LSSTApplications  20.0.0
LSSTDataManagementBasePackage
TemplateInvoker.h
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23 
24 #ifndef LSST_UTILS_PYTHON_TEMPLATEINVOKER_H
25 #define LSST_UTILS_PYTHON_TEMPLATEINVOKER_H
26 
27 #include "pybind11/pybind11.h"
28 #include "pybind11/numpy.h"
29 
30 #include <iostream>
31 
32 namespace lsst { namespace utils { namespace python {
33 
107 public:
108 
110  template <typename ...Types>
111  struct Tag {};
112 
114  using OnErrorCallback = std::function<pybind11::object(pybind11::dtype const & dtype)>;
115 
117  static pybind11::object handleErrorDefault(pybind11::dtype const & dtype) {
118  PyErr_Format(PyExc_TypeError, "dtype '%R' not supported.", dtype.ptr());
119  throw pybind11::error_already_set();
120  }
121 
129  explicit TemplateInvoker(OnErrorCallback onError) : _onError(std::move(onError)) {}
130 
133 
155  template <typename Function, typename ...TypesToTry>
156  pybind11::object apply(
157  Function function,
158  pybind11::dtype const & dtype,
159  Tag<TypesToTry...> typesToTry
160  ) const {
161  return _apply(function, dtype, typesToTry);
162  }
163 
164 private:
165 
166  template <typename Function>
167  pybind11::object _apply(Function & function, pybind11::dtype const & dtype, Tag<>) const {
168  return _onError(dtype);
169  }
170 
171  template <typename Function, typename T, typename ...A>
172  pybind11::object _apply(Function & function, pybind11::dtype const & dtype, Tag<T, A...>) const {
173  if (pybind11::detail::npy_api::get().PyArray_EquivTypes_(dtype.ptr(),
174  pybind11::dtype::of<T>().ptr())) {
175  return pybind11::cast(function(static_cast<T>(0)));
176  }
177  return _apply(function, dtype, Tag<A...>());
178  }
179 
180  OnErrorCallback _onError;
181 };
182 
183 }}} // namespace lsst::utils::python
184 
185 #endif
std::function< pybind11::object(pybind11::dtype const &dtype)>
lsst::utils::python::TemplateInvoker::Tag
A simple tag type used to pass one or more types as a function argument.
Definition: TemplateInvoker.h:111
lsst::utils::python::TemplateInvoker::apply
pybind11::object apply(Function function, pybind11::dtype const &dtype, Tag< TypesToTry... > typesToTry) const
Call and return function(static_cast<T>(0)) with the type T that matches a given NumPy dtype object.
Definition: TemplateInvoker.h:156
lsst::utils::python::TemplateInvoker
A helper class for wrapping C++ template functions as Python functions with dtype arguments.
Definition: TemplateInvoker.h:106
lsst::utils::python::TemplateInvoker::handleErrorDefault
static pybind11::object handleErrorDefault(pybind11::dtype const &dtype)
Callback used for handling unmatched-type errors by default.
Definition: TemplateInvoker.h:117
lsst
A base class for image defects.
Definition: imageAlgorithm.dox:1
lsst::utils::python::TemplateInvoker::TemplateInvoker
TemplateInvoker()
Construct a TemplateInvoker that calls handleErrorDefault when no match is found.
Definition: TemplateInvoker.h:132
lsst::utils::python::TemplateInvoker::OnErrorCallback
std::function< pybind11::object(pybind11::dtype const &dtype)> OnErrorCallback
Callback type for handling unmatched-type errors.
Definition: TemplateInvoker.h:114
std
STL namespace.
lsst::utils::python::TemplateInvoker::TemplateInvoker
TemplateInvoker(OnErrorCallback onError)
Construct a TemplateInvoker that calls the given object when no match is found.
Definition: TemplateInvoker.h:129