Introduce the concept of "weak fallback" in the parser. A weak fallback
only occurs if a syntax error would result otherwise. FossilOrigin-Name: c41d7079fb63831bd2f009b64cbf5a423e8119e6b841bfd9bd5a2d85fba3b142
This commit is contained in:
drh
parent
01e1229063
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manifest
21
manifest
@ -1,5 +1,5 @@
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C Add\smissing\sVdbeCoverage()\sand\sVdbeCoverageNeverTaken()\smacros\sto\swindow.c.
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D 2018-06-27T20:24:59.489
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C Introduce\sthe\sconcept\sof\s"weak\sfallback"\sin\sthe\sparser.\s\sA\sweak\sfallback\nonly\soccurs\sif\sa\ssyntax\serror\swould\sresult\sotherwise.
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D 2018-06-28T03:38:49.164
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F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
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F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
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F Makefile.in 0a3a6c81e6fcb969ff9106e882f0a08547014ba463cb6beca4c4efaecc924ee6
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@ -484,7 +484,7 @@ F src/os_win.c ac29c25cde4cfb4adacc59cdec4aa45698ca0e29164ea127859585ccd9faa354
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F src/os_win.h 7b073010f1451abe501be30d12f6bc599824944a
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F src/pager.c 1bb6a57fa0465296a4d6109a1a64610a0e7adde1f3acf3ef539a9d972908ce8f
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F src/pager.h c571b064df842ec8f2e90855dead9acf4cbe0d1b2c05afe0ef0d0145f7fd0388
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F src/parse.y 4661ac1382c18bc67e1680ea3e44a6835ebc770667fe32ee1720c38454304165
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F src/parse.y 9517b50d35e5e495a241541b49f5512b8e9bcbac3fbfdc659215555efa5c4f40
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F src/pcache.c 135ef0bc6fb2e3b7178d49ab5c9176254c8a691832c1bceb1156b2fbdd0869bd
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F src/pcache.h 072f94d29281cffd99e46c1539849f248c4b56ae7684c1f36626797fee375170
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F src/pcache1.c 716975564c15eb6679e97f734cec1bfd6c16ac3d4010f05f1f8e509fc7d19880
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@ -1662,8 +1662,8 @@ F tool/genfkey.README cf68fddd4643bbe3ff8e31b8b6d8b0a1b85e20f4
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F tool/genfkey.test 4196a8928b78f51d54ef58e99e99401ab2f0a7e5
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F tool/getlock.c f4c39b651370156cae979501a7b156bdba50e7ce
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F tool/kvtest-speed.sh 4761a9c4b3530907562314d7757995787f7aef8f
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F tool/lemon.c 33892e2a243865f73e6c6e7cecce3c6eb4bb95db4a3d9d86d146c8064feb92fd
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F tool/lempar.c bf7db78e7213f1d51516710483eab506fd52bf632c7abfb3e2e9b885c90c03e1
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F tool/lemon.c 93a321bd82b5c73191e95b2f27203048bf4d054fdab4a257b7a6c9541f31828d
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F tool/lempar.c c7371bad027fd516b7eaed36d03353972df35163672637cddd00f472889932f9
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F tool/libvers.c caafc3b689638a1d88d44bc5f526c2278760d9b9
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F tool/loadfts.c c3c64e4d5e90e8ba41159232c2189dba4be7b862
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F tool/logest.c 11346aa019e2e77a00902aa7d0cabd27bd2e8cca
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@ -1743,7 +1743,10 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
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F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
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F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
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F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
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P 336de43a47e206fe7629072e5b8c80d4ede17ead8ef4dcf5d8da6833ff22d2f9
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R b7bd98ed0e43c8f2d4cb4f0d7b13d574
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U dan
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Z 38db85555459c758350756078d19d70e
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P 4383cb68a1241768ddb3f180f8cbb9ea1638f8806210b10aac1384b8a7ecdca2
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R 341c5aa0d73cc2ef03cecacf95853224
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T *branch * weak-fallback
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T *sym-weak-fallback *
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T -sym-exp-window-functions *
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U drh
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Z 196c50a9819aa6d1d98f4a403b164e6b
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@ -1 +1 @@
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4383cb68a1241768ddb3f180f8cbb9ea1638f8806210b10aac1384b8a7ecdca2
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c41d7079fb63831bd2f009b64cbf5a423e8119e6b841bfd9bd5a2d85fba3b142
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@ -216,6 +216,10 @@ columnname(A) ::= nm(A) typetoken(Y). {sqlite3AddColumn(pParse,&A,&Y);}
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%ifdef SQLITE_OMIT_COMPOUND_SELECT
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EXCEPT INTERSECT UNION
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%endif SQLITE_OMIT_COMPOUND_SELECT
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%ifndef SQLITE_OMIT_WINDOWFUNC
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CURRENT FILTER FOLLOWING ?OVER PARTITION
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PRECEDING RANGE UNBOUNDED ?WINDOW
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%endif SQLITE_OMIT_WINDOWFUNC
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REINDEX RENAME CTIME_KW IF
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.
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%wildcard ANY.
