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README: new doc: Parsing

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Max Bruckner 2017-11-10 22:08:57 +01:00
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@ -9,6 +9,7 @@ Ultralightweight JSON parser in ANSI C.
* [Building](#building)
* [Including cJSON](#including-cjson)
* [Data Structure](#data-structure)
* [Parsing JSON](#parsing-json)
* [Some JSON](#some-json)
* [Here's the structure](#heres-the-structure)
* [Caveats](#caveats)
@ -163,6 +164,24 @@ Additionally there are the following two flags:
* `cJSON_IsReference`: Specifies that the item that `child` points to and/or `valuestring` is not owned by this item, it is only a reference. So `cJSON_Delete` and other functions will only deallocate this item, not it's children/valuestring.
* `cJSON_StringIsConst`: This means that `string` points to a constant string. This means that `cJSON_Delete` and other functions will not try to deallocate `string`.
### Parsing JSON
Given some JSON in a zero terminated string, you can parse it with `cJSON_Parse`.
```c
cJSON *json = cJSON_Parse(string);
```
It will parse the JSON and allocate a tree of `cJSON` items that represents it. Once it returns, you are fully responsible for deallocating it after use with `cJSON_Delete`.
The allocator used by `cJSON_Parse` is `malloc` and `free` by default but can be changed (globally) with `cJSON_InitHooks`.
If an error occurs a pointer to the position of the error in the input string can be accessed using `cJSON_GetErrorPtr`. Note though that this can produce race conditions in multithreading scenarios, in that case it is better to use `cJSON_ParseWithOpts` with `return_parse_end`.
By default, characters in the input string that follow the parsed JSON will not be considered as an error.
If you want more options, use `cJSON_ParseWithOpts(const char *value, const char **return_parse_end, cJSON_bool require_null_terminated)`.
`return_parse_end` returns a pointer to the end of the JSON in the input string or the position that an error occurs at (thereby replacing `cJSON_GetErrorPtr` in a thread safe way). `require_null_terminated`, if set to `1` will make it an error if the input string contains data after the JSON.
### Some JSON:
```json