Exit Zen
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To go from JSON to a user-defined type we use <<ref_value_to>>, which uses another overload of `tag_invoke`. This converts a JSON value to a `customer`. It throws an exception if the contents of the value do not match what is expected:
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{icon_good} Parsing and serialization performance is better than most other
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The result is equal to the result of conversion of the active variant
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<<ref_string>> directly supports access to its storage in the range `[size(), capacity())`. This can be used for efficient assembly of a string from several parts. After the string is assembled, use the member function <<ref_string_grow>> to update the string's size and insert the null terminator. For example:
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when reading the input. For example, `std::getline` removes the endline characters from the string it produces.
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The largest file, containing a large number of 2-element arrays holding
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alternative. |The result holds the first alternative for which a conversion succeeds.
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The library's generic algorithms recognize when you are converting a <<ref_value>> to a container which resembles an array or object, so if you wanted to turn a JSON array into a vector of customers you might write:
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floating-point coordinate pairs.
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The default algorithm that the library uses to parse numbers is fast, but may result in slight precision loss. This may not be suitable for some applications, so there is an option to enable an alternative algorithm that doesn't have that flaw, but is somewhat slower. To do this, you also need to use <<ref_parse_options>> structure.
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Note that full precision number parsing requires the algorithm to see the full number. This means, that when used with <<ref_stream_parser>>, additional memory allocations may be necessary to store the number parts which were so far accepted by the parser. The library does try its best to avoid such allocations.
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Type satisfying <<ref_is_map_like>>.
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Instances of <<ref_parser>> and <<ref_stream_parser>> offer functionality beyond what is available when using the <<ref_parse>> free functions:
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The result is an <<ref_object>>.
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Type satisfying <<ref_is_sequence_like>>.
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Visit https://boost.org/libs/json for complete documentation.
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The default memory resource uses the global `operator new` and `operator delete` to allocate memory. This resource is not reference counted and has a non-trivial deallocate function. All default-constructed <<ref_storage_ptr>> objects reference the same memory resource:
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The parser implementation uses temporary storage space to accumulate values during parsing. When using the <<ref_parse>> free functions, this storage is allocated and freed in each call. However, by declaring an instance of <<ref_parser>> or <<ref_stream_parser>>, this temporary storage can be reused when parsing more than one JSON text, reducing the total number of dynamic memory allocations.
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The result is an <<ref_array>>.
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To use the <<ref_parser>>, declare an instance. Then call <<ref_parser_write>> once with the buffer containing representing the input JSON. Finally, call <<ref_parser_release>> to take ownership of the resulting <<ref_value>> upon success. This example persists the parser instance in a class member to reuse across calls:
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