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Lemon update 2016-02-17 04:33:10 on branch parser-performance

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- Enhance Lemon so that if reduce code contains a comment of the form "/*A-overwrites-X*/" then a LHS label A is allowed to overwrite the RHS label X. (user: drh)
This commit is contained in:
Randy Heit 2016-03-20 10:57:03 -05:00
parent ab4c3a0c5e
commit 25972d79a7
1 changed files with 21 additions and 6 deletions
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15
tools/lemon/lemon.c
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@ -3412,10 +3412,12 @@ PRIVATE int translate_code(struct lemon *lemp, struct rule *rp){
char *cp, *xp;
int i;
int rc = 0; /* True if yylhsminor is used */
const char *zSkip = 0; /* The zOvwrt comment within rp->code, or NULL */
char lhsused = 0; /* True if the LHS element has been used */
char lhsdirect; /* True if LHS writes directly into stack */
char used[MAXRHS]; /* True for each RHS element which is used */
char zLhs[50]; /* Convert the LHS symbol into this string */
char zOvwrt[900]; /* Comment that to allow LHS to overwrite RHS */
for(i=0; i<rp->nrhs; i++) used[i] = 0;
lhsused = 0;
@ -3455,9 +3457,17 @@ PRIVATE int translate_code(struct lemon *lemp, struct rule *rp){
rp->lhs->name, rp->lhsalias, rp->rhs[0]->name, rp->rhsalias[0]);
lemp->errorcnt++;
}
}else{
sprintf(zOvwrt, "/*%s-overwrites-%s*/", rp->lhsalias, rp->rhsalias[0]);
zSkip = strstr(rp->code, zOvwrt);
if( zSkip!=0 ){
/* The code contains a special comment that indicates that it is safe
** for the LHS label to overwrite left-most RHS label. */
lhsdirect = 1;
}else{
lhsdirect = 0;
}
}
if( lhsdirect ){
sprintf(zLhs, "yymsp[%d].minor.yy%d",1-rp->nrhs,rp->lhs->dtnum);
}else{
@ -3469,6 +3479,11 @@ PRIVATE int translate_code(struct lemon *lemp, struct rule *rp){
/* This const cast is wrong but harmless, if we're careful. */
for(cp=(char *)rp->code; *cp; cp++){
if( cp==zSkip ){
append_str(zOvwrt,0,0,0,0);
cp += lemonStrlen(zOvwrt)-1;
continue;
}
if( ISALPHA(*cp) && (cp==rp->code || (!ISALNUM(cp[-1]) && cp[-1]!='_')) ){
char saved;
for(xp= &cp[1]; ISALNUM(*xp) || *xp=='_'; xp++);