JSONX: extended JSON syntax for Go

JSONX is a superset of JSON that allows additional types and has a more relaxed syntax.

Example:

{
  k01: null,
  k02: false,
  k03: true,
  k04: "test",
  k05: 1.45678e-98,
  k06: int(-454365464),
  k07: uint(455645765),
  k08: int8(-128),
  k09: uint8(255),
  k10: int16(32767),
  k11: uint16(65535),
  k12: int32(2147483647),
  k13: uint32(4294967295),
  k14: int64("9223372036854775807"),
  k15: uint64("18446744073709551615"),
  k16: datetime("2017-12-25T15:00:00Z"),
  k17: ip("192.168.1.2"),
  k18: ipport("192.168.1.2:65000"),
  k19: ip("::1"),
  k20: ipport("[::1]:65000"),
  k21: [
    "test",
    int(123),
  ],
  k22: {
    test: true
  }
}

Differences from JSON:

• Keys may be unquoted as long as they match ^[A-Za-z_][0-9A-Za-z_]*$.
• Trailing commas after the last array or object elements are permitted.
• Additional types can be represented as 'type(value)'. The example above contains all currently supported types.

Usage

The package includes a parser and a serialiser. They are both schemaless (i.e. only accept and produce primitive values, []interface{} and map[string]interface{})

Because JSONX is a superset of JSON you can use the parser as a faster alternative to the standard json.Unmarshal():

var v interface{}
err := json.Unmarshal(data, &v)

// or
v, err := jsonx.Decode(data)

Non-greedy decoding example:

b := []byte(`{test: 1} blah`)
v, err := jsonx.Decode(b)
if err, ok := err.(*jsonx.ExtraDataError); ok {
    tail := b[err.Offset:] // "blah"
    // parse tail
}

As JSONX is a valid ES5 expression you could parse it in Javascript using eval() providing the type functions (int(), int8(), datetime(), etc..) are defined.

Encoding example:

v := map[string]interface{}{"test": true}

// encoding/json compatible API
b, err := jsonx.Marshal(v)
b1, err := jsonx.MarshalIndent(v, ">", "\t")

// encoding to an io.Writer
enc := jsonx.NewEncoder(os.Stdout)
err = enc.Encode(v)
enc1 := jsonx.NewEncoderIndent(os.Stdout, ">", "\t")
err = enc1.Encode(v)

Acknowledgements

Decoder is based on djson which saved me a lot of time writing it from scratch.

The code was tested with go-fuzz which I think is a must for any projects like this.