libgo/go/bytes/bytes_generic.go

   1 // Copyright 2015 The Go Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style
   3 // license that can be found in the LICENSE file.
   4
   5 // -build !amd64,!s390x
   6
   7 package bytes
   8
   9 // TODO: implements short string optimization on non amd64 platforms
  10 // and get rid of bytes_amd64.go
  11
  12 // Index returns the index of the first instance of sep in s, or -1 if sep is not present in s.
  13 func Index(s, sep []byte) int {
  14         n := len(sep)
  15         if n == 0 {
  16                 return 0
  17         }
  18         if n > len(s) {
  19                 return -1
  20         }
  21         c := sep[0]
  22         if n == 1 {
  23                 return IndexByte(s, c)
  24         }
  25         i := 0
  26         t := s[:len(s)-n+1]
  27         for i < len(t) {
  28                 if t[i] != c {
  29                         o := IndexByte(t[i:], c)
  30                         if o < 0 {
  31                                 break
  32                         }
  33                         i += o
  34                 }
  35                 if Equal(s[i:i+n], sep) {
  36                         return i
  37                 }
  38                 i++
  39         }
  40         return -1
  41 }