mcs/class/System.Net.Http/System.Net.Http.Headers/Lexer.cs

   1 //
   2 // Lexer.cs
   3 //
   4 // Authors:
   5 //      Marek Safar  <marek.safar@gmail.com>
   6 //
   7 // Copyright (C) 2011 Xamarin Inc (http://www.xamarin.com)
   8 //
   9 // Permission is hereby granted, free of charge, to any person obtaining
  10 // a copy of this software and associated documentation files (the
  11 // "Software"), to deal in the Software without restriction, including
  12 // without limitation the rights to use, copy, modify, merge, publish,
  13 // distribute, sublicense, and/or sell copies of the Software, and to
  14 // permit persons to whom the Software is furnished to do so, subject to
  15 // the following conditions:
  16 //
  17 // The above copyright notice and this permission notice shall be
  18 // included in all copies or substantial portions of the Software.
  19 //
  20 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  21 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  22 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  23 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  24 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  25 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  26 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  27 //
  28
  29 using System.Globalization;
  30
  31 namespace System.Net.Http.Headers
  32 {
  33         struct Token
  34         {
  35                 public enum Type
  36                 {
  37                         Error,
  38                         End,
  39                         Token,
  40                         QuotedString,
  41                         SeparatorEqual,
  42                         SeparatorSemicolon,
  43                         SeparatorSlash,
  44                         SeparatorDash,
  45                         SeparatorComma,
  46                         OpenParens,
  47                 }
  48
  49                 public static readonly Token Empty = new Token (Type.Token, 0, 0);
  50
  51                 readonly Type type;
  52
  53                 public Token (Type type, int startPosition, int endPosition)
  54                         : this ()
  55                 {
  56                         this.type = type;
  57                         StartPosition = startPosition;
  58                         EndPosition = endPosition;
  59                 }
  60
  61                 public int StartPosition { get; private set; }
  62                 public int EndPosition { get; private set; }
  63
  64                 public Type Kind {
  65                         get {
  66                                 return type;
  67                         }
  68                 }
  69
  70                 public static implicit operator Token.Type (Token token)
  71                 {
  72                         return token.type;
  73                 }
  74
  75                 public override string ToString ()
  76                 {
  77                         return type.ToString ();
  78                 }
  79         }
  80
  81         class Lexer
  82         {
  83                 // any CHAR except CTLs or separators
  84                 static readonly bool[] token_chars = {
  85                         /*0*/   false, false, false, false, false, false, false, false, false, false,
  86                         /*10*/  false, false, false, false, false, false, false, false, false, false,
  87                         /*20*/  false, false, false, false, false, false, false, false, false, false,
  88                         /*30*/  false, false, false, true, false, true, true, true, true, true,
  89                         /*40*/  false, false, true, true, false, true, true, false, true, true,
  90                         /*50*/  true, true, true, true, true, true, true, true, false, false,
  91                         /*60*/  false, false, false, false, false, true, true, true, true, true,
  92                         /*70*/  true, true, true, true, true, true, true, true, true, true,
  93                         /*80*/  true, true, true, true, true, true, true, true, true, true,
  94                         /*90*/  true, false, false, false, true, true, true, true, true, true,
  95                         /*100*/ true, true, true, true, true, true, true, true, true, true,
  96                         /*110*/ true, true, true, true, true, true, true, true, true, true,
  97                         /*120*/ true, true, true, false, true, false
  98                         };
  99
 100                 static readonly int last_token_char = token_chars.Length;
 101                 static readonly string[] dt_formats = new[] {
 102                                 "r",
 103                                 "dddd, dd'-'MMM'-'yy HH:mm:ss 'GMT'",
 104                                 "ddd MMM d HH:mm:ss yyyy",
 105                                 "d MMM yy H:m:s",
 106                                 "ddd, d MMM yyyy H:m:s zzz"
 107                 };
 108
 109                 readonly string s;
 110                 int pos;
 111
 112                 public Lexer (string stream)
 113                 {
 114                         this.s = stream;
 115                 }
 116
 117                 public string GetStringValue (Token token)
 118                 {
 119                         return s.Substring (token.StartPosition, token.EndPosition - token.StartPosition);
 120                 }
 121
 122                 public string GetStringValue (Token start, Token end)
 123                 {
 124                         return s.Substring (start.StartPosition, end.EndPosition - start.StartPosition);
 125                 }
 126
 127                 public string GetQuotedStringValue (Token start)
 128                 {
 129                         return s.Substring (start.StartPosition + 1, start.EndPosition - start.StartPosition - 2);
 130                 }
 131
 132                 public string GetRemainingStringValue (int position)
 133                 {
 134                         return position > s.Length ? null : s.Substring (position);
 135                 }
 136
 137                 public bool IsStarStringValue (Token token)
 138                 {
 139                         return (token.EndPosition - token.StartPosition) == 1 && s[token.StartPosition] == '*';
 140                 }
 141
 142                 public bool TryGetNumericValue (Token token, out int value)
 143                 {
 144                         return int.TryParse (GetStringValue (token), NumberStyles.None, CultureInfo.InvariantCulture, out value);
 145                 }
 146
 147                 public TimeSpan? TryGetTimeSpanValue (Token token)
 148                 {
 149                         int seconds;
 150                         if (TryGetNumericValue (token, out seconds)) {
 151                                 return TimeSpan.FromSeconds (seconds);
 152                         }
 153
 154                         return null;
 155                 }
 156
 157                 public bool TryGetDateValue (Token token, out DateTimeOffset value)
 158                 {
 159                         string text = token == Token.Type.QuotedString ?
