pybind/pybind11
1
0
Fork 0
mirror of https://github.com/pybind/pybind11.git synced 2026-03-14 20:27:47 +00:00
Code Issues Packages Projects Releases Wiki Activity

Expand std::string_view support to str, bytes, memoryview (#3521)

Browse Source 
* Expand string_view support to str, bytes, memoryview

1. Allows constructing a str or bytes implicitly from a string_view;
   this is essentially a small shortcut allowing a caller to write
   `py::bytes{sv}` rather than `py::bytes{sv.data(), sv.size()}`.

2. Allows implicit conversion *to* string_view from py::bytes -- this
   saves a fair bit more as currently there is no simple way to get such
   a view of the bytes without copying it (or resorting to Python API
   calls).

   (This is not done for `str` because when the str contains unicode we
   have to allocate to a temporary and so there might not be some string
   data we can properly view without owning.)

3. Allows `memoryview::from_memory` to accept a string_view.  As with
   the other from_memory calls, it's entirely your responsibility to
   keep it alive.

This also required moving the string_view availability detection into
detail/common.h because this PR needs it in pytypes.h, which is higher
up the include chain than cast.h where it was being detected currently.

* Move string_view include to pytypes.h

* CI-testing a fix for the "ambiguous conversion" issue.

This change is known to fix the `tensorflow::tstring` issue reported under https://github.com/pybind/pybind11/pull/3521#issuecomment-985100965

TODO: Minimal reproducer for the `tensorflow::tstring` issue.

* Make clang-tidy happy (hopefully).

* Adding minimal reproducer for the `tensorflow::tstring` issue.

Error without the enable_if trick:

```
/usr/local/google/home/rwgk/forked/pybind11/tests/test_builtin_casters.cpp:169:16: error: ambiguous conversion for functional-style cast from 'TypeWithBothOperatorStringAndStringView' to 'py::bytes'
        return py::bytes(TypeWithBothOperatorStringAndStringView());
               ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/local/google/home/rwgk/forked/pybind11/include/pybind11/detail/../pytypes.h:1174:5: note: candidate constructor
    bytes(const std::string &s) : bytes(s.data(), s.size()) { }
    ^
/usr/local/google/home/rwgk/forked/pybind11/include/pybind11/detail/../pytypes.h:1191:5: note: candidate constructor
    bytes(std::string_view s) : bytes(s.data(), s.size()) { }
    ^
```

* Adding missing NOLINTNEXTLINE

* Also apply ambiguous conversion workaround to str()

Co-authored-by: Ralf W. Grosse-Kunstleve <rwgk@google.com>
This commit is contained in:
Jason Rhinelander
2021-12-03 13:20:32 -04:00
committed by GitHub
parent cd176ceeff
commit b4939fcbfb
5 changed files with 95 additions and 17 deletions
Download Patch File Download Diff File Expand all files Collapse all files

24
tests/test_builtin_casters.cpp
View File

@@ -140,11 +140,35 @@ TEST_SUBMODULE(builtin_casters, m) {
m.def("string_view16_return", []() { return std::u16string_view(u"utf16 secret \U0001f382"); });
m.def("string_view32_return", []() { return std::u32string_view(U"utf32 secret \U0001f382"); });
// The inner lambdas here are to also test implicit conversion
using namespace std::literals;
m.def("string_view_bytes", []() { return [](py::bytes b) { return b; }("abc \x80\x80 def"sv); });
m.def("string_view_str", []() { return [](py::str s) { return s; }("abc \342\200\275 def"sv); });
m.def("string_view_from_bytes", [](const py::bytes &b) { return [](std::string_view s) { return s; }(b); });
#if PY_MAJOR_VERSION >= 3
m.def("string_view_memoryview", []() {
static constexpr auto val = "Have some \360\237\216\202"sv;
return py::memoryview::from_memory(val);
});
#endif
# ifdef PYBIND11_HAS_U8STRING
m.def("string_view8_print", [](std::u8string_view s) { py::print(s, s.size()); });
m.def("string_view8_chars", [](std::u8string_view s) { py::list l; for (auto c : s) l.append((std::uint8_t) c); return l; });
m.def("string_view8_return", []() { return std::u8string_view(u8"utf8 secret \U0001f382"); });
m.def("string_view8_str", []() { return py::str{std::u8string_view{u8"abc ‽ def"}}; });
# endif
struct TypeWithBothOperatorStringAndStringView {
// NOLINTNEXTLINE(google-explicit-constructor)
operator std::string() const { return "success"; }
// NOLINTNEXTLINE(google-explicit-constructor)
operator std::string_view() const { return "failure"; }
};
m.def("bytes_from_type_with_both_operator_string_and_string_view",
[]() { return py::bytes(TypeWithBothOperatorStringAndStringView()); });
m.def("str_from_type_with_both_operator_string_and_string_view",
[]() { return py::str(TypeWithBothOperatorStringAndStringView()); });
#endif
// test_integer_casting