Commit Graph
9 Commits
Author SHA1 Message Date
Niels Lohmann 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>
2026-10-21 10:21:29 +02:00
Niels Lohmann 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 5cbb8e6d6.
Lookups in edited objects (navigation of editable documents) stop at the
first match, like those of parsed objects.

The tests that commit added expect the first member from lookups now. In the
seeded differential test, the documents with repeated keys repeat them after
the real members; the reference holds the first members, which the edits
address and the lookups are compared with, while materialize() is compared
with what parse() makes of the document's dump.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* Fix MSVC C4127 in the lookups of editable json documents

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>
(cherry picked from commit 0effbaa7a2)

* Fix clang-tidy 22 findings in unit-json_view_edit.cpp and edit.hpp

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* Keep a raw string with a backslash out of a CHECK (MSVC C2017)

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), and the headers that json.hpp
already provides (abi_config, abi_macros, input_adapters, json_pointer,
cpp_future, string_concat, value_t, json_fwd), plus <version> for
std::nullptr_t, and removing <cstddef> and edit_storage.hpp.

- 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>

* Keep the view's edit headers clean for clang-tidy in C++17 mode

clang-tidy 22 checks the headers with -std=gnu++17 as well, where it asks
for a transparent comparator and std::make_unique. The regions map uses its
default comparator, and the allocation of the edit state keeps new (the
library is C++11) with a NOLINT.

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>

* Expect count() to count every member in the edit tests

Since #5622, count() counts every member with the key, so documents
with duplicate keys no longer give 1.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* Count matching keys as unsigned in the json_view edit tests

Like in the access test, adding the int result of the conditional to a
std::size_t fails -Werror=sign-conversion with GCC.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* Address the review of erase() in editable json documents

From gregmarr's review of #5630:

- invalid_iterator.202 is thrown by overloads 1 and 2 only; the page said
  "every overload" and then excluded 3 in parentheses.
- The note on links says what moves (the links after the removed element,
  as insert() moves them the other way) and that every iterator over the
  container is invalidated, not only those after the removed element.
- edit.hpp compares keys with document_data::key_equals().

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* Regenerate the amalgamated headers

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* Address the review of editable json documents

From gregmarr's review of #5630:

- set() with a JSON pointer below a null value checks for "-" before
  scanning the token for digits.
- node_flags::storage is defined as escaped | edited, and the comment on
  document_data::base says that the fourth slot is unused.
- source_extent() names its root check.
- The integer-index overloads of set(), insert(), and erase() use a named
  trait instead of a negated condition, which astyle formats like the
  library's other enable_ifs.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* Regenerate the amalgamated headers

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* Address the rest of the review of editable json documents

From gregmarr's review of #5630:

- alloc_nodes() gives a request of half of the next chunk or more a chunk
  of its own, so that the rest of the current chunk stays available for
  smaller requests instead of being abandoned.
- The comments on edit_state, append_text(), and reserve_moved() say that
  views stay valid across every edit (not just the first), that n is 0 for
  empty strings, and why both capacities are checked.
- The architecture page names flag bits 3, 4, and 5 (linked) separately
  and says that a discarded view has no node; erase.md rewords overload 3
  and says why it never throws invalid_iterator.202.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* Call alloc_nodes() before reading chunks.back() in the json_view chunk test

The operands of == are unsequenced, and MSVC evaluated
d->edits->chunks.back() before alloc_nodes() added the new chunk, so the
check compared the result with the previous chunk and failed on
msvc-arm64 (Debug and Release).

