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// Copyright 2017 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// +build ignore
package bytes
func countByte(s []byte, c byte) int // bytes_arm64.s
// Index returns the index of the first instance of sep in s, or -1 if sep is not present in s.
func Index(s, sep []byte) int {
n := len(sep)
switch {
case n == 0:
return 0
case n == 1:
return IndexByte(s, sep[0])
case n == len(s):
if Equal(sep, s) {
return 0
}
return -1
case n > len(s):
return -1
}
c := sep[0]
i := 0
fails := 0
t := s[:len(s)-n+1]
for i < len(t) {
if t[i] != c {
o := IndexByte(t[i:], c)
if o < 0 {
break
}
i += o
}
if Equal(s[i:i+n], sep) {
return i
}
i++
fails++
if fails >= 4+i>>4 && i < len(t) {
// Give up on IndexByte, it isn't skipping ahead
// far enough to be better than Rabin-Karp.
// Experiments (using IndexPeriodic) suggest
// the cutover is about 16 byte skips.
// TODO: if large prefixes of sep are matching
// we should cutover at even larger average skips,
// because Equal becomes that much more expensive.
// This code does not take that effect into account.
j := indexRabinKarp(s[i:], sep)
if j < 0 {
return -1
}
return i + j
}
}
return -1
}
// Count counts the number of non-overlapping instances of sep in s.
// If sep is an empty slice, Count returns 1 + the number of UTF-8-encoded code points in s.
func Count(s, sep []byte) int {
if len(sep) == 1 {
return countByte(s, sep[0])
}
return countGeneric(s, sep)
}
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