CleanPath is the URL version of path.Clean, it returns a canonical URL path for p, eliminating . and .. elements. The following rules are applied iteratively until no further processing can be done: 1. Replace multiple slashes with a single slash. 2. Eliminate each . path name element (the curren
(p string)
| 19 | // |
| 20 | // If the result of this process is an empty string, "/" is returned |
| 21 | func CleanPath(p string) string { |
| 22 | // Turn empty string into "/" |
| 23 | if p == "" { |
| 24 | return "/" |
| 25 | } |
| 26 | |
| 27 | n := len(p) |
| 28 | var buf []byte |
| 29 | |
| 30 | // Invariants: |
| 31 | // reading from path; r is index of next byte to process. |
| 32 | // writing to buf; w is index of next byte to write. |
| 33 | |
| 34 | // path must start with '/' |
| 35 | r := 1 |
| 36 | w := 1 |
| 37 | |
| 38 | if p[0] != '/' { |
| 39 | r = 0 |
| 40 | buf = make([]byte, n+1) |
| 41 | buf[0] = '/' |
| 42 | } |
| 43 | |
| 44 | trailing := n > 1 && p[n-1] == '/' |
| 45 | |
| 46 | // A bit more clunky without a 'lazybuf' like the path package, but the loop |
| 47 | // gets completely inlined (bufApp). So in contrast to the path package this |
| 48 | // loop has no expensive function calls (except 1x make) |
| 49 | |
| 50 | for r < n { |
| 51 | switch { |
| 52 | case p[r] == '/': |
| 53 | // empty path element, trailing slash is added after the end |
| 54 | r++ |
| 55 | |
| 56 | case p[r] == '.' && r+1 == n: |
| 57 | trailing = true |
| 58 | r++ |
| 59 | |
| 60 | case p[r] == '.' && p[r+1] == '/': |
| 61 | // . element |
| 62 | r += 2 |
| 63 | |
| 64 | case p[r] == '.' && p[r+1] == '.' && (r+2 == n || p[r+2] == '/'): |
| 65 | // .. element: remove to last / |
| 66 | r += 3 |
| 67 | |
| 68 | if w > 1 { |
| 69 | // can backtrack |
| 70 | w-- |
| 71 | |
| 72 | if buf == nil { |
| 73 | for w > 1 && p[w] != '/' { |
| 74 | w-- |
| 75 | } |
| 76 | } else { |
| 77 | for w > 1 && buf[w] != '/' { |
| 78 | w-- |