xref: /illumos-gate/usr/src/lib/libsqlite/tool/lempar.c (revision 1da57d551424de5a9d469760be7c4b4d4f10a755)
1 /* Driver template for the LEMON parser generator.
2 ** The author disclaims copyright to this source code.
3 */
4 /* First off, code is include which follows the "include" declaration
5 ** in the input file. */
6 #include <stdio.h>
7 %%
8 /* Next is all token values, in a form suitable for use by makeheaders.
9 ** This section will be null unless lemon is run with the -m switch.
10 */
11 /*
12 ** These constants (all generated automatically by the parser generator)
13 ** specify the various kinds of tokens (terminals) that the parser
14 ** understands.
15 **
16 ** Each symbol here is a terminal symbol in the grammar.
17 */
18 %%
19 /* Make sure the INTERFACE macro is defined.
20 */
21 #ifndef INTERFACE
22 # define INTERFACE 1
23 #endif
24 /* The next thing included is series of defines which control
25 ** various aspects of the generated parser.
26 **    YYCODETYPE         is the data type used for storing terminal
27 **                       and nonterminal numbers.  "unsigned char" is
28 **                       used if there are fewer than 250 terminals
29 **                       and nonterminals.  "int" is used otherwise.
30 **    YYNOCODE           is a number of type YYCODETYPE which corresponds
31 **                       to no legal terminal or nonterminal number.  This
32 **                       number is used to fill in empty slots of the hash
33 **                       table.
34 **    YYFALLBACK         If defined, this indicates that one or more tokens
35 **                       have fall-back values which should be used if the
36 **                       original value of the token will not parse.
37 **    YYACTIONTYPE       is the data type used for storing terminal
38 **                       and nonterminal numbers.  "unsigned char" is
39 **                       used if there are fewer than 250 rules and
40 **                       states combined.  "int" is used otherwise.
41 **    ParseTOKENTYPE     is the data type used for minor tokens given
42 **                       directly to the parser from the tokenizer.
43 **    YYMINORTYPE        is the data type used for all minor tokens.
44 **                       This is typically a union of many types, one of
45 **                       which is ParseTOKENTYPE.  The entry in the union
46 **                       for base tokens is called "yy0".
47 **    YYSTACKDEPTH       is the maximum depth of the parser's stack.
48 **    ParseARG_SDECL     A static variable declaration for the %extra_argument
49 **    ParseARG_PDECL     A parameter declaration for the %extra_argument
50 **    ParseARG_STORE     Code to store %extra_argument into yypParser
51 **    ParseARG_FETCH     Code to extract %extra_argument from yypParser
52 **    YYNSTATE           the combined number of states.
53 **    YYNRULE            the number of rules in the grammar
54 **    YYERRORSYMBOL      is the code number of the error symbol.  If not
55 **                       defined, then do no error processing.
56 */
57 %%
58 #define YY_NO_ACTION      (YYNSTATE+YYNRULE+2)
59 #define YY_ACCEPT_ACTION  (YYNSTATE+YYNRULE+1)
60 #define YY_ERROR_ACTION   (YYNSTATE+YYNRULE)
61 
62 /* Next are that tables used to determine what action to take based on the
63 ** current state and lookahead token.  These tables are used to implement
64 ** functions that take a state number and lookahead value and return an
65 ** action integer.
66 **
67 ** Suppose the action integer is N.  Then the action is determined as
68 ** follows
69 **
70 **   0 <= N < YYNSTATE                  Shift N.  That is, push the lookahead
71 **                                      token onto the stack and goto state N.
72 **
73 **   YYNSTATE <= N < YYNSTATE+YYNRULE   Reduce by rule N-YYNSTATE.
74 **
75 **   N == YYNSTATE+YYNRULE              A syntax error has occurred.
76 **
77 **   N == YYNSTATE+YYNRULE+1            The parser accepts its input.
78 **
79 **   N == YYNSTATE+YYNRULE+2            No such action.  Denotes unused
80 **                                      slots in the yy_action[] table.
81 **
82 ** The action table is constructed as a single large table named yy_action[].
