strings.Contains vs regexp.MatchString (with ToLower and MustCompile)

bench_substrings_match_test_with_lower.go

package bench

import (
	"regexp"
	"strings"
	"testing"
)

var (
	inputTexts = []string{
		"カワ",
		"カワウソ",
		"Otter",
		"ot",
	}

	names = []string{"コツメカワウソ",
		"オオカワウソ",
		"ユーラシアカワウソ",
		"ビロードカワウソ",
		"ツメナシカワウソ",
		"かわうそ",
		"otter",
		"sea otter",
		"liver otter",
		"ラッコ",
	}
)

func BenchmarkStringsContains(b *testing.B) {
	for n := 0; n < b.N; n++ {
		for _, inputText := range inputTexts {
			for _, name := range names {
				strings.Contains(name, strings.ToLower(inputText))
				// fmt.Printf("%s, %s: %v\n", name, inputText, strings.Contains(name, strings.ToLower(inputText)))
			}
		}
	}
}

func BenchmarkRegexMatchString(b *testing.B) {
	for n := 0; n < b.N; n++ {
		for _, inputText := range inputTexts {
			re := regexp.MustCompile(`(?i)` + inputText)
			for _, name := range names {
				re.MatchString(name)
				// fmt.Printf("%s, %s: %v\n", name, inputText, re.MatchString(name))
			}
		}
	}
}

Result

% go test -bench . -benchmem
BenchmarkStringsContains-8    	  546682	      2154 ns/op	      53 B/op	      10 allocs/op
BenchmarkRegexMatchString-8   	  170746	      7003 ns/op	    4652 B/op	      62 allocs/op