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21
tool/lemon.c
21
tool/lemon.c
@ -272,6 +272,7 @@ struct symbol {
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** union is the correct data type for this object */
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int bContent; /* True if this symbol ever carries content - if
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** it is ever more than just syntax */
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int bWeakFallback; /* True for a weak fallback */
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/* The following fields are used by MULTITERMINALs only */
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int nsubsym; /* Number of constituent symbols in the MULTI */
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struct symbol **subsym; /* Array of constituent symbols */
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@ -2209,6 +2210,7 @@ enum e_state {
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WAITING_FOR_DESTRUCTOR_SYMBOL,
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WAITING_FOR_DATATYPE_SYMBOL,
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WAITING_FOR_FALLBACK_ID,
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WAITING_FOR_WEAK_FALLBACK_ID,
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WAITING_FOR_WILDCARD_ID,
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WAITING_FOR_CLASS_ID,
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WAITING_FOR_CLASS_TOKEN,
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@ -2667,6 +2669,12 @@ to follow the previous rule.");
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}
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break;
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case WAITING_FOR_FALLBACK_ID:
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if( x[0]=='?' ){
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psp->state = WAITING_FOR_WEAK_FALLBACK_ID;
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break;
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}
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/* Fall through */
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case WAITING_FOR_WEAK_FALLBACK_ID:
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if( x[0]=='.' ){
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psp->state = WAITING_FOR_DECL_OR_RULE;
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}else if( !ISUPPER(x[0]) ){
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@ -2683,6 +2691,8 @@ to follow the previous rule.");
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psp->errorcnt++;
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}else{
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sp->fallback = psp->fallback;
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sp->bWeakFallback = (psp->state==WAITING_FOR_WEAK_FALLBACK_ID);
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psp->state = WAITING_FOR_FALLBACK_ID;
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psp->gp->has_fallback = 1;
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}
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}
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@ -4493,6 +4503,9 @@ void ReportTable(
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struct symbol *p = lemp->symbols[i];
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if( p->fallback==0 ){
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fprintf(out, " 0, /* %10s => nothing */\n", p->name);
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}else if( p->bWeakFallback ){
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fprintf(out, " %4d, /* %10s => %s (weak) */\n",
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-p->fallback->index, p->name, p->fallback->name);
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}else{
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fprintf(out, " %3d, /* %10s => %s */\n", p->fallback->index,
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p->name, p->fallback->name);
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@ -5112,18 +5125,12 @@ struct symbol *Symbol_new(const char *x)
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if( sp==0 ){
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sp = (struct symbol *)calloc(1, sizeof(struct symbol) );
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MemoryCheck(sp);
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memset(sp, 0, sizeof(*sp));
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sp->name = Strsafe(x);
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sp->type = ISUPPER(*x) ? TERMINAL : NONTERMINAL;
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sp->rule = 0;
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sp->fallback = 0;
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sp->prec = -1;
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sp->assoc = UNK;
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sp->firstset = 0;
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sp->lambda = LEMON_FALSE;
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sp->destructor = 0;
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sp->destLineno = 0;
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sp->datatype = 0;
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sp->useCnt = 0;
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Symbol_insert(sp,sp->name);
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}
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sp->useCnt++;
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@ -90,6 +90,7 @@
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/************* Begin control #defines *****************************************/
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%%
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/************* End control #defines *******************************************/
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#define YY_NLOOKAHEAD ((int)(sizeof(yy_lookahead)/sizeof(yy_lookahead[0])))
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/* Define the yytestcase() macro to be a no-op if is not already defined
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** otherwise.
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@ -172,7 +173,7 @@
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** it appears.
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*/
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#ifdef YYFALLBACK
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static const YYCODETYPE yyFallback[] = {
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static const int yyFallback[] = {
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%%
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};
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#endif /* YYFALLBACK */
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@ -519,24 +520,34 @@ static YYACTIONTYPE yy_find_shift_action(
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do{
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i = yy_shift_ofst[stateno];
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assert( i>=0 );
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assert( i+YYNTOKEN<=(int)sizeof(yy_lookahead)/sizeof(yy_lookahead[0]) );
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/*assert( i+YYNTOKEN<=YY_NLOOKAHEAD );*/
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assert( iLookAhead!=YYNOCODE );
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assert( iLookAhead < YYNTOKEN );
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i += iLookAhead;
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if( yy_lookahead[i]!=iLookAhead ){
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if( i>=YY_NLOOKAHEAD || yy_lookahead[i]!=iLookAhead
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){
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#ifdef YYFALLBACK
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YYCODETYPE iFallback; /* Fallback token */
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int iFallback; /* Fallback token */
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if( iLookAhead<sizeof(yyFallback)/sizeof(yyFallback[0])
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&& (iFallback = yyFallback[iLookAhead])!=0 ){
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#ifndef NDEBUG
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if( yyTraceFILE ){
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fprintf(yyTraceFILE, "%sFALLBACK %s => %s\n",
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yyTracePrompt, yyTokenName[iLookAhead], yyTokenName[iFallback]);
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&& (iFallback = yyFallback[iLookAhead])!=0
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){
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if( iFallback<0 && yy_default[stateno]==YY_ERROR_ACTION ){
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/* A weak fallback only happens if current lookahead is a
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** syntax error */
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iFallback = -iFallback;
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}
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if( iFallback>0 ){
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/* A strong fallback happens regardless */
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#ifndef NDEBUG
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if( yyTraceFILE ){
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fprintf(yyTraceFILE, "%sFALLBACK %s => %s\n",
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yyTracePrompt, yyTokenName[iLookAhead], yyTokenName[iFallback]);
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}
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#endif
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assert( yyFallback[iFallback]==0 ); /* Fallback loop must terminate */
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iLookAhead = iFallback;
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continue;
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assert( yyFallback[iFallback]==0 ); /* Fallback loop must terminate */
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iLookAhead = iFallback;
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continue;
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}
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}
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#endif
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#ifdef YYWILDCARD
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