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Commits
| Author | SHA1 | Message | Date | |
|---|---|---|---|---|
 Niels Lohmann
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4155e2938f |
Write json_view's dump() without a call or conversion per token (#5633)
* Write json_view's dump() without a call or conversion per token The default dump() (no indentation, no ensure_ascii) gets its own writer that makes the same walk and produces the same output: - the write position stays in a local variable instead of a member, so the compiler keeps it in a register across stores through aliasing char pointers; - strings and number tokens are copied with fixed-size 32-byte moves wherever enough source bytes remain, instead of one memcpy call per token; - the innermost open container lives in local variables; a stack that starts as a local array of 32 entries holds the rest; - unedited documents are walked through the node array in order, and integer tokens are read from the source directly. On top of that, float tokens of at most 15 significant digits are written straight from their digits via zmij::to_shortest() and write_shortest(), without converting to a double and back: such decimals are farther apart than a double's rounding interval, so the token's digits are the double's shortest digits. Tokens of 16+ digits, or edited values, still go through decimal_to_float(). The view's own NEON write_decimal() is removed in favor of the shared writer, and the dump output now grows in 64 KiB steps instead of being resized to its estimate at once. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Fix MSVC C4127 and Infer finding in the view serializer Test the template options through enabled() so that conditions combined with them are not constant, and mark the nav::value() null dereference as a false positive like materialize.hpp does. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Fix out-of-bounds read when dumping a float token of an unchecked image A float node of an image loaded with image_check::bounds can hold a token whose bytes are not digits, so its value need not have the digit count recorded in the node. write_double_at() passed that count to write_short_decimal(), which indexes its table of powers of ten by it: an assertion failure in debug builds, an out-of-bounds read in release builds. Use the counted overload only if the value has exactly that many digits, otherwise count them. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Tidy the view serializer: doxygen block placement, enabled() for a constant Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Use a named document in the dump test: root() of a temporary does not compile Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Test write_short_decimal and powers_of_ten_16 against to_chars Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Fix clang-tidy 22 findings in unit-to_chars.cpp Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Write doubles from their bits only where double is IEEE 754 binary64 Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Split the value and pointer edit tests off unit-json_view_edit.cpp The MinGW linker of the Windows clang jobs cannot link object files with more than 32767 sections ("relocation truncated to fit: IMAGE_REL_AMD64_REL32 against `.rdata'"). unit-json_view_edit.cpp has 35409 sections since the fast dump instantiates more code for editable documents, so its test cases "views and values", "deeply nested values", "pointers below a null value", and "strings of other documents are checked" move into unit-json_view_edit_values.cpp. The helper exception_of_call() that both files use moves into json_view_test_helpers.hpp. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Move the dump tests of this branch to unit-json_view_dump.cpp The dump and comparison tests moved to their own file in the dump pull request; the tests of the fast dump() join them there. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Regenerate the amalgamated headers Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Address review: one powers-of-ten table, literal sizes from the type - dtoa_impl::powers_of_ten() (10^0 to 10^19, one entry per line) replaces powers_of_ten_16() and the table of int_pow10() - put_literal() takes the length of a string literal from its type - small_stack holds the heap vector by reference - the growth step of the output buffer is written in hex Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Explain why the growth of the dump's stack is static 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> |
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Niels Lohmann
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4971200b54 |
Add images of json_documents: save() and load() (#5632)
* Add images of json_documents: save() and load()
An image is a document stored so that loading it needs no
parsing: save() writes the node index, the text and the decoded
strings; the static load() reads an image written by save().
load() takes a pointer and size, a borrowed vector, or an owned
rvalue vector; the nodes are copied so they are aligned and can
be edited, while the text and decoded strings stay in the image.
image_check controls how much load() trusts the input: full
checks structure, bounds, strings and numbers, the parser's own
guarantees; bounds checks structure and bounds only; none skips
all checks, for images from a trusted source.
Layout is little-endian only ("NJVI" header, nodes, text, decoded
strings), following the idea of zero-copy formats such as
FlatBuffers and YaFF; the check follows FlatBuffers' Verifier.
New errors: parse_error.116 for a malformed image or a failed
check, type_error.320 for a discarded document or a big-endian
target.