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

---------

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-21 10:21:29 +02:00
Niels Lohmann 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>
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
Niels Lohmann 6197341a21 Clean up non-code files (#5801)
* Clean up README, contribution guide, and repository metadata

- REUSE.toml: fix the Hedley path and SPDX id (CC0-1.0), mark the docset
  icons as the public-domain JSON logo
- CITATION.cff: v3.12.0 was released on 2025-04-11
- FILES.md: list all workflows, describe the Meson option defaults
- README: ctest -LE, table of contents, typos, stale Android/MinGW advice,
  moved links, merge duplicate Thanks entries, list the analysis tools
  used in CI
- CONTRIBUTING: iterative parser, json_literals.hpp is generated, links
- .gitignore: backups and release outputs; .gitattributes: mark
  generated files
- labeler: label other build systems and .github documentation
- MODULE.bazel: add the module version

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* Clean up CI, CMake, Makefile, and Bazel files

- CMakeLists.txt: avoid VERSION_GREATER_EQUAL, which CMake < 3.7 lacks
- ci.cmake: test JSON_DisableTupleReferenceConversion in ci_cmake_flags,
  remove unused variables and unreachable per-compiler targets, look up
  Clang tools consistently, forward CMAKE_CXX_FLAGS to ci_module_cpp20,
  format json_literals.hpp and remove backups in ci_test_amalgamation
- BUILD.bazel: add json_literals.hpp to the single-header target
- workflows: format json_literals.hpp before copying it, drop the obsolete
  natvis --version plumbing, name natvis and macro_builder in failure
  messages, drop the duplicate amalgamation job, install Valgrind only
  where needed, republish docs on version bumps, fix stale names
- Makefile: complete .PHONY and help, check-amalgamation always restores
  the checked-in files, natvis uses its own venv, macro_builder_check
  installs astyle, clean removes the fuzzer binaries
- remove tools/amalgamate/config_json_view.json (json_view.hpp is not on
  develop yet)

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* Fix inaccuracies in the documentation

- version history: json_base_class_t (3.11.3), JSON_HAS_CPP_11 (3.10.0),
  JSON_HAS_RANGES exclusions, define-type macros, ABI tags
- releases: 3.12.0 raised the minimum CMake version
- from_*: the (ptr, len) overloads are deleted, not removed, in 4.0.0
- contains/count/find: document the deleted integral overloads
- add JSON_HAS_RANGE_VIEW_CONVERSION and list the JSON_HAS_* macros in
  the macro overview
- mention BON8 and error_handler where binary formats are listed
- broken links, outdated URLs, warning count, Hunter v0.26.12
- copy_markdown_source hook: expand snippets in the Markdown copies

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* Pass /EHsc to the Windows C++20 module build

ci_module_cpp20 now forwards CMAKE_CXX_FLAGS to the module build. The
Windows workflow sets CMAKE_CXX_FLAGS, which replaces CMake's MSVC
defaults including /EHsc, so <chrono> failed with C4530 under /WX.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

---------

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-11 08:21:51 +02:00
Niels Lohmann 1e101ecac1 Add BON8 support (#2998)
* Add BON8 support

Add to_bon8/from_bon8 and input_format_t::bon8 for BON8, a binary format
that uses the byte values that cannot begin a UTF-8 character as type
markers, so strings need no length prefix. It is the most compact of the
supported binary formats on the benchmark files.

The reader is non-recursive like the other binary readers. A string ends
at the first byte that cannot continue it, so the reader hands the one or
two bytes it reads past a string back to the value that follows. The
writer produces the canonical representation of the specification, except
for NFC normalization; its output is identical to that of the reference
implementation (HikoGUI) on all files of the test data.

The round-trip tests need the .bon8 files of json_test_data 3.2.0.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* Address review comments

- Reuse detail::validate_one_utf8 to check strings in to_bon8; the error
  now names the first byte of the invalid sequence.
- Document that to_bon8 leaves bytes in the output adapter on an
  exception, and that string_open is only an output of write_bon8_marker.
- Explain why the pushback buffer of the BON8 reader cannot overflow.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* Select the BON8 float prefix by type

get_bon8_float_prefix only depends on the type of its argument, so make
the type a template parameter instead of passing an unused value.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* Rename a test variable that Flawfinder mistakes for read()