83 ** Given state S and lookahead X, the action is computed as
84 **
85 **      yy_action[ yy_shift_ofst[S] + X ]
86 **
87 ** If the index value yy_shift_ofst[S]+X is out of range or if the value
88 ** yy_lookahead[yy_shift_ofst[S]+X] is not equal to X or if yy_shift_ofst[S]
89 ** is equal to YY_SHIFT_USE_DFLT, it means that the action is not in the table
90 ** and that yy_default[S] should be used instead.
91 **
92 ** The formula above is for computing the action when the lookahead is
93 ** a terminal symbol.  If the lookahead is a non-terminal (as occurs after
94 ** a reduce action) then the yy_reduce_ofst[] array is used in place of
95 ** the yy_shift_ofst[] array and YY_REDUCE_USE_DFLT is used in place of
96 ** YY_SHIFT_USE_DFLT.
97 **
98 ** The following are the tables generated in this section:
99 **
100 **  yy_action[]        A single table containing all actions.
101 **  yy_lookahead[]     A table containing the lookahead for each entry in
102 **                     yy_action.  Used to detect hash collisions.
103 **  yy_shift_ofst[]    For each state, the offset into yy_action for
104 **                     shifting terminals.
105 **  yy_reduce_ofst[]   For each state, the offset into yy_action for
106 **                     shifting non-terminals after a reduce.
107 **  yy_default[]       Default action for each state.
108 */
109 %%
110 #define YY_SZ_ACTTAB (sizeof(yy_action)/sizeof(yy_action[0]))
111 
112 /* The next table maps tokens into fallback tokens.  If a construct
113 ** like the following:
114 **
115 **      %fallback ID X Y Z.
116 **
117 ** appears in the grammer, then ID becomes a fallback token for X, Y,
118 ** and Z.  Whenever one of the tokens X, Y, or Z is input to the parser
119 ** but it does not parse, the type of the token is changed to ID and
120 ** the parse is retried before an error is thrown.
121 */
122 #ifdef YYFALLBACK
123 static const YYCODETYPE yyFallback[] = {
124 %%
125 };
126 #endif /* YYFALLBACK */
127 
128 /* The following structure represents a single element of the
129 ** parser's stack.  Information stored includes:
130 **
131 **   +  The state number for the parser at this level of the stack.
132 **
133 **   +  The value of the token stored at this level of the stack.
134 **      (In other words, the "major" token.)
135 **
136 **   +  The semantic value stored at this level of the stack.  This is
137 **      the information used by the action routines in the grammar.
138 **      It is sometimes called the "minor" token.
139 */
140 struct yyStackEntry {
141   int stateno;       /* The state-number */
142   int major;         /* The major token value.  This is the code
143                      ** number for the token at this stack level */
144   YYMINORTYPE minor; /* The user-supplied minor token value.  This
145                      ** is the value of the token  */
146 };
147 typedef struct yyStackEntry yyStackEntry;
148 
149 /* The state of the parser is completely contained in an instance of
150 ** the following structure */
151 struct yyParser {
152   int yyidx;                    /* Index of top element in stack */
153   int yyerrcnt;                 /* Shifts left before out of the error */
154   ParseARG_SDECL                /* A place to hold %extra_argument */
155   yyStackEntry yystack[YYSTACKDEPTH];  /* The parser's stack */
156 };
157 typedef struct yyParser yyParser;
158 
159 #ifndef NDEBUG
160 #include <stdio.h>
161 static FILE *yyTraceFILE = 0;
162 static char *yyTracePrompt = 0;
163 #endif /* NDEBUG */
164 
165 #ifndef NDEBUG
166 /*
167 ** Turn parser tracing on by giving a stream to which to write the trace
168 ** and a prompt to preface each trace message.  Tracing is turned off
169 ** by making either argument NULL
170 **
171 ** Inputs:
172 ** <ul>
173 ** <li> A FILE* to which trace output should be written.
174 **      If NULL, then tracing is turned off.
175 ** <li> A prefix string written at the beginning of every
176 **      line of trace output.  If NULL, then tracing is
177 **      turned off.
