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direct serialization docs

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Dmitry Arkhipov 2024-09-16 18:47:48 +03:00
parent 7b493e792a
commit 8e1fc20896
2 changed files with 17 additions and 8 deletions
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21
doc/qbk/conversion/direct.qbk
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@ -13,8 +13,10 @@
[section Direct parsing]
For large inputs parsing into the library's containers followed by conversion
via __value_to__ might be prohibitively expensive. For these cases the library
provides components that allow parsing directly into user-provided objects.
via __value_to__ (or vice versa __value_from__ followed by serialization from
a __value__) might be prohibitively expensive. For these cases the library
provides components that allow parsing directly into and serializing directly
from user-provided objects.
The drawback of this approach is that fully custom type representations are
not supported, only the library-provided conversions are. Also all objects that
@ -23,8 +25,8 @@ includes not only the top-level object, but e.g. elements of containers,
members of described `struct`s, and alternatives of variants.
That being said, if your types are default-constructible and you don't need
the customisability allowed by __value_to__, then you can get a significant
performance boost with direct parsing.
the customisability allowed by __value_to__ and __value_from__, then you can
get a significant performance boost with direct parsing.
Direct parsing is performed by the __parse_into__ family of functions. The
library provides overloads that take either __string_view__ or `std::istream`,
@ -32,9 +34,12 @@ and can report errors either via throwing exceptions or setting an error code.
[doc_parse_into_1]
Finally, if you need to combine incremental parsing with direct parsing, you
can resort to __parser_for__. `parser_for<T>` is an instantiation of
__basic_parser__ that parses into an object of type `T`, and is what
__parse_into__ uses under the hood.
If you need to combine incremental parsing with direct parsing, you can resort
to __parser_for__. `parser_for<T>` is an instantiation of __basic_parser__ that
parses into an object of type `T`, and is what __parse_into__ uses under
the hood.
Direct serialization doesn't require any special components and works with the
refular __serializer__ and __serialize__.
[endsect]

4
test/snippets.cpp
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@ -1152,6 +1152,10 @@ usingParseInto()
string_view input = R"( { "even": [2,4,6], "odd": [1,3,5] } )";
parse_into(vectors, input);
//]
std::string output = serialize(vectors);
(void)output;
assert( output == R"({"even":[2,4,6],"odd":[1,3,5]})" );
}
} // namespace