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bytes: rely on utf8.AppendRune

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This is both simpler and more performant.

WriteRune                                 23.9µs ± 1%   22.8µs ± 8%   -4.43%  (p=0.006 n=8+10)
ToUpper/longɐstringɐwithɐnonasciiⱯchars    573ns ± 4%    474ns ± 6%  -17.27%  (p=0.000 n=10+10)
ToUpper/ɐɐɐɐɐ                              236ns ± 6%    202ns ± 5%  -14.12%  (p=0.000 n=10+10)
ToUpper/a\u0080\U0010ffff                 98.8ns ± 6%   91.2ns ± 3%   -7.67%  (p=0.000 n=10+10)
ToLower/LONGⱯSTRINGⱯWITHⱯNONASCIIⱯCHARS    511ns ± 3%    409ns ± 4%  -20.02%  (p=0.000 n=10+10)
ToLower/ⱭⱭⱭⱭⱭ                              178ns ± 4%    173ns ± 2%   -2.76%  (p=0.005 n=10+10)
ToLower/A\u0080\U0010ffff                  100ns ± 3%     91ns ± 2%   -8.55%  (p=0.000 n=10+10)

Change-Id: I968ef194da2c115cbdcac2d3575c34c65e6a8a56
Reviewed-on: https://go-review.googlesource.com/c/go/+/412337
Reviewed-by: Ian Lance Taylor <iant@google.com>
Auto-Submit: Joseph Tsai <joetsai@digital-static.net>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>
Run-TryBot: Joseph Tsai <joetsai@digital-static.net>
This commit is contained in:
Joe Tsai 2022-06-15 17:03:27 -07:00 committed by Gopher Robot
parent 556c978400
commit 70de482d17
2 changed files with 5 additions and 19 deletions
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5
src/bytes/buffer.go
View File

@ -298,9 +298,8 @@ func (b *Buffer) WriteRune(r rune) (n int, err error) {
if !ok {
m = b.grow(utf8.UTFMax)
}
n = utf8.EncodeRune(b.buf[m:m+utf8.UTFMax], r)
b.buf = b.buf[:m+n]
return n, nil
b.buf = utf8.AppendRune(b.buf[:m], r)
return len(b.buf) - m, nil
}
// Read reads the next len(p) bytes from the buffer or until the buffer

19
src/bytes/bytes.go
View File

@ -560,9 +560,7 @@ func Map(mapping func(r rune) rune, s []byte) []byte {
// In the worst case, the slice can grow when mapped, making
// things unpleasant. But it's so rare we barge in assuming it's
// fine. It could also shrink but that falls out naturally.
maxbytes := len(s) // length of b
nbytes := 0 // number of bytes encoded in b
b := make([]byte, maxbytes)
b := make([]byte, 0, len(s))
for i := 0; i < len(s); {
wid := 1
r := rune(s[i])
@ -571,22 +569,11 @@ func Map(mapping func(r rune) rune, s []byte) []byte {
}
r = mapping(r)
if r >= 0 {
rl := utf8.RuneLen(r)
if rl < 0 {
rl = len(string(utf8.RuneError))
}
if nbytes+rl > maxbytes {
// Grow the buffer.
maxbytes = maxbytes*2 + utf8.UTFMax
nb := make([]byte, maxbytes)
copy(nb, b[0:nbytes])
b = nb
}
nbytes += utf8.EncodeRune(b[nbytes:maxbytes], r)
b = utf8.AppendRune(b, r)
}
i += wid
}
return b[0:nbytes]
return b
}
// Repeat returns a new byte slice consisting of count copies of b.