woodpecker/vendor/github.com/golangci/misspell/ascii.go
Lukas c28f7cb29f
Add golangci-lint (#502)
Initial part of #435
2021-11-14 21:01:54 +01:00

62 lines
1.5 KiB
Go

package misspell
// ByteToUpper converts an ascii byte to upper cases
// Uses a branchless algorithm
func ByteToUpper(x byte) byte {
b := byte(0x80) | x
c := b - byte(0x61)
d := ^(b - byte(0x7b))
e := (c & d) & (^x & 0x7f)
return x - (e >> 2)
}
// ByteToLower converts an ascii byte to lower case
// uses a branchless algorithm
func ByteToLower(eax byte) byte {
ebx := eax&byte(0x7f) + byte(0x25)
ebx = ebx&byte(0x7f) + byte(0x1a)
ebx = ((ebx & ^eax) >> 2) & byte(0x20)
return eax + ebx
}
// ByteEqualFold does ascii compare, case insensitive
func ByteEqualFold(a, b byte) bool {
return a == b || ByteToLower(a) == ByteToLower(b)
}
// StringEqualFold ASCII case-insensitive comparison
// golang toUpper/toLower for both bytes and strings
// appears to be Unicode based which is super slow
// based from https://codereview.appspot.com/5180044/patch/14007/21002
func StringEqualFold(s1, s2 string) bool {
if len(s1) != len(s2) {
return false
}
for i := 0; i < len(s1); i++ {
c1 := s1[i]
c2 := s2[i]
// c1 & c2
if c1 != c2 {
c1 |= 'a' - 'A'
c2 |= 'a' - 'A'
if c1 != c2 || c1 < 'a' || c1 > 'z' {
return false
}
}
}
return true
}
// StringHasPrefixFold is similar to strings.HasPrefix but comparison
// is done ignoring ASCII case.
// /
func StringHasPrefixFold(s1, s2 string) bool {
// prefix is bigger than input --> false
if len(s1) < len(s2) {
return false
}
if len(s1) == len(s2) {
return StringEqualFold(s1, s2)
}
return StringEqualFold(s1[:len(s2)], s2)
}