3 Commits

Include renames

Author	SHA1	Message	Date
Niels Lohmann	dd7686a269	json_view: faster reading, indexing and C-stream parsing (#5888) ... * Read C streams into a json_document in blocks json_document::parse(FILE*) (and read(), accept(), parse_copy()) went through the library's file input adapter and appended the text character by character with fgetc. Read it with fread in blocks instead, like the std::istream overload already does. Parsing citm_catalog.json (1.7 MB) from a FILE*: Apple M1: 80.6 M -> 8.4 M instructions, 4.8 ms -> 0.55 ms (parse of the same text from a std::string: 8.7 M) Linux x86-64 Ir (whole run), GCC 13 / Clang 18: 47.0 M -> 13.7 M / 45.8 M -> 14.2 M The parsed documents and the error cases are identical (checked over the test corpus and 30 mutants of each file). A null FILE* is handled as before (by the library's adapter). Belongs to the PR "json_view: read-side speedups". Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Index arrays without subtrees directly operator[](idx), at(idx) and back() skipped the elements of an array one after the other, whatever they were. In an array none of whose elements is an array or object (numbers, strings, booleans, null) the elements are adjacent nodes, which the array node's own sizes tell: its subtree has exactly one node more than it has elements. Such an element is now the node idx after the array node; any other array is walked as before. Reading r[i] for every i of an array of 3000 integers: Apple M1: 28.8 M instructions, 3.1 ms -> 0.1 M instructions, 4 us Linux x86-64 Ir (whole run), GCC 13 / Clang 18: 84.1 M -> 3.1 M / 75.0 M -> 3.0 M Arrays that contain arrays are unchanged. Belongs to the PR "json_view: read-side speedups". Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Skip the bounds checks of number and string tokens in NUL-terminated input For a NUL-terminated input (std::string, C string, string literal), the parser reads the terminator instead of comparing p with the end, via cursor::cur(). Number and string scanning still tested `p != e` before each look at the next byte (after the integer digits for '.', for 'e', after the exponent sign and digits, and after a string for its closing quote), although the terminator can never be one of those characters. They now use cur(), which is the plain load for NUL-terminated input and the bounds check for ptr+len input, as before. Parsing, Apple M1 instructions per parse: twitter 3.126 M -> 3.089 M (-1.2 %), citm_catalog 8.70 M -> 8.58 M (-1.3 %), jeopardy 306.1 M -> 302.5 M (-1.2 %), signed integers 281 M -> 266 M (-5.4 %), canada and floats -0.1 % / -0.9 %. Linux x86-64 Ir, GCC 13 / Clang 18: twitter -0.5 % / -0.0 %, signed integers +0.2 % / -0.7 %. Belongs to the PR "json_view: read-side speedups". Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Make the index text of items() on arrays lazy basic_json_view::items() on an array formatted every element's index with std::to_string when the item was made, whether or not the loop asks for the key. The item now keeps the position and makes the text on the first key() call. Objects are not affected. Iterating over the items of an array of 3000 numbers and reading only the values: Apple M1: 25.5 us -> 4.6 us (0.45 M -> ~0 net instructions) Linux x86-64 Ir (whole run), GCC 13 / Clang 18: 14.9 M -> 4.1 M / 15.3 M -> 4.6 M Reading key() costs what it did (24.5 us). Belongs to the PR "json_view: read-side speedups". Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Make the default of value() with a C string only if the member is missing basic_json_view::value(key, "text") and value(pointer, "text") built a std::string from the default first and passed it on, so a call allocated for the default even when the member exists, and copied it again when it does not. They now look the member up and make the result directly: from the member if there is one, else from the C string. Behavior, including the exceptions, is the same. Two calls (member found, member missing) with a 40 character default, Apple M1: 1.6 K -> 0.7 K instructions Linux x86-64 Ir (500 rounds), GCC 13 / Clang 18: 2.46 M -> 2.22 M / 2.40 M -> 2.15 M Belongs to the PR "json_view: read-side speedups". Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Materialize scalars directly and keep the stack of small subtrees local basic_json_view::materialize() (and get<BasicJsonType>()) always set up the SAX handler that parse() uses and a std::vector for the open containers, sized from the document's deepest nesting. For a scalar, which is most of what is materialized one value at a time, neither is needed: the value is made directly (the same constructors the handler ends up calling). For arrays and objects the stack of open containers is now a local array for the first 16 levels, and the vector is only used for deeper documents. Materializing five scalars of a small document, Apple M1: 3.6 K -> 0.9 K instructions Linux x86-64 Ir (500 rounds), GCC 13 / Clang 18: 2.96 M -> 2.37 M / 2.90 M -> 2.29 M Belongs to the PR "json_view: read-side speedups". Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Copy the text between escapes while scanning it A string that contains an escape is decoded by builder::slow_string(). After each escape it scanned the next run of plain bytes (8 or 16 byte-by-byte steps, then a vector loop), and then copied that run to the decode arena in a second pass. The run is now copied 16 bytes at a time while it is scanned (one vector load, a store of the same 16 bytes, and the mask of the bytes that end the run), and the write position lives in a local variable, not in the builder, since a store of a character may alias the builder's members and made the compiler reload it after every escape. A run that ends at a quote needs no scan, and non-ASCII text goes through the UTF-8 check as before; the portable code is unchanged. Parsing, Apple M1 instructions: jeopardy.json 304.0 M -> 293.8 M (-3.4 %), 3000 strings with escapes 1.72 M -> 1.54 M (-10 %), twitter -0.6 %. Linux x86-64 Ir, GCC 13 / Clang 18: escaped strings -7.6 % / -11.4 %, twitter 0.0 % / 0.0 %. Documents and error messages are identical on 900 k random strings of escapes, UTF-8 and control characters (also under ASan), and on mutants of the test corpus. Belongs to the PR "json_view: read-side speedups". Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Hash the last bytes of a key of a large object without a loop key_hash() mixed a key eight bytes at a time and then packed the remaining 0-7 bytes one by one, in a loop. The last word of a key of eight or more bytes is now read as the last eight bytes of the key (overlapping the word before), and a key of 2-7 bytes as two overlapping words of four or two bytes. A product only moves bits upwards, and the slot is taken from the low bits: the high bits of the last word are folded down before the multiplication, since keys that differ only in their last characters ("user_17", "user_18") would otherwise share slots. The hash is not stored, so its values may change. Looking up every key of an object of 1000 random keys, Apple M1 instructions per 1000 lookups: keys of 5 bytes 175 K -> 93 K, hex strings of 8 bytes 177 K -> 168 K, keys of 12 bytes 196 K -> 186 K Linux x86-64 Ir (whole run), GCC 13 / Clang 18: 5-byte keys -4.7 % / -8.8 %, 12-byte keys -3.3 % / -7.4 %. Building the tables while parsing such objects is cheaper as well (5-byte keys: 13.3 us -> 10.1 us). Belongs to the PR "json_view: read-side speedups". Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Compare short keys of a large object without a call of memcmp find_indexed() compared the key of a member the table points to with memcmp, a library call for any length. Up to 16 bytes, the bytes are now compared as two overlapping words (the first and the last 8, 4, or 2 bytes), as find_member() already does for the objects without a table; longer keys still use memcmp. Looking up every key of an object of 1000 random keys, Apple M1 instructions per 1000 lookups (with the previous commit): keys of 5 bytes 93 K -> 72 K, hex strings of 8 bytes 168 K -> 148 K, keys of 12 bytes 186 K -> 170 K, keys of 24 bytes 198 K -> 193 K (unchanged, memcmp). Linux x86-64 Ir (whole run), GCC 13 / Clang 18: 5-byte keys -7.2 % / -7.3 %, 12-byte keys -5.9 % / -6.6 %. Belongs to the PR "json_view: read-side speedups". Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Read an unedited editable document like a read-only one Views of a json_editable_document followed edits at every step: the lookup, the element access, back(), dump() and materialize() were built for nodes that can be moved or linked, though no edit changes the index until the first one (every edit creates the edit state before it touches a node). Until then these now take the read-only code: one check of the document's edit state per call, not per member or per node. After the first edit nothing changes. Views that were made earlier keep working, as the check is made when they are used. Unedited editable document, Apple M1: dump() of twitter.json 1.40 M -> 1.22 M instructions (-12.6 %); lookups unchanged. Linux x86-64 Ir, GCC 13 / Clang 18: dump -1.7 % / -1.0 %, lookups -0.1 % / 0.0 %. Walking with iterators is unchanged, and so is dump() after an edit. Belongs to the PR "json_view: read-side speedups". Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Format the numbered test keys of json_view's index with a stream The keys were made with snprintf() and a format from a list, which Flawfinder reports as an error (CWE-134, a format string that is not a literal). A stream now formats them; the 30000 keys of the test are the same as before. