Move buffer_info to its own header

Upcoming changes to buffer_info make it need some things declared in
common.h; it also feels a bit misplaced in common.h (which is arguably
too large already), so move it out.  (Separating this and the subsequent
changes into separate commits to make the changes easier to distinguish
from the move.)

CMakeLists.txt

@@ -36,6 +36,7 @@ set(PYTHON_MODULE_EXTENSION ${PYTHON_MODULE_EXTENSION} CACHE INTERNAL "")
 
 set(PYBIND11_HEADERS
   include/pybind11/attr.h
+  include/pybind11/buffer_info.h
   include/pybind11/cast.h
   include/pybind11/chrono.h
   include/pybind11/class_support.h

include/pybind11/buffer_info.h

+/*
+    pybind11/buffer_info.h: Python buffer object interface
+
+    Copyright (c) 2016 Wenzel Jakob <wenzel.jakob@epfl.ch>
+
+    All rights reserved. Use of this source code is governed by a
+    BSD-style license that can be found in the LICENSE file.
+*/
+
+#pragma once 
+
+#include "common.h"
+
+NAMESPACE_BEGIN(pybind11)
+
+/// Information record describing a Python buffer object
+struct buffer_info {
+    void *ptr = nullptr;         // Pointer to the underlying storage
+    size_t itemsize = 0;         // Size of individual items in bytes
+    size_t size = 0;             // Total number of entries
+    std::string format;          // For homogeneous buffers, this should be set to format_descriptor<T>::format()
+    size_t ndim = 0;             // Number of dimensions
+    std::vector<size_t> shape;   // Shape of the tensor (1 entry per dimension)
+    std::vector<size_t> strides; // Number of entries between adjacent entries (for each per dimension)
+
+    buffer_info() { }
+
+    buffer_info(void *ptr, size_t itemsize, const std::string &format, size_t ndim,
+                const std::vector<size_t> &shape, const std::vector<size_t> &strides)
+        : ptr(ptr), itemsize(itemsize), size(1), format(format),
+          ndim(ndim), shape(shape), strides(strides) {
+        for (size_t i = 0; i < ndim; ++i)
+            size *= shape[i];
+    }
+
+    buffer_info(void *ptr, size_t itemsize, const std::string &format, size_t size)
+    : buffer_info(ptr, itemsize, format, 1, std::vector<size_t> { size },
+                  std::vector<size_t> { itemsize }) { }
+
+    explicit buffer_info(Py_buffer *view, bool ownview = true)
+        : ptr(view->buf), itemsize((size_t) view->itemsize), size(1), format(view->format),
+          ndim((size_t) view->ndim), shape((size_t) view->ndim), strides((size_t) view->ndim), view(view), ownview(ownview) {
+        for (size_t i = 0; i < (size_t) view->ndim; ++i) {
+            shape[i] = (size_t) view->shape[i];
+            strides[i] = (size_t) view->strides[i];
+            size *= shape[i];
+        }
+    }
+
+    buffer_info(const buffer_info &) = delete;
+    buffer_info& operator=(const buffer_info &) = delete;
+
+    buffer_info(buffer_info &&other) {
+        (*this) = std::move(other);
+    }
+
+    buffer_info& operator=(buffer_info &&rhs) {
+        ptr = rhs.ptr;
+        itemsize = rhs.itemsize;
+        size = rhs.size;
+        format = std::move(rhs.format);
+        ndim = rhs.ndim;
+        shape = std::move(rhs.shape);
+        strides = std::move(rhs.strides);
+        std::swap(view, rhs.view);
+        std::swap(ownview, rhs.ownview);
+        return *this;
+    }
+
+    ~buffer_info() {
+        if (view && ownview) { PyBuffer_Release(view); delete view; }
+    }
+
+private:
+    Py_buffer *view = nullptr;
+    bool ownview = false;
+};
+
+NAMESPACE_BEGIN(detail)
+
+template <typename T, typename SFINAE = void> struct compare_buffer_info {
+    static bool compare(const buffer_info& b) {
+        return b.format == format_descriptor<T>::format() && b.itemsize == sizeof(T);
+    }
+};
+
+template <typename T> struct compare_buffer_info<T, detail::enable_if_t<std::is_integral<T>::value>> {
+    static bool compare(const buffer_info& b) {
+        return b.itemsize == sizeof(T) && (b.format == format_descriptor<T>::value ||
+            ((sizeof(T) == sizeof(long)) && b.format == (std::is_unsigned<T>::value ? "L" : "l")) ||
+            ((sizeof(T) == sizeof(size_t)) && b.format == (std::is_unsigned<T>::value ? "N" : "n")));
+    }
+};
+
+NAMESPACE_END(detail)
+NAMESPACE_END(pybind11)

include/pybind11/common.h

@@ -286,69 +286,6 @@ enum class return_value_policy : uint8_t {
     reference_internal
 };
 
