JSON C Parser And Codec

As the title states, this is to be a C-based parser and codec (outputter/writer) for JSON data.

Usage Example

// heap memory
arena_t arena;
arena_create(&arena, 4096 * 4);

// json creation
json_value_t * obj = json_make_object(&arena);
json_object_add(&arena, obj, "name", json_make_string(&arena, "Sailor"));
json_object_add(&arena, obj, "age", json_make_number(&arena, 42));

json_value_t * array =  json_make_array(&arena);
json_array_append(&arena, array, json_make_string(&arena, "one"));
json_array_append(&arena, array, json_make_string(&arena, "two"));
json_object_add(&arena, obj, "list", array);

// final node
json_result_t result = {
    .root = obj,
    .err = NULL
};

// dump to terminal
json_dump(result);

// cleanup heap memory
arena_destroy(&arena);

The expected result is:

{
  "name" : "Sailor",
  "age" : 42,
  "list" : [
    "one",
    "two"
  ]
}

Resources about JSON

JSON API
JSON ORG
Wikipedia/JSON
RFC4627
Library: cJSON
Library: jsmn (jasmine)
Library: sheredom/utf8.h
IBM: JSON Parser Limits

Information

JSON uses the filename extension ".json"
The media type (MIME) is "application/json"
It uses UTF-8 character encoding.

JSON Data Types

Data Type	Description
Number	a signed decimal number that may use E notation but cannot be non-numbers like NaN
String	zero or more Unicode chars, delimited with '"' and supports '\n' escape syntax
Boolean	either 'true' or 'false
Array	ordererd list of zero or more elements. Uses '[' and ']' bracket notation with ',' separeted elements
Object	A collection of name-value pairs or [UTF-8 String]Key-Value pairs
null	an empty value - not a pointer

Whitespace is allowed and ignored around syntactic elements but not withing a string value. Four specific characters are whitespace in JSON: Space:' ', Tab:'\t', LF:'\n', CR:'\r'.
For UTF-8 and other, the Byte Order Mark (BOM) must not be generated by a conforming implementation. (U+FEFF = zero width no-break space) JSON allows for U+2028 (Unicode: Line Separator) and U+2029 (Unicode: Paragraph Separator) to appear UNESCAPED in qouted strings.
JSON does not have comments.
JSON does not differentiate between numbers as integers or floating-point values (real). (Thus '42', '42.0', '4.2E+1' can all be the same number, depending on the implementation)
Note: JS uses IEEE-754 double-precision floating-point format for all its numeric values.

Since JSON uses UTF-8, it can support the full Unicode character set, including characters outside the Basic Multilingual Plane (U+0000 to U+FFFF). If escaped, those characters MUST be written using UTF-16 surrogate pairs.
Example: (U+1F610, Unicode: Neutral Face) '😐' has be (in JSON):

{ "face": "😐" }
// or
{ "face": "\uD83D\uDE10" }

Syntax example

{
  "first_name": "John",
  "last_name": "Smith",
  "is_alive": true,
  "age": 27,
  "address": {
    "street_address": "21 2nd Street",
    "city": "New York",
    "state": "NY",
    "postal_code": "10021-3100"
  },
  "phone_numbers": [
    {
      "type": "home",
      "number": "212 555-1234"
    },
    {
      "type": "office",
      "number": "646 555-4567"
    }
  ],
  "children": [
    "Catherine",
    "Thomas",
    "Trevor"
  ],
  "spouse": null
}

Complex Syntax Example

{
    "medications":[{
        "aceInhibitors":[{
            "name":"lisinopril",
            "strength":"10 mg Tab",
            "dose":"1 tab",
            "route":"PO",
            "sig":"daily",
            "pillCount":"#90",
            "refills":"Refill 3"
        }],
        "antianginal":[{
            "name":"nitroglycerin",
            "strength":"0.4 mg Sublingual Tab",
            "dose":"1 tab",
            "route":"SL",
            "sig":"q15min PRN",
            "pillCount":"#30",
            "refills":"Refill 1"
        }],
        "anticoagulants":[{
            "name":"warfarin sodium",
            "strength":"3 mg Tab",
            "dose":"1 tab",
            "route":"PO",
            "sig":"daily",
            "pillCount":"#90",
            "refills":"Refill 3"
        }],
            "betaBlocker":[{
                "name":"metoprolol tartrate",
                "strength":"25 mg Tab",
                "dose":"1 tab",
                "route":"PO",
                "sig":"daily",
                "pillCount":"#90",
                "refills":"Refill 3"
            }],
            "diuretic":[{
                "name":"furosemide",
                "strength":"40 mg Tab",
                "dose":"1 tab",
                "route":"PO",
                "sig":"daily",
                "pillCount":"#90",
                "refills":"Refill 3"
            }],
            "mineral":[{
                "name":"potassium chloride ER",
                "strength":"10 mEq Tab",
                "dose":"1 tab",
                "route":"PO",
                "sig":"daily",
                "pillCount":"#90",
                "refills":"Refill 3"
            }]
        }
    ],
    "labs":[{
        "name":"Arterial Blood Gas",
        "time":"Today",
        "location":"Main Hospital Lab"      
        },
        {
        "name":"BMP",
        "time":"Today",
        "location":"Primary Care Clinic"    
        },
        {
        "name":"BNP",
        "time":"3 Weeks",
        "location":"Primary Care Clinic"    
        },
        {
        "name":"BUN",
        "time":"1 Year",
        "location":"Primary Care Clinic"    
        },
        {
        "name":"Cardiac Enzymes",
        "time":"Today",
        "location":"Primary Care Clinic"    
        },
        {
        "name":"CBC",
        "time":"1 Year",
        "location":"Primary Care Clinic"    
        },
        {
        "name":"Creatinine",
        "time":"1 Year",
        "location":"Main Hospital Lab"  
        },
        {
        "name":"Electrolyte Panel",
        "time":"1 Year",
        "location":"Primary Care Clinic"    
        },
        {
        "name":"Glucose",
        "time":"1 Year",
        "location":"Main Hospital Lab"  
        },
        {
        "name":"PT/INR",
        "time":"3 Weeks",
        "location":"Primary Care Clinic"    
        },
        {
        "name":"PTT",
        "time":"3 Weeks",
        "location":"Coumadin Clinic"    
        },
        {
        "name":"TSH",
        "time":"1 Year",
        "location":"Primary Care Clinic"    
        }
    ],
    "imaging":[{
            "name":"Chest X-Ray",
            "time":"Today",
            "location":"Main Hospital Radiology"    
        },
        {
            "name":"Chest X-Ray",
            "time":"Today",
            "location":"Main Hospital Radiology"    
        },
        {
            "name":"Chest X-Ray",
            "time":"Today",
            "location":"Main Hospital Radiology"    
        }
    ]
}