jay/skeleton.cs

   1 #       jay skeleton
   2
   3 #       character in column 1 determines outcome...
   4 #               # is a comment
   5 #               . is copied
   6 #               t is copied as //t if -t is set
   7 #       other lines are interpreted to call jay procedures
   8
   9 .// created by jay 0.7 (c) 1998 Axel.Schreiner@informatik.uni-osnabrueck.de
  10 .
  11  prolog         ## %{ ... %} prior to the first %%
  12
  13 .
  14 .  /** error output stream.
  15 .      It should be changeable.
  16 .    */
  17 .  public System.IO.TextWriter ErrorOutput = System.Console.Out;
  18 .
  19 .  /** simplified error message.
  20 .      @see <a href="#yyerror(java.lang.String, java.lang.String[])">yyerror</a>
  21 .    */
  22 .  public void yyerror (string message) {
  23 .    yyerror(message, null);
  24 .  }
  25 .
  26 .  /* An EOF token */
  27 .  public int eof_token;
  28 .
  29 .  /** (syntax) error message.
  30 .      Can be overwritten to control message format.
  31 .      @param message text to be displayed.
  32 .      @param expected vector of acceptable tokens, if available.
  33 .    */
  34 .  public void yyerror (string message, string[] expected) {
  35 .    if ((yacc_verbose_flag > 0) && (expected != null) && (expected.Length  > 0)) {
  36 .      ErrorOutput.Write (message+", expecting");
  37 .      for (int n = 0; n < expected.Length; ++ n)
  38 .        ErrorOutput.Write (" "+expected[n]);
  39 .        ErrorOutput.WriteLine ();
  40 .    } else
  41 .      ErrorOutput.WriteLine (message);
  42 .  }
  43 .
  44 .  /** debugging support, requires the package jay.yydebug.
  45 .      Set to null to suppress debugging messages.
  46 .    */
  47 t  internal yydebug.yyDebug debug;
  48 .
  49  debug                  ## tables for debugging support
  50 .
  51 .  /** index-checked interface to yyNames[].
  52 .      @param token single character or %token value.
  53 .      @return token name or [illegal] or [unknown].
  54 .    */
  55 t  public static string yyname (int token) {
  56 t    if ((token < 0) || (token > yyNames.Length)) return "[illegal]";
  57 t    string name;
  58 t    if ((name = yyNames[token]) != null) return name;
  59 t    return "[unknown]";
  60 t  }
  61 .
  62 .  int yyExpectingState;
  63 .  /** computes list of expected tokens on error by tracing the tables.
  64 .      @param state for which to compute the list.
  65 .      @return list of token names.
  66 .    */
  67 .  protected int [] yyExpectingTokens (int state){
  68 .    int token, n, len = 0;
  69 .    bool[] ok = new bool[yyNames.Length];
  70 .    if ((n = yySindex[state]) != 0)
  71 .      for (token = n < 0 ? -n : 0;
  72 .           (token < yyNames.Length) && (n+token < yyTable.Length); ++ token)
  73 .        if (yyCheck[n+token] == token && !ok[token] && yyNames[token] != null) {
  74 .          ++ len;
  75 .          ok[token] = true;
  76 .        }
  77 .    if ((n = yyRindex[state]) != 0)
  78 .      for (token = n < 0 ? -n : 0;
  79 .           (token < yyNames.Length) && (n+token < yyTable.Length); ++ token)
  80 .        if (yyCheck[n+token] == token && !ok[token] && yyNames[token] != null) {
  81 .          ++ len;
  82 .          ok[token] = true;
  83 .        }
  84 .    int [] result = new int [len];
  85 .    for (n = token = 0; n < len;  ++ token)
  86 .      if (ok[token]) result[n++] = token;
  87 .    return result;
  88 .  }
  89 .  protected string[] yyExpecting (int state) {
  90 .    int [] tokens = yyExpectingTokens (state);
  91 .    string [] result = new string[tokens.Length];
  92 .    for (int n = 0; n < tokens.Length;  n++)
  93 .      result[n++] = yyNames[tokens [n]];
  94 .    return result;
  95 .  }
  96 .