A dedicated fuzzer and 6,000 seeded corruptions, checked under
ASan/UBSan, found and fixed two gaps: unchecked reserved header
fields, and unbounded null/boolean offsets that could make
dump() throw std::length_error.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Fix MSVC errors in image test and add image_check doc anchor
Move the raw string literal out of the CHECK macro (MSVC preprocessor),
cast 64-bit header fields to std::size_t (C4244 on 32-bit), and give the
image_check section in load.md a real anchor for the mkdocs strict build.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Check each distinct string and float range once in the full image check
The full check scanned the contents of every string node and every float token over its own range, so many nodes pointing to one large range made load() quadratic. The structural walk now only collects the ranges; after it, each kind is sorted and checked once per distinct range. Ranges of one kind that overlap without being identical are rejected, as save() never writes them (nodes that share a value share the whole range). The cost is linear in the size of the image plus sorting the ranges.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Adapt the image tests to named documents and last-wins lookups
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Test that the targets of links never reach an image
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Test lookups in loaded images with duplicate and colliding keys
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Release the list of large objects once load() has built the indexes
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Test that invalid UTF-8 of a loaded image is not copied into an editable document
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Document that editable documents refuse invalid UTF-8 copied from a loaded image
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Expect first-wins lookups in the image tests
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Avoid useless casts of header fields in the image tests
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Fix clang-tidy 22 findings in unit-json_view_image.cpp and image.hpp
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Fix MSVC C4244 and C2017 in the image test
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Fix the indentation of a loop in the image test
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
- drop edit_storage.hpp, which edit.hpp includes
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Silence a clang-tidy C++17 finding in the image test
bugprone-suspicious-stringview-data-usage flags data() of the source view
under C++17, although the length is passed and checked by the REQUIRE
before it.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Build the image link test without exceptions
load_result() exists only with exceptions; with JSON_NOEXCEPTION the test
loads the image with the check directly (a failed check aborts).
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 the emit lambda in the image writer for Qt compatibility
Qt defines emit as an empty macro, so a Qt header included before
json_view.hpp broke the lambda's declaration (see #5865). The slots
variables in the image tests are renamed as well.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Address the review of json_document images
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>
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Niels Lohmann
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823eee3b59 |
Add editable json_documents: set, push_back, insert, and erase (#5630)
* Add editable json_documents: set, push_back, insert, and erase basic_json_document gets a second template parameter, Editable (false by default), plus the aliases json_editable_document, json_editable_view, ordered_json_editable_document and ordered_json_editable_view. Editable documents can change values and structure without rewriting the source text: set()/push_back() on values, keys, array indices and JSON pointers; insert() before an array element; erase() of an object key, array index or JSON pointer. New values and element sequences go into edit storage that the document owns and never moves, so views keep referring to their value across edits and a parsed node never moves. Read-only documents walk the plain node array and are unaffected. Strings are checked for UTF-8 on entry, so dump() of an editable document never throws type_error.316. Binary values cannot be stored (type_error.319). A seeded differential test applies random edits to an editable document and to the equivalent ordered_json and compares both after every step. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Fix old clang and MSVC C4127 in editable json documents Value-initialize the const std::less in find_parent (clang 3.4/3.6 do not implement DR 253), and test the Editable template argument through a function to avoid MSVC C4127. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Copy nested values into a document without recursion Counting and copying the nodes of a view or a basic_json value into an editable document recursed once per nesting level, so that a deeply nested value overflowed the stack. The four functions now walk the value with an explicit stack, as materialize() does. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Do not leave a half-assigned container when set_moved() throws assign() rewrote the kind, length and extent of a slot before set_moved() registered its new element sequence. set_moved() can throw (std::bad_alloc from reserving the bookkeeping vectors) for a slot that is not moved yet, which left a container without the moved flag that showed its old children. The bookkeeping is now reserved first (reserve_moved()), so that nothing after the first write to the slot can throw. block_of() reserves before it marks anything for the same reason. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Check strings copied from another document for valid UTF-8 An editable document only holds valid UTF-8, but copy_scalar() copied the strings and keys of a view of another document unchecked. A document of a weaker check (or a borrowed text that changed after parsing) could therefore bring ill-formed UTF-8 into it. The copy is checked now, with the error that dump() reports for the string; copies within the same document stay unchecked. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Allow the edit arena to grow up to 4 GiB - 1 bytes append_text() doubled the capacity of the arena and rejected the result if it exceeded 4 GiB, so that an arena of more than 2 GiB could not grow even though the 32-bit offsets of nodes address 4 GiB - 1 bytes. The capacity is now clamped to that limit (text_capacity()), and an append is rejected only if the bytes themselves do not fit. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Set a null value below a pointer as basic_json does set(json_pointer, value) turned a null parent into an object for every last reference token, so "/a/0" and "/a/-" below {"a":null} made {"a":{"0":1}}, where basic_json's operator[](json_pointer) makes an array. A null parent now becomes an array for "-" and for digit tokens (filled with nulls up to the index) and an object otherwise. An invalid index is reported before the parent changes. