mcs/class/System.XML/System.Xml.XPath/XPathScanner.cs

   1 //\r
   2 // System.Xml.XPath.XPathScanner\r
   3 //\r
   4 // Author:\r
   5 //   Jason Diamond (jason@injektilo.org)\r
   6 //\r
   7 // (C) 2002 Jason Diamond  http://injektilo.org/\r
   8 //\r
   9 \r
  10 using System;\r
  11 using System.IO;\r
  12 using System.Text;\r
  13 \r
  14 // [28] ExprToken         ::= '(' | ')' | '[' | ']' | '.' | '..' | '@' | ',' | '::'\r
  15 //                            | NameTest\r
  16 //                            | NodeType\r
  17 //                            | Operator\r
  18 //                            | FunctionName\r
  19 //                            | AxisName\r
  20 //                            | Literal\r
  21 //                            | Number\r
  22 //                            | VariableReference\r
  23 // [29] Literal           ::= '"' [^"]* '"'\r
  24 //                            | "'" [^']* "'"\r
  25 // [30] Number            ::= Digits ('.' Digits?)?\r
  26 //                            | '.' Digits\r
  27 // [31] Digits            ::= [0-9]+\r
  28 // [32] Operator          ::= OperatorName\r
  29 //                            | MultiplyOperator\r
  30 //                            | '/' | '//' | '|' | '+' | '-' | '=' | '!=' | '<' | '<=' | '>' | '>='\r
  31 // [33] OperatorName      ::= 'and' | 'or' | 'mod' | 'div'\r
  32 // [34] MultiplyOperator  ::= '*'\r
  33 // [35] FunctionName      ::= QName - NodeType\r
  34 // [36] VariableReference ::= '$' QName\r
  35 // [37] NameTest          ::= '*'\r
  36 //                            | NCName ':' '*'\r
  37 //                            | QName\r
  38 // [38] NodeType          ::= 'comment'\r
  39 //                            | 'text'\r
  40 //                            | 'processing-instruction'\r
  41 //                            | 'node'\r
  42 // [39] ExprWhitespace    ::= S\r
  43 \r
  44 namespace System.Xml.XPath\r
  45 {\r
  46         public enum XPathTokenType\r
  47         {\r
  48                 Start,\r
  49                 End,\r
  50                 Error,\r
  51                 LeftParen,\r
  52                 RightParen,\r
  53                 LeftBracket,\r
  54                 RightBracket,\r
  55                 Dot,\r
  56                 DotDot,\r
  57                 At,\r
  58                 Comma,\r
  59                 ColonColon,\r
  60                 NameTest,\r
  61                 NodeType,\r
  62                 Operator,\r
  63                 FunctionName,\r
  64                 AxisName,\r
  65                 Literal,\r
  66                 Number,\r
  67                 VariableReference\r
  68         }\r
  69 \r
  70         public sealed class XPathScanner\r
  71         {\r
  72                 private string xpath;\r
  73                 private int index;\r
  74                 private XPathTokenType tokenType;\r
  75                 private string value;\r
  76                 private XPathTokenType precedingTokenType;\r
  77 \r
  78                 public XPathScanner (string xpath)\r
  79                 {\r
  80                         this.xpath = xpath;\r
  81                         index = 0;\r
  82                         tokenType = XPathTokenType.Start;\r
  83                 }\r
  84 \r
  85                 public XPathTokenType TokenType {\r
  86                         get {\r
  87                                 return tokenType;\r
  88                         }\r
  89                 }\r
  90 \r
  91                 public string Value {\r
  92                         get {\r
  93                                 return value;\r
  94                         }\r
  95                 }\r
  96 \r
  97                 private int Read ()\r
  98                 {\r
  99                         int c = Peek ();\r
 100                         if (c != -1)\r
 101                                 MoveNext ();\r
 102                         return c;\r
 103                 }\r
 104 \r
 105                 private int Peek ()\r
 106                 {\r
 107                         if (index < xpath.Length)\r
 108                                 return xpath[index];\r
 109                         return -1;\r
 110                 }\r
 111 \r
 112                 private int Peek2 ()\r
 113                 {\r
 114                         if (index + 1 < xpath.Length)\r
 115                                 return xpath[index + 1];\r
 116                         return -1;\r
 117                 }\r
 118 \r
 119                 private void MoveNext ()\r
 120                 {\r
 121                         ++index;\r
 122                 }\r
 123 \r
 124                 private void MovePrevious ()\r
 125                 {\r
 126                         if (index > 0)\r
 127                                 --index;\r
 128                 }\r
 129 \r
 130                 public XPathTokenType Scan ()\r
 131                 {\r
 132                         precedingTokenType = tokenType;\r
 133 \r
 134                         int c = Read ();\r
 135 \r
 136                         if (c == -1) {\r
 137                                 tokenType = XPathTokenType.End;\r
 138                                 value = null;\r
 139                         } else if (c != ':' && XmlChar.IsFirstNameChar (c)) {\r
 140                                 StringBuilder builder = new StringBuilder ();\r
 141                                 builder.Append ((char) c);\r
 142                                 while (Peek () != ':' && XmlChar.IsNameChar (Peek ())) {\r
 143                                         builder.Append ((char) Read ());\r
 144                                 }\r
 145                                 if (Peek () == ':' && Peek2 () != ':') {\r
 146                                         Read();\r
 147                                         if (XmlChar.IsFirstNameChar (Peek ())) {\r
 148                                                 builder.Append (':');\r
 149                                                 builder.Append ((char) Read ());\r
 150                                                 while (XmlChar.IsNameChar (Peek ())) {\r
 151                                                         builder.Append ((char) Read ());\r
 152                                                 }\r
 153                                                 tokenType = XPathTokenType.NameTest;\r
 154                                         } else if (Peek () == '*') {\r
 155                                                 builder.Append (':');\r
 156                                                 builder.Append ((char) Read ());\r
 157                                                 tokenType = XPathTokenType.NameTest;\r
 158                                                 value = builder.ToString ();\r
