return attr("dtype").cast<pybind11::dtype>();
@@ -243,6 +259,18 @@ public:
 
 protected:
     template <typename T, typename SFINAE> friend struct detail::npy_format_descriptor;
+
+    static std::vector<size_t> default_strides(const std::vector<size_t>& shape, size_t itemsize) {
+        auto ndim = shape.size();
+        std::vector<size_t> strides(ndim);
+        if (ndim) {
+            std::fill(strides.begin(), strides.end(), itemsize);
+            for (size_t i = 0; i < ndim - 1; i++)
+                for (size_t j = 0; j < ndim - 1 - i; j++)
+                    strides[j] *= shape[ndim - 1 - i];
+        }
+        return strides;
+    }
 };
 
 template <typename T, int ExtraFlags = array::forcecast> class array_t : public array {