Avoid division in common case. There are 5438 ranges in unicode/tables.go
4110 of them have stride 1.
Stride 1 case got significantly faster. Other stride is a bit slower.
Measured by
import (
"testing"
"unicode"
)
func BenchmarkDiv1(b *testing.B) {
rtb := &unicode.RangeTable{
R16: []unicode.Range16{
{0xa800, 0xdfff, 1}, // or 3
},
}
for i := 0; i < b.N; i++ {
unicode.Is(rtb, rune(0xc700))
}
}