stream pipeline example

main.go

package main

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

func removeEs(input io.Reader, output *io.PipeWriter) {
	buff := make([]byte, 10)
	for {
		tempBuffer := make([]byte, 0, 10)
		n, err := input.Read(buff)
		for i := 0; i < n; i++ {
			if buff[i] != 'e' {
				tempBuffer = append(tempBuffer, buff[i])
			}
		}
		if n != 0 {
			output.Write(tempBuffer[:n])
		}
		if err != nil {
			output.Close()
			break
		}
	}
}

func streamUpper(input *io.PipeReader, output *io.PipeWriter) {
	buff := make([]byte, 10)
	for {
		tempBuffer := make([]byte, 0, 10)
		n, err := input.Read(buff)
		for i := 0; i < n; i++ {
			tempBuffer = append(tempBuffer, byte(unicode.ToUpper(rune(buff[i]))))
		}
		if n != 0 {
			output.Write(tempBuffer[:n])
		}
		if err != nil {
			output.Close()
			break
		}
	}
}

func removeSpace(input *io.PipeReader, output io.Writer) {
	buff := make([]byte, 10)
	for {
		tempBuffer := make([]byte, 0, 10)
		n, err := input.Read(buff)
		for i := 0; i < n; i++ {
			if buff[i] == ' ' {
				tempBuffer = append(tempBuffer, ',')
			} else {
				tempBuffer = append(tempBuffer, buff[i])
			}
		}
		if n != 0 {
			output.Write(tempBuffer[:n])
		}
		if err != nil {
			break
		}
	}
}

func main() {
	reader1, writer1 := io.Pipe()
	reader2, writer2 := io.Pipe()
	str := "here is a string where all the letters are going to be uppercased and all 'e' are going to be removed and spaces changed with comas\n"
	fmt.Println(str)
	strReader := strings.NewReader(str)

	go removeEs(strReader, writer1)
	go streamUpper(reader1, writer2)
	removeSpace(reader2, os.Stdout)

}