Golang: simple string processing vs char map vs regexp

README.md

simple string processing vs char map vs regexp

BenchmarkRune	20000000	       152 ns/op
BenchmarkMap	 5000000	       346 ns/op
BenchmarkRegexp	 1000000	      1034 ns/op

str_test.go

package main

import (
	"regexp"
	"strconv"
	"testing"
)

type matches struct {
	r      *regexp.Regexp
	intMap map[rune]bool
}

func New() *matches {
	return &matches{
		regexp.MustCompile(`^[0-9]+$`),
		map[rune]bool{
			'0': true,
			'1': true,
			'2': true,
			'3': true,
			'4': true,
			'5': true,
			'6': true,
			'7': true,
			'8': true,
			'9': true,
		},
	}
}

func isDigit(r rune) bool {
	return '0' <= r && r <= '9'
}

func (m *matches) isStringDigit(s string) bool {
	for _, r := range s {
		if !isDigit(r) {
			return false
		}
	}
	return true
}

func (m *matches) MatchString(s string) bool {
	return m.r.MatchString(s)
}

func (m *matches) hasStringInMap(s string) bool {
	for _, r := range s {
		if _, ok := m.intMap[r]; !ok {
			return false
		}
	}
	return true
}

func BenchmarkRune(b *testing.B) {
	var total int
	m := New()
	for i := 0; i < b.N; i++ {
		num := strconv.Itoa(i)
		if m.isStringDigit(num) {
			total++
		}
	}
}

func BenchmarkMap(b *testing.B) {
	var total int
	m := New()
	for i := 0; i < b.N; i++ {
		num := strconv.Itoa(i)
		if m.hasStringInMap(num) {
			total++
		}
	}
}

func BenchmarkRegexp(b *testing.B) {
	var total int
	m := New()
	for i := 0; i < b.N; i++ {
		num := strconv.Itoa(i)
		if m.MatchString(num) {
			total++
		}
	}
}