mcs/class/corlib/System.IO/SearchPattern.cs

   1 //\r
   2 // System.IO.SearchPattern.cs: Filename glob support.\r
   3 //\r
   4 // Author:\r
   5 //   Dan Lewis (dihlewis@yahoo.co.uk)\r
   6 //\r
   7 // (C) 2002\r
   8 //\r
   9 \r
  10 using System;\r
  11 \r
  12 namespace System.IO {\r
  13 \r
  14         // FIXME: there's a complication with this algorithm under windows.\r
  15         // the pattern '*.*' matches all files (i think . matches the extension),\r
  16         // whereas under UNIX it should only match files containing the '.' character.\r
  17 \r
  18         class SearchPattern {\r
  19                 public SearchPattern (string pattern) : this (pattern, false) { }\r
  20 \r
  21                 public SearchPattern (string pattern, bool ignore)\r
  22                 {\r
  23                         this.ignore = ignore;\r
  24                         Compile (pattern);\r
  25                 }\r
  26 \r
  27                 public bool IsMatch (string text)\r
  28                 {\r
  29                         return Match (ops, text, 0);\r
  30                 }\r
  31 \r
  32                 // private\r
  33 \r
  34                 private Op ops;         // the compiled pattern\r
  35                 private bool ignore;    // ignore case\r
  36 \r
  37                 private void Compile (string pattern)\r
  38                 {\r
  39                         if (pattern == null || pattern.IndexOfAny (InvalidChars) >= 0)\r
  40                                 throw new ArgumentException ("Invalid search pattern.");\r
  41 \r
  42                         if (pattern == "*") {   // common case\r
  43                                 ops = new Op (OpCode.True);\r
  44                                 return;\r
  45                         }\r
  46 \r
  47                         ops = null;\r
  48 \r
  49                         int ptr = 0;\r
  50                         Op last_op = null;\r
  51                         while (ptr < pattern.Length) {\r
  52                                 Op op;\r
  53                         \r
  54                                 switch (pattern [ptr]) {\r
  55                                 case '?':\r
  56                                         op = new Op (OpCode.AnyChar);\r
  57                                         ++ ptr;\r
  58                                         break;\r
  59 \r
  60                                 case '*':\r
  61                                         op = new Op (OpCode.AnyString);\r
  62                                         ++ ptr;\r
  63                                         break;\r
  64                                         \r
  65                                 default:\r
  66                                         op = new Op (OpCode.ExactString);\r
  67                                         int end = pattern.IndexOfAny (WildcardChars, ptr);\r
  68                                         if (end < 0)\r
  69                                                 end = pattern.Length;\r
  70 \r
  71                                         op.Argument = pattern.Substring (ptr, end - ptr);\r
  72                                         if (ignore)\r
  73                                                 op.Argument = op.Argument.ToLower ();\r
  74 \r
  75                                         ptr = end;\r
  76                                         break;\r
  77                                 }\r
  78 \r
  79                                 if (last_op == null)\r
  80                                         ops = op;\r
  81                                 else\r
  82                                         last_op.Next = op;\r
  83 \r
  84                                 last_op = op;\r
  85                         }\r
  86 \r
  87                         if (last_op == null)\r
  88                                 ops = new Op (OpCode.End);\r
  89                         else\r
  90                                 last_op.Next = new Op (OpCode.End);\r
  91                 }\r
  92 \r
  93                 private bool Match (Op op, string text, int ptr)\r
  94                 {\r
  95                         while (op != null) {\r
  96                                 switch (op.Code) {\r
  97                                 case OpCode.True:\r
  98                                         return true;\r
  99 \r
 100                                 case OpCode.End:\r
 101                                         if (ptr == text.Length)\r
 102                                                 return true;\r
 103 \r
 104                                         return false;\r
 105                                 \r
 106                                 case OpCode.ExactString:\r
 107                                         int length = op.Argument.Length;\r
 108                                         if (ptr + length > text.Length)\r
 109                                                 return false;\r
 110 \r
 111                                         string str = text.Substring (ptr, length);\r
 112                                         if (ignore)\r
 113                                                 str = str.ToLower ();\r
 114 \r
 115                                         if (str != op.Argument)\r
 116                                                 return false;\r
 117 \r
 118                                         ptr += length;\r
 119                                         break;\r
 120 \r
 121                                 case OpCode.AnyChar:\r
 122                                         if (++ ptr > text.Length)\r
 123                                                 return false;\r
 124                                         break;\r
 125 \r
 126                                 case OpCode.AnyString:\r
 127                                         while (ptr <= text.Length) {\r
 128                                                 if (Match (op.Next, text, ptr))\r
 129                                                         return true;\r
 130 \r
 131                                                 ++ ptr;\r
 132                                         }\r
 133 \r
 134                                         return false;\r
 135                                 }\r
 136 \r
 137                                 op = op.Next;\r
 138                         }\r
 139 \r
 140                         return true;\r
 141                 }\r
 142 \r
 143                 // private static\r
 144 \r
 145                 internal static readonly char [] WildcardChars = { '*', '?' };\r
 146                 internal static readonly char [] InvalidChars = { Path.DirectorySeparatorChar, Path.AltDirectorySeparatorChar };\r
 147 \r
 148                 private class Op {\r
 149                         public Op (OpCode code)\r
 150                         {\r
 151                                 this.Code = code;\r
 152                                 this.Argument = null;\r
 153                                 this.Next = null;\r
 154                         }\r
 155                 \r
 156                         public OpCode Code;\r
 157                         public string Argument;\r
 158                         public Op Next;\r
 159                 }\r
 160 \r
 161                 private enum OpCode {\r
 162                         ExactString,            // literal\r
 163                         AnyChar,                // ?\r
 164                         AnyString,              // *\r
 165                         End,                    // end of pattern\r
 166                         True                    // always succeeds\r
 167                 };\r
 168         }\r
 169 }\r