diff options
Diffstat (limited to 'src/bytes')
| -rw-r--r-- | src/bytes/bytes.go | 21 |
1 files changed, 11 insertions, 10 deletions
diff --git a/src/bytes/bytes.go b/src/bytes/bytes.go index 16d1854c44..aa07b9fbc1 100644 --- a/src/bytes/bytes.go +++ b/src/bytes/bytes.go @@ -458,8 +458,10 @@ func FieldsFunc(s []byte, f func(rune) bool) [][]byte { spans := make([]span, 0, 32) // Find the field start and end indices. - wasField := false - fromIndex := 0 + // Doing this in a separate pass (rather than slicing the string s + // and collecting the result substrings right away) is significantly + // more efficient, possibly due to cache effects. + start := -1 // valid span start if >= 0 for i := 0; i < len(s); { size := 1 r := rune(s[i]) @@ -467,22 +469,21 @@ func FieldsFunc(s []byte, f func(rune) bool) [][]byte { r, size = utf8.DecodeRune(s[i:]) } if f(r) { - if wasField { - spans = append(spans, span{start: fromIndex, end: i}) - wasField = false + if start >= 0 { + spans = append(spans, span{start, i}) + start = -1 } } else { - if !wasField { - fromIndex = i - wasField = true + if start < 0 { + start = i } } i += size } // Last field might end at EOF. - if wasField { - spans = append(spans, span{fromIndex, len(s)}) + if start >= 0 { + spans = append(spans, span{start, len(s)}) } // Create subslices from recorded field indices. |