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