  97 .  /** the generated parser, with debugging messages.
  98 .      Maintains a state and a value stack, currently with fixed maximum size.
  99 .      @param yyLex scanner.
 100 .      @param yydebug debug message writer implementing yyDebug, or null.
 101 .      @return result of the last reduction, if any.
 102 .      @throws yyException on irrecoverable parse error.
 103 .    */
 104 .  internal Object yyparse (yyParser.yyInput yyLex, Object yyd)
 105 .                                {
 106 t    this.debug = (yydebug.yyDebug)yyd;
 107 .    return yyparse(yyLex);
 108 .  }
 109 .
 110 .  /** initial size and increment of the state/value stack [default 256].
 111 .      This is not final so that it can be overwritten outside of invocations
 112 .      of yyparse().
 113 .    */
 114 .  protected int yyMax;
 115 .
 116 .  /** executed at the beginning of a reduce action.
 117 .      Used as $$ = yyDefault($1), prior to the user-specified action, if any.
 118 .      Can be overwritten to provide deep copy, etc.
 119 .      @param first value for $1, or null.
 120 .      @return first.
 121 .    */
 122 .  protected Object yyDefault (Object first) {
 123 .    return first;
 124 .  }
 125 .
 126 .  /** the generated parser.
 127 .      Maintains a state and a value stack, currently with fixed maximum size.
 128 .      @param yyLex scanner.
 129 .      @return result of the last reduction, if any.
 130 .      @throws yyException on irrecoverable parse error.
 131 .    */
 132 .  internal Object yyparse (yyParser.yyInput yyLex)
 133 .  {
 134 .    if (yyMax <= 0) yyMax = 256;                       // initial size
 135 .    int yyState = 0;                                   // state stack ptr
 136 .    int [] yyStates = new int[yyMax];                  // state stack
 137 .    Object yyVal = null;                               // value stack ptr
 138 .    Object [] yyVals = new Object[yyMax];              // value stack
 139 .    int yyToken = -1;                                  // current input
 140 .    int yyErrorFlag = 0;                               // #tks to shift
 141 .
 142  local          ## %{ ... %} after the first %%
 143
 144 .    /*yyLoop:*/ for (int yyTop = 0;; ++ yyTop) {
 145 .      if (yyTop >= yyStates.Length) {                  // dynamically increase
 146 .        int[] i = new int[yyStates.Length+yyMax];
 147 .        yyStates.CopyTo (i, 0);
 148 .        yyStates = i;
 149 .        Object[] o = new Object[yyVals.Length+yyMax];
 150 .        yyVals.CopyTo (o, 0);
 151 .        yyVals = o;
 152 .      }
 153 .      yyStates[yyTop] = yyState;
 154 .      yyVals[yyTop] = yyVal;
 155 t      if (debug != null) debug.push(yyState, yyVal);
 156 .
 157 .      /*yyDiscarded:*/ for (;;) {      // discarding a token does not change stack
 158 .        int yyN;
 159 .        if ((yyN = yyDefRed[yyState]) == 0) {  // else [default] reduce (yyN)
 160 .          if (yyToken < 0) {
 161 .            yyToken = yyLex.advance() ? yyLex.token() : 0;
 162
 163 t            if (debug != null)
 164 t              debug.lex(yyState, yyToken, yyname(yyToken), yyLex.value());
 165 .          }
 166 .          if ((yyN = yySindex[yyState]) != 0 && ((yyN += yyToken) >= 0)
 167 .              && (yyN < yyTable.Length) && (yyCheck[yyN] == yyToken)) {
 168 t            if (debug != null)
 169 t              debug.shift(yyState, yyTable[yyN], yyErrorFlag-1);
 170 .            yyState = yyTable[yyN];            // shift to yyN
 171 .            yyVal = yyLex.value();
 172 .            yyToken = -1;
 173 .            if (yyErrorFlag > 0) -- yyErrorFlag;
 174 .            goto continue_yyLoop;
 175 .          }
 176 .          if ((yyN = yyRindex[yyState]) != 0 && (yyN += yyToken) >= 0
 177 .              && yyN < yyTable.Length && yyCheck[yyN] == yyToken)
 178 .            yyN = yyTable[yyN];                        // reduce (yyN)
 179 .          else
 180 .            switch (yyErrorFlag) {
 181 .
