Simple parser for URL pattern

router_parser.url

package main

import (
	"fmt"
	"regexp"
)

var reResVars = regexp.MustCompile(`\\\{[^{}]+\\\}`)

func main() {
	matched, err := parsePathParams("https://google.com/user/7878/documents/123/aa", "/user/{user_id}/documents/{document_id}")
	if err != nil {
		panic(err)
	}

	for key, value := range matched {
		if key == "" {
			continue
		}

		fmt.Printf("%s:%s\n", key, value)
	}
}

func parsePathParams(rawurl string, pattern string) (map[string]string, error) {
	pattern = regexp.QuoteMeta(pattern)
	pattern = reResVars.ReplaceAllStringFunc(pattern, func(s string) string {
		group := s[2 : len(s)-2]
		return "(?P<" + group + ">[a-zA-Z0-9-]+)"
	})

	re := regexp.MustCompile(pattern)
	matches := re.FindStringSubmatch(rawurl)
	names := re.SubexpNames()

	m := map[string]string{}
	for i, match := range matches {
		m[names[i]] = match
	}
	return m, nil
}

// https://play.golang.org/p/pje8t-IqI7s