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Put the key number of the json_view index test in parentheses astyle formatted i * step after << as a pointer declaration (i* step), which failed the amalgamation check. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Fix the compiler and lint findings of json_view's read side and tests - find() and contains() dispatch on Editable for the member lookup; for documents that cannot be edited both branches were the same call (GCC -Wduplicated-branches) - json_view.hpp includes <cstdio> for the FILE overload (cpplint) - the arena check macro of the builder is on one line (cpplint read it as an if body without braces) - tests: no nested conditional (also MSVC C4018), no useless cast, parentheses around mixed operators, raw string literals, += instead of temporary concatenations, and NOLINT for the fixed seeds and a find() != npos, as elsewhere in the tests Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Grow the decode arena through a function and store its position back on every return slow_string() kept its write position in locals and grew the arena through the macro NLOHMANN_VIEW_ENSURE. The macro is now the always-inline member arena_ensure() (a lambda is not inlined at every call site by clang, which then keeps the position in memory: +11 % instructions on escape-heavy strings), and a guard stores the position back into m_arena_write on every return instead of by hand on the successful one. Instruction counts are unchanged (clang) or 1 % lower (GCC). Also word the complexity of back() as that of at(). Signed-off-by: Niels Lohmann <mail@nlohmann.me> --------- Signed-off-by: Niels Lohmann <mail@nlohmann.me>	2026-10-24 07:41:06 +02:00
Niels Lohmann	3ff37ead75	Scan json_view strings with SIMD and index large objects (#5628) ... * Scan json_view strings with SIMD and index large objects Speed up json_view's parser with SIMD scanning and a hash table for large objects. Long runs of string bytes are scanned 16 bytes at a time with NEON (AArch64, GCC and Clang) and SSE2 (x86-64), both baseline instruction sets. Keys keep 16 table checks before the vector loop, because their lengths repeat from record to record; string values get 8, because their lengths vary more. Non-ASCII text is validated 16 bytes at a time with simdjson's "lookup4" check (Keiser and Lemire, 2021), with NEON on AArch64 and, on x86-64, with SSSE3. SSSE3 is not part of baseline x86-64, so the check is compiled for SSSE3 with a function attribute and used only where CPUID reports it, which all x86-64 CPUs since about 2011 do; the answer is cached in a statically initialized atomic, so there is no guard of a local static and no global constructor. The same input is accepted either way. JSON_VIEW_NO_SIMD selects the portable code. On x86-64, string runs are now checked vector-first: one SSE2 compare from the first byte finds the end of most keys and short values, instead of a branch per byte for the first 8-16 bytes. AArch64 keeps the byte-wise steps, where a NEON mask costs more and the branches predict well. Entering an object or array no longer stalls: open() stores the parent's frame field by field instead of building it on the stack and reading it back with wider loads, which waited for the narrower stores to retire. Objects with 128 members or more get an open-addressing hash table built when the object closes, so operator[], at(), find(), contains(), count(), value(), and JSON pointers take constant time on average in such objects; of duplicate keys, the first is kept, as for the linear search. The idea comes from Boost.JSON. simdjson is credited in simd.hpp's SPDX block, the README, and license.md. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Fix GCC module build and MSVC C4127 in the json_view SIMD code GCC ignores the target attribute in modules, so the SSSE3 dispatch is disabled for the module interface (the check stays portable, SSE2 is kept). Make the 8-vs-16 byte unrolling condition in scan_string_run a preprocessor/template split to avoid a constant condition (C4127). Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Remove an accidentally committed GCC module cache Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Bound the probe length of the large-object hash index The key hash is not seeded, so keys chosen to collide made building the table quadratic (20,000 colliding keys took 470 ms to parse). A key may now sit at most 64 slots from its home slot; if a key would sit further away, the table is dropped and the object is searched linearly. Lookups stop after the same distance. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Release the spare capacity of the hash index in shrink_to_fit shrink_to_fit() now trims the tables of large objects like the node array and the decoded strings, and the list of large objects is released as soon as the tables are built. