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https://github.com/nlohmann/json.git
synced 2026-10-10 08:27:13 +00:00
Niels Lohmann
da1ca7f9d7
Add basic_json_view::dump() and the comparison operators, and read floats from the parser's digit layout instead of rescanning the token. dump(indent, indent_char, ensure_ascii, number_format) writes a value the way 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, using the library's scanning kernels; floats written with the library's to_chars conversion, so the output equals basic_json's byte for byte; integers copied from the source, where they are already canonical, except -0, which parse() reads as 0. There is no error_handler argument, because the view only holds valid UTF-8. number_format::source copies numbers exactly as they appear in the source (e.g. "1.50", "1E2", "-0"), which basic_json cannot provide. operator<< takes the indentation from the stream width, as for basic_json. The writer walks iteratively, so nesting depth is limited by memory only. operator== and operator!= compare two views, or a view and a basic_json value in either order, by the rules basic_json's operator== uses: numbers compare by value across their types, objects compare by their members with duplicate keys resolved as parse() resolves them, member order matters only where the object type keeps one, and discarded views compare as discarded basic_json values do, including under JSON_USE_LEGACY_DISCARDED_VALUE_COMPARISON. Nothing is materialized except single scalars. While parsing, the view now records where the integer digits, the fraction digits, and the exponent of a float token are, so floats and doubles with at most 19 digits are read from that layout with the library's decimal_to_float() instead of rescanning the token. Both round correctly, so the values are those of parse(). get<double>(), materialize(), dump(), and the comparisons all use it. Signed-off-by: Niels Lohmann <mail@nlohmann.me>
181 lines
7.8 KiB
C++
181 lines
7.8 KiB
C++
// __ _____ _____ _____
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// __| | __| | | | JSON for Modern C++ (supporting code)
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// | | |__ | | | | | | version 3.12.0
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// |_____|_____|_____|_|___| https://github.com/nlohmann/json
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//
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// SPDX-FileCopyrightText: 2013-2026 Niels Lohmann <https://nlohmann.me>
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// SPDX-License-Identifier: MIT
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// Benchmarks of json_document (nlohmann/json_view.hpp). They use the inputs of
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// ParseString and ParseIndented in benchmarks.cpp, so that each ViewParse row
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// can be read against the json::parse row of the same file.
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#include <benchmark/benchmark.h>
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#include <nlohmann/json_view.hpp>
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#include <fstream>
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#include <iterator>
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#include <string>
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#include <test_data.hpp>
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using json = nlohmann::json;
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using json_document = nlohmann::json_document;
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static std::string read_file(const char* filename)
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{
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std::ifstream f(filename, std::ios::binary);
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return std::string((std::istreambuf_iterator<char>(f)), std::istreambuf_iterator<char>());
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}
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#define JSON_VIEW_BENCHMARK_FILES(fn) \
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BENCHMARK_CAPTURE(fn, jeopardy, TEST_DATA_DIRECTORY "/jeopardy/jeopardy.json"); \
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BENCHMARK_CAPTURE(fn, canada, TEST_DATA_DIRECTORY "/nativejson-benchmark/canada.json"); \
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BENCHMARK_CAPTURE(fn, citm_catalog, TEST_DATA_DIRECTORY "/nativejson-benchmark/citm_catalog.json"); \
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BENCHMARK_CAPTURE(fn, twitter, TEST_DATA_DIRECTORY "/nativejson-benchmark/twitter.json"); \
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BENCHMARK_CAPTURE(fn, floats, TEST_DATA_DIRECTORY "/regression/floats.json"); \
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BENCHMARK_CAPTURE(fn, signed_ints, TEST_DATA_DIRECTORY "/regression/signed_ints.json"); \
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BENCHMARK_CAPTURE(fn, unsigned_ints, TEST_DATA_DIRECTORY "/regression/unsigned_ints.json"); \
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BENCHMARK_CAPTURE(fn, small_signed_ints, TEST_DATA_DIRECTORY "/regression/small_signed_ints.json")
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//////////////////////////////////////////////////////////////////////////////
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// parse into a new document (compare with ParseString)
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//////////////////////////////////////////////////////////////////////////////
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static void ViewParse(benchmark::State& state, const char* filename)
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{
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const std::string str = read_file(filename);
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while (state.KeepRunning())
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{
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state.PauseTiming();
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auto* d = new json_document();
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state.ResumeTiming();
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*d = json_document::parse(str);
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state.PauseTiming();
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delete d;
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state.ResumeTiming();
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}
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state.SetBytesProcessed(state.iterations() * str.size());
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}
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JSON_VIEW_BENCHMARK_FILES(ViewParse);
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//////////////////////////////////////////////////////////////////////////////
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// parse into a document that is reused (its memory stays allocated)
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//////////////////////////////////////////////////////////////////////////////
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static void ViewRead(benchmark::State& state, const char* filename)
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{
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const std::string str = read_file(filename);
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json_document d;
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while (state.KeepRunning())
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{
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d.read(str);
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benchmark::DoNotOptimize(d);
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}
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state.SetBytesProcessed(state.iterations() * str.size());
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}
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JSON_VIEW_BENCHMARK_FILES(ViewRead);
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//////////////////////////////////////////////////////////////////////////////
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// parse pretty-printed JSON (compare with ParseIndented)