 182 .            case 0:
 183 .              yyExpectingState = yyState;
 184 .              // yyerror(String.Format ("syntax error, got token `{0}'", yyname (yyToken)), yyExpecting(yyState));
 185 t              if (debug != null) debug.error("syntax error");
 186 .              if (yyToken == 0 /*eof*/ || yyToken == eof_token) throw new yyParser.yyUnexpectedEof ();
 187 .              goto case 1;
 188 .            case 1: case 2:
 189 .              yyErrorFlag = 3;
 190 .              do {
 191 .                if ((yyN = yySindex[yyStates[yyTop]]) != 0
 192 .                    && (yyN += Token.yyErrorCode) >= 0 && yyN < yyTable.Length
 193 .                    && yyCheck[yyN] == Token.yyErrorCode) {
 194 t                  if (debug != null)
 195 t                    debug.shift(yyStates[yyTop], yyTable[yyN], 3);
 196 .                  yyState = yyTable[yyN];
 197 .                  yyVal = yyLex.value();
 198 .                  goto continue_yyLoop;
 199 .                }
 200 t                if (debug != null) debug.pop(yyStates[yyTop]);
 201 .              } while (-- yyTop >= 0);
 202 t              if (debug != null) debug.reject();
 203 .              throw new yyParser.yyException("irrecoverable syntax error");
 204 .
 205 .            case 3:
 206 .              if (yyToken == 0) {
 207 t                if (debug != null) debug.reject();
 208 .                throw new yyParser.yyException("irrecoverable syntax error at end-of-file");
 209 .              }
 210 t              if (debug != null)
 211 t                debug.discard(yyState, yyToken, yyname(yyToken),
 212 t                                                       yyLex.value());
 213 .              yyToken = -1;
 214 .              goto continue_yyDiscarded;               // leave stack alone
 215 .            }
 216 .        }
 217 .        int yyV = yyTop + 1-yyLen[yyN];
 218 t        if (debug != null)
 219 t          debug.reduce(yyState, yyStates[yyV-1], yyN, YYRules.getRule (yyN), yyLen[yyN]);
 220 .        yyVal = yyDefault(yyV > yyTop ? null : yyVals[yyV]);
 221 .        switch (yyN) {
 222
 223  actions                ## code from the actions within the grammar
 224
 225 .        }
 226 .        yyTop -= yyLen[yyN];
 227 .        yyState = yyStates[yyTop];
 228 .        int yyM = yyLhs[yyN];
 229 .        if (yyState == 0 && yyM == 0) {
 230 t          if (debug != null) debug.shift(0, yyFinal);
 231 .          yyState = yyFinal;
 232 .          if (yyToken < 0) {
 233 .            yyToken = yyLex.advance() ? yyLex.token() : 0;
 234
 235 t            if (debug != null)
 236 t               debug.lex(yyState, yyToken,yyname(yyToken), yyLex.value());
 237 .          }
 238 .          if (yyToken == 0) {
 239 t            if (debug != null) debug.accept(yyVal);
 240 .            return yyVal;
 241 .          }
 242 .          goto continue_yyLoop;
 243 .        }
 244 .        if (((yyN = yyGindex[yyM]) != 0) && ((yyN += yyState) >= 0)
 245 .            && (yyN < yyTable.Length) && (yyCheck[yyN] == yyState))
 246 .          yyState = yyTable[yyN];
 247 .        else
 248 .          yyState = yyDgoto[yyM];
 249 t        if (debug != null) debug.shift(yyStates[yyTop], yyState);
 250 .        goto continue_yyLoop;
 251 .      continue_yyDiscarded: continue;  // implements the named-loop continue: 'continue yyDiscarded'
 252 .      }
 253 .    continue_yyLoop: continue;         // implements the named-loop continue: 'continue yyLoop'
 254 .    }
 255 .  }
 256 .
 257  tables                 ## tables for rules, default reduction, and action calls
 258 .
