walk

walk.go

package main

import (
	"fmt"
	"log"
	"os"
	"path/filepath"
	"sort"
	"strings"
)

func handleErr(err error) {
	if err != nil {
		log.Fatal(err)
	}
}

func readDirNames(dirname string) []string {
	f, err := os.Open(dirname)
	handleErr(err)
	names, err := f.Readdirnames(-1)
	f.Close()
	handleErr(err)
	sort.Strings(names)
	return names
}

func isDir(dir string) bool {
	fi, err := os.Stat(dir)
	handleErr(err)
	return fi.IsDir()
}

func min(a, b int) int {
	if a > b {
		return b
	}
	return a
}

func pathcmp(a, b string) int {
	spa := strings.Split(a, "/")
	spb := strings.Split(b, "/")
	for i := 0; i < min(len(spa), len(spb)); i++ {
		if spa[i] > spb[i] {
			return 1
		} else if spa[i] < spb[i] {
			return -1
		}
	}
	if len(spa) < len(spb) {
		return -1
	} else if len(spa) > len(spb) {
		return 1
	}
	return 0
}

func next(baseDir, current string) string {
	dir := current
	if !isDir(current) {
		dir = filepath.Dir(current)
	}
	for _, name := range readDirNames(dir) {
		ne := filepath.Join(dir, name)
		if pathcmp(ne, current) > 0 {
			return ne
		}
	}
	parent := current
	for {
		parent = filepath.Dir(parent)
		for _, name := range readDirNames(parent) {
			ne := filepath.Join(parent, name)
			if !strings.HasPrefix(ne, baseDir) {
				return ""
			}
			if pathcmp(ne, current) > 0 {
				return ne
			}
		}
	}
	return ""
}

func walk(baseDir, from string) {
	var err error
	baseDir, err = filepath.Abs(baseDir)
	handleErr(err)
	from, err = filepath.Abs(from)
	handleErr(err)
	for {
		from = next(baseDir, from)
		if from == "" {
			break
		}
		if !isDir(from) {
			fmt.Println(from)
		}
	}
}

func main() {
	walk(os.Args[1], os.Args[2])
}