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bytes: optimize ToLower and ToUpper for ASCII-only case

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Follow what CL 68370 and CL 76470 did for the respective functions in
package strings.

Also adjust godoc strings to match the respective strings functions and
mention the special case for ASCII-only byte slices which don't need
conversion.

name                                       old time/op  new time/op  delta
ToUpper/#00-8                              9.35ns ± 3%  6.08ns ± 2%  -35.04%  (p=0.000 n=9+9)
ToUpper/ONLYUPPER-8                        77.7ns ± 1%  16.9ns ± 2%  -78.22%  (p=0.000 n=10+10)
ToUpper/abc-8                              36.5ns ± 1%  22.1ns ± 1%  -39.43%  (p=0.000 n=10+8)
ToUpper/AbC123-8                           56.9ns ± 2%  28.2ns ± 2%  -50.54%  (p=0.000 n=8+10)
ToUpper/azAZ09_-8                          62.3ns ± 1%  26.9ns ± 1%  -56.82%  (p=0.000 n=9+10)
ToUpper/longStrinGwitHmixofsmaLLandcAps-8   219ns ± 2%    63ns ± 2%  -71.17%  (p=0.000 n=10+10)
ToUpper/longɐstringɐwithɐnonasciiⱯchars-8   367ns ± 2%   374ns ± 3%   +2.05%  (p=0.000 n=9+10)
ToUpper/ɐɐɐɐɐ-8                             200ns ± 1%   206ns ± 1%   +2.49%  (p=0.000 n=10+10)
ToUpper/a\u0080\U0010ffff-8                90.4ns ± 1%  93.8ns ± 0%   +3.82%  (p=0.000 n=10+7)
ToLower/#00-8                              9.59ns ± 1%  6.13ns ± 2%  -36.08%  (p=0.000 n=10+10)
ToLower/abc-8                              36.4ns ± 1%  10.4ns ± 1%  -71.50%  (p=0.000 n=10+10)
ToLower/AbC123-8                           55.8ns ± 1%  27.5ns ± 1%  -50.61%  (p=0.000 n=10+10)
ToLower/azAZ09_-8                          61.7ns ± 1%  30.2ns ± 1%  -50.98%  (p=0.000 n=8+10)
ToLower/longStrinGwitHmixofsmaLLandcAps-8   226ns ± 1%    64ns ± 1%  -71.53%  (p=0.000 n=10+9)
ToLower/LONGⱯSTRINGⱯWITHⱯNONASCIIⱯCHARS-8   354ns ± 0%   361ns ± 0%   +2.18%  (p=0.000 n=10+10)
ToLower/ⱭⱭⱭⱭⱭ-8                             180ns ± 1%   186ns ± 0%   +3.45%  (p=0.000 n=10+9)
ToLower/A\u0080\U0010ffff-8                91.7ns ± 0%  94.5ns ± 0%   +2.99%  (p=0.000 n=10+10)

Change-Id: Ifdb8ae328ff9feacd1c170db8eebbf98c399e204
Reviewed-on: https://go-review.googlesource.com/c/go/+/170954
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
This commit is contained in:
Tobias Klauser 2019-04-08 15:53:35 +02:00 committed by Tobias Klauser
parent 2ab75c0f40
commit 08e1823a63
2 changed files with 94 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

