Basic string_view support #1217
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independent of UNICODE vs MBCS setting Set CPPREST_FORCE_NARROW_STRINGS=ON to enable. Simplistic cleanup throughout project is not possible as some Windows APIs require utf16 such as HTTPSPolicyCallbackData in http_client_winhttp.cpp. HTTP related code is not completely updated so a full package may not be produced, though settings exist to have a clean build. Use: -DCPPREST_FORCE_NARROW_STRING=ON -DCPPREST_EXCLUDE_WEBSOCKETS=ON -DCPPREST_HTTP_LISTENER_IMPL=none -DBUILD_SAMPLES=OFF
…omponents like just json support extractions from asyncrt_utils.h: base64_utils.h (to/form base64) memory_utils.h (details::make_unique) string_utils.cpp (string utils) asyncrt_utils retains error, date-time, and nounce utils
- default to enable CPPREST_USE_STRING_VIEWS when compiler supports C++ 17 most string utility and json APIs are changed to support string_views (deprecated APIs left alone) primary argument replacements: const utility::string_t& -> utility::string_view_t const std::string& -> utility::nstring_view_t const std::wstring& -> utility::wstring_view_t const utf16string& -> utf16string_view potential client fallout when enabling option: For clients passing char* to conversion that does not require conversion, string_view will be the result. If string type is actually required then an explicit ctor would need to be added. Otherwise client may be able to use more string_view in own code and futher reduce memory copies. See searchfile.cpp in Samples for example. Use of foo.c_str() and &foo[0] on a potential string_view is now foo.data().
- forced on for VS 2017 - forced off for VS 2015 - default for all others
+ add respect for CMAKE_CXX_STANDARD when set
barcharcraz
reviewed
Aug 28, 2019
…nto jason-ha/basic_string_view_support
…nto jason-ha/basic_string_view_support
| #else | ||
| inline const utility::string_t& to_string_t(const std::string& s) { return s; } | ||
| #if CPPREST_USE_STRING_VIEWS | ||
| inline utility::string_view_t to_string_t(utility::nstring_view_t s) { return s; } |
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All overloads of to_string_t should return a string object, not a string view, since the expectations of the function is to return a string object:
/// <param name="s">A single byte character UTF-8 string.</param>
If you sometimes return a string object and sometimes a string view it may lead to unexpected disasters, e.g.:
auto text = to_string_t(getSomeText());
If getSomeText() returns a string object or a string view, you're OK.
But if it returns something convertible to string view, after that statement the returned temporary is destroyed, text is dangling now and you're most certainly screwed.
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addresses issue #1216
Add CPPREST_USE_STRING_VIEWS option to accept string_views as input
most string utility and json APIs are changed to support string_views
(deprecated APIs left alone)
primary argument replacements:
const utility::string_t& -> utility::string_view_t
const std::string& -> utility::nstring_view_t
const std::wstring& -> utility::wstring_view_t
const utf16string& -> utf16string_view
potential client fallout when enabling option:
For clients passing char* to conversion that does not require conversion, string_view will be the result. If string type is actually required then an explicit ctor would need to be added. Otherwise client may be able to use more string_view in own code and futher reduce memory copies. See searchfile.cpp in Samples for example.
Use of foo.c_str() and &foo[0] on a potential string_view is now foo.data().
This PR also includes changes from PR #1230
To see changes with that PR as baseline review jason-ha#3.