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nlohmann::basic_json::sax_parse

// (1)
template <typename InputType, typename SAX>
static bool sax_parse(InputType&& i,
                      SAX* sax,
                      input_format_t format = input_format_t::json,
                      const bool strict = true,
                      const bool ignore_comments = false);

// (2)
template<class IteratorType, class SAX>
static bool sax_parse(IteratorType first, IteratorType last,
                      SAX* sax,
                      input_format_t format = input_format_t::json,
                      const bool strict = true,
                      const bool ignore_comments = false);

Read from input and generate SAX events

Read from a compatible input.
Read from a pair of character iterators

The value_type of the iterator must be an integral type with size of 1, 2 or 4 bytes, which will be interpreted respectively as UTF-8, UTF-16 and UTF-32.

The SAX event lister must follow the interface of json_sax.

Template parameters

InputType

A compatible input, for instance:

an std::istream object
a FILE pointer
a C-style array of characters
a pointer to a null-terminated string of single byte characters
an object obj for which begin(obj) and end(obj) produces a valid pair of iterators.

IteratorType

Description

SAX

Description

Parameters

i (in): Input to parse from.
sax (in): SAX event listener
format (in): the format to parse (JSON, CBOR, MessagePack, or UBJSON) (optional, input_format_t::json by default), see input_format_t for more information
strict (in): whether the input has to be consumed completely (optional, #!cpp true by default)
ignore_comments (in): whether comments should be ignored and treated like whitespace (#!cpp true) or yield a parse error (#!cpp false); (optional, #!cpp false by default)
first (in): iterator to start of character range
last (in): iterator to end of character range

Return value

return value of the last processed SAX event

Exception safety

Complexity

Linear in the length of the input. The parser is a predictive LL(1) parser. The complexity can be higher if the SAX consumer sax has a super-linear complexity.

Notes

A UTF-8 byte order mark is silently ignored.

Examples

??? example

The example below demonstrates the `sax_parse()` function reading from string and processing the events with a
user-defined SAX event consumer.

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

Output:

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

Version history

Added in version 3.2.0.
Ignoring comments via ignore_comments added in version 3.9.0.

!!! warning "Deprecation"

Overload (2) replaces calls to `sax_parse` with a pair of iterators as their first parameter which has been
deprecated in version 3.8.0. This overload will be removed in version 4.0.0. Please replace all calls like
`#!cpp sax_parse({ptr, ptr+len});` with `#!cpp sax_parse(ptr, ptr+len);`.

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