strings: faster equality check on simple cases

Author: miton18

src/strings/strings.go

@@ -1185,9 +1185,13 @@ func ReplaceAll(s, old, new string) string {
 // are equal under simple Unicode case-folding, which is a more general
 // form of case-insensitivity.
 func EqualFold(s, t string) bool {
+if len(s) != len(t) {
+return false
+}
+
 // ASCII fast path
 i := 0
-for ; i < len(s) && i < len(t); i++ {
+for ; i < len(s); i++ {
 sr := s[i]
 tr := t[i]
 if sr|tr >= utf8.RuneSelf {
@@ -1205,22 +1209,15 @@ func EqualFold(s, t string) bool {
 }
 // ASCII only, sr/tr must be upper/lower case
 if 'A' <= sr && sr <= 'Z' && tr == sr+'a'-'A' {
-continue
+return false
 }
-return false
 }
-// Check if we've exhausted both strings.
-return len(s) == len(t)
+return true
 
 hasUnicode:
 s = s[i:]
 t = t[i:]
 for _, sr := range s {
-// If t is exhausted the strings are not equal.
-if len(t) == 0 {
-return false
-}
-
 // Extract first rune from second string.
 var tr rune
 if t[0] < utf8.RuneSelf {
@@ -1256,14 +1253,12 @@ hasUnicode:
 for r != sr && r < tr {
 r = unicode.SimpleFold(r)
 }
-if r == tr {
-continue
+if r != tr {
+return false
 }
-return false
 }
 
-// First string is empty, so check if the second one is also empty.
-return len(t) == 0
+return true
 }
 
 // Index returns the index of the first instance of substr in s, or -1 if substr is not present in s.