Niels Lohmann
6a852ab96d
* Split the json_view feature page into sub-pages
The single features/json_view.md page grew to ~600 lines covering eight
topics. Split it into features/json_view/ with an overview page and
pages for ownership and lifetime, differences from basic_json, reading
values, generic code, editing, and images.
The new differences page collects what was spread over several sections
("What is the same", "What is different", "Duplicate keys", and notes in
the conversion and serialization sections) under one summary table, and
adds the parts of the basic_json interface a view does not have. The
other pages now link to it instead of restating the rules.
Internal links across the documentation point to the new pages.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Docs: fix stale comments and trim repeated text in json_view pages
- fig-jsonview.js/.css: point the header comments at the new pages
- reading.md: views' strings are valid as long as the document (and a
borrowed source text), as lifetime.md says
- reading.md, generic_code.md: link to differences.md instead of
restating the member-order and repeated-key rules
- differences.md: drop the third mention of ordering comparisons, name
rbegin()/rend() in the iterator row
- exceptions.md: link editable documents to editing.md
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
---------
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
1.8 KiB
1.8 KiB
nlohmann::basic_json_view::source_offset
std::size_t source_offset() const noexcept;
Returns the byte offset of this value in the document's source() text, without
materializing anything.
Return value
- For a string with no escapes, a number,
#!json true/#!json false/#!json null, an array, or an object: the byte offset of the first byte of the value's token (for a string: the first byte after the opening quote) insource(). #!cpp static_cast<std::size_t>(-1)for a discarded view, and for a string that contains escapes — such a string was decoded once into the document's own buffer, so there is no single byte range insource()left to point at.
Exception safety
No-throw guarantee: this function never throws exceptions.
Complexity
Constant.
Notes
This is a raw offset, not a length: the API does not (yet) expose how many bytes the token occupies in the source
text, so source_offset() alone is enough to report where a value came from (for an error message, for syntax
highlighting, ...) but not to slice its exact text back out of source() for a
string, whose token length is not the same as its decoded size().
Examples
??? example
```cpp
--8<-- "examples/basic_json_view__source_offset.cpp"
```
Output:
```json
--8<-- "examples/basic_json_view__source_offset.output"
```
See also
source- the parsed textis_string- return whether the value is a string- Zero-copy JSON views - images and the source text
Version history
- Added in version 3.13.0.