 160                                 s.Substring (token.StartPosition + 1, token.EndPosition - token.StartPosition - 2) :
 161                                 GetStringValue (token);
 162
 163                         return TryGetDateValue (text, out value);
 164                 }
 165
 166                 public static bool TryGetDateValue (string text, out DateTimeOffset value)
 167                 {
 168                         const DateTimeStyles DefaultStyles = DateTimeStyles.AssumeUniversal | DateTimeStyles.AllowWhiteSpaces;
 169
 170                         return DateTimeOffset.TryParseExact (text, dt_formats, DateTimeFormatInfo.InvariantInfo, DefaultStyles, out value);
 171                 }
 172
 173                 public bool TryGetDoubleValue (Token token, out double value)
 174                 {
 175                         string s = GetStringValue (token);
 176                         return double.TryParse (s, NumberStyles.AllowDecimalPoint, CultureInfo.InvariantCulture, out value);
 177                 }
 178
 179                 public static bool IsValidToken (string input)
 180                 {
 181                         int i = 0;
 182                         //
 183                         // any CHAR except CTLs or separator
 184                         //
 185                         for (; i < input.Length; ++i) {
 186                                 char s = input[i];
 187                                 if (s > last_token_char || !token_chars[s])
 188                                         return false;
 189                         }
 190
 191                         return i > 0;
 192                 }
 193
 194                 public void EatChar ()
 195                 {
 196                         ++pos;
 197                 }
 198
 199                 public int PeekChar ()
 200                 {
 201                         return pos < s.Length ? s[pos] : -1;
 202                 }
 203
 204                 public bool ScanCommentOptional (out string value)
 205                 {
 206                         Token t;
 207                         if (ScanCommentOptional (out value, out t))
 208                                 return true;
 209
 210                         return t == Token.Type.End;
 211                 }
 212
 213                 public bool ScanCommentOptional (out string value, out Token readToken)
 214                 {
 215                         readToken = Scan ();
 216                         if (readToken != Token.Type.OpenParens) {
 217                                 value = null;
 218                                 return false;
 219                         }
 220
 221                         while (pos < s.Length) {
 222                                 var ch = s[pos];
 223                                 if (ch == ')') {
 224                                         ++pos;
 225                                         var start = readToken.StartPosition;
 226                                         value = s.Substring (start, pos - start);
 227                                         return true;
 228                                 }
 229
 230                                 // any OCTET except CTLs, but including LWS
 231                                 if (ch < 32 || ch > 126)
 232                                         break;
 233
 234                                 ++pos;
 235                         }
 236
 237                         value = null;
 238                         return false;
 239                 }
 240
 241                 public Token Scan ()
 242                 {
 243                         int start = pos;
 244                         if (s == null)
 245                                 return new Token (Token.Type.Error, 0, 0);
 246
 247                         Token.Type ttype;
 248                         if (pos >= s.Length) {
 249                                 ttype = Token.Type.End;
 250                         } else {
 251                                 ttype = Token.Type.Error;
 252                         start:
 253                                 char ch = s[pos++];
 254                                 switch (ch) {
 255                                 case ' ':
 256                                 case '\t':
 257                                         if (pos == s.Length) {
 258                                                 ttype = Token.Type.End;
 259                                                 break;
 260                                         }
 261
 262                                         goto start;
 263                                 case '=':
 264                                         ttype = Token.Type.SeparatorEqual;
 265                                         break;
 266                                 case ';':
 267                                         ttype = Token.Type.SeparatorSemicolon;
 268                                         break;
 269                                 case '/':
 270                                         ttype = Token.Type.SeparatorSlash;
 271                                         break;
 272                                 case '-':
 273                                         ttype = Token.Type.SeparatorDash;
 274                                         break;
 275                                 case ',':
 276                                         ttype = Token.Type.SeparatorComma;
 277                                         break;
 278                                 case '"':
 279                                         // Quoted string
 280                                         start = pos - 1;
 281                                         while (pos < s.Length) {
 282                                                 ch = s[pos];
 283                                                 if (ch == '"') {
 284                                                         ++pos;
 285                                                         ttype = Token.Type.QuotedString;
 286                                                         break;
 287                                                 }
 288
 289                                                 // any OCTET except CTLs, but including LWS
 290                                                 if (ch < 32 || ch > 126)
 291                                                         break;
 292
 293                                                 ++pos;
 294                                         }
 295
 296                                         break;
 297                                 case '(':
 298                                         start = pos - 1;
 299                                         ttype = Token.Type.OpenParens;
 300                                         break;
 301                                 default:
 302                                         if (ch <= last_token_char && token_chars[ch]) {
 303                                                 start = pos - 1;
 304
 305                                                 ttype = Token.Type.Token;
 306                                                 while (pos < s.Length) {
 307                                                         ch = s[pos];
 308                                                         if (ch > last_token_char || !token_chars[ch]) {
 309                                                                 break;
 310                                                         }
 311
 312                                                         ++pos;
 313                                                 }
 314                                         }
 315
 316                                         break;
 317                                 }
 318                         }
 319
 320                         return new Token (ttype, start, pos);
 321                 }
 322         }
 323 }