Dumps Go text/scanner tokens to stdout as JSON

scandump.go

package main

import (
	"encoding/json"
	"os"
	"text/scanner"
)

type Token struct {
	Position scanner.Position `json:"pos"`
	Text     string           `json:"text"`
	Rune     rune             `json:"rune"`
}

func main() {
	var j = json.NewEncoder(os.Stdout)

	var s scanner.Scanner
	s.Mode = scanner.GoTokens
	s.Init(os.Stdin)

	var t Token
	for {
		r := s.Scan()
		switch r {
		case scanner.EOF:
			return
		}
		t.Rune = r
		t.Text = s.TokenText()
		t.Position = s.Pos()
		j.Encode(&t)
	}
}

For echo '{a:"alpha", b:1}' | go run scandump.go, output is:

{"pos":{"Filename":"","Offset":1,"Line":1,"Column":2},"text":"{","rune":123}
{"pos":{"Filename":"","Offset":2,"Line":1,"Column":3},"text":"a","rune":-2}
{"pos":{"Filename":"","Offset":3,"Line":1,"Column":4},"text":":","rune":58}
{"pos":{"Filename":"","Offset":10,"Line":1,"Column":11},"text":"\"alpha\"","rune":-6}
{"pos":{"Filename":"","Offset":11,"Line":1,"Column":12},"text":",","rune":44}
{"pos":{"Filename":"","Offset":13,"Line":1,"Column":14},"text":"b","rune":-2}
{"pos":{"Filename":"","Offset":14,"Line":1,"Column":15},"text":":","rune":58}
{"pos":{"Filename":"","Offset":15,"Line":1,"Column":16},"text":"1","rune":-3}
{"pos":{"Filename":"","Offset":16,"Line":1,"Column":17},"text":"}","rune":125}