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Enhance Lemon so that if reduce code contains a comment of the form

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"/*A-overwrites-X*/" then a LHS label A is allowed to overwrite the
RHS label X.

FossilOrigin-Name: 5cfe9545d478a2c500083613dd20e14b2ffce645
This commit is contained in:
drh
2016-02-17 04:33:10 +00:00
parent dabd04c656
commit cf82f0d3d2
4 changed files with 66 additions and 48 deletions
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28
tool/lemon.c
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@ -3476,11 +3476,13 @@ PRIVATE char *append_str(const char *zText, int n, int p1, int p2){
PRIVATE int translate_code(struct lemon *lemp, struct rule *rp){
char *cp, *xp;
int i;
int rc = 0; /* True if yylhsminor is used */
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 */
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;
@ -3522,7 +3524,16 @@ PRIVATE int translate_code(struct lemon *lemp, struct rule *rp){
lemp->errorcnt++;
}
}else{
lhsdirect = 0;
lemon_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);
@ -3535,6 +3546,11 @@ 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);
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++);