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Overview
| Comment: | In the LEMON-generated parser, avoid unnecessary tests for the acceptance state. |
|---|---|
| Downloads: | Tarball | ZIP archive |
| Timelines: | family | ancestors | descendants | both | lemon-improvements |
| Files: | files | file ages | folders |
| SHA3-256: |
fdbb35c54f2b6cb65d04ac295f207ff3 |
| User & Date: | drh 2017-12-25 00:10:05.418 |
Context
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2017-12-25
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| 04:15 | Enhance LEMON so that it generates the action table in such a way that no range check is needed on the lookahead table to verify that the next input token is valid. This makes the lookahead table slightly larger (about 120 bytes) but helps the parser to run faster. (check-in: 7eb0198d01 user: drh tags: lemon-improvements) | |
| 00:10 | In the LEMON-generated parser, avoid unnecessary tests for the acceptance state. (check-in: fdbb35c54f user: drh tags: lemon-improvements) | |
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2017-12-24
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| 23:38 | In the LEMON-generated parser, rearrange the meanings of integer action codes so that reduce actions occur last. This means that the most common case (reduce actions) can be recognized with a single comparison operation, thus speeding up the main parser loop, slightly. (check-in: 7bfe7a3602 user: drh tags: lemon-improvements) | |
Changes
Changes to tool/lempar.c.
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static unsigned int yy_find_shift_action(
yyParser *pParser, /* The parser */
YYCODETYPE iLookAhead /* The look-ahead token */
){
int i;
int stateno = pParser->yytos->stateno;
| | | 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 |
static unsigned int yy_find_shift_action(
yyParser *pParser, /* The parser */
YYCODETYPE iLookAhead /* The look-ahead token */
){
int i;
int stateno = pParser->yytos->stateno;
if( stateno>YY_MAX_SHIFT ) return stateno;
assert( stateno <= YY_SHIFT_COUNT );
do{
i = yy_shift_ofst[stateno];
assert( iLookAhead!=YYNOCODE );
i += iLookAhead;
if( i<0 || i>=YY_ACTTAB_COUNT || yy_lookahead[i]!=iLookAhead ){
#ifdef YYFALLBACK
|
| ︙ | ︙ | |||
732 733 734 735 736 737 738 | /* There are no SHIFTREDUCE actions on nonterminals because the table ** generator has simplified them to pure REDUCE actions. */ assert( !(yyact>YY_MAX_SHIFT && yyact<=YY_MAX_SHIFTREDUCE) ); /* It is not possible for a REDUCE to be followed by an error */ assert( yyact!=YY_ERROR_ACTION ); | < < < < | | | | | < | 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 | /* There are no SHIFTREDUCE actions on nonterminals because the table ** generator has simplified them to pure REDUCE actions. */ assert( !(yyact>YY_MAX_SHIFT && yyact<=YY_MAX_SHIFTREDUCE) ); /* It is not possible for a REDUCE to be followed by an error */ assert( yyact!=YY_ERROR_ACTION ); yymsp += yysize+1; yypParser->yytos = yymsp; yymsp->stateno = (YYACTIONTYPE)yyact; yymsp->major = (YYCODETYPE)yygoto; yyTraceShift(yypParser, yyact, "... then shift"); } /* ** The following code executes when the parse fails */ #ifndef YYNOERRORRECOVERY static void yy_parse_failed( |
| ︙ | ︙ | |||
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yy_reduce(yypParser,yyact-YY_MIN_REDUCE,yymajor,yyminor);
}else if( yyact <= YY_MAX_SHIFTREDUCE ){
yy_shift(yypParser,yyact,yymajor,yyminor);
#ifndef YYNOERRORRECOVERY
yypParser->yyerrcnt--;
#endif
yymajor = YYNOCODE;
}else{
assert( yyact == YY_ERROR_ACTION );
yyminorunion.yy0 = yyminor;
#ifdef YYERRORSYMBOL
int yymx;
#endif
#ifndef NDEBUG
| > > > > | 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 |
yy_reduce(yypParser,yyact-YY_MIN_REDUCE,yymajor,yyminor);
}else if( yyact <= YY_MAX_SHIFTREDUCE ){
yy_shift(yypParser,yyact,yymajor,yyminor);
#ifndef YYNOERRORRECOVERY
yypParser->yyerrcnt--;
#endif
yymajor = YYNOCODE;
}else if( yyact==YY_ACCEPT_ACTION ){
yypParser->yytos--;
yy_accept(yypParser);
return;
}else{
assert( yyact == YY_ERROR_ACTION );
yyminorunion.yy0 = yyminor;
#ifdef YYERRORSYMBOL
int yymx;
#endif
#ifndef NDEBUG
|
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