jscan provides high-performance zero-allocation JSON iterator and validator for Go. This module doesn't provide Marshal/Unmarshal capabilities yet, instead it focuses on highly efficient iteration over JSON data with on-the-fly validation.
An experimental decoder with backward compatibility to encoding/json is WiP 🧪 and is expected to be introduced together with jscan v3.
jscan is tested against https://github.com/nst/JSONTestSuite, a comprehensive test suite for RFC 8259 compliant JSON parsers.
See jscan-benchmark for benchmark results 🏎️ 🏁.
https://go.dev/play/p/moP3l9EkebF
package main import ( "fmt" "github.com/romshark/jscan/v2" ) func main() { j := `{ "s": "value", "t": true, "f": false, "0": null, "n": -9.123e3, "o0": {}, "a0": [], "o": { "k": "\"v\"", "a": [ true, null, "item", -67.02e9, ["foo"] ] }, "a3": [ 0, { "a3.a3":8 } ] }` err := jscan.Scan(j, func(i *jscan.Iterator[string]) (err bool) { fmt.Printf("%q:\n", i.Pointer()) fmt.Printf("├─ valueType: %s\n", i.ValueType().String()) if k := i.Key(); k != "" { fmt.Printf("├─ key: %q\n", k[1:len(k)-1]) } if ai := i.ArrayIndex(); ai != -1 { fmt.Printf("├─ arrayIndex: %d\n", ai) } if v := i.Value(); v != "" { fmt.Printf("├─ value: %q\n", v) } fmt.Printf("└─ level: %d\n", i.Level()) return false // Resume scanning }) if err.IsErr() { fmt.Printf("ERR: %s\n", err) return } }