安装 1.5 时，直接覆盖 1.4.2，结果不能用了，报错：imports runtime: C source files not allowed when not using cgo or SWIG

　　解决方法是删掉 go 1.5……然后修复安装一遍。

　　优化：1、加了计时功能，纯属蛋疼。2、学到一个不占空间的 struct{}，map[string]bool 改为 map[string]struct{}。

// UMU @ 2015-08-17 11:30
// Last update: 2015-08-21 17:40
package main

import (
	"bufio"
	"fmt"
	"os"
	"path"
	"path/filepath"
	"time"
)

func isSourceFile(ext string) bool {
	var kSourceFileExts = []string{".c",".cc",".cpp",".h",".hpp",".go",".java"}
	for _,r := range kSourceFileExts {
		if r == ext {
			return true
		}
	}
	return false
}

func main() {
	if len(os.Args) < 2 {
		fmt.Println("Usage: ",os.Args[0],"[file or folder]...")
		return
	}

	start := time.Now()
	files := make(map[string]struct{})
	lines := 0

	for _,r := range os.Args {
		fi,err := os.Stat(r)
		if err == nil || os.IsExist(err) {
			if fi.IsDir() {
				AddDirectory(r,files)
			} else {
				AddFile(r,files)
			}
		}
	}

	for file,_ := range files {
		l := CountLine(file)
		lines += l
		fmt.Println(file,l)
	}
	fmt.Printf("Total lines: %d,cost %fs\n",lines,timeElapsed(start))
}

func AddDirectory(name string,files map[string]struct{}) {
	filepath.Walk(name,func(path string,fi os.FileInfo,err error) error {
		if nil == fi {
			return err
		}
		if fi.IsDir() {
			return nil
		}
		AddFile(path,files)
		return nil
	})
}

func AddFile(name string,files map[string]struct{}) {
	ext := path.Ext(name)
	if isSourceFile(ext) {
		path,err := filepath.Abs(name)
		if err == nil {
			_,exists := files[path]
			if exists {
				fmt.Println("Duplicated",path)
			} else {
				files[path] = struct{}{}
				fmt.Println("Add",path)
			}
		}
	}
}

func CountLine(path string) (num int) {
	f,err := os.Open(path)
	if nil != err {
		return
	}
	defer f.Close()

	s := bufio.NewScanner(f)
	for s.Scan() {
		num += 1
	}
	return
}

func timeElapsed(start time.Time) float64 {
	dis := time.Since(start).Seconds()
	return dis
}