listdir by go. support format and insert some strings for blank line.

listdir.go

package main

import (
	"flag"
	"fmt"
	"io/ioutil"
	"path/filepath"
	"sort"
	"strconv"
	"strings"
)

const (
	//PATTERN format by this pattern
	PATTERN = "___"
)

var path = flag.String("p", "./", "path")
var format = flag.String("f", "", "format: xxx"+PATTERN+"xxx")
var blankLine = flag.String("b", "", "blank line by")
var blankLineNum = flag.Int("bn", 0, "blank line number")
var sortByNum = flag.Bool("sn", true, "sort by num")

type ByNum []string

func (paths ByNum) Len() int {
	return len(paths)
}

func (paths ByNum) Swap(i, j int) {
	paths[i], paths[j] = paths[j], paths[i]
}

func (paths ByNum) Less(i, j int) bool {
	pathi := filepath.Base(paths[i])
	pathj := filepath.Base(paths[j])
	namei := strings.Split(pathi, ".")[0]
	namej := strings.Split(pathj, ".")[0]
	numi, _ := strconv.Atoi(namei)
	numj, _ := strconv.Atoi(namej)
	return numi < numj
}

func listDir(path *string) []string {
	files, _ := ioutil.ReadDir(*path)
	fileSlice := make([]string, len(files))

	absPath, _ := filepath.Abs(*path)
	for i, file := range files {
		fileSlice[i] = absPath + "/" + file.Name()
	}

	if *sortByNum {
		sort.Sort(ByNum(fileSlice))
	} else {
		sort.Strings(fileSlice)
	}

	return fileSlice
}

func formatStr(str *string) *string {
	if len(*format) > 0 && strings.Contains(*format, PATTERN) {
		replace := strings.Replace(*format, PATTERN, *str, -1)
		return &replace
	}
	return str
}

func main() {
	flag.Parse()

	rets := listDir(path)
	var ret string
	for i := 0; i < len(rets); i++ {
		ret = rets[i]
		fmt.Println(*(formatStr(&ret)))
		if i == len(rets)-1 {
			break
		}
		for i := 0; i < *blankLineNum; i++ {
			fmt.Println(*blankLine)
		}
	}
}