Lillith's json.c

A simple JSON parser in pure C!

<500 lines excluding whitespace!

That's it! That's the library!

Here's the header file to explain how to use it:

typedef enum {    // pointer contents:
    JSON_INVALID, // null pointer, unused enum variant
    JSON_OBJECT,  // json_object
    JSON_ARRAY,   // json_array
    JSON_STRING,  // null-terminated string
    JSON_NUMBER,  // double
    JSON_BOOL,    // bool
    JSON_NULL,    // null pointer
} json_element_type;

typedef struct struct_json_object json_object;
typedef struct struct_json_array json_array;

typedef struct struct_json_element {
    json_element_type type;
    union {
        json_object *object;
        json_array *array;
        char *string;
        double *number;
        bool *boolean;
        void *raw;
    } value;
} json_element;

typedef struct struct_json_pair {
    char *key;
    json_element *value;
} json_pair;

struct struct_json_object {
    unsigned int size;
    json_pair *values[];
};

struct struct_json_array {
    unsigned int size;
    json_element *values[];
};

json_element *json_parse(const char *src);
void json_dump(const json_element *element);
void json_dump_pretty(const json_element *element);
void json_free(json_element *element);
bool json_has_key(const json_element *object, const char *key);
json_element *json_get_key(const json_element *object, const char *key);

size_t curl_json_writefunction(char *src, size_t _, size_t size, void *data);

Call json_parse on your input string. If it returns NULL, the JSON had an error somewhere in it. Otherwise, it was valid, and you have a JSON object! Check type to see what it was, and use the appropriate union value to cast it. Then once you're done, call json_free on the root object you received. If you call it on subtrees and leak memory, it's your fault not mine!

For retrieving values out of objects, there is json_has_key (to check if a key is present) and json_get_key to get the value of a key. json_get_key will return NULL if the key is not found.

For debugging, there are json_dump and json_dump_pretty. Former dumps without indents, latter dumps with indents.

Finally, curl_json_writefunction, as the name implies, is a writefunction for libcurl that stores its JSON output to data. Specifically, data is treated as a json_element **.

Issues? Feature Request?

Contact me through an appropriate method on https://inx.moe

Keep in mind though, I am unlikely to implement any feature requests, as it is complete enough for my needs. It's supposed to be a simple JSON parser after all, not a complex JSON parser.