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// Copyright 2015 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 !amd64,!s390x
package strings
// TODO: implements short string optimization on non amd64 platforms
// and get rid of strings_amd64.go
// Index returns the index of the first instance of substr in s, or -1 if substr is not present in s.
func Index(s, substr string) int {
n := len(substr)
switch {
case n == 0:
return 0
case n == 1:
return IndexByte(s, substr[0])
case n == len(s):
if substr == s {
return 0
}
return -1
case n > len(s):
return -1
}
c := substr[0]
i := 0
t := s[:len(s)-n+1]
fails := 0
for i < len(t) {
if t[i] != c {
o := IndexByte(t[i:], c)
if o < 0 {
return -1
}
i += o
}
if s[i:i+n] == substr {
return i
}
i++
fails++
if fails >= 4+i>>4 && i < len(t) {
// See comment in ../bytes/bytes_generic.go.
j := indexRabinKarp(s[i:], substr)
if j < 0 {
return -1
}
return i + j
}
}
return -1
}
// Count counts the number of non-overlapping instances of substr in s.
// If substr is an empty string, Count returns 1 + the number of Unicode code points in s.
func Count(s, substr string) int {
return countGeneric(s, substr)
}
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