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Niels Lohmann 1d59a0f4a6 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>

2026-10-11 10:27:40 +02:00

amalgamate.py

Keep external headers as #include when amalgamating (#5615 )

2026-09-30 20:05:51 +02:00

CHANGES.md

Keep external headers as #include when amalgamating (#5615 )

2026-09-30 20:05:51 +02:00

config_json_fwd.json

Amalgamate the forward declaration header (#3679 )

2022-08-07 13:57:32 +02:00

config_json_view.json

Add json_document and json_view: node index, parser, and document

2026-10-11 10:27:40 +02:00

config_json.json

Amalgamate the forward declaration header (#3679 )

2022-08-07 13:57:32 +02:00

README.md

Remove dead Makefile targets; document macro_builder; tidy serve_header (#5735 )

2026-09-30 22:21:27 +02:00

README.md

amalgamate.py - Amalgamate C source and header files

Origin: https://github.com/edlund/amalgamate (formerly hosted at https://bitbucket.org/erikedlund/amalgamate, which no longer exists; see CHANGES.md for the upstream commit this copy is based on)

amalgamate.py aims to make it easy to use SQLite-style C source and header amalgamation in projects.

For more information, please refer to: http://sqlite.org/amalgamation.html

Here be dragons

amalgamate.py is quite dumb, it only knows the bare minimum about C code required in order to be able to handle trivial include directives. It can produce weird results for unexpected code.

Things to be aware of:

amalgamate.py will not handle complex include directives correctly:

    #define HEADER_PATH "path/to/header.h"
    #include HEADER_PATH

In the above example, path/to/header.h will not be included in the amalgamation (HEADER_PATH is never expanded).

amalgamate.py makes the assumption that each source and header file which is not empty will end in a new-line character, which is not immediately preceded by a backslash character (see 5.1.1.2p1.2 of ISO C99).

amalgamate.py should be usable with C++ code, but raw string literals from C++11 will definitely cause problems:

    R"delimiter(Terrible raw \ data " #include <sneaky.hpp>)delimiter"
    R"delimiter(Terrible raw \ data " escaping)delimiter"

In the examples above, amalgamate.py will stop parsing the raw string literal when it encounters the first quotation mark, which will produce unexpected results.

Installing amalgamate.py

Python 3 is required.

In this repository, amalgamate.py is not installed separately; it is run in place through make amalgamate, which calls it once for json.hpp and once for json_fwd.hpp (see the root Makefile).

Using amalgamate.py

    amalgamate.py -c path/to/config.json -s path/to/source/dir \
            [-p path/to/prologue.(c|h)] [--verbose=yes|no]

The -c, --config option should specify the path to a JSON config file which lists the source files, include paths and where to write the resulting amalgamation. config_json.json and config_json_fwd.json in this directory are the configs used for json.hpp and json_fwd.hpp; each sets target, sources and include_paths.

The optional external list names include paths that are kept as #include directives instead of being inlined, e.g. ["nlohmann/json.hpp"] for a header that includes another amalgamated header. Only the first directive for each of these paths is kept; the repeated ones are commented out.
The -s, --source option should specify the path to the source directory. This is useful for supporting separate source and build directories.
The -p, --prologue option should specify the path to a file which will be added to the beginning of the amalgamation. It is optional.
The -v, --verbose option takes yes or no (for example --verbose=yes, as used by the Makefile). It is optional.