Add json parse and stringify function to jerryscript c api (#2243)

JerryScript-DCO-1.0-Signed-off-by: Zsolt Raduska rzsolt@inf.u-szeged.hu

docs/02.API-REFERENCE.md

@@ -5921,3 +5921,73 @@ jerry_value_t jerry_get_typedarray_buffer (jerry_value_t value,
 **See also**
 
 - [jerry_create_typedarray](#jerry_create_typedarray)
+
+# JSON functions
+
+## jerry_json_parse
+
+**Summary**
+
+Returns the same result as JSON.parse ecmascript function.
+
+**Prototype**
+
+```c
+jerry_value_t jerry_json_parse (const jerry_char_t *string_p, jerry_size_t string_size)
+```
+
+- `string_p` - a JSON string
+- `string_size` - size of the string
+- return
+  - jerry_value_t containing the same as json.parse()
+  - jerry_value_t containing error massage
+
+**Example**
+
+```c
+{
+  const char *data = "{\"name\": \"John\", \"age\": 5}";
+  jerry_size_t str_length = (jerry_size_t)strlen (data);
+  jerry_value_t parsed_json = jerry_json_parse ((jerry_char_t*)data, str_length);
+
+  // parsed_json now conatins all data stored in data_in_json
+
+  jerry_release_value (parsed_json);
+}
+```
+
+## jerry_stringify
+
+  **Summary**
+
+  Returns the same value as JSON.stringify() ecmascript function.
+
+  **Prototype**
+
+```c
+jerry_value_t jerry_json_stringfy (const jerry_value_t object_to_stringify)
+```
+
+- `object_to_stringify` - a jerry_value_t object to stringify
+- return
+  - jerry_value_t containing the same as json.stringify()
+  - jerry_value_t containing error massage
+
+**Example**
+
+```c
+{
+  jerry_value_t obj = jerry_create_object ();
+  jerry_value_t key = jerry_create_string ((const jerry_char_t *) "name");
+  jerry_value_t value = jerry_create_string ((const jerry_char_t *) "John");
+  jerry_set_property (obj, key, value);
+  jerry_value_t stringified = jerry_json_stringfy (obj);
+
+  //stringified now contains a json formated string
+
+  jerry_release_value (obj);
+  jerry_release_value (key);
+  jerry_release_value (value);
+  jerry_release_value (stringified);
+}
+```