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Replace a container by a scalar in constant time once it is linked Replacing an array or object that spans several nodes by a scalar looks up its parent from the root (find_parent), which is linear in the size of the document: setting every element of a 20,000 element array took more than half a second. The parent only has to switch to links once; afterward the extent of the replaced value no longer matters. Nodes that an entry of a moved sequence links to are now marked (node_flags::linked), and assign() skips the lookup for them. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Update the json_view banner and type_error.319 for editable documents The banner still described a read-only view, and the documentation of type_error.319 listed set and push_back only, although insert rejects binary values as well. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Assign the member that lookups find when set() meets duplicate keys An editable document reads the last member of a repeated key (as the read-only document does), but set(object, key, value) assigned the first one: a view taken from object[key] before the call did not show the new value. It now assigns the last member's value, keeps the key at the position of its first occurrence (where materialize() puts it), and drops the other members. The seeded differential test now also edits documents whose objects repeat keys and compares every lookup (operator[], at, find, value, contains, count, and JSON pointers) with the parsed basic_json value. A targeted test covers duplicates before and after edits that move the object, in large objects with an index, in moved arrays, and in values copied from other documents. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Assign the first member when set() meets duplicate keys again Lookups find the first member of a repeated key again, so set(object, key, value) assigns that member (keeping the key where it is) and drops the others, as documented before, and a view taken from object[key] shows the new value. This undoes the code and documentation changes of |
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Niels Lohmann
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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> |
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Niels Lohmann
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4c3a3eb5b5 |
Add dump() and comparisons to json_view (#5624)
* Add dump() and comparisons to json_view 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> * Avoid raw string with escapes inside CHECK macro (MSVC C2017) Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Size the dump buffer of a small value by its own extent The source extent of a value was read from the next node, falling back to the rest of the document when that node held a decoded string. dump() of a small value could thus allocate a buffer as large as the document. Skip a few such nodes, cap the fallback estimate, and shrink a buffer that is much larger than its output. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Hold the documents of the dump and comparison tests in names root() of a temporary document is deleted: its views would dangle. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Do not shrink the output of dump() finish() copied the whole output when the buffer was more than twice as large as the result (citm dump +11%). The tighter source_extent() estimate already keeps the buffer of a small value small. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Document and test first-wins lookups next to dump() and == dump() writes every member and == resolves duplicate keys as parse() does, whereas lookups find the first member of a duplicate key. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Fix the clang-tidy 22 findings in json_view and its tests Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Split the dump and comparison tests off unit-json_view.cpp The MinGW linker of the Windows clang jobs cannot link object files with more than 32767 sections ("relocation truncated to fit: IMAGE_REL_AMD64_REL32 against `.rdata'"). unit-json_view.cpp reaches that limit as the stack grows, so its "json_view dump" and "json_view comparison" test cases move into unit-json_view_dump.cpp. The test generator and has_duplicate_keys() that both files use move into json_view_test_helpers.hpp. The new file mentions JSON_HAS_CPP_17, so it is built for C++17 like the file it was split from. 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> * 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> * Keep the stream includes of json_view.hpp for IWYU json_view.hpp uses std::istream and std::ostream itself, but IWYU sees them through the exported json.hpp and asked to remove both includes, which fails ci_single_binaries (single_json_view). Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Address the review of json_view dump() and comparisons From gregmarr's review of #5624: - The output buffer takes string literals without a length. - write_float() names the IEEE single/double condition once, as the library's serializer does. - equal() checks the types first and compares with !=; the reference to the top frame is noted as dangling after pop_back(). - dump.md: one paragraph per case in the notes. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Regenerate the amalgamated headers Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Exclude all json_view test files from Infer's reports The same std::unique_ptr false positive (USE_AFTER_DELETE) also shows for two json_documents parsed in one lambda in unit-json_view_dump.cpp (ci_infer). It affects any test that holds several documents, so the exclusion now covers tests/src/unit-json_view*.cpp; ASan and Valgrind cover these tests. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Allow the string literal parameter of the view serializer's put() for clang-tidy The overload takes the literal by array reference so that its length is a template parameter, like scan_literal() and the C array overloads of to_json() and from_json(). Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Bind the serializer's frame only after the check for its end 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> |
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Niels Lohmann
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43e97b629b |
Add element access, iteration, values, and JSON pointers to json_view (#5622)
