A simple Json parsing library

In simple terms, the library translates a valid json file into a structure of nested array lists and hash maps.

Dependencies:

• C Generic Hash Map
• C Generic Linked List
• C Generic Array List
• C Utilities

All of these can be found on my github page.

A simple example

{
    "foo": true,
    "bar": 123,
    "baz": [
        "qux",
        "quux"
    ],
    "quuz": {
        "corge": null
    }
}

Calling parseJson(simple.json) will return a jsonBundle*. This jsonBundle contains a pointer to the root element of the json structure (member: structure); which is either an arrayList* or hashMap* (stored as void* to enable genericity). It also contains a private variable containing a list of all memory allocated during the parsing, which is needed to properly free the parsed structure and prevent memory leaks (see below).

The root element of simple.json will be a hashMap with four keys:

1. foo
2. bar
3. baz
4. quuz

To print out the value in foo, call getValueForKey(structure, "foo"), which will return a void* which can be casted to a bool* and then printed:

jsonBundle* bundle = parseJson("testJsonFiles/simple.json");
bool* fooVal = getValueForKey(bundle->structure, "foo");
puts(*fooVal == 0 ? "false" : "true");

Similarly for bar:

jsonBundle* bundle = parseJson("testJsonFiles/simple.json");
int* barVal = getValueForKey(bundle->structure, "bar");
printf("%d\n", *barVal);

For baz, because its value is an array, it will be represented in structure as an arrayList. You will therefore have to first get the pointer to this list and then use arrayList methods to get the enclosed values:

jsonBundle* bundle = parseJson("testJsonFiles/simple.json");
arrayList* bazVal = getValueForKey(bundle->structure, "baz");
char* secondItem = getItemAt(bazVal, 1);
puts(secondItem);

For quuz, because its value is another json object, it will be represented in structure as a further hashMap. You will therefore have to first get the pointer to this map and then use getValueForKey(structure, "foo") again to get the enclosed values. It you wanted to get the value for 'corge':

jsonBundle* bundle = parseJson("testJsonFiles/simple.json");
hashMap* quuzVal = getValueForKek(bundle->structure, "quuz");
void* corgeVal = getValueForKey(quuzVal, "corge");
puts(corgeVal ? "Corge val was not null" : "Corge val was null");

Freeing the jsonBundle

The function freeJsonBundle(jsonBundle* bundle) MUST be called on the bundle returned by parseJson or memory leaks will occur. After this has been called, the json structure and all of its values will be freed from memory and will therefore not be accessible anymore.

freeJsonBundle(bundle);

Other considerations

• The parser itself is not thread safe, although I could make it so if there was demand.