 159                                                 return tokenType;\r
 160                                         } else {\r
 161                                                 tokenType = XPathTokenType.Error;\r
 162                                                 return tokenType;\r
 163                                         }\r
 164                                 }\r
 165                                 value = builder.ToString ();\r
 166                                 if (precedingTokenType != XPathTokenType.Start &&\r
 167                                         precedingTokenType != XPathTokenType.At &&\r
 168                                         precedingTokenType != XPathTokenType.ColonColon &&\r
 169                                         precedingTokenType != XPathTokenType.LeftParen &&\r
 170                                         precedingTokenType != XPathTokenType.LeftBracket &&\r
 171                                         precedingTokenType != XPathTokenType.Operator)\r
 172                                         tokenType = XPathTokenType.Operator;\r
 173                                 else if (Peek () == '(') {\r
 174                                         if (value == "comment" || \r
 175                                                 value == "node" || \r
 176                                                 value == "processing-instruction" || \r
 177                                                 value == "text")\r
 178                                                 tokenType = XPathTokenType.NodeType;\r
 179                                         else\r
 180                                                 tokenType = XPathTokenType.FunctionName;\r
 181                                 } else {\r
 182                                         if (Peek () == ':' && Peek2 () == ':')\r
 183                                                 tokenType = XPathTokenType.AxisName;\r
 184                                         else\r
 185                                                 tokenType = XPathTokenType.NameTest;\r
 186                                 }\r
 187                                 value = builder.ToString ();\r
 188                         } else {\r
 189                                 switch (c) {\r
 190                                 case '(':\r
 191                                         tokenType = XPathTokenType.LeftParen;\r
 192                                         value = "(";\r
 193                                         break;\r
 194                                 case ')':\r
 195                                         tokenType = XPathTokenType.RightParen;\r
 196                                         value = ")";\r
 197                                         break;\r
 198                                 case '[':\r
 199                                         tokenType = XPathTokenType.LeftBracket;\r
 200                                         break;\r
 201                                 case ']':\r
 202                                         tokenType = XPathTokenType.RightBracket;\r
 203                                         break;\r
 204                                 case '.':\r
 205                                         if (Peek () != '.') {\r
 206                                                 tokenType = XPathTokenType.Dot;\r
 207                                                 value = ".";\r
 208                                         } else {\r
 209                                                 Read ();\r
 210                                                 tokenType = XPathTokenType.DotDot;\r
 211                                                 value = "..";\r
 212                                         }\r
 213                                         break;\r
 214                                 case '@':\r
 215                                         tokenType = XPathTokenType.At;\r
 216                                         value = "@";\r
 217                                         break;\r
 218                                 case ',':\r
 219                                         tokenType = XPathTokenType.Comma;\r
 220                                         break;\r
 221                                 case ':':\r
 222                                         if (Peek () == ':') {\r
 223                                                 Read ();\r
 224                                                 tokenType = XPathTokenType.ColonColon;\r
 225                                                 value = "::";\r
 226                                         } else\r
 227                                                 tokenType = XPathTokenType.Error;\r
 228                                         break;\r
 229                                 case '*':\r
 230                                         if (precedingTokenType != XPathTokenType.Start &&\r
 231                                                 precedingTokenType != XPathTokenType.At &&\r
 232                                                 precedingTokenType != XPathTokenType.ColonColon &&\r
 233                                                 precedingTokenType != XPathTokenType.LeftParen &&\r
 234                                                 precedingTokenType != XPathTokenType.LeftBracket &&\r
 235                                                 precedingTokenType != XPathTokenType.Operator) {\r
 236                                                 tokenType = XPathTokenType.Operator;\r
 237                                                 value = "*";\r
 238                                         } else {\r
 239                                                 tokenType = XPathTokenType.NameTest;\r
 240                                                 value = "*";\r
 241                                         }\r
 242                                         break;\r
 243                                 default:\r
 244                                         if (c == '/') {\r
 245                                                 tokenType = XPathTokenType.Operator;\r
 246                                                 if (Peek () != '/')\r
 247                                                         value = "/";\r
 248                                                 else {\r
 249                                                         Read ();\r
 250                                                         value = "//";\r
 251                                                 }\r
 252                                         }\r
 253                                         break;\r
 254                                 }\r
 255                         }\r
 256 \r
 257                         return tokenType;\r
 258                 }\r
 259         }\r
 260 }\r