diff options
Diffstat (limited to 'tool/lemon.c')
| -rw-r--r-- | tool/lemon.c | 28 |
1 files changed, 22 insertions, 6 deletions
diff --git a/tool/lemon.c b/tool/lemon.c index 1f81717c7..1058d14ae 100644 --- a/tool/lemon.c +++ b/tool/lemon.c @@ -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++); |