strings: it's logically better to use singleStringReplacer when the new string's length is 0. #33369
Description
Lines 46 to 58 in fbb819e
It will make generic replacer when there's only one pair of oldnew, and the new string's length is zero. It's better to use singleStringReplacer logically, and that won't affect the performance.
as bench below:
the old:
# go test -run ^$ -bench BenchmarkSingleMatchToEmpty -count 4
goos: linux
goarch: amd64
pkg: strings
BenchmarkSingleMatchToEmpty 30000 43017 ns/op 348.69 MB/s
BenchmarkSingleMatchToEmpty 30000 42026 ns/op 356.92 MB/s
BenchmarkSingleMatchToEmpty 30000 41708 ns/op 359.64 MB/s
BenchmarkSingleMatchToEmpty 30000 42200 ns/op 355.44 MB/sthe new:
# go test -run ^$ -bench BenchmarkSingleMatchToEmpty -count 4
goos: linux
goarch: amd64
pkg: strings
BenchmarkSingleMatchToEmpty 30000 42260 ns/op 354.94 MB/s
BenchmarkSingleMatchToEmpty 30000 41242 ns/op 363.70 MB/s
BenchmarkSingleMatchToEmpty 30000 43471 ns/op 345.06 MB/s
BenchmarkSingleMatchToEmpty 30000 42606 ns/op 352.06 MB/smy code :
if len(oldnew) == 2 && len(oldnew[0]) != 1 {
return makeSingleStringReplacer(oldnew[0], oldnew[1])
}
allNewBytes := true
for i := 0; i < len(oldnew); i += 2 {
if len(oldnew[i]) != 1 {
return makeGenericReplacer(oldnew)
}
if len(oldnew[i+1]) != 1 {
allNewBytes = false
}
}benchmark:
func benchmarkSingleString(b *testing.B, pattern, text, value string) {
r := NewReplacer(pattern, value)
b.SetBytes(int64(len(text)))
b.ResetTimer()
for i := 0; i < b.N; i++ {
r.Replace(text)
}
}
func BenchmarkSingleMatchToEmpty(b *testing.B) {
benchmarkSingleString(b, "abcdef", Repeat("abcdefghijklmno", 1000), "")
}