178 ** </ul>
179 **
180 ** Outputs:
181 ** None.
182 */
ParseTrace(FILE * TraceFILE,char * zTracePrompt)183 void ParseTrace(FILE *TraceFILE, char *zTracePrompt){
184   yyTraceFILE = TraceFILE;
185   yyTracePrompt = zTracePrompt;
186   if( yyTraceFILE==0 ) yyTracePrompt = 0;
187   else if( yyTracePrompt==0 ) yyTraceFILE = 0;
188 }
189 #endif /* NDEBUG */
190 
191 #ifndef NDEBUG
192 /* For tracing shifts, the names of all terminals and nonterminals
193 ** are required.  The following table supplies these names */
194 static const char *yyTokenName[] = {
195 %%
196 };
197 #endif /* NDEBUG */
198 
199 #ifndef NDEBUG
200 /* For tracing reduce actions, the names of all rules are required.
201 */
202 static const char *yyRuleName[] = {
203 %%
204 };
205 #endif /* NDEBUG */
206 
207 /*
208 ** This function returns the symbolic name associated with a token
209 ** value.
210 */
ParseTokenName(int tokenType)211 const char *ParseTokenName(int tokenType){
212 #ifndef NDEBUG
213   if( tokenType>0 && tokenType<(sizeof(yyTokenName)/sizeof(yyTokenName[0])) ){
214     return yyTokenName[tokenType];
215   }else{
216     return "Unknown";
217   }
218 #else
219   return "";
220 #endif
221 }
222 
223 /*
224 ** This function allocates a new parser.
225 ** The only argument is a pointer to a function which works like
226 ** malloc.
227 **
228 ** Inputs:
229 ** A pointer to the function used to allocate memory.
230 **
231 ** Outputs:
232 ** A pointer to a parser.  This pointer is used in subsequent calls
233 ** to Parse and ParseFree.
234 */
ParseAlloc(void * (* mallocProc)(size_t))235 void *ParseAlloc(void *(*mallocProc)(size_t)){
236   yyParser *pParser;
237   pParser = (yyParser*)(*mallocProc)( (size_t)sizeof(yyParser) );
238   if( pParser ){
239     pParser->yyidx = -1;
240   }
241   return pParser;
242 }
243 
244 /* The following function deletes the value associated with a
245 ** symbol.  The symbol can be either a terminal or nonterminal.
246 ** "yymajor" is the symbol code, and "yypminor" is a pointer to
247 ** the value.
248 */
yy_destructor(YYCODETYPE yymajor,YYMINORTYPE * yypminor)249 static void yy_destructor(YYCODETYPE yymajor, YYMINORTYPE *yypminor){
250   switch( yymajor ){
251     /* Here is inserted the actions which take place when a
252     ** terminal or non-terminal is destroyed.  This can happen
253     ** when the symbol is popped from the stack during a
254     ** reduce or during error processing or when a parser is
255     ** being destroyed before it is finished parsing.
256     **
257     ** Note: during a reduce, the only symbols destroyed are those
258     ** which appear on the RHS of the rule, but which are not used
259     ** inside the C code.
260     */
261 %%
262     default:  break;   /* If no destructor action specified: do nothing */
263   }
264 }
265 
266 /*
267 ** Pop the parser's stack once.
268 **
269 ** If there is a destructor routine associated with the token which
270 ** is popped from the stack, then call it.
271 **
272 ** Return the major token number for the symbol popped.
273 */
yy_pop_parser_stack(yyParser * pParser)274 static int yy_pop_parser_stack(yyParser *pParser){
275   YYCODETYPE yymajor;
276   yyStackEntry *yytos = &pParser->yystack[pParser->yyidx];
277 
278   if( pParser->yyidx<0 ) return 0;
279 #ifndef NDEBUG
280   if( yyTraceFILE && pParser->yyidx>=0 ){
281     fprintf(yyTraceFILE,"%sPopping %s\n",
282       yyTracePrompt,
283       yyTokenName[yytos->major]);
284   }
285 #endif
286   yymajor = yytos->major;
287   yy_destructor( yymajor, &yytos->minor);
288   pParser->yyidx--;
289   return yymajor;
290 }
291 
292 /*
293 ** Deallocate and destroy a parser.  Destructors are all called for
294 ** all stack elements before shutting the parser down.
