My answer to a slack question: "Anyone know of a package for parsing semi-structured queries of the style title:something description:"something else" visibility:public?"

parse_key_val_query.go

package main

import (
	"fmt"
	"strconv"
	"strings"
	"text/scanner"
)

func main() {
	src := `title:something description:"something else" visibility:public`

	var s scanner.Scanner
	s.Init(strings.NewReader(src))

	const (
		keyState = iota
		sepState
		valState
	)

	state := keyState
	result := make(map[string]string)

	var key string
	for tok := s.Scan(); tok != scanner.EOF; tok = s.Scan() {
		switch state {

		case keyState:
			key = s.TokenText()
			state = sepState

		case sepState:
			state = valState

		case valState:
			val := s.TokenText()
			if v, err := strconv.Unquote(val); err == nil {
				val = v
			}
			result[key] = val
			state = keyState
			key = ""

		}

	}
	fmt.Printf("%+v\n", result)
}

I wrote this circa 2019 in response to a slack message from a co-worker.