Result types module

Result and error types.

Instead of using exceptions, scn::scan and others return an object of type scn::scan_result, wrapped inside a scn::scan_expected.

Classes

template <typename T, typename E>
class scn::v3::expected
class scn::v3::scan_error
template <typename T>
struct scn::v3::scan_expected

Functions

template <typename Result, typename... Args>
auto make_scan_result(scan_expected<Result>&& result, std::tuple<Args...>&& args) →  scan_expected< scan_result< Result, Args... >> -> auto

Function documentation

template <typename Result, typename... Args>
auto make_scan_result(scan_expected<Result>&& result, std::tuple<Args...>&& args) →  scan_expected< scan_result< Result, Args... >>

Convenience function to construct the value to return from scan, based on the return value of vscan, and the argument store.

Takes its arguments by rvalue reference to disallow extraneous copying.

Note: Because vscan places the values it scanned into the argument store passed to it, the call to make_scan_result needs to happen strictly after calling vscan. This means, that this is UB: return scn::make_scan_result(scn::vscan(...), std::move(args.args()));

Example:

auto args = scn::make_scan_args<scan_context, Args...>();
auto result = scn::vscan(std::forward<Source>(source), format, args);
return scn::make_scan_result(std::move(result), std::move(args.args()));