line ending checker

lec.go

package main

import (
	"bufio"
	"fmt"
	"io"
	"os"
	"strings"
)

const BUFSIZE = 1024

func getPathFromArgs() string {
	if len(os.Args) == 1 {
		return ""
	}
	return os.Args[1]
}

type Stat struct {
	lfCount   int
	crlfCount int
}

func (s *Stat) MajorType() string {
	if s.crlfCount > s.lfCount {
		return "crlf"
	} else {
		return "lf"
	}
}

func (s *Stat) MinorType() string {
	if s.crlfCount > s.lfCount {
		return "lf"
	} else {
		return "crlf"
	}
}

func aggregateCrLfFromFile(f *os.File) (stat Stat) {
	reader := bufio.NewReader(f)
	lfCount := 0
	crlfCount := 0
	for {
		line, err := reader.ReadString('\n')
		lineBody := strings.TrimRight(line, "\r\n")
		if line == lineBody {
			break
		}
		isCrLf := strings.TrimSuffix(line, "\r\n") != line
		if isCrLf {
			crlfCount++
		} else {
			lfCount++
		}
		//fmt.Println(isCrLf, lineBody)
		if err == io.EOF {
			break
		}
	}
	return Stat{lfCount, crlfCount}
}

func showSpecificLineEndingFromFile(f *os.File, lineEnding string) {
	reader := bufio.NewReader(f)
	lineNo := 1
	for {
		line, err := reader.ReadString('\n')
		lineBody := strings.TrimRight(line, "\r\n")
		if line == lineBody {
			break
		}
		isCrLf := strings.TrimSuffix(line, "\r\n") != line
		if (isCrLf && lineEnding == "crlf") || (!isCrLf && lineEnding == "lf") {
			fmt.Println(lineNo, ":", lineEnding, lineBody)
		}
		if err == io.EOF {
			break
		}
		lineNo++
	}
}

func main() {
	inputPath := getPathFromArgs()
	if inputPath == "" {
		return
	}
	fmt.Println("path:", inputPath)
	f, err := os.Open(inputPath)
	if err != nil {
		fmt.Println("Error!", err)
	}
	defer f.Close()

	stat := aggregateCrLfFromFile(f)
	fmt.Printf("(lf, crlf) = (%d, %d)\n", stat.lfCount, stat.crlfCount)
	fmt.Println("MajorType:", stat.MajorType())

	f.Seek(0, 0)
	showSpecificLineEndingFromFile(f, stat.MinorType())
}