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Niels Lohmann
a59d1f64e9
Add API pages for basic_json_document::save() and load(), including the image_check enumeration and its three levels. Add examples that show caching a parsed document as an image, loading it without parsing, the difference between a borrowed and an owned image, and a full check rejecting a damaged image that a bounds check still reads safely. Add an "Images" section to the json_view feature page, register the new pages in mkdocs.yml and docSet.sql, group basic_json_document's member list by parsing/access/images/edits, and document parse_error.116 and type_error.320 on the exceptions page, extending out_of_range.416 for images. Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2.3 KiB
2.3 KiB
nlohmann::basic_json_document::read
template<typename InputType>
void read(InputType&& input,
const bool allow_exceptions = true,
const bool ignore_comments = false,
const bool ignore_trailing_commas = false);
(Re-)parses input into #!cpp *this, discarding the document's previous value and reusing its memory (the node
index, the decoded-string buffer, and, if applicable, the owned copy of the text) rather than allocating a fresh
document. parse() is implemented in terms of this function, applied to a default-constructed document.
Template parameters
InputType- A compatible input; see
parse.
Parameters
input(in)- Input to parse from.
allow_exceptions(in)- whether to throw exceptions in case of a parse error (optional,
#!cpp trueby default) ignore_comments(in)- whether comments should be ignored and treated like whitespace (
#!cpp true) or yield a parse error (#!cpp false); (optional,#!cpp falseby default) ignore_trailing_commas(in)- whether trailing commas in arrays or objects should be ignored and treated like whitespace (
#!cpp true) or yield a parse error (#!cpp false); (optional,#!cpp falseby default)
Exceptions
Same as parse.
Complexity
Linear in the length of the input.
Notes
Every view taken from #!cpp *this before the call -- including the previous root() -- is invalidated,
whether or not the new parse succeeds; take fresh views from root() afterward.
input is borrowed or owned by the same rules as parse(); a document can borrow on one call and
own on the next, since ownership is decided freshly each time.
Examples
??? example
The example below parses a sequence of messages into the same document, reusing its memory instead of allocating
a new document for each one.
```cpp
--8<-- "examples/basic_json_document__read.cpp"
```
Output:
```json
--8<-- "examples/basic_json_document__read.output"
```
See also
- parse - deserialize from a compatible input
- root - the view of the root value
- load - read a document from an image instead of parsing JSON text
Version history
- Added in version 3.13.0.