Merge pull request #379 from nevion/buffer_info

Buffer info improvements

include/pybind11/common.h

@@ -203,15 +203,15 @@ enum class return_value_policy : uint8_t {
 
 /// Information record describing a Python buffer object
 struct buffer_info {
-    void *ptr;                   // Pointer to the underlying storage
-    size_t itemsize;             // Size of individual items in bytes
-    size_t size;                 // Total number of entries
+    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;                 // Number of dimensions
+    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() : ptr(nullptr), view(nullptr) {}
+    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)
@@ -225,9 +225,9 @@ struct buffer_info {
     : buffer_info(ptr, itemsize, format, 1, std::vector<size_t> { size },
                   std::vector<size_t> { itemsize }) { }
 
-    buffer_info(Py_buffer *view)
+    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) {
+          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];
@@ -235,12 +235,33 @@ struct buffer_info {
         }
     }
 
+    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) { PyBuffer_Release(view); delete view; }
+        if (view && ownview) { PyBuffer_Release(view); delete view; }
     }
 
 private:
     Py_buffer *view = nullptr;
+    bool ownview = false;
 };
 
 NAMESPACE_BEGIN(detail)