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Niels Lohmann a47170346a docs: new design for the documentation site (#5934)
* docs: new design for the documentation site

Apply the brand to the Material for MkDocs site: Inter and JetBrains Mono
served by the site (upright and real italic), brand colours, blue header band
with the syntax pattern, wordmark in the header, new home page (hero, cards,
animated feature tour), 404 page, polish for tabs, search, footer, focus
rings, tables and code blocks, and theme features (code copy, previous/next
footer, TOC follow, search suggestions).

Draw the number railroad diagram, the parser callback events and the iterator
illustrations as inline SVGs that follow the light and dark scheme. The
generator scripts are in docs/mkdocs/scripts/figures; the feature slideshow
(json-light.svg, json-dark.svg, replacing json.gif on the home page) is built
by docs/mkdocs/scripts/slideshow. Decision nodes in five flowcharts become
hexagons, which need far less room.

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

* docs: add figures, table captions and a macro chooser

- Figures with numbered captions: SAX stepper, json_view layout and edit
  stepper, exception map, JSON pointer and patch walkers, QA pipeline,
  scaling and binary size charts, roadmap lanes, release timeline,
  integration decision tree and namespace builder
- Table captions (nj-table-caption) on 9 pages
- Compile times: modules and PCH charts, filesystem section, re-measured
  Figure 1, links between features/modules.md and compile_times.md
- Interactive macro chooser for features/arbitrary_types.md
- Link check: exclude URLs that answer the plugin with 400/401/419 or are
  dead (customers.md)

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

* docs: macro chooser generates adl_serializer for non-default-constructible types

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

* docs: cross-link concept pages and API pages in See also sections

Add See also links in both directions between the concept pages (features,
home, integration) and the API pages, write API links in code font, give every
entry a comment after a dash, and show the callback event figure on the parser
callbacks page.

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

* docs: address review comments on the new design

- Home: add a "Latest release" button
- Sponsors: update the list and group it by tier
- Features: list all feature pages on the index page
- Releases: add highlights per release, link the 4.0 roadmap, add the first commit to the timeline
- Exceptions: prefix all example messages with the exception name
- API: no code font for format names in the See also links of the to_/from_ pages
- Merge Patch: show the document before, the patch, and the result
- Replace "--" with typographic dashes, mark external links with an icon, center Mermaid diagrams

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

---------

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-27 07:41:42 +01:00

3.1 KiB

nlohmann::basic_json::to_bon8

// (1)
static std::vector<std::uint8_t> to_bon8(const basic_json& j);

// (2)
static void to_bon8(const basic_json& j, detail::output_adapter<std::uint8_t> o);
static void to_bon8(const basic_json& j, detail::output_adapter<char> o);

Serializes a given JSON value j to a byte vector using the BON8 (Binary Object Notation 8) serialization format. BON8 is a compact binary serialization format that stores strings as UTF-8 without a length prefix.

  1. Returns a byte vector containing the BON8 serialization.
  2. Writes the BON8 serialization to an output adapter.

The exact mapping and its limitations are described on a dedicated page.

Parameters

j (in)
JSON value to serialize
o (in)
output adapter to write serialization to

Return value

  1. BON8 serialization as a byte vector
  2. (none)

Exception safety

Strong guarantee: if an exception is thrown, there are no changes in the JSON value j, which is never modified. With (2), the bytes written before the exception remain in the output adapter.

Exceptions

  • Throws out_of_range.407 if j contains an integer outside the range of int64 (an unsigned integer above 9223372036854775807, or, with a number type wider than 64 bits, any integer beyond int64), which BON8 cannot represent
  • Throws type_error.316 if j contains a string that is not valid UTF-8
  • Throws type_error.321 if j or a value nested in it is discarded; example: "cannot serialize discarded value to BON8"

Complexity

Linear in the size of the JSON value j.

Examples

??? example "Example: serialize a JSON value to BON8"

The example shows the serialization of a JSON value to a byte vector in BON8 format.
 
```cpp
--8<-- "examples/to_bon8.cpp"
```

Output:

```json
--8<-- "examples/to_bon8.output"
```

??? example "Example: type_error.316 exception"

The example shows how serializing a string that is not valid UTF-8 throws an exception, because BON8 stores strings
as UTF-8.

```cpp
--8<-- "examples/to_bon8__exception.cpp"
```

Output:

```json
--8<-- "examples/to_bon8__exception.output"
```

See also

  • BON8 - the format, its byte layout and how values are mapped
  • Binary formats - overview and comparison of the supported binary formats
  • from_bon8 - create a JSON value from an input in BON8 format
  • to_cbor - create a CBOR serialization of a JSON value
  • to_msgpack - create a MessagePack serialization of a JSON value
  • to_bson - create a BSON serialization of a JSON value
  • to_ubjson - create a UBJSON serialization of a JSON value
  • to_bjdata - create a BJData serialization of a JSON value

Version history

  • Added in version 3.13.0.