Created
July 23, 2015 14:51
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package main | |
import ( | |
"fmt" | |
"math/rand" | |
"regexp" | |
"time" | |
) | |
func getRandomBytes(n uint32) []byte { | |
rand.Seed(0) | |
toReturn := make([]byte, n) | |
for i := 0; i < len(toReturn); i++ { | |
toReturn[i] = byte(rand.Int()) | |
} | |
return toReturn | |
} | |
var tests = []*regexp.Regexp{ | |
regexp.MustCompile(`abcdef ghijklmnopqrstuv`), | |
regexp.MustCompile(`abcdef.{0,20}ghijklmnopqrstuv`), | |
regexp.MustCompile(`(?i)abcdef.{0,20}ghijklmnopqrstuv`), | |
regexp.MustCompile(`(abc|def).{0,20}ghijklmnopqrstuv`), | |
} | |
func main() { | |
fmt.Printf("Generating random data... ") | |
data := getRandomBytes(15 * 1024 * 1024) | |
fmt.Printf("done.\n") | |
matched := false | |
var t time.Time | |
var elapsed time.Duration | |
for i, re := range tests { | |
t = time.Now() | |
matched = re.Match(data) | |
elapsed = time.Now().Sub(t) | |
fmt.Printf("Test %d took %f seconds.\n", i, elapsed.Seconds()) | |
if matched { | |
fmt.Printf("How did a match occur in random data?\n") | |
} | |
} | |
} |
2017 update: case-insensitive regexes or regexes with |
are still much slower:
Generating random data... done.
Test 0 took 0.005006 seconds.
Test 1 took 0.005000 seconds.
Test 2 took 1.326073 seconds.
Test 3 took 1.950103 seconds.
Go Version:
go version go1.8 windows/amd64
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Output for me:
Go Version:
go version go1.4 linux/amd64