295 **
296 ** Inputs:
297 ** <ul>
298 ** <li>  A pointer to the parser.  This should be a pointer
299 **       obtained from ParseAlloc.
300 ** <li>  A pointer to a function used to reclaim memory obtained
301 **       from malloc.
302 ** </ul>
303 */
ParseFree(void * p,void (* freeProc)(void *))304 void ParseFree(
305   void *p,                    /* The parser to be deleted */
306   void (*freeProc)(void*)     /* Function used to reclaim memory */
307 ){
308   yyParser *pParser = (yyParser*)p;
309   if( pParser==0 ) return;
310   while( pParser->yyidx>=0 ) yy_pop_parser_stack(pParser);
311   (*freeProc)((void*)pParser);
312 }
313 
314 /*
315 ** Find the appropriate action for a parser given the terminal
316 ** look-ahead token iLookAhead.
317 **
318 ** If the look-ahead token is YYNOCODE, then check to see if the action is
319 ** independent of the look-ahead.  If it is, return the action, otherwise
320 ** return YY_NO_ACTION.
321 */
yy_find_shift_action(yyParser * pParser,int iLookAhead)322 static int yy_find_shift_action(
323   yyParser *pParser,        /* The parser */
324   int iLookAhead            /* The look-ahead token */
325 ){
326   int i;
327   int stateno = pParser->yystack[pParser->yyidx].stateno;
328 
329   /* if( pParser->yyidx<0 ) return YY_NO_ACTION;  */
330   i = yy_shift_ofst[stateno];
331   if( i==YY_SHIFT_USE_DFLT ){
332     return yy_default[stateno];
333   }
334   if( iLookAhead==YYNOCODE ){
335     return YY_NO_ACTION;
336   }
337   i += iLookAhead;
338   if( i<0 || i>=YY_SZ_ACTTAB || yy_lookahead[i]!=iLookAhead ){
339 #ifdef YYFALLBACK
340     int iFallback;            /* Fallback token */
341     if( iLookAhead<sizeof(yyFallback)/sizeof(yyFallback[0])
342            && (iFallback = yyFallback[iLookAhead])!=0 ){
343 #ifndef NDEBUG
344       if( yyTraceFILE ){
345         fprintf(yyTraceFILE, "%sFALLBACK %s => %s\n",
346            yyTracePrompt, yyTokenName[iLookAhead], yyTokenName[iFallback]);
347       }
348 #endif
349       return yy_find_shift_action(pParser, iFallback);
350     }
351 #endif
352     return yy_default[stateno];
353   }else{
354     return yy_action[i];
355   }
356 }
357 
358 /*
359 ** Find the appropriate action for a parser given the non-terminal
360 ** look-ahead token iLookAhead.
361 **
362 ** If the look-ahead token is YYNOCODE, then check to see if the action is
363 ** independent of the look-ahead.  If it is, return the action, otherwise
364 ** return YY_NO_ACTION.
365 */
yy_find_reduce_action(yyParser * pParser,int iLookAhead)366 static int yy_find_reduce_action(
367   yyParser *pParser,        /* The parser */
368   int iLookAhead            /* The look-ahead token */
369 ){
370   int i;
371   int stateno = pParser->yystack[pParser->yyidx].stateno;
372 
373   i = yy_reduce_ofst[stateno];
374   if( i==YY_REDUCE_USE_DFLT ){
375     return yy_default[stateno];
376   }
377   if( iLookAhead==YYNOCODE ){
378     return YY_NO_ACTION;
379   }
380   i += iLookAhead;
381   if( i<0 || i>=YY_SZ_ACTTAB || yy_lookahead[i]!=iLookAhead ){
382     return yy_default[stateno];
383   }else{
384     return yy_action[i];
385   }
386 }
387 
388 /*
389 ** Perform a shift action.
