Golang fast reader standard input

fast_reader.go

package main

import (
	"bufio"
	"os"
	"regexp"
	"strconv"
	"strings"
)

type FastReader struct {
	Reader *bufio.Reader
	Re     *regexp.Regexp
}

func NewReader(useRegex bool) *FastReader {
	var re *regexp.Regexp
	if useRegex {
		re = regexp.MustCompile(`[-]?\d[\d,]*[.]?[\d{2}]*`)
	}

	return &FastReader{Reader: bufio.NewReader(os.Stdin), Re: re}
}

func (f *FastReader) nextInt() int {
	numberString, _ := f.Reader.ReadString('\n')
	numberString = strings.TrimSuffix(numberString, "\n")
	n, _ := strconv.Atoi(numberString)
	return n
}

func (f *FastReader) nextIntScan() int {
	var i int
	_, err := fmt.Fscan(f.Reader, &i)
	if err != nil {
		fmt.Println(err)
		return 0
	}
	return i
}

func (f *FastReader) nextLineInt() []int {
	stringNumbers, _ := f.Reader.ReadString('\n')
	stringNumbersArray := f.Re.FindAllString(stringNumbers, -1)
	var res []int

	for _, i := range stringNumbersArray {
		j, err := strconv.Atoi(i)
		if err != nil {
			panic(err)
		}
		res = append(res, j)
	}
	return res
}

func (f *FastReader) nextLine() string {
	line, _ := f.Reader.ReadString('\n')
	line = strings.TrimSpace(strings.TrimSuffix(line, "\n"))
	return line
}