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Use the portable string scan on non-x86 targets that define __SSE2__ WebAssembly with -msse2 defines __SSE2__, but has no <cpuid.h> or x86 intrinsics headers. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Document the hash index number in node::extra Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Keep the last of duplicate keys in the object hash index Lookups in objects with 128 members or more now return the last member of a repeated key, like the linear search of smaller objects and like materialize() and basic_json::parse(). build_object_index let the first occurrence win, so the same text gave different results depending on the size of the object. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Keep the first of duplicate keys in the object hash index again Lookups in objects with 128 members or more return the first member of a repeated key again, like the linear search of smaller objects. This undoes the code change of a69542046; its test now expects the first member from lookups (with and without a table) and the last value from materialize() and basic_json::parse(). Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Fix clang-tidy 22 findings in the json_view headers Silence bugprone-casting-through-void for the SSE loads (a reinterpret_cast would trip -Wcast-align=strict), use auto for a cast initialiser, add parentheses to a mixed expression, and name bugprone-std-namespace-modification in the NOLINTs of the tuple_size/tuple_element specialisations. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Fix clang-tidy 22 findings in unit-json_view.cpp and unit-json_view_builder.cpp Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Avoid GCC useless-cast and strict-overflow warnings in unit-json_view.cpp Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Index strings with size_t in the colliding-keys test (MSVC C4244 on Win32) Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Make json_view.hpp pass include-what-you-use ci_single_binaries runs IWYU with --error on every header. For json_view.hpp it suggested adding <array> (std::array is used), the headers that json.hpp already provides (abi_config, abi_macros, input_adapters, json_pointer, cpp_future, string_concat, value_t, json_fwd), and <version> for std::nullptr_t, and removing <cstddef>. - include <array> - keep <cstddef> (nullptr_t, size_t; IWYU attributes them to <version> and <cstring>) - tell IWYU not to suggest the headers that json.hpp provides: the amalgamated json_view.hpp only includes json.hpp, so including them here would duplicate their definitions Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Move the dump, comparison, and large-object tests to unit-json_view_dump.cpp The dump and comparison tests moved to their own file in the dump pull request; the hash index tests of this branch join them there. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Regenerate the amalgamated headers Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Follow the renames from the review of the view builder The review of #5620 renamed document_data's tape/tape_size/tape_cap to nodes/node_count/node_capacity and made the decode arena a std::vector<char>; adapt the code of this change to it. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Rename slots in the object index for Qt compatibility Qt defines slots as a macro, so a Qt header included before json_view.hpp broke the declarations of the local variable (see #5865). The test variable is renamed as well. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Address the review of the json_view object index and SIMD scan From gregmarr's review of #5628: - Docs and comments say that the hash index is one of the object's keys. - object_index.hpp: conditional_static_cast for the hash, "slot" for the table position, no flag for a degenerate table, and a static_assert that the smallest indexed object is larger than the probe window. - scan.hpp unrolls with NLOHMANN_VIEW_REPEAT_FIRST_8/SECOND_8. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Regenerate the amalgamated headers Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Encode JSON_VIEW_NO_SIMD and JSON_VIEW_USE_SSSE3 in the ABI namespace Both macros select between definitions of the same inline functions, so translation units that disagree on them violated the ODR. Like the other ABI-affecting macros, they now add a tag to the inline namespace (_vns and _vssse3), and the docs replace the "Define consistently" warning with the usual ABI compatibility note. From gregmarr's review of #5628. nlohmann_json.natvis covers twice as many tags now, so it lists four times as many namespaces (14.7 MB instead of 3.4 MB). Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Regenerate the amalgamated headers Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Do not include type_traits.hpp directly in the object index json.hpp, which object_index.hpp already includes, provides it; included directly, the json_view amalgamation (which only treats nlohmann/json.hpp as external) copied the json internals into json_view.hpp a second time, so the fuzzers, which include both single headers, failed with redefinitions (make_void, integer_sequence, priority_tag, ...). Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Compare keys with key_equals() in the object hash index As the linear lookups do since the second review round of #5622. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Regenerate the amalgamated headers Signed-off-by: Niels Lohmann <mail@nlohmann.me> --------- Signed-off-by: Niels Lohmann <mail@nlohmann.me>	2026-10-21 10:21:28 +02:00
Niels Lohmann	122d718330	Add json_document and json_view: node index, parser, and document (#5620) ... * Add json_document and json_view: node index, parser, and document Add json_document and json_view, a read-only, zero-copy index of a JSON text, as the first public slice of the zero-copy view (#5295). A parse produces a flat array of 16-byte nodes in document order, one per value and one per object key. Strings stay in the source text; escaped strings are decoded into an arena. Integers are converted while their digits are in the cache; floats keep only their digit layout and are converted on read. Containers store the size of their subtree, so a reader can step over one in constant time. A document makes a handful of allocations, however many values it has. The parser accepts exactly what json::parse accepts, with every combination of ignore_comments and ignore_trailing_commas, with and without a trailing NUL, and under JSON_STRICT_NUL_HANDLING. It is portable C++11 and does not depend on byte order. basic_json_document adds parse, parse_copy, accept, read (reuses a document's memory), root, is_discarded, source, owns_source, node_count, memory_usage, and shrink_to_fit. basic_json_view adds type, the is_* queries, operator bool, size, empty, materialize, and source_offset. A parse error throws the same exception basic_json::parse would throw for the same input, message and position included. detail::abi_config keeps JSON_STRICT_NUL_HANDLING and JSON_USE_LEGACY_DISCARDED_VALUE_COMPARISON readable after json.hpp undefines them, in the ABI namespace so they always match the basic_json in use. A NUL byte that ends a // comment is the end of the input, as in parse() since #5696. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Fix document_data for old Clang (3.4-3.6) Drop the empty braced NSDMIs of the std::string members: old Clang rejects the defaulted constructor when it is used by a member initializer before the end of the class definition. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Exclude libstdc++'s string_view comparison from the sign-change check basic_string_view::_S_compare stores the difference of two lengths in a signed difference_type on purpose, which -fsanitize=integer reports for every comparison with a shorter view (test-json_view_cpp17). Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Reject integer lengths in json_document::parse parse(ptr, len) compiled: len converted to allow_exceptions, and ptr was read as a C string, past the end of a buffer without a terminating NUL. Delete the overloads of parse, parse_copy, accept, and read that take an integer other than bool where the flags are expected. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Copy const rvalue strings and document the accepted inputs json_document::parse(std::move(const_string)) failed to compile with "no matching read_kind": only a non-const rvalue std::string can be moved from. Treat a const rvalue as a copied byte container. parse() does not accept everything BasicJsonType::parse() does: a FILE* and pointers to or arrays of wide characters are rejected at compile time. List the supported inputs instead. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Remove the conversion to bool from json_view explicit operator bool meant "refers to a value", which silently differs from what a basic_json converts to. Use !v.is_discarded() instead. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Delete json_document::root() on temporary documents auto v = json_document::parse(text).root() compiled and left the view dangling. Delete the overload for rvalue documents, take a named document in the tests, and document the lifetime rule. