Better NumPy support

README.md

@@ -17,7 +17,7 @@ become an excessively large and unnecessary dependency.
 
 Think of this library as a tiny self-contained version of Boost.Python with
 everything stripped away that isn't relevant for binding generation. The whole
-codebase requires less than 2000 lines of code and just depends on Python and
+codebase requires just over 2000 lines of code and just depends on Python and
 the C++ standard library. This compact implementation was possible thanks to
 some of the new C++11 language features (tuples, lambda functions and variadic
 templates), and by only targeting Python 3.x and higher.

include/pybind/cast.h

@@ -206,6 +206,22 @@ public:
     TYPE_CASTER(std::string, "str");
 };
 
+#ifdef HAVE_WCHAR_H
+template <> class type_caster<std::wstring> {
+public:
+    bool load(PyObject *src, bool) {
+        const wchar_t *ptr = PyUnicode_AsWideCharString(src, nullptr);
+        if (!ptr) { PyErr_Clear(); return false; }
+        value = std::wstring(ptr);
+        return true;
+    }
+    static PyObject *cast(const std::wstring &src, return_value_policy /* policy */, PyObject * /* parent */) {
+        return PyUnicode_FromWideChar(src.c_str(), src.length());
+    }
+    TYPE_CASTER(std::wstring, "wstr");
+};
+#endif
+
 template <> class type_caster<char> {
 public:
     bool load(PyObject *src, bool) {
@@ -474,6 +490,7 @@ TYPE_CASTER_PYTYPE(list)
 TYPE_CASTER_PYTYPE(slice)
 TYPE_CASTER_PYTYPE(tuple)
 TYPE_CASTER_PYTYPE(function)
+TYPE_CASTER_PYTYPE(array)
 
 #undef TYPE_CASTER
 #undef TYPE_CASTER_PYTYPE

include/pybind/pybind.h

@@ -132,7 +132,10 @@ private:
             entry = backup;
         }
         std::string signatures;
+        int it = 0;
         while (entry) { /* Create pydoc entry */
+            if (sibling.ptr())
+                signatures += std::to_string(++it) + ". ";
             signatures += "Signature : " + std::string(entry->signature) + "\n";
             if (!entry->doc.empty())
                 signatures += "\n" + std::string(entry->doc) + "\n";

include/pybind/pytypes.h

@@ -322,6 +322,88 @@ private:
     Py_buffer *view = nullptr;
 };
 
+class array : public buffer {
+protected:
+    struct API {
+        enum Entries {
+            API_PyArray_Type = 2,
+            API_PyArray_DescrFromType = 45,
+            API_PyArray_NewCopy = 85,
+            API_PyArray_NewFromDescr = 94
+        };
+
+        static API lookup() {
+            PyObject *numpy = PyImport_ImportModule("numpy.core.multiarray");
+            PyObject *capsule = numpy ? PyObject_GetAttrString(numpy, "_ARRAY_API") : nullptr;
+            void **api_ptr = (void **) (capsule ? PyCapsule_GetPointer(capsule, NULL) : nullptr);
+            Py_XDECREF(capsule);
+            Py_XDECREF(numpy);
+            if (api_ptr == nullptr)
+                throw std::runtime_error("Could not acquire pointer to NumPy API!");
+            API api;
+            api.PyArray_DescrFromType = (decltype(api.PyArray_DescrFromType)) api_ptr[API_PyArray_DescrFromType];
+            api.PyArray_NewFromDescr  = (decltype(api.PyArray_NewFromDescr))  api_ptr[API_PyArray_NewFromDescr];
+            api.PyArray_NewCopy       = (decltype(api.PyArray_NewCopy))       api_ptr[API_PyArray_NewCopy];
+            api.PyArray_Type          = (decltype(api.PyArray_Type))          api_ptr[API_PyArray_Type];
+            return api;
+        }
+
+        bool PyArray_Check(PyObject *obj) const {
+            return (bool) PyObject_TypeCheck(obj, PyArray_Type);
+        }
+
+        PyObject *(*PyArray_DescrFromType)(int);
+        PyObject *(*PyArray_NewFromDescr)
+            (PyTypeObject *, PyObject *, int, Py_intptr_t *,
+             Py_intptr_t *, void *, int, PyObject *);
+        PyObject *(*PyArray_NewCopy)(PyObject *, int);
+        PyTypeObject *PyArray_Type;
+    };
+public:
+    PYTHON_OBJECT_DEFAULT(array, buffer, lookup_api().PyArray_Check)
+    
+    template <typename Type> array(size_t size, const Type *ptr) {
+        API& api = lookup_api();
+        PyObject *descr = api.PyArray_DescrFromType(
+            (int) format_descriptor<Type>::value()[0]);
+        if (descr == nullptr)
+            throw std::runtime_error("NumPy: unsupported buffer format!");
+        Py_intptr_t shape = (Py_intptr_t) size;
+        PyObject *tmp = api.PyArray_NewFromDescr(
+            api.PyArray_Type, descr, 1, &shape, nullptr, (void *) ptr, 0, nullptr);
+        if (tmp == nullptr)
+            throw std::runtime_error("NumPy: unable to create array!");
+        m_ptr = api.PyArray_NewCopy(tmp, -1 /* any order */);
+        Py_DECREF(tmp);
+        if (m_ptr == nullptr)
+            throw std::runtime_error("NumPy: unable to copy array!");
+    }
+
+    array(const buffer_info &info) {
+        API& api = lookup_api();
+        if (info.format.size() != 1)
+            throw std::runtime_error("Unsupported buffer format!");
+        PyObject *descr = api.PyArray_DescrFromType(info.format[0]);
+        if (descr == nullptr)
+            throw std::runtime_error("NumPy: unsupported buffer format '" + info.format + "'!");
+        PyObject *tmp = api.PyArray_NewFromDescr(
+            api.PyArray_Type, descr, info.ndim, (Py_intptr_t *) &info.shape[0],
+            (Py_intptr_t *) &info.strides[0], info.ptr, 0, nullptr);
+        if (tmp == nullptr)
+            throw std::runtime_error("NumPy: unable to create array!");
+        m_ptr = api.PyArray_NewCopy(tmp, -1 /* any order */);
+        Py_DECREF(tmp);
+        if (m_ptr == nullptr)
+            throw std::runtime_error("NumPy: unable to copy array!");
+    }
+protected:
+    static API &lookup_api() {
+        static API api = API::lookup();
+        return api;
+    }
+};
+
+
 NAMESPACE_BEGIN(detail)
 inline internals &get_internals() {
     static internals *internals_ptr = nullptr;