Golang: simple string processing vs regexp

README.md

string processing vs Regexp benchmark

BenchmarkFirstWithStringMatch	20000000	       127 ns/op
BenchmarkFirstWithRegexpMatch	 1000000	      1067 ns/op

str_test.go

package main

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

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

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

func (m *matches) isDigit(ch byte) bool {
	return '0' <= ch && ch <= '9'
}

func (m *matches) isStringDigit(str string) bool {
	for i, l := 0, len(str); i < l; i++ {
		if !m.isDigit(str[i]) {
			return false
		}
	}
	return true
}

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

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