From 13cfb15cb18a8c0c31212c302175a4cb4c050155 Mon Sep 17 00:00:00 2001 From: Agniva De Sarker Date: Thu, 28 Sep 2017 15:07:48 +0530 Subject: [PATCH] strings: optimize ToUpper MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Handling the ASCII case inline and call unicode.ToUpper only for non-ascii cases. Gives good improvements for the ascii case and minor perf degrade for non-ascii case name old time/op new time/op delta ToUpper/#00 11.7ns ± 8% 8.0ns ± 1% -31.95% (p=0.008 n=5+5) ToUpper/ONLYUPPER 45.6ns ± 5% 19.9ns ± 1% -56.40% (p=0.008 n=5+5) ToUpper/abc 77.4ns ± 1% 57.0ns ± 1% -26.32% (p=0.008 n=5+5) ToUpper/AbC123 92.1ns ± 4% 67.7ns ± 2% -26.57% (p=0.008 n=5+5) ToUpper/azAZ09_ 105ns ± 6% 67ns ± 2% -36.26% (p=0.000 n=5+4) ToUpper/longStrinGwitHmixofsmaLLandcAps 255ns ± 1% 140ns ± 1% -45.01% (p=0.029 n=4+4) ToUpper/longɐstringɐwithɐnonasciiⱯchars 440ns ± 1% 447ns ± 0% +1.49% (p=0.016 n=5+4) ToUpper/ɐɐɐɐɐ 370ns ± 4% 366ns ± 1% ~ (p=0.667 n=5+5) name old alloc/op new alloc/op delta ToUpper/#00 0.00B 0.00B ~ (all equal) ToUpper/ONLYUPPER 0.00B 0.00B ~ (all equal) ToUpper/abc 16.0B ± 0% 6.0B ± 0% -62.50% (p=0.008 n=5+5) ToUpper/AbC123 16.0B ± 0% 16.0B ± 0% ~ (all equal) ToUpper/azAZ09_ 24.0B ± 0% 16.0B ± 0% -33.33% (p=0.008 n=5+5) ToUpper/longStrinGwitHmixofsmaLLandcAps 80.0B ± 0% 64.0B ± 0% -20.00% (p=0.008 n=5+5) ToUpper/longɐstringɐwithɐnonasciiⱯchars 96.0B ± 0% 96.0B ± 0% ~ (all equal) ToUpper/ɐɐɐɐɐ 64.0B ± 0% 64.0B ± 0% ~ (all equal) Ran on a machine with Intel(R) Core(TM) i5-5200U CPU @ 2.20GHz Updates #17859 Change-Id: I0735ac4a4a36e8a8f6cc06f2c16b871f12b4abf9 Reviewed-on: https://go-review.googlesource.com/68370 Reviewed-by: Joe Tsai Reviewed-by: Brad Fitzpatrick Run-TryBot: Joe Tsai TryBot-Result: Gobot Gobot --- src/strings/strings.go | 28 +++++++++++++++++++++++++++- src/strings/strings_test.go | 16 ++++++++++++++++ 2 files changed, 43 insertions(+), 1 deletion(-) diff --git a/src/strings/strings.go b/src/strings/strings.go index a7941fbb90..73bba9278c 100644 --- a/src/strings/strings.go +++ b/src/strings/strings.go @@ -542,7 +542,33 @@ func Repeat(s string, count int) string { } // ToUpper returns a copy of the string s with all Unicode letters mapped to their upper case. -func ToUpper(s string) string { return Map(unicode.ToUpper, s) } +func ToUpper(s string) string { + isASCII, hasLower := true, false + for i := 0; i < len(s); i++ { + c := s[i] + if c >= utf8.RuneSelf { + isASCII = false + break + } + hasLower = hasLower || (c >= 'a' && c <= 'z') + } + + if isASCII { // optimize for ASCII-only strings. + if !hasLower { + return s + } + b := make([]byte, len(s)) + for i := 0; i < len(s); i++ { + c := s[i] + if c >= 'a' && c <= 'z' { + c -= 'a' - 'A' + } + b[i] = c + } + return string(b) + } + return Map(unicode.ToUpper, s) +} // ToLower returns a copy of the string s with all Unicode letters mapped to their lower case. func ToLower(s string) string { return Map(unicode.ToLower, s) } diff --git a/src/strings/strings_test.go b/src/strings/strings_test.go index 869be9c477..b185e7eec8 100644 --- a/src/strings/strings_test.go +++ b/src/strings/strings_test.go @@ -518,9 +518,12 @@ func runStringTests(t *testing.T, f func(string) string, funcName string, testCa var upperTests = []StringTest{ {"", ""}, + {"ONLYUPPER", "ONLYUPPER"}, {"abc", "ABC"}, {"AbC123", "ABC123"}, {"azAZ09_", "AZAZ09_"}, + {"longStrinGwitHmixofsmaLLandcAps", "LONGSTRINGWITHMIXOFSMALLANDCAPS"}, + {"long\u0250string\u0250with\u0250nonascii\u2C6Fchars", "LONG\u2C6FSTRING\u2C6FWITH\u2C6FNONASCII\u2C6FCHARS"}, {"\u0250\u0250\u0250\u0250\u0250", "\u2C6F\u2C6F\u2C6F\u2C6F\u2C6F"}, // grows one byte per char } @@ -648,6 +651,19 @@ func TestToUpper(t *testing.T) { runStringTests(t, ToUpper, "ToUpper", upperTest func TestToLower(t *testing.T) { runStringTests(t, ToLower, "ToLower", lowerTests) } +func BenchmarkToUpper(b *testing.B) { + for _, tc := range upperTests { + b.Run(tc.in, func(b *testing.B) { + for i := 0; i < b.N; i++ { + actual := ToUpper(tc.in) + if actual != tc.out { + b.Errorf("ToUpper(%q) = %q; want %q", tc.in, actual, tc.out) + } + } + }) + } +} + func BenchmarkMapNoChanges(b *testing.B) { identity := func(r rune) rune { return r