ipsort/main.go

// command svsort sorts lines of text by semver at beginning of line
package main

import (
	"bufio"
	"bytes"
	"fmt"
	"log"
	"net"
	"os"
	"sort"
)

type lines []string

func (l lines) Len() int      { return len(l) }
func (l lines) Swap(i, j int) { l[i], l[j] = l[j], l[i] }
func (l lines) Less(i, j int) bool {
	a, b := net.ParseIP(l[i]), net.ParseIP(l[j])
	return bytes.Compare(a, b) < 0
}

func main() {
	s := bufio.NewScanner(os.Stdin)

	ls := lines{}
	for s.Scan() {
		ls = append(ls, s.Text())
	}

	if err := s.Err(); err != nil {
		log.Fatalf("scan: %v")
	}

	sort.Sort(ls)
	for _, l := range ls {
		fmt.Printf("%v\n", l)
	}
}