UJSON is:
- Complete and simple JSON reader and writer written in C
- Produces nice and human readable error messages
- Passes JSONTestSuite
See generated documentation at: https://metan-ucw.github.io/ujson/files.html
The key point of this parser is that:
- works on a buffer in a memory that is not modified during the parsing
- parser does not allocate memory
- nearly stateless, the only state the parser maintains is an offset to the string buffer, recursion depth and error flag
- if error flag is raised all parser functions return immediatelly with error
The parser is started by a call to ujson_start() function in order to
determine if first element in the buffer is object or an array.
switch (ujson_reader_start(reader)) {
case UJSON_ARR:
//parse array
break;
case UJSON_OBJ:
//parse object
break;
default:
break;
}
if (ujson_reader_err(reader))
ujson_err_print(reader);Then you can loop recursively over arrays and objects with:
char sbuf[128];
struct ujson_val json = {.buf = sbuf, .buf_size = sizeof(sbuf)};
UJSON_OBJ_FOREACH(reader, &json) {
switch (json.type) {
case UJSON_OBJ:
//parse object
break;
case UJSON_ARR:
//parse array
break;
case UJSON_STR:
...
}
}The supported types are:
- UJSON_ARR - an array, needs to be parsed recursivelly
- UJSON_OBJ - an object, needs to be parsed recursivelly
- UJSON_INT - an integer number stored as val_int (also sets val_float for convinience)
- UJSON_FLOAT - a floating point number stored as val_float
- UJSON_BOOL - a boolean stored as val_bool
- UJSON_NULL - a null has no value
- UJSON_STR - a string, stored in user supplied buffer