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//////////////////////////////////////////////////////////////////////////////
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static void ViewParseIndented(benchmark::State& state, const char* filename, int indent)
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{
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const std::string indented = json::parse(read_file(filename)).dump(indent);
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json_document d;
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while (state.KeepRunning())
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{
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d.read(indented);
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benchmark::DoNotOptimize(d);
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}
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state.SetBytesProcessed(state.iterations() * indented.size());
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}
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BENCHMARK_CAPTURE(ViewParseIndented, jeopardy / 4, TEST_DATA_DIRECTORY "/jeopardy/jeopardy.json", 4);
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BENCHMARK_CAPTURE(ViewParseIndented, canada / 4, TEST_DATA_DIRECTORY "/nativejson-benchmark/canada.json", 4);
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BENCHMARK_CAPTURE(ViewParseIndented, citm_catalog / 4, TEST_DATA_DIRECTORY "/nativejson-benchmark/citm_catalog.json", 4);
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BENCHMARK_CAPTURE(ViewParseIndented, twitter / 4, TEST_DATA_DIRECTORY "/nativejson-benchmark/twitter.json", 4);
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//////////////////////////////////////////////////////////////////////////////
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// validate only (compare with Accept)
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//////////////////////////////////////////////////////////////////////////////
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static void ViewAccept(benchmark::State& state, const char* filename)
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{
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const std::string str = read_file(filename);
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while (state.KeepRunning())
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{
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benchmark::DoNotOptimize(json_document::accept(str));
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}
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state.SetBytesProcessed(state.iterations() * str.size());
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}
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JSON_VIEW_BENCHMARK_FILES(ViewAccept);
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//////////////////////////////////////////////////////////////////////////////
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// convert a parsed document into a json value
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//////////////////////////////////////////////////////////////////////////////
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static void ViewMaterialize(benchmark::State& state, const char* filename)
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{
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const std::string str = read_file(filename);
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const json_document d = json_document::parse(str);
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while (state.KeepRunning())
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{
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state.PauseTiming();
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auto* j = new json();
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state.ResumeTiming();
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*j = d.root().materialize();
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state.PauseTiming();
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delete j;
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state.ResumeTiming();
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}
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state.SetBytesProcessed(state.iterations() * str.size());
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}
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JSON_VIEW_BENCHMARK_FILES(ViewMaterialize);
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//////////////////////////////////////////////////////////////////////////////
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// serialize a parsed document (compare with Dump)
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//////////////////////////////////////////////////////////////////////////////
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static void ViewDump(benchmark::State& state, const char* filename, int indent)
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{
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const std::string str = read_file(filename);
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const json_document d = json_document::parse(str);
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while (state.KeepRunning())
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{
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std::string output = d.root().dump(indent);
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benchmark::DoNotOptimize(output);
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}
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state.SetBytesProcessed(state.iterations() * d.root().dump(indent).size());
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}
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BENCHMARK_CAPTURE(ViewDump, jeopardy / -, TEST_DATA_DIRECTORY "/jeopardy/jeopardy.json", -1);
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BENCHMARK_CAPTURE(ViewDump, jeopardy / 4, TEST_DATA_DIRECTORY "/jeopardy/jeopardy.json", 4);
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BENCHMARK_CAPTURE(ViewDump, canada / -, TEST_DATA_DIRECTORY "/nativejson-benchmark/canada.json", -1);
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BENCHMARK_CAPTURE(ViewDump, canada / 4, TEST_DATA_DIRECTORY "/nativejson-benchmark/canada.json", 4);
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BENCHMARK_CAPTURE(ViewDump, citm_catalog / -, TEST_DATA_DIRECTORY "/nativejson-benchmark/citm_catalog.json", -1);
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BENCHMARK_CAPTURE(ViewDump, citm_catalog / 4, TEST_DATA_DIRECTORY "/nativejson-benchmark/citm_catalog.json", 4);
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BENCHMARK_CAPTURE(ViewDump, twitter / -, TEST_DATA_DIRECTORY "/nativejson-benchmark/twitter.json", -1);
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BENCHMARK_CAPTURE(ViewDump, twitter / 4, TEST_DATA_DIRECTORY "/nativejson-benchmark/twitter.json", 4);
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BENCHMARK_CAPTURE(ViewDump, floats / -, TEST_DATA_DIRECTORY "/regression/floats.json", -1);
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BENCHMARK_CAPTURE(ViewDump, floats / 4, TEST_DATA_DIRECTORY "/regression/floats.json", 4);
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BENCHMARK_CAPTURE(ViewDump, signed_ints / -, TEST_DATA_DIRECTORY "/regression/signed_ints.json", -1);
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BENCHMARK_CAPTURE(ViewDump, signed_ints / 4, TEST_DATA_DIRECTORY "/regression/signed_ints.json", 4);
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BENCHMARK_CAPTURE(ViewDump, unsigned_ints / -, TEST_DATA_DIRECTORY "/regression/unsigned_ints.json", -1);
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BENCHMARK_CAPTURE(ViewDump, unsigned_ints / 4, TEST_DATA_DIRECTORY "/regression/unsigned_ints.json", 4);
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BENCHMARK_CAPTURE(ViewDump, small_signed_ints / -, TEST_DATA_DIRECTORY "/regression/small_signed_ints.json", -1);
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BENCHMARK_CAPTURE(ViewDump, small_signed_ints / 4, TEST_DATA_DIRECTORY "/regression/small_signed_ints.json", 4);
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