1 /* Copyright 2019 The TensorFlow Authors. All Rights Reserved.
2 
3 Licensed under the Apache License, Version 2.0 (the "License");
4 you may not use this file except in compliance with the License.
5 You may obtain a copy of the License at
6 
7     http://www.apache.org/licenses/LICENSE-2.0
8 
9 Unless required by applicable law or agreed to in writing, software
10 distributed under the License is distributed on an "AS IS" BASIS,
11 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 See the License for the specific language governing permissions and
13 limitations under the License.
14 ==============================================================================*/
15 
16 #ifndef TENSORFLOW_COMPILER_XLA_PYTHON_ABSL_CASTERS_H_
17 #define TENSORFLOW_COMPILER_XLA_PYTHON_ABSL_CASTERS_H_
18 
19 #include "absl/strings/string_view.h"
20 #include "absl/types/optional.h"
21 #include "absl/types/span.h"
22 #include "absl/types/variant.h"
23 #include "pybind11/cast.h"
24 #include "pybind11/pybind11.h"
25 #include "pybind11/stl.h"
26 
27 namespace pybind11 {
28 namespace detail {
29 
30 // absl::Span
31 template <typename T>
32 struct type_caster<absl::Span<const T>> {
33   using value_conv = make_caster<T>;
34 
35   PYBIND11_TYPE_CASTER(absl::Span<const T>,
36                        _("Span[") + value_conv::name + _("]"));
37 
38   // absl::Span doesn't hold ownership. We therefore need a temporary array.
39   // Pybind appears to keep type_casters alive until the callee has run.
40   std::vector<T> storage;
41 
42   bool load(handle src, bool convert) {
43     if (!isinstance<sequence>(src)) {
44       return false;
45     }
46     auto seq = reinterpret_borrow<sequence>(src);
47     storage.clear();
48     storage.reserve(seq.size());
49     for (const auto& it : seq) {
50       value_conv conv;
51       if (!conv.load(it, convert)) {
52         return false;
53       }
54       storage.push_back(cast_op<T&&>(std::move(conv)));
55     }
56     value = absl::Span<const T>(storage);
57     return true;
58   }
59 };
60 
61 // When absl::optional is an alias for std::optional, the type_caster
62 // specializations are provided by pybind11.
63 #ifndef ABSL_HAVE_STD_OPTIONAL
64 // absl::optional
65 template <typename T>
66 struct type_caster<absl::optional<T>> : optional_caster<absl::optional<T>> {};
67 
68 template <>
69 struct type_caster<absl::nullopt_t> : public void_caster<absl::nullopt_t> {};
70 #endif
71 
72 #ifndef ABSL_HAVE_STD_VARIANT
73 template <typename... Ts>
74 struct type_caster<absl::variant<Ts...>>
75     : variant_caster<absl::variant<Ts...>> {};
76 
77 #endif
78 
79 // Convert between absl::string_view and python.
80 //
81 // pybind11 supports std::string_view, and absl::string_view is meant to be a
82 // drop-in replacement for std::string_view, so we can just use the built in
83 // implementation. This is only needed until absl::string_view becomes an alias
84 // for std::string_view.
85 #ifndef ABSL_USES_STD_STRING_VIEW
86 template <>
87 struct type_caster<absl::string_view> : string_caster<absl::string_view, true> {
88 };
89 #endif
90 
91 }  // namespace detail
92 }  // namespace pybind11
93 
94 #endif  // TENSORFLOW_COMPILER_XLA_PYTHON_ABSL_CASTERS_H_
95