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Store node integers by halves on big-endian targets The non-little-endian path of the node writer wrote the integer's native word over len and next, so len got the high half there. Compose and split the value explicitly (len is the low half, next the high half); the little-endian path stays a plain memcpy. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Check the node array size for overflow reserve(n) and the growth of the index computed n * sizeof(node) without a check, which wraps around on 32-bit targets for inputs of about 1 GiB and allocates a too small array. Throw std::bad_alloc for a count beyond the address space and clamp the growth step to it. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * State the exact input size limit of json_document The check rejects inputs of 0xFFFFFFF0 bytes or more, but the exception message and the documentation said 4 GiB. Name the limit once (max_input_size), and state 4 GiB minus 16 bytes in the message and the documentation. Test the limit with a container that only claims the size. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Remove the unused legacy_discarded_value_comparison from abi_config Nothing reads it: the view does not compare values. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Align the banner comment of json_view.hpp Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Fuzz json_document with exact-size buffers and parse options The fuzzer only parsed a std::string with default options. Also parse an exact-size byte vector, which has no NUL after its last byte and takes the bounds-checked path, and derive ignore_comments and ignore_trailing_commas from the first input byte, comparing against json::parse and json::accept with the same options. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Give document_data a user-provided constructor Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Fix clang-tidy findings in unit-json_view_builder.cpp Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Annotate intentional patterns in unit-json_view.cpp for clang-tidy Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Suppress Flawfinder's read() finding on the deleted overload Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Check the steps of the deep-nesting test separately Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Make max_input_size a function (GCC -Wunused-const-variable) Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Make json_view.hpp pass include-what-you-use ci_single_binaries runs IWYU with --error on every header. For json_view.hpp it suggested adding <array> (std::array is used), the headers that json.hpp already provides (abi_config, abi_macros, input_adapters, json_pointer, cpp_future, string_concat, value_t, json_fwd), and <version> for std::nullptr_t, and removing <cstddef>. - include <array> - keep <cstddef> (nullptr_t, size_t; IWYU attributes them to <version> and <cstring>) - tell IWYU not to suggest the headers that json.hpp provides: the amalgamated json_view.hpp only includes json.hpp, so including them here would duplicate their definitions - export json.hpp, keep macro_unscope.hpp, and drop the unused forward declaration of the document class Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Read the node array base after emit() in the view builder's open() emit() moves the node array when it grows, and the subtraction read base in the same expression, so the order was unspecified. MSVC Release builds without forced inlining read the old base; the container index then pointed outside the array and close() wrote out of bounds. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Silence a clang-tidy use-after-move finding in the json_view test const_text is const, so std::move does not move from it; the second call is part of the const rvalue test. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Regenerate the amalgamated headers Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Address the review of the view builder and document Changes promised in the replies to the review of #5620: - read() reuses the owned copy: a copied input (an rvalue byte container, a stream, FILE*, wide characters, an iterator range) is appended to the cleared owned buffer instead of a fresh std::string being move-assigned over it. A moved-in std::string still replaces it. - The error replay runs the library parser with a SAX handler that stores nothing and throws the reported exception, instead of BasicJsonType::parse(), which built a DOM up to the error. - Pointers to and arrays of wide characters, and FILE*, take the input adapter path (converted to UTF-8 into an owned buffer) instead of failing a static_assert. Wide pointers are NUL-terminated. - Streams are read in blocks through rdbuf() into the buffer, instead of character by character through the input adapter; eofbit is set at the end, as by the library's stream adapter. - tape/tape_size/tape_cap are now