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Overview
| Comment: | In the lemon-generated parser, automatically promote SHIFTREDUCE actions on nonterminal systems to pure REDUCE actions, for a performance enhancement. |
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| Downloads: | Tarball | ZIP archive | SQL archive |
| Timelines: | family | ancestors | descendants | both | trunk |
| Files: | files | file ages | folders |
| SHA3-256: |
c46d94a8cde816ca383e771721ebd490 |
| User & Date: | drh 2017-06-28 11:56:18 |
Context
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2017-06-28
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| 13:47 | In the lemon-generated parser, store the number of symbols on the RHS of each rule as a negative number and add it to the stack pointer, rather than storing the value as a positive and subtracting it. This makes the parser faster. (check-in: b362f0d8 user: drh tags: trunk) | |
| 11:56 | In the lemon-generated parser, automatically promote SHIFTREDUCE actions on nonterminal systems to pure REDUCE actions, for a performance enhancement. (check-in: c46d94a8 user: drh tags: trunk) | |
| 01:21 | Simplify error handling logic in sqlite3_exec() to save about 40 bytes. (check-in: 6480916c user: drh tags: trunk) | |
Changes
Changes to tool/lemon.c.
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** Return negative if no action should be generated.
*/
PRIVATE int compute_action(struct lemon *lemp, struct action *ap)
{
int act;
switch( ap->type ){
case SHIFT: act = ap->x.stp->statenum; break;
case SHIFTREDUCE: act = ap->x.rp->iRule + lemp->nstate; break;
case REDUCE: act = ap->x.rp->iRule + lemp->nstate+lemp->nrule; break;
case ERROR: act = lemp->nstate + lemp->nrule*2; break;
case ACCEPT: act = lemp->nstate + lemp->nrule*2 + 1; break;
default: act = -1; break;
}
return act;
}
|
> | > > > > > > |
3293 3294 3295 3296 3297 3298 3299 3300 3301 3302 3303 3304 3305 3306 3307 3308 3309 3310 3311 3312 3313 3314 |
** Return negative if no action should be generated.
*/
PRIVATE int compute_action(struct lemon *lemp, struct action *ap)
{
int act;
switch( ap->type ){
case SHIFT: act = ap->x.stp->statenum; break;
case SHIFTREDUCE: {
act = ap->x.rp->iRule + lemp->nstate;
/* Since a SHIFT is inherient after a prior REDUCE, convert any
** SHIFTREDUCE action with a nonterminal on the LHS into a simple
** REDUCE action: */
if( ap->sp->index>=lemp->nterminal ) act += lemp->nrule;
break;
}
case REDUCE: act = ap->x.rp->iRule + lemp->nstate+lemp->nrule; break;
case ERROR: act = lemp->nstate + lemp->nrule*2; break;
case ACCEPT: act = lemp->nstate + lemp->nrule*2 + 1; break;
default: act = -1; break;
}
return act;
}
|
Changes to tool/lempar.c.
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%% /********** End reduce actions ************************************************/ }; assert( yyruleno<sizeof(yyRuleInfo)/sizeof(yyRuleInfo[0]) ); yygoto = yyRuleInfo[yyruleno].lhs; yysize = yyRuleInfo[yyruleno].nrhs; yyact = yy_find_reduce_action(yymsp[-yysize].stateno,(YYCODETYPE)yygoto); if( yyact <= YY_MAX_SHIFTREDUCE ){ if( yyact>YY_MAX_SHIFT ){ yyact += YY_MIN_REDUCE - YY_MIN_SHIFTREDUCE; } yymsp -= yysize-1; yypParser->yytos = yymsp; yymsp->stateno = (YYACTIONTYPE)yyact; yymsp->major = (YYCODETYPE)yygoto; yyTraceShift(yypParser, yyact); }else{ assert( yyact == YY_ACCEPT_ACTION ); yypParser->yytos -= yysize; yy_accept(yypParser); } } /* ** The following code executes when the parse fails */ #ifndef YYNOERRORRECOVERY |
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%% /********** End reduce actions ************************************************/ }; assert( yyruleno<sizeof(yyRuleInfo)/sizeof(yyRuleInfo[0]) ); yygoto = yyRuleInfo[yyruleno].lhs; yysize = yyRuleInfo[yyruleno].nrhs; yyact = yy_find_reduce_action(yymsp[-yysize].stateno,(YYCODETYPE)yygoto); /* 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 ); if( yyact==YY_ACCEPT_ACTION ){ yypParser->yytos -= yysize; yy_accept(yypParser); }else{ yymsp -= yysize-1; yypParser->yytos = yymsp; yymsp->stateno = (YYACTIONTYPE)yyact; yymsp->major = (YYCODETYPE)yygoto; yyTraceShift(yypParser, yyact); } } /* ** The following code executes when the parse fails */ #ifndef YYNOERRORRECOVERY |