63
src/bytes/bytes.go
View File

@ -521,11 +521,66 @@ func Repeat(b []byte, count int) []byte {
return nb
}
// ToUpper treats s as UTF-8-encoded bytes and returns a copy with all the Unicode letters within it mapped to their upper case.
func ToUpper(s []byte) []byte { return Map(unicode.ToUpper, s) }
// ToUpper returns a copy of the byte slice s with all Unicode letters mapped to
// their upper case.
func ToUpper(s []byte) []byte {
isASCII, hasLower := true, false
for i := 0; i < len(s); i++ {
c := s[i]
if c >= utf8.RuneSelf {
isASCII = false
break
}
hasLower = hasLower || ('a' <= c && c <= 'z')
}
// ToLower treats s as UTF-8-encoded bytes and returns a copy with all the Unicode letters mapped to their lower case.
func ToLower(s []byte) []byte { return Map(unicode.ToLower, s) }
if isASCII { // optimize for ASCII-only byte slices.
if !hasLower {
// Just return a copy.
return append([]byte(""), s...)
}
b := make([]byte, len(s))
for i := 0; i < len(s); i++ {
c := s[i]
if 'a' <= c && c <= 'z' {
c -= 'a' - 'A'
}
b[i] = c
}
return b
}
return Map(unicode.ToUpper, s)
}
// ToLower returns a copy of the byte slice s with all Unicode letters mapped to
// their lower case.
func ToLower(s []byte) []byte {
isASCII, hasUpper := true, false
for i := 0; i < len(s); i++ {
c := s[i]
if c >= utf8.RuneSelf {
isASCII = false
break
}
hasUpper = hasUpper || ('A' <= c && c <= 'Z')
}
if isASCII { // optimize for ASCII-only byte slices.
if !hasUpper {
return append([]byte(""), s...)
}
b := make([]byte, len(s))
for i := 0; i < len(s); i++ {
c := s[i]
if 'A' <= c && c <= 'Z' {
c += 'a' - 'A'
}
b[i] = c
}
return b
}
return Map(unicode.ToLower, s)
}
// ToTitle treats s as UTF-8-encoded bytes and returns a copy with all the Unicode letters mapped to their title case.
func ToTitle(s []byte) []byte { return Map(unicode.ToTitle, s) }

35
src/bytes/bytes_test.go
View File

@ -891,10 +891,14 @@ type StringTest struct {
var upperTests = []StringTest{
{"", []byte("")},
{"ONLYUPPER", []byte("ONLYUPPER")},
{"abc", []byte("ABC")},
{"AbC123", []byte("ABC123")},
{"azAZ09_", []byte("AZAZ09_")},
{"longStrinGwitHmixofsmaLLandcAps", []byte("LONGSTRINGWITHMIXOFSMALLANDCAPS")},
{"long\u0250string\u0250with\u0250nonascii\u2C6Fchars", []byte("LONG\u2C6FSTRING\u2C6FWITH\u2C6FNONASCII\u2C6FCHARS")},
{"\u0250\u0250\u0250\u0250\u0250", []byte("\u2C6F\u2C6F\u2C6F\u2C6F\u2C6F")}, // grows one byte per char
{"a\u0080\U0010FFFF", []byte("A\u0080\U0010FFFF")}, // test utf8.RuneSelf and utf8.MaxRune
}
var lowerTests = []StringTest{
@ -902,7 +906,10 @@ var lowerTests = []StringTest{
{"abc", []byte("abc")},
{"AbC123", []byte("abc123")},
{"azAZ09_", []byte("azaz09_")},
{"longStrinGwitHmixofsmaLLandcAps", []byte("longstringwithmixofsmallandcaps")},
{"LONG\u2C6FSTRING\u2C6FWITH\u2C6FNONASCII\u2C6FCHARS", []byte("long\u0250string\u0250with\u0250nonascii\u0250chars")},
{"\u2C6D\u2C6D\u2C6D\u2C6D\u2C6D", []byte("\u0251\u0251\u0251\u0251\u0251")}, // shrinks one byte per char
{"A\u0080\U0010FFFF", []byte("a\u0080\U0010FFFF")}, // test utf8.RuneSelf and utf8.MaxRune
}
const space = "\t\v\r\f\n\u0085\u00a0\u2000\u3000"
@ -1029,6 +1036,34 @@ 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 {
tin := []byte(tc.in)
b.Run(tc.in, func(b *testing.B) {
for i := 0; i < b.N; i++ {
actual := ToUpper(tin)
if !Equal(actual, tc.out) {
b.Errorf("ToUpper(%q) = %q; want %q", tc.in, actual, tc.out)
}
}
})
}
}
func BenchmarkToLower(b *testing.B) {
for _, tc := range lowerTests {
tin := []byte(tc.in)
b.Run(tc.in, func(b *testing.B) {
for i := 0; i < b.N; i++ {
actual := ToLower(tin)
if !Equal(actual, tc.out) {
b.Errorf("ToLower(%q) = %q; want %q", tc.in, actual, tc.out)
}
}
})
}
}
func TestTrimSpace(t *testing.T) { runStringTests(t, TrimSpace, "TrimSpace", trimSpaceTests) }
type RepeatTest struct {