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Niels Lohmann
1e101ecac1
* Add BON8 support Add to_bon8/from_bon8 and input_format_t::bon8 for BON8, a binary format that uses the byte values that cannot begin a UTF-8 character as type markers, so strings need no length prefix. It is the most compact of the supported binary formats on the benchmark files. The reader is non-recursive like the other binary readers. A string ends at the first byte that cannot continue it, so the reader hands the one or two bytes it reads past a string back to the value that follows. The writer produces the canonical representation of the specification, except for NFC normalization; its output is identical to that of the reference implementation (HikoGUI) on all files of the test data. The round-trip tests need the .bon8 files of json_test_data 3.2.0. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Address review comments - Reuse detail::validate_one_utf8 to check strings in to_bon8; the error now names the first byte of the invalid sequence. - Document that to_bon8 leaves bytes in the output adapter on an exception, and that string_open is only an output of write_bon8_marker. - Explain why the pushback buffer of the BON8 reader cannot overflow. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Select the BON8 float prefix by type get_bon8_float_prefix only depends on the type of its argument, so make the type a template parameter instead of passing an unused value. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Rename a test variable that Flawfinder mistakes for read() Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Fix the BON8 CI failures - compare the float in write_bon8_float with number_float_t constants, so GCC does not warn about a float-to-double conversion - mark check_bon8_utf8's context as used when exceptions are disabled - choose the compact float prefix in a helper rather than with nested conditional operators (clang-tidy) - use auto for the cast in the BON8 integer reader (clang-tidy) - write the int32 minimum test values as long long literals (MSVC C4146) Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Amalgamate Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Read BON8 strings in bulk from contiguous input - copy the valid UTF-8 of a string in one step when the input is contiguous (twitter.json is read in 1.68 instead of 2.52 ms, jeopardy.json in 196 instead of 297 ms, close to CBOR and MessagePack) - share the new valid_utf8_prefix() with the writer's UTF-8 check, which now skips ASCII 8 bytes at a time - let the fuzzer check that contiguous and stream input give the same value or error, and test both paths in the unit tests - clarify that a second 0xFF after a string is an empty string Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Link the BON8 functions from the other binary format pages Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Name the bulk scan flag after the input, not BON8 Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Read BSON keys in bulk from contiguous input BSON keys (and array indices) are C-style strings, which were read byte by byte. For contiguous input they are now read up to their \x00-byte in one step, using the same bulk_scan flag as BON8 strings: twitter.json is read in 1.46 instead of 2.01 ms, citm_catalog.json in 2.93 instead of 3.33 ms, jeopardy.json in 182 instead of 207 ms. canada.json, whose keys are almost all one-digit array indices, takes 2 % longer. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Fix the BON8 CI failures of the bulk-read tests - skip the contiguous-versus-stream tests of BON8 strings and BSON keys when exceptions are disabled: they catch the parse errors of invalid input, and without exceptions the library aborts instead - use static_cast for the int64 test value (google-readability-casting) Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Move the explicit basic_json instantiation into its own test file Linking test-regression3_cpp20 with clang and MinGW failed with "relocation truncated to fit: IMAGE_REL_AMD64_REL32 against `.rdata'", as test-regression2 did before #5511. The explicit instantiation of basic_json<> for #4825 compiles every member function, including the BON8 reader and writer, into that object, and it was already close to the limit (2,226,104 bytes on develop, 2,234,960 with BON8; clang -O1, C++20). Give the instantiation a file of its own: unit-regression3 is now 1,594,736 bytes and unit-explicit_instantiation 1,095,064. The new file mentions JSON_HAS_CPP_17 and JSON_HAS_CPP_20 so it keeps being built for the C++17 standard the regression was about. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Convert the bytes of the BON8 test strings explicitly The str() helper constructed a std::string from a byte range, which converts each unsigned char implicitly; -fsanitize=integer reports that for bytes of 0x80 and above (ci_test_clang_sanitizer). Signed-off-by: Niels Lohmann <mail@nlohmann.me> --------- Signed-off-by: Niels Lohmann <mail@nlohmann.me>
54 lines
3.2 KiB
Markdown
54 lines
3.2 KiB
Markdown
# Features
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This section describes the features of the library in detail. If you are new to the library, the pages below are
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roughly ordered along a typical workflow: create or parse a value, access and modify it, convert it to and from your own
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C++ types, and finally serialize it again.
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## Creating and reading values
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- [Creating JSON values](creating_values.md) — build values from literals, initializer lists, and STL containers, and
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understand the `#!cpp {}` vs. `#!cpp []` ambiguity.
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- [Parsing](parsing/index.md) — read a JSON value from a string, file, or stream, including
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[JSON Lines](parsing/json_lines.md), [callbacks](parsing/parser_callbacks.md), the
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[SAX interface](parsing/sax_interface.md), and [error handling](parsing/parse_exceptions.md).
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- [Comments](comments.md) and [trailing commas](trailing_commas.md) — opt-in relaxations of the JSON grammar.
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## Accessing and modifying values
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- [Element access](element_access/index.md) — unchecked ([`operator[]`](element_access/unchecked_access.md)),
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checked ([`at`](element_access/checked_access.md)), and access with a
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[default value](element_access/default_value.md).
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- [JSON Pointer](json_pointer.md) — address values deep inside a document with [RFC 6901](https://tools.ietf.org/html/rfc6901) pointers.
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- [Iterators](iterators.md) — traverse arrays and objects.
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- [Modifying values](modifying_values.md) — add, update, merge, and remove elements.
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- [JSON Patch and Diff](json_patch.md) and [JSON Merge Patch](merge_patch.md) — apply and compute structured changes.
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## Converting to and from C++ types
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- [Converting values](conversions.md) — get values out with [`get`](../api/basic_json/get.md)/[`get_to`](../api/basic_json/get_to.md),
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and understand implicit conversions.
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- [Arbitrary types conversions](arbitrary_types.md) — teach the library about your own structs and classes.
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- [Specializing enum conversion](enum_conversion.md) — map enums to strings instead of integers.
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## Serializing values
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- [Serialization](serialization.md) — turn a value back into JSON text with [`dump`](../api/basic_json/dump.md),
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including pretty-printing and handling of non-ASCII and invalid UTF-8.
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- [Binary formats](binary_formats/index.md) — encode values more compactly as
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[BJData](binary_formats/bjdata.md), [BON8](binary_formats/bon8.md), [BSON](binary_formats/bson.md),
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[CBOR](binary_formats/cbor.md), [MessagePack](binary_formats/messagepack.md), or [UBJSON](binary_formats/ubjson.md).
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- [Binary values](binary_values.md) — store and exchange raw byte sequences.
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## How values are stored and configured
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- [Types](types/index.md) and [number handling](types/number_handling.md) — how JSON types map to C++ types and how
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numbers are treated.
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- [Object order](object_order.md) — keep insertion order with [`ordered_json`](../api/ordered_json.md).
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- [Runtime assertions](assertions.md), [supported macros](macros.md), the [`nlohmann` namespace](namespace.md), and
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[C++ modules](modules.md) — build-time and runtime configuration.
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!!! tip "Looking for a specific function?"
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This section gives conceptual overviews. For the precise signature, parameters, and return value of a function, see
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the [API Documentation](../api/basic_json/index.md).
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