390 */
yy_shift(yyParser * yypParser,int yyNewState,int yyMajor,YYMINORTYPE * yypMinor)391 static void yy_shift(
392   yyParser *yypParser,          /* The parser to be shifted */
393   int yyNewState,               /* The new state to shift in */
394   int yyMajor,                  /* The major token to shift in */
395   YYMINORTYPE *yypMinor         /* Pointer ot the minor token to shift in */
396 ){
397   yyStackEntry *yytos;
398   yypParser->yyidx++;
399   if( yypParser->yyidx>=YYSTACKDEPTH ){
400      ParseARG_FETCH;
401      yypParser->yyidx--;
402 #ifndef NDEBUG
403      if( yyTraceFILE ){
404        fprintf(yyTraceFILE,"%sStack Overflow!\n",yyTracePrompt);
405      }
406 #endif
407      while( yypParser->yyidx>=0 ) yy_pop_parser_stack(yypParser);
408      /* Here code is inserted which will execute if the parser
409      ** stack every overflows */
410 %%
411      ParseARG_STORE; /* Suppress warning about unused %extra_argument var */
412      return;
413   }
414   yytos = &yypParser->yystack[yypParser->yyidx];
415   yytos->stateno = yyNewState;
416   yytos->major = yyMajor;
417   yytos->minor = *yypMinor;
418 #ifndef NDEBUG
419   if( yyTraceFILE && yypParser->yyidx>0 ){
420     int i;
421     fprintf(yyTraceFILE,"%sShift %d\n",yyTracePrompt,yyNewState);
422     fprintf(yyTraceFILE,"%sStack:",yyTracePrompt);
423     for(i=1; i<=yypParser->yyidx; i++)
424       fprintf(yyTraceFILE," %s",yyTokenName[yypParser->yystack[i].major]);
425     fprintf(yyTraceFILE,"\n");
426   }
427 #endif
428 }
429 
430 /* The following table contains information about every rule that
431 ** is used during the reduce.
432 */
433 static struct {
434   YYCODETYPE lhs;         /* Symbol on the left-hand side of the rule */
435   unsigned char nrhs;     /* Number of right-hand side symbols in the rule */
436 } yyRuleInfo[] = {
437 %%
438 };
439 
440 static void yy_accept(yyParser*);  /* Forward Declaration */
441 
442 /*
443 ** Perform a reduce action and the shift that must immediately
444 ** follow the reduce.
445 */
yy_reduce(yyParser * yypParser,int yyruleno)446 static void yy_reduce(
447   yyParser *yypParser,         /* The parser */
448   int yyruleno                 /* Number of the rule by which to reduce */
449 ){
450   int yygoto;                     /* The next state */
451   int yyact;                      /* The next action */
452   YYMINORTYPE yygotominor;        /* The LHS of the rule reduced */
453   yyStackEntry *yymsp;            /* The top of the parser's stack */
454   int yysize;                     /* Amount to pop the stack */
455   ParseARG_FETCH;
456   yymsp = &yypParser->yystack[yypParser->yyidx];
457 #ifndef NDEBUG
458   if( yyTraceFILE && yyruleno>=0
459         && yyruleno<sizeof(yyRuleName)/sizeof(yyRuleName[0]) ){
460     fprintf(yyTraceFILE, "%sReduce [%s].\n", yyTracePrompt,
461       yyRuleName[yyruleno]);
462   }
463 #endif /* NDEBUG */
464 
465   switch( yyruleno ){
466   /* Beginning here are the reduction cases.  A typical example
467   ** follows:
468   **   case 0:
469   **  #line <lineno> <grammarfile>
470   **     { ... }           // User supplied code
471   **  #line <lineno> <thisfile>
472   **     break;
473   */
474 %%
475   };
476   yygoto = yyRuleInfo[yyruleno].lhs;
477   yysize = yyRuleInfo[yyruleno].nrhs;
478   yypParser->yyidx -= yysize;
479   yyact = yy_find_reduce_action(yypParser,yygoto);
480   if( yyact < YYNSTATE ){
481     yy_shift(yypParser,yyact,yygoto,&yygotominor);
482   }else if( yyact == YYNSTATE + YYNRULE + 1 ){
483     yy_accept(yypParser);
484   }
485 }
486 
487 /*
488 ** The following code executes when the parse fails
489 */
yy_parse_failed(yyParser * yypParser)490 static void yy_parse_failed(
491   yyParser *yypParser           /* The parser */
492 ){
493   ParseARG_FETCH;
494 #ifndef NDEBUG
495   if( yyTraceFILE ){
496     fprintf(yyTraceFILE,"%sFail!\n",yyTracePrompt);
497   }
498 #endif
499   while( yypParser->yyidx>=0 ) yy_pop_parser_stack(yypParser);
500   /* Here code is inserted which will be executed whenever the
501   ** parser fails */
502 %%
503   ParseARG_STORE; /* Suppress warning about unused %extra_argument variable */
504 }
505 
506 /*
507 ** The following code executes when a syntax error first occurs.