* Add element access, iteration, values, and JSON pointers to json_view Give basic_json_view the read-only access functions of basic_json: operator[] and at() with keys and indices, front()/back(), find(), contains(), count(), begin()/end() and cbegin()/cend(), items() with structured bindings from C++17 on, and type_name(). Exceptions have the ids and messages of the const functions of basic_json. Where basic_json has undefined behavior the view answers safely: operator[] with a missing key or an out-of-range index returns a discarded view, and front()/back() of an empty container throw invalid_iterator.214. Objects are iterated in document order, and all members are visited; duplicate-key lookups find the first member (as yyjson and simdjson do), while parse(), materialize(), and the map conversions keep the last value, as parse() does. Keys of up to 16 bytes are compared with two overlapping loads. Add value conversions: get<T>()/get_to() for arithmetic types, bool, nullptr_t, strings (std::basic_string copied, string_view_t without a copy), BasicJsonType, views, std::vector, and maps with string keys; get_string() for the string without a copy; number_token() for the number exactly as written in the source; value() with keys and JSON pointers; and operator[]/at()/ contains() with JSON pointers. Everything else, including types with from_json(), goes through materialize() of that subtree. get<T>() of arithmetic types is inlined down to the conversion, so reading an integer needs no call. detail::json_pointer_access exposes a pointer's reference tokens to code outside basic_json. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Make view lookups last-wins and chained access safe * Lookups (operator[], at, find, contains, count, value, JSON pointers) return the last member of a duplicate key, as materialize() and parse() keep it. * operator[] on a discarded view returns a discarded view instead of throwing, so v["a"]["b"] is safe for a missing "a". * operator[] and at() take any integer type (not only int and size_t), fixing ambiguous calls with unsigned, long, std::int64_t, ... * Fix the operator[] documentation, which claimed a discarded view for a type mismatch where type_error.305 is thrown. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Replace the removed operator bool of basic_json_view in the header and its tests A view is tested with is_discarded(); the lookups in at(), value() and contains(json_pointer) and the unit tests no longer rely on the explicit conversion to bool. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Use named documents in the json_view tests that called root() on a temporary root() of an rvalue document is deleted, because the views would dangle. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Test discarded views with is_discarded() in the operator[] docs and examples The explicit conversion to bool of basic_json_view is gone. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Return the first member of duplicate keys from lookups again Looking up the last member of a duplicate key cannot stop at a match, so every lookup scanned the whole object (1.6 to 3.4 times slower for small objects). operator[](key), at, find, value, contains, count, and JSON pointer resolution return the first member again, as yyjson and simdjson do; materialize() and get<map>() keep the last value, as parse(). The documentation says so in the feature page and on each lookup page, and explains how to get the value parse() would give. The integer index templates and the discarded chaining of operator[] stay. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Do not force-inline the view's functions on MSVC __forceinline makes MSVC report C4714 for function templates it cannot inline (get<std::string>), an error under /WX. The forced inlining is only a performance hint, so use plain inline there. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Make json_view.hpp pass include-what-you-use Mark the includes that are needed by design (json.hpp, the macro unscope, <tuple> for the tuple_size specialization), take size_t from <cstring>, and drop the forward declaration of basic_json_document that the friend declaration makes redundant. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Avoid GCC useless-cast warnings in the integer index tests 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> * Fix the clang-tidy 22 findings in json_view and its tests The same changes as on the dump branch, where they were first made, so that this branch passes clang-tidy on its own. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Regenerate the amalgamated headers Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Report one-character non-numeric array indices like basic_json in the view Develop's #5800 made basic_json report a JSON pointer array index such as "/a" as parse_error.109 instead of out_of_range.404, as longer ones were; the view's array_index() follows, with "-" and the empty token still unresolved. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Address the review of json_view element access From gregmarr's review of #5622: - count() counts every member with the key, so count(key) > 1 detects duplicate keys; it was contains() as 0/1 before. - get_to() passes types that get<T>() does not convert directly to from_json with the existing value, as basic_json::get_to() does, so that a from_json which sets only the fields present keeps the others. - array_index() checks the empty token and "-" first; the results are unchanged. - Docs: no "if an exception is thrown" where a view never changes anything; the borrowed source must also stay unmodified; items() on a temporary view is safe; back()/front() notes shortened; the basic_json see-also entries say how the view's results can differ. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Regenerate the amalgamated headers Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Count matching keys as unsigned in the json_view access test The conditional added 1 or 0 as int to a std::size_t, which GCC rejects with -Werror=sign-conversion (ci_test_standards_gcc). Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Address the second review round of json_view element access From gregmarr's review of #5622: - begin()/end(): "a null value or a discarded view iterates as an empty range", singular like the primitive case before it. - The class page's list of function groups has no trailing commas. - document_data::key_equals() compares a key node with a string, for the key comparisons that were spelled out in each lookup. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Regenerate the amalgamated headers Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Write the negated enable_if conditions of json_view with negation<> With a ! or && in the condition, astyle spaces the whole template header (template < ... >); detail::negation and a named trait keep it compact, as the library writes such conditions elsewhere. From gregmarr's review of #5630. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Regenerate the amalgamated headers Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Keep detail::negation out of json_view.hpp's enable_ifs include-what-you-use asks json_view.hpp to include detail/meta/type_traits.hpp for it, which the single header must not do (the amalgamation would duplicate json's internals). The two conditions of value() go through a trait in value.hpp, like the others. 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> |
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Niels Lohmann
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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> |