libgo/go/cmd/internal/objabi/path.go

   1 // Copyright 2017 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 package objabi
   6
   7 import "strings"
   8
   9 // PathToPrefix converts raw string to the prefix that will be used in the
  10 // symbol table. All control characters, space, '%' and '"', as well as
  11 // non-7-bit clean bytes turn into %xx. The period needs escaping only in the
  12 // last segment of the path, and it makes for happier users if we escape that as
  13 // little as possible.
  14 func PathToPrefix(s string) string {
  15         slash := strings.LastIndex(s, "/")
  16         // check for chars that need escaping
  17         n := 0
  18         for r := 0; r < len(s); r++ {
  19                 if c := s[r]; c <= ' ' || (c == '.' && r > slash) || c == '%' || c == '"' || c >= 0x7F {
  20                         n++
  21                 }
  22         }
  23
  24         // quick exit
  25         if n == 0 {
  26                 return s
  27         }
  28
  29         // escape
  30         const hex = "0123456789abcdef"
  31         p := make([]byte, 0, len(s)+2*n)
  32         for r := 0; r < len(s); r++ {
  33                 if c := s[r]; c <= ' ' || (c == '.' && r > slash) || c == '%' || c == '"' || c >= 0x7F {
  34                         p = append(p, '%', hex[c>>4], hex[c&0xF])
  35                 } else {
  36                         p = append(p, c)
  37                 }
  38         }
  39
  40         return string(p)
  41 }