dparval - a delayed parsing value system

The goal is offer a consistent type structure to allow you to process JSON end-to-end with minimal parsing.

Features

• Create Value objects with unparsed JSON bytes or with JSON compatible go datatypes
• Access nested data using Path() and Index() methods
  • these also return Value objects (or Undefined) allowing you to delay parsing of nested objects as well
• Values of type OBJECT and ARRAY are mutable
  • SetPath() and SetIndex() allow you to overlay new Values into these objects
• Returning to []byte can be done at any time by calling Bytes()
  • the underlying raw bytes are reused if possible to avoid JSON encoding
• Exit the type system at any time by calling Value()
  • this will trigger parsing of any required values that have not yet been parsed
• Arbitrary data may be attached to a Value using the Set/Get/Remove Attachment() methods
• Check the type of Value using the Type() method

Documentation

See GoDoc

Performance

Two simple benchmarks which process a 1MB JSON file. The first uses NewValueFromBytes() with Path(), Index() and Value() calls and the second using json.Unmarshal() and map/slice calls. Both versions access the same property.

$ go test -bench .
PASS
BenchmarkLargeValue	      20	  76905386 ns/op	  25.23 MB/s
BenchmarkLargeMap	      20	 116378934 ns/op	  16.67 MB/s
ok  	github.com/mschoch/dparval	4.179s

Usage

// read some JSON
bytes := []byte(`{"type":"test"}`)

// create a Value object
doc := dparval.NewValueFromBytes(bytes)

// attempt to access a nested Value
docType, err := doc.Path("type")
if err != nil {
	panic("no property type exists")
}

// convert docType to a native go value
docTypeValue := docType.Value()

// display the value
fmt.Printf("document type is %v\n", docTypeValue)

Output

$ ./example
document type is test