508 */
yy_syntax_error(yyParser * yypParser,int yymajor,YYMINORTYPE yyminor)509 static void yy_syntax_error(
510   yyParser *yypParser,           /* The parser */
511   int yymajor,                   /* The major type of the error token */
512   YYMINORTYPE yyminor            /* The minor type of the error token */
513 ){
514   ParseARG_FETCH;
515 #define TOKEN (yyminor.yy0)
516 %%
517   ParseARG_STORE; /* Suppress warning about unused %extra_argument variable */
518 }
519 
520 /*
521 ** The following is executed when the parser accepts
522 */
yy_accept(yyParser * yypParser)523 static void yy_accept(
524   yyParser *yypParser           /* The parser */
525 ){
526   ParseARG_FETCH;
527 #ifndef NDEBUG
528   if( yyTraceFILE ){
529     fprintf(yyTraceFILE,"%sAccept!\n",yyTracePrompt);
530   }
531 #endif
532   while( yypParser->yyidx>=0 ) yy_pop_parser_stack(yypParser);
533   /* Here code is inserted which will be executed whenever the
534   ** parser accepts */
535 %%
536   ParseARG_STORE; /* Suppress warning about unused %extra_argument variable */
537 }
538 
539 /* The main parser program.
540 ** The first argument is a pointer to a structure obtained from
541 ** "ParseAlloc" which describes the current state of the parser.
542 ** The second argument is the major token number.  The third is
543 ** the minor token.  The fourth optional argument is whatever the
544 ** user wants (and specified in the grammar) and is available for
545 ** use by the action routines.
546 **
547 ** Inputs:
548 ** <ul>
549 ** <li> A pointer to the parser (an opaque structure.)
550 ** <li> The major token number.
551 ** <li> The minor token number.
552 ** <li> An option argument of a grammar-specified type.
553 ** </ul>
554 **
555 ** Outputs:
556 ** None.
557 */
Parse(void * yyp,int yymajor,ParseTOKENTYPE yyminor ParseARG_PDECL)558 void Parse(
559   void *yyp,                   /* The parser */
560   int yymajor,                 /* The major token code number */
561   ParseTOKENTYPE yyminor       /* The value for the token */
562   ParseARG_PDECL               /* Optional %extra_argument parameter */
563 ){
564   YYMINORTYPE yyminorunion;
565   int yyact;            /* The parser action. */
566   int yyendofinput;     /* True if we are at the end of input */
567   int yyerrorhit = 0;   /* True if yymajor has invoked an error */
568   yyParser *yypParser;  /* The parser */
569 
570   /* (re)initialize the parser, if necessary */
571   yypParser = (yyParser*)yyp;
572   if( yypParser->yyidx<0 ){
573     if( yymajor==0 ) return;
574     yypParser->yyidx = 0;
575     yypParser->yyerrcnt = -1;
576     yypParser->yystack[0].stateno = 0;
577     yypParser->yystack[0].major = 0;
578   }
579   yyminorunion.yy0 = yyminor;
580   yyendofinput = (yymajor==0);
581   ParseARG_STORE;
582 
583 #ifndef NDEBUG
584   if( yyTraceFILE ){
585     fprintf(yyTraceFILE,"%sInput %s\n",yyTracePrompt,yyTokenName[yymajor]);
586   }
587 #endif
588 
589   do{
590     yyact = yy_find_shift_action(yypParser,yymajor);
591     if( yyact<YYNSTATE ){
592       yy_shift(yypParser,yyact,yymajor,&yyminorunion);
593       yypParser->yyerrcnt--;
594       if( yyendofinput && yypParser->yyidx>=0 ){
595         yymajor = 0;
596       }else{
597         yymajor = YYNOCODE;
598       }
599     }else if( yyact < YYNSTATE + YYNRULE ){
600       yy_reduce(yypParser,yyact-YYNSTATE);
601     }else if( yyact == YY_ERROR_ACTION ){
602       int yymx;
603 #ifndef NDEBUG
604       if( yyTraceFILE ){
605         fprintf(yyTraceFILE,"%sSyntax Error!\n",yyTracePrompt);
606       }
607 #endif
608 #ifdef YYERRORSYMBOL
609       /* A syntax error has occurred.
