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 ๐งช 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 ๐๏ธ ๐.
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("โโ valueType: %s\n", i.ValueType().String())
if k := i.Key(); k != "" {
fmt.Printf("โโ key: %q\n", k[1:len(k)-1])
}
if ai := i.ArrayIndex(); ai != -1 {
fmt.Printf("โโ arrayIndex: %d\n", ai)
}
if v := i.Value(); v != "" {
fmt.Printf("โโ value: %q\n", v)
}
fmt.Printf("โโ level: %d\n", i.Level())
return false // Resume scanning
})
if err.IsErr() {
fmt.Printf("ERR: %s\n", err)
return
}
}