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|
package strings
import (
"github.com/gofiber/utils/v2/internal/caseconv"
"github.com/gofiber/utils/v2/internal/unsafeconv"
)
// ToLower converts an ASCII string to lower-case without modifying the input.
func ToLower(s string) string {
n := len(s)
if n == 0 {
return s
}
table := caseconv.ToLowerTable
for i := range n {
c := s[i]
low := table[c]
if low != c {
res := make([]byte, n)
copy(res, s[:i])
res[i] = low
j := i + 1
for ; j+3 < n; j += 4 {
res[j+0] = table[s[j+0]]
res[j+1] = table[s[j+1]]
res[j+2] = table[s[j+2]]
res[j+3] = table[s[j+3]]
}
for ; j < n; j++ {
res[j] = table[s[j]]
}
return unsafeconv.UnsafeString(res)
}
}
return s
}
// ToUpper converts an ASCII string to upper-case without modifying the input.
func ToUpper(s string) string {
n := len(s)
if n == 0 {
return s
}
table := caseconv.ToUpperTable
for i := range n {
c := s[i]
up := table[c]
if up != c {
res := make([]byte, n)
copy(res, s[:i])
res[i] = up
j := i + 1
for ; j+3 < n; j += 4 {
res[j+0] = table[s[j+0]]
res[j+1] = table[s[j+1]]
res[j+2] = table[s[j+2]]
res[j+3] = table[s[j+3]]
}
for ; j < n; j++ {
res[j] = table[s[j]]
}
return unsafeconv.UnsafeString(res)
}
}
return s
}
// UnsafeToLower converts an ASCII string to lower-case by mutating its backing bytes in-place.
// This function is unsafe: it breaks string immutability and must only be used when the
// string is known to reference mutable memory.
func UnsafeToLower(s string) string {
b := unsafeconv.UnsafeBytes(s)
table := caseconv.ToLowerTable
n := len(b)
i := 0
limit := n &^ 3
for i < limit {
b0 := b[i+0]
b1 := b[i+1]
b2 := b[i+2]
b3 := b[i+3]
b[i+0] = table[b0]
b[i+1] = table[b1]
b[i+2] = table[b2]
b[i+3] = table[b3]
i += 4
}
for i < n {
b[i] = table[b[i]]
i++
}
return s
}
// UnsafeToUpper converts an ASCII string to upper-case by mutating its backing bytes in-place.
// This function is unsafe: it breaks string immutability and must only be used when the
// string is known to reference mutable memory.
func UnsafeToUpper(s string) string {
b := unsafeconv.UnsafeBytes(s)
table := caseconv.ToUpperTable
n := len(b)
i := 0
limit := n &^ 3
for i < limit {
b0 := b[i+0]
b1 := b[i+1]
b2 := b[i+2]
b3 := b[i+3]
b[i+0] = table[b0]
b[i+1] = table[b1]
b[i+2] = table[b2]
b[i+3] = table[b3]
i += 4
}
for i < n {
b[i] = table[b[i]]
i++
}
return s
}
|