610       ** The response to an error depends upon whether or not the
611       ** grammar defines an error token "ERROR".
612       **
613       ** This is what we do if the grammar does define ERROR:
614       **
615       **  * Call the %syntax_error function.
616       **
617       **  * Begin popping the stack until we enter a state where
618       **    it is legal to shift the error symbol, then shift
619       **    the error symbol.
620       **
621       **  * Set the error count to three.
622       **
623       **  * Begin accepting and shifting new tokens.  No new error
624       **    processing will occur until three tokens have been
625       **    shifted successfully.
626       **
627       */
628       if( yypParser->yyerrcnt<0 ){
629         yy_syntax_error(yypParser,yymajor,yyminorunion);
630       }
631       yymx = yypParser->yystack[yypParser->yyidx].major;
632       if( yymx==YYERRORSYMBOL || yyerrorhit ){
633 #ifndef NDEBUG
634         if( yyTraceFILE ){
635           fprintf(yyTraceFILE,"%sDiscard input token %s\n",
636              yyTracePrompt,yyTokenName[yymajor]);
637         }
638 #endif
639         yy_destructor(yymajor,&yyminorunion);
640         yymajor = YYNOCODE;
641       }else{
642          while(
643           yypParser->yyidx >= 0 &&
644           yymx != YYERRORSYMBOL &&
645           (yyact = yy_find_shift_action(yypParser,YYERRORSYMBOL)) >= YYNSTATE
646         ){
647           yy_pop_parser_stack(yypParser);
648         }
649         if( yypParser->yyidx < 0 || yymajor==0 ){
650           yy_destructor(yymajor,&yyminorunion);
651           yy_parse_failed(yypParser);
652           yymajor = YYNOCODE;
653         }else if( yymx!=YYERRORSYMBOL ){
654           YYMINORTYPE u2;
655           u2.YYERRSYMDT = 0;
656           yy_shift(yypParser,yyact,YYERRORSYMBOL,&u2);
657         }
658       }
659       yypParser->yyerrcnt = 3;
660       yyerrorhit = 1;
661 #else  /* YYERRORSYMBOL is not defined */
662       /* This is what we do if the grammar does not define ERROR:
663       **
664       **  * Report an error message, and throw away the input token.
665       **
666       **  * If the input token is $, then fail the parse.
667       **
668       ** As before, subsequent error messages are suppressed until
669       ** three input tokens have been successfully shifted.
670       */
671       if( yypParser->yyerrcnt<=0 ){
672         yy_syntax_error(yypParser,yymajor,yyminorunion);
673       }
674       yypParser->yyerrcnt = 3;
675       yy_destructor(yymajor,&yyminorunion);
676       if( yyendofinput ){
677         yy_parse_failed(yypParser);
678       }
679       yymajor = YYNOCODE;
680 #endif
681     }else{
682       yy_accept(yypParser);
683       yymajor = YYNOCODE;
684     }
685   }while( yymajor!=YYNOCODE && yypParser->yyidx>=0 );
686   return;
687 }
688