-/// Information record describing a Python buffer object
-struct buffer_info {
-    void *ptr = nullptr;         // Pointer to the underlying storage
-    size_t itemsize = 0;         // Size of individual items in bytes
-    size_t size = 0;             // Total number of entries
-    std::string format;          // For homogeneous buffers, this should be set to format_descriptor<T>::format()
-    size_t ndim = 0;             // Number of dimensions
-    std::vector<size_t> shape;   // Shape of the tensor (1 entry per dimension)
-    std::vector<size_t> strides; // Number of entries between adjacent entries (for each per dimension)
-
-    buffer_info() { }
-
-    buffer_info(void *ptr, size_t itemsize, const std::string &format, size_t ndim,
-                const std::vector<size_t> &shape, const std::vector<size_t> &strides)
-        : ptr(ptr), itemsize(itemsize), size(1), format(format),
-          ndim(ndim), shape(shape), strides(strides) {
-        for (size_t i = 0; i < ndim; ++i)
-            size *= shape[i];
-    }
-
-    buffer_info(void *ptr, size_t itemsize, const std::string &format, size_t size)
-    : buffer_info(ptr, itemsize, format, 1, std::vector<size_t> { size },
-                  std::vector<size_t> { itemsize }) { }
-
-    explicit buffer_info(Py_buffer *view, bool ownview = true)
-        : ptr(view->buf), itemsize((size_t) view->itemsize), size(1), format(view->format),
-          ndim((size_t) view->ndim), shape((size_t) view->ndim), strides((size_t) view->ndim), view(view), ownview(ownview) {
-        for (size_t i = 0; i < (size_t) view->ndim; ++i) {
-            shape[i] = (size_t) view->shape[i];
-            strides[i] = (size_t) view->strides[i];
-            size *= shape[i];
-        }
-    }
-
-    buffer_info(const buffer_info &) = delete;
-    buffer_info& operator=(const buffer_info &) = delete;
-
-    buffer_info(buffer_info &&other) {
-        (*this) = std::move(other);
-    }
-
-    buffer_info& operator=(buffer_info &&rhs) {
-        ptr = rhs.ptr;
-        itemsize = rhs.itemsize;
-        size = rhs.size;
-        format = std::move(rhs.format);
-        ndim = rhs.ndim;
-        shape = std::move(rhs.shape);
-        strides = std::move(rhs.strides);
-        std::swap(view, rhs.view);
-        std::swap(ownview, rhs.ownview);
-        return *this;
-    }
-
-    ~buffer_info() {
-        if (view && ownview) { PyBuffer_Release(view); delete view; }
-    }
-
-private:
-    Py_buffer *view = nullptr;
-    bool ownview = false;
-};
-
 NAMESPACE_BEGIN(detail)
 
 inline static constexpr int log2(size_t n, int k = 0) { return (n <= 1) ? k : log2(n >> 1, k + 1); }
@@ -669,24 +606,6 @@ template <typename T> struct format_descriptor<T, detail::enable_if_t<detail::is
 template <typename T> constexpr const char format_descriptor<
     T, detail::enable_if_t<detail::is_fmt_numeric<T>::value>>::value[2];
 
-NAMESPACE_BEGIN(detail)
-
-template <typename T, typename SFINAE = void> struct compare_buffer_info {
-    static bool compare(const buffer_info& b) {
-        return b.format == format_descriptor<T>::format() && b.itemsize == sizeof(T);
-    }
-};
-
-template <typename T> struct compare_buffer_info<T, detail::enable_if_t<std::is_integral<T>::value>> {
-    static bool compare(const buffer_info& b) {
-        return b.itemsize == sizeof(T) && (b.format == format_descriptor<T>::value ||
-            ((sizeof(T) == sizeof(long)) && b.format == (std::is_unsigned<T>::value ? "L" : "l")) ||
-            ((sizeof(T) == sizeof(size_t)) && b.format == (std::is_unsigned<T>::value ? "N" : "n")));
-    }
-};
-
-NAMESPACE_END(detail)
-
 /// RAII wrapper that temporarily clears any Python error state
 struct error_scope {
     PyObject *type, *value, *trace;

include/pybind11/pytypes.h

@@ -10,6 +10,7 @@
 #pragma once
 
 #include "common.h"
+#include "buffer_info.h"
 #include <utility>
 #include <type_traits>