Commit Graph
2 Commits
Author SHA1 Message Date
Niels Lohmann be837d5470 Add json_document and json_view: parse, accept, types, materialize
The public classes of the zero-copy view (#5295), in the new header
<nlohmann/json_view.hpp>:

- basic_json_document<BasicJsonType>: parse (borrowing contiguous byte
  inputs, owning rvalue strings, streams, and other inputs), parse_copy,
  accept, read, root, is_discarded, source, owns_source, node_count,
  memory_usage, shrink_to_fit
- basic_json_view<BasicJsonType>: type and the is_* queries, size, empty,
  materialize (the value parse() would produce, built by the same SAX
  handler), source_offset
- the aliases json_document, json_view, ordered_json_document, and
  ordered_json_view

A parse error throws the exception basic_json::parse would throw for the
same input: the library parser is run on the failing input, so messages,
positions, and exception ids are the same. Inputs of 4 GiB or more are
rejected with out_of_range.416.

The single header single_include/nlohmann/json_view.hpp keeps including
json.hpp; make amalgamate, check-amalgamation, include.zip, and release
handle it.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-09-29 09:54:04 +02:00
Niels Lohmann 1ab017bbfe Add the node index and scanning primitives of json_view (internal)
Internal parts of the zero-copy view (#5295), under detail/view and not
included by json.hpp, so that users of json.hpp compile nothing of it:

- macro_scope.hpp/macro_unscope.hpp: the few macros the view needs, under
  its own prefix (json.hpp undefines its own at its end); the throw macro
  honors JSON_NOEXCEPTION and JSON_THROW_USER like JSON_THROW
- string_ref.hpp: std::string_view from C++17 on, else a small stand-in
- node.hpp: the 16-byte node of the index; its kinds are value_t values
  (checked by a static_assert)
- document_data.hpp: the storage of a parsed document (node array, decode
  arena, owned input)
- scan.hpp: string and digit scanning with unrolled checks at fixed offsets
  (after yyjson) and the library's SWAR and UTF-8 checks, independent of the
  byte order

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-09-29 03:49:29 +02:00