basic_json_view::dump(indent, indent_char, ensure_ascii, number_format)
writes the text of a value as ordered_json::parse(text).dump() writes it
for the same arguments: members in document order (all of them, should a
key occur more than once), strings escaped by the same rules and with the
library's scanning kernels, floats with the library's conversion, and
integers copied from the source, where they are canonical except "-0".
With number_format::source, numbers are copied as they appear in the
source ("1.50", "1E2", "-0", all digits of long integers). operator<<
takes the indentation from the stream width, as for basic_json.
The writer (detail/view/serializer.hpp) writes through a raw pointer into
a string sized from the source extent of the value, and walks the index
iteratively, so the nesting depth is limited by memory only.
Tests compare the output of 2,000 generated documents with
ordered_json::dump() for several indentations and ensure_ascii, strings
with every kind of escape, numbers (5,000 random doubles, float as
number_float_t), duplicate keys, 100,000 levels of nesting, and streams.
ViewDump joins the benchmarks.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
benchmarks_view.cpp adds ViewParse, ViewRead (a reused document),
ViewParseIndented, ViewAccept, and ViewMaterialize on the files of
ParseString, so that each row can be read against the json::parse row of
the same file; benchmarks.cpp gains Accept (json::accept) as the
counterpart of ViewAccept. The view benchmarks are built only if the
header directory has json_view.hpp, so that older versions can still be
benchmarked.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Document the benchmarks, and make them build and compare versions again
The benchmark project hasn't configured since #4793: download_test_data.cmake
compiles cmake/detect_libcpp_version.cpp relative to CMAKE_SOURCE_DIR, which
is tests/benchmarks when that is the top-level project, so try_run fails and
so does `make run_benchmarks`. The path is now relative to the module itself,
which is the same file for the main build.
The Dump benchmark discarded dump()'s result, which is [[nodiscard]] by now;
it warned, and left the optimizer free to shorten the loop. The result is
now kept with benchmark::DoNotOptimize.
A new cache variable, JSON_BENCHMARK_INCLUDE_DIR, names the directory holding
the nlohmann/json.hpp to benchmark (single_include by default, as before),
so the same benchmarks can be built against two versions and compared.
tests/benchmarks/README.md documents what is measured, how to build and run
the benchmarks, how to read the output, and how to compare two versions with
Google Benchmark's compare.py; it recommends doing so by hand before a
release rather than in CI.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Point ci_benchmarks at tests/benchmarks
The target has configured ${PROJECT_SOURCE_DIR}/benchmarks since it was
added in #2561, but the benchmarks live in tests/benchmarks.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Pin Google Benchmark to release 1.9.5
The benchmarks fetched Google Benchmark's main branch, so two builds on
different days could measure with different library code, and CMake 3.30
and later warn that the single-argument FetchContent_Populate() is
deprecated. Fetch the 1.9.5 release archive, verified by its SHA-256,
with FetchContent_MakeAvailable() instead. That needs CMake 3.14; Google
Benchmark itself already needed 3.13.
Its -Werror is switched off, so a newer compiler's new warnings cannot
break the pinned release, and its install rules are no longer added.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
---------
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