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* Fix the BON8 CI failures

- compare the float in write_bon8_float with number_float_t constants,
  so GCC does not warn about a float-to-double conversion
- mark check_bon8_utf8's context as used when exceptions are disabled
- choose the compact float prefix in a helper rather than with nested
  conditional operators (clang-tidy)
- use auto for the cast in the BON8 integer reader (clang-tidy)
- write the int32 minimum test values as long long literals (MSVC C4146)

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* Amalgamate

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* Read BON8 strings in bulk from contiguous input

- copy the valid UTF-8 of a string in one step when the input is
  contiguous (twitter.json is read in 1.68 instead of 2.52 ms,
  jeopardy.json in 196 instead of 297 ms, close to CBOR and MessagePack)
- share the new valid_utf8_prefix() with the writer's UTF-8 check, which
  now skips ASCII 8 bytes at a time
- let the fuzzer check that contiguous and stream input give the same
  value or error, and test both paths in the unit tests
- clarify that a second 0xFF after a string is an empty string

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* Link the BON8 functions from the other binary format pages

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* Name the bulk scan flag after the input, not BON8

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* Read BSON keys in bulk from contiguous input

BSON keys (and array indices) are C-style strings, which were read byte
by byte. For contiguous input they are now read up to their \x00-byte in
one step, using the same bulk_scan flag as BON8 strings: twitter.json is
read in 1.46 instead of 2.01 ms, citm_catalog.json in 2.93 instead of
3.33 ms, jeopardy.json in 182 instead of 207 ms. canada.json, whose keys
are almost all one-digit array indices, takes 2 % longer.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* Fix the BON8 CI failures of the bulk-read tests

- skip the contiguous-versus-stream tests of BON8 strings and BSON keys
  when exceptions are disabled: they catch the parse errors of invalid
  input, and without exceptions the library aborts instead
- use static_cast for the int64 test value (google-readability-casting)

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* Move the explicit basic_json instantiation into its own test file

Linking test-regression3_cpp20 with clang and MinGW failed with
"relocation truncated to fit: IMAGE_REL_AMD64_REL32 against `.rdata'",
as test-regression2 did before #5511. The explicit instantiation of
basic_json<> for #4825 compiles every member function, including the
BON8 reader and writer, into that object, and it was already close to
the limit (2,226,104 bytes on develop, 2,234,960 with BON8; clang -O1,
C++20).

Give the instantiation a file of its own: unit-regression3 is now
1,594,736 bytes and unit-explicit_instantiation 1,095,064. The new file
mentions JSON_HAS_CPP_17 and JSON_HAS_CPP_20 so it keeps being built
for the C++17 standard the regression was about.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* Convert the bytes of the BON8 test strings explicitly

The str() helper constructed a std::string from a byte range, which
converts each unsigned char implicitly; -fsanitize=integer reports that
for bytes of 0x80 and above (ci_test_clang_sanitizer).

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

---------

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-09-27 16:56:21 +02:00
Niels Lohmann 5f659c881a Let the labeler assign "aspect: binary formats", "python" and more "CI" (#5557)
- "aspect: binary formats" for changes to the binary reader or writer,
  their tests, fuzzers and docs, or with a binary format in the title;
- "python" for Python sources and pip requirements files, matching the
  label Dependabot sets on its pip updates, so it is never removed there;
- "CI" also for changes to the Dependabot and labeler configurations.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-09-24 17:03:48 +02:00
Niels Lohmann 272411c5e6 Overwork project infrastructure (#5218)
* 📝 overwork project infrastructure

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* 🐛 fix GCC16 issue

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* 🐛 fix GCC16 issue

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* 🐛 only build module for GCC

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* 🐛 fix build

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* 📝 fix documentation

Closes #5012: fix the error_handler_t::ignore wording

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* 📝 fix documentation

Closes #4354: fix "Custom data source" example

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

---------

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-06-30 18:09:06 +02:00
Niels Lohmann 500bdc56bf Add labeler action (#3671)
👷 add labeler action
2022-08-04 16:46:45 +02:00