 259  epilog                 ## text following second %%
 260 .namespace yydebug {
 261 .        using System;
 262 .        internal interface yyDebug {
 263 .                void push (int state, Object value);
 264 .                void lex (int state, int token, string name, Object value);
 265 .                void shift (int from, int to, int errorFlag);
 266 .                void pop (int state);
 267 .                void discard (int state, int token, string name, Object value);
 268 .                void reduce (int from, int to, int rule, string text, int len);
 269 .                void shift (int from, int to);
 270 .                void accept (Object value);
 271 .                void error (string message);
 272 .                void reject ();
 273 .        }
 274 .
 275 .        class yyDebugSimple : yyDebug {
 276 .                void println (string s){
 277 .                        Console.Error.WriteLine (s);
 278 .                }
 279 .
 280 .                public void push (int state, Object value) {
 281 .                        println ("push\tstate "+state+"\tvalue "+value);
 282 .                }
 283 .
 284 .                public void lex (int state, int token, string name, Object value) {
 285 .                        println("lex\tstate "+state+"\treading "+name+"\tvalue "+value);
 286 .                }
 287 .
 288 .                public void shift (int from, int to, int errorFlag) {
 289 .                        switch (errorFlag) {
 290 .                        default:                               // normally
 291 .                                println("shift\tfrom state "+from+" to "+to);
 292 .                                break;
 293 .                        case 0: case 1: case 2:                // in error recovery
 294 .                                println("shift\tfrom state "+from+" to "+to
 295 .                                            +"\t"+errorFlag+" left to recover");
 296 .                                break;
 297 .                        case 3:                                // normally
 298 .                                println("shift\tfrom state "+from+" to "+to+"\ton error");
 299 .                                break;
 300 .                        }
 301 .                }
 302 .
 303 .                public void pop (int state) {
 304 .                        println("pop\tstate "+state+"\ton error");
 305 .                }
 306 .
 307 .                public void discard (int state, int token, string name, Object value) {
 308 .                        println("discard\tstate "+state+"\ttoken "+name+"\tvalue "+value);
 309 .                }
 310 .
 311 .                public void reduce (int from, int to, int rule, string text, int len) {
 312 .                        println("reduce\tstate "+from+"\tuncover "+to
 313 .                                    +"\trule ("+rule+") "+text);
 314 .                }
 315 .
 316 .                public void shift (int from, int to) {
 317 .                        println("goto\tfrom state "+from+" to "+to);
 318 .                }
 319 .
 320 .                public void accept (Object value) {
 321 .                        println("accept\tvalue "+value);
 322 .                }
 323 .
 324 .                public void error (string message) {
 325 .                        println("error\t"+message);
 326 .                }
 327 .
 328 .                public void reject () {
 329 .                        println("reject");
 330 .                }
 331 .
 332 .        }
 333 .}
 334 .// %token constants
 335 . class Token {
 336  tokens public const int
 337 . }
 338 . namespace yyParser {
 339 .  using System;
 340 .  /** thrown for irrecoverable syntax errors and stack overflow.
 341 .    */
 342 .  internal class yyException : System.Exception {
 343 .    public yyException (string message) : base (message) {
 344 .    }
 345 .  }
 346 .  internal class yyUnexpectedEof : yyException {
 347 .    public yyUnexpectedEof (string message) : base (message) {
 348 .    }
 349 .    public yyUnexpectedEof () : base ("") {
 350 .    }
 351 .  }
 352 .
 353 .  /** must be implemented by a scanner object to supply input to the parser.
 354 .    */
 355 .  internal interface yyInput {
 356 .    /** move on to next token.
 357 .        @return false if positioned beyond tokens.
 358 .        @throws IOException on input error.
 359 .      */
 360 .    bool advance (); // throws java.io.IOException;
 361 .    /** classifies current token.
 362 .        Should not be called if advance() returned false.
 363 .        @return current %token or single character.
 364 .      */
 365 .    int token ();
 366 .    /** associated with current token.
 367 .        Should not be called if advance() returned false.
 368 .        @return value for token().
 369 .      */
 370 .    Object value ();
 371 .  }
 372 . }
 373 .} // close outermost namespace, that MUST HAVE BEEN opened in the prolog