nodes/node_count/node_capacity. - The builder's members get descriptive, m_-prefixed names. - The shallow frame stack is a std::array (in a wrapper with a user-provided constructor: -Weffc++ wants the member initialized, and value-initializing the 64 frames costs up to 30 % on small documents). - The value dispatch macro has no NEXT parameter; the switch is left with break, and the macro is undefined after its last use. - literal() and digits_exceed() deduce the length from the string literal; each literal has one helper; the two `if (!is_float)` blocks are merged. - arena_ensure() sits right before the writes; the decode arena is a std::vector<char>. - The builder records the deepest nesting, and materialize() sizes its stack from it once (growing it only if a subtree is deeper). - Comment fixes (hex4, slow_string, the NUL rule, put_utf8, 0 - m, the arena resize, grow()) and formatting (macro backslashes, digit cases, one power of ten per line, value_t assertion next to is_container()). - build_with's template parameters follow the builder's order. Greg's idea of keeping the source offset in `off` and the arena offset in `next` for escaped strings was measured and not adopted: string access got 7-18 % slower with a select, and 3.5-18 % slower with a branch-free field pick (Apple M-series, clang -O3), parsing was unchanged. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Apply the review's wording fixes to the json_view documentation - Copying is disabled because of its cost, not because of two documents borrowing the same buffer; the unique_ptr follows from move-only. - Inputs: streams, FILE*, and wide characters (strings, arrays, pointers) are all supported and owned; point to parse_copy() for owned copies. - The error replay only runs for failing input, builds no values, and is skipped with allow_exceptions = false. - read() writes copied inputs into the previous owned copy. - Views can dangle like std::string_view, and why there is no shared/weak pointer design. - The 4 GiB limit (16-byte nodes, 16-byte scanner steps), streams being read to the end first, which macros apply, why materialize() has no source positions, and wording nits (accept() vs basic_json::accept(), is_binary, is_discarded, see-also lists, size table, "back into"). Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Say that json_view converts integers while parsing Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Address the review: null inline nodes, trait spelling, and max() in json_view - inline_nodes is null when the document has no inline nodes, instead of pointing past the end of the allocation; shrink_to_fit() no longer passes it to memcpy() for an empty node array - is_byte_char and is_wide_char use conjunction/disjunction, which astyle leaves unspaced - append_stream() uses (std::max) for the count read Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Include materialize.hpp in the view builder test The test calls detail::view::materialize(), which only the single header pulled in; the multiple-header build (JSON_TEST_USING_MULTIPLE_HEADERS) failed with "'materialize' is not a member of detail::view". Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Rename emit() in the view builder for Qt compatibility Qt defines emit as an empty macro, so a Qt header included before json_view.hpp broke the declaration of the builder's emit(), see issue #5865. It is now called push_node(). Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Do not copy an empty run into an unallocated arena memcpy() must not be passed a null pointer even for zero bytes, which arena_run() did for an empty run while the arena was still empty (ci_test_clang_sanitizer: "null pointer passed as argument 1" in builder.hpp). Only the slow path can see such a run. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Exclude the view builder test from Infer's reports Infer's std::unique_ptr model confuses the values that the test's build() helper returns by value and reports USE_AFTER_DELETE for one of them after the destructor of an unrelated temporary (ci_infer, 12 reports, all in tests/src/unit-json_view_builder.cpp). AddressSanitizer is clean on the same tests. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Skip the deleted-overload checks of json_view on MSVC 2015 MSVC 2015 does not treat selecting a deleted function in decltype as a substitution failure, so is_detected reports the deleted parse/parse_copy/accept/read(ptr, len) overloads as callable and the static_asserts in "integer arguments do not compile" fail (AppVeyor VS2015 jobs). Calling them still fails to compile there. Guard the negative checks as unit-delete_deprecated_functions.cpp does. Signed-off-by: Niels Lohmann <mail@nlohmann.me> --------- Signed-off-by: Niels Lohmann <mail@nlohmann.me>	2026-10-21 10:21:27 +02:00