zephyr-tomlc99

Wrapper around tomlc99 library for Zephyr RTOS.

Installation

To install this library in a zephyr example-application

cd lib
git clone https://github.com/Dalachowsky/zephyr-tomlc99

in lib/Kconfig

menu "Libraries"

...
rsource "tomlc99/Kconfig"
...

endmenu

in lib/CMakeLists.txt

...
add_subdirectory_ifdef(CONFIG_TOMLC99 tomlc99)
...

Usage

Parsing simple config in Zephyr RTOS

const char *config = "foo = \"bar\"";
uint8_t heap[1024];
toml_parser_get(&heap, sizeof(heap), K_NO_WAIT);
if (toml_parser_get(&heap, 1024, K_NO_WAIT) != 0) {
    LOG_ERR("Error");
    return -1;
}
toml_table_t *table = toml_parse_string(config);
toml_datum_t foo = toml_string_in(table, "foo");
LOG_INF("foo: %s", foo.u.s);

toml_parser_free();

Heap

Since toml is mostly used for config files I have decided implement a "heap buffer". tomlc99 makes use of malloc() and free() functions. I did not want to reserve heap space for parsing a config file that is done once or twice. Instead i added the heap parameter to toml_parser_get which is used to initialize temporary heap space.

Limitations

Only one file can be parsed at a time. This is due to my override of malloc and free functions. In some time I might try making my implementation nicer, this one was supposed to be quick and easy.

Parsing float values is not supported since no strtod() implementation

Accessing Table Content

TOML tables are dictionaries where lookups are done using string keys. In general, all access functions on tables are named toml_*_in(...).

In the normal case, you know the key and its content type, and retrievals can be done using one of these functions:

toml_string_in(tab, key);
toml_bool_in(tab, key);
toml_int_in(tab, key);
//toml_double_in(tab, key); Not supported yet
toml_timestamp_in(tab, key);
toml_table_in(tab, key);
toml_array_in(tab, key);

You can also interrogate the keys in a table using an integer index:

toml_table_t* tab = toml_parse_string(...);
for (int i = 0; ; i++) {
    const char* key = toml_key_in(tab, i);
    if (!key) break;
    printf("key %d: %s\n", i, key);
}

Accessing Array Content

TOML arrays can be deref-ed using integer indices. In general, all access methods on arrays are named toml_*_at().

To obtain the size of an array:

int size = toml_array_nelem(arr);

To obtain the content of an array, use a valid index and call one of these functions:

toml_string_at(arr, idx);
toml_bool_at(arr, idx);
toml_int_at(arr, idx);
//toml_double_at(arr, idx); Not supported yet
toml_timestamp_at(arr, idx);
toml_table_at(arr, idx);
toml_array_at(arr, idx);

toml_datum_t

Some toml_*_at and toml_*_in functions return a toml_datum_t structure. The ok flag in the structure indicates if the function call was successful. If so, you may proceed to read the value corresponding to the type of the content.

For example:

toml_datum_t host = toml_string_in(tab, "host");
if (host.ok) {
	printf("host: %s\n", host.u.s);
	free(host.u.s);   /* FREE applies to string and timestamp types only */
}

** IMPORTANT: if the accessed value is a string or a timestamp, you must call free(datum.u.s) or free(datum.u.ts) respectively after usage. **