matrix-handler/vendor/github.com/rs/cors/utils.go

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2021-02-04 07:25:16 +00:00
package cors
import "strings"
const toLower = 'a' - 'A'
type converter func(string) string
type wildcard struct {
prefix string
suffix string
}
func (w wildcard) match(s string) bool {
return len(s) >= len(w.prefix)+len(w.suffix) && strings.HasPrefix(s, w.prefix) && strings.HasSuffix(s, w.suffix)
}
// convert converts a list of string using the passed converter function
func convert(s []string, c converter) []string {
out := []string{}
for _, i := range s {
out = append(out, c(i))
}
return out
}
// parseHeaderList tokenize + normalize a string containing a list of headers
func parseHeaderList(headerList string) []string {
l := len(headerList)
h := make([]byte, 0, l)
upper := true
// Estimate the number headers in order to allocate the right splice size
t := 0
for i := 0; i < l; i++ {
if headerList[i] == ',' {
t++
}
}
headers := make([]string, 0, t)
for i := 0; i < l; i++ {
b := headerList[i]
switch {
case b >= 'a' && b <= 'z':
if upper {
h = append(h, b-toLower)
} else {
h = append(h, b)
}
case b >= 'A' && b <= 'Z':
if !upper {
h = append(h, b+toLower)
} else {
h = append(h, b)
}
case b == '-' || b == '_' || (b >= '0' && b <= '9'):
h = append(h, b)
}
if b == ' ' || b == ',' || i == l-1 {
if len(h) > 0 {
// Flush the found header
headers = append(headers, string(h))
h = h[:0]
upper = true
}
} else {
upper = b == '-' || b == '_'
}
}
return headers
}