Golang : files, directories

first_script.go

//usr/bin/env go run $0 $@ ; exit
package main

import (
	"fmt"
	"io/ioutil"
	"log"
	"os"
	"path/filepath"
	"strings"
)

type DirParser struct {
	path              string
	extensionsToParse []string
	totalCharToPrint  int
	outputFile        *os.File
}

func (d DirParser) ReadDir() (files []os.FileInfo) {
	files, err := ioutil.ReadDir(d.path)
	if err != nil {
		log.Fatal(err)
	}
	return
}

func (d DirParser) ParseDir() {
	for _, file := range d.ReadDir() {
		d.PrintFileContent(file)
	}
	d.End()
}

func (d DirParser) PrintFileContent(file os.FileInfo) {
	go_on := false
	for _, allowedExt := range d.extensionsToParse {
		if filepath.Ext(file.Name()) == allowedExt {
			go_on = true
			break
		}
	}
	if !(go_on) {
		log.Printf("Skipping \"%s\"", file.Name())
		return
	}
	log.Printf("Parsing \"%s\"", file.Name())
	fileContent, err := ioutil.ReadFile(file.Name())
	if err != nil {
		log.Fatal(err)
	}
	for _, line := range strings.Split(string(fileContent), "\n") {
		var fmtLine string
		if len(line) > d.totalCharToPrint {
			fmtLine = fmt.Sprintf("> %s(...)\n", line[:d.totalCharToPrint])
		} else {
			fmtLine = fmt.Sprintf("> %s\n", line)
		}
		if d.outputFile != nil {
			if _, err := d.outputFile.Write([]byte(fmtLine)); err != nil {
				log.Fatal(err)
			}
		} else {
			fmt.Print(fmtLine)
		}
	}
}

func (d DirParser) End() {
	if d.outputFile != nil {
		if err := d.outputFile.Close(); err != nil {
			log.Fatal(err)
		}
	}
}

func ParseArgs() *os.File {
	if len(os.Args) > 1 {
		f, err := os.OpenFile(os.Args[1], os.O_CREATE|os.O_WRONLY, 0644)
		if err != nil {
			log.Fatal(err)
		}
		return f
	} else {
		return nil
	}
}

func main() {
	parser := DirParser{".", []string{".go", ".txt"}, 30, ParseArgs()}
	parser.ParseDir()
}