Bug fix in lemon: 3-way conflicts (SHIFT/REDUCE/REDUCE) were not detected or

resolved.  This is now fixed.  Also, table compression works a little better. (CVS 388)

FossilOrigin-Name: 8da0ac9a8bb859377613dd18f4f423eb49c7338b

manifest

@@ -1,5 +1,5 @@
-C Code\sto\simplement\sCREATE\sVIEW\sis\sin\splace.\s\sA\squick\ssmoke\stest\sshows\sthat\nit\sworks,\sbut\sthere\sare\sprobably\sstill\smany\sbugs.\s(CVS\s387)
+C Bug\sfix\sin\slemon:\s3-way\sconflicts\s(SHIFT/REDUCE/REDUCE)\swere\snot\sdetected\sor\nresolved.\s\sThis\sis\snow\sfixed.\s\sAlso,\stable\scompression\sworks\sa\slittle\sbetter.\s(CVS\s388)
-D 2002-02-23T02:32:10
+D 2002-02-23T18:45:13
 F Makefile.in 9fa4277413bf1d9cf91365f07d4108d7d87ed2af
 F Makefile.template 3372d45f8853afdb70bd30cc6fb50a3cd9069834
 F README a4c0ba11354ef6ba0776b400d057c59da47a4cc0
@@ -99,7 +99,7 @@ F test/unique.test 07776624b82221a80c8b4138ce0dd8b0853bb3ea
 F test/update.test 3cf1ca0565f678063c2dfa9a7948d2d66ae1a778
 F test/vacuum.test 8acf8669f3b627e54149b25165b034aa06c2432e
 F test/where.test 032d581c3de4893eba33b569e581c46b941bb02a
-F tool/lemon.c bfd036ab9309c7f34e1357d9a065ad137814e741
+F tool/lemon.c 7502222a5d704d9d5d1ac437f73667855d687862
 F tool/lempar.c 9b604e6a8b3d55c0b9cbcb130a7302fb8bafe2b9
 F tool/memleak.awk 296dfbce7a9ca499b95ce04e30334e64a50052e0
 F tool/opNames.awk 5ba1f48aa854ee3b7c3d2b54233665bc3e649ea2
@@ -125,7 +125,7 @@ F www/speed.tcl 83457b2bf6bb430900bd48ca3dd98264d9a916a5
 F www/sqlite.tcl 8b5884354cb615049aed83039f8dfe1552a44279
 F www/tclsqlite.tcl 829b393d1ab187fd7a5e978631b3429318885c49
 F www/vdbe.tcl 2013852c27a02a091d39a766bc87cff329f21218
-P b2a9807fed544e83002366149b9a363759338c5d
+P 39fed2df11382b9855d518502a6c2ca200fa66b8
-R e0b567ef590e442398fe19c801c19dbc
+R bbf759a9eca350d9e39199c34c6ab1fb
 U drh
-Z 84f7f5c8e0889cae09918887440ad98b
+Z 95f9230334dd6740861a9a25c1c709f1

manifest.uuid

@@ -1 +1 @@
-39fed2df11382b9855d518502a6c2ca200fa66b8
+8da0ac9a8bb859377613dd18f4f423eb49c7338b

tool/lemon.c

@@ -770,7 +770,7 @@ struct lemon *lemp;
     stp = lemp->sorted[i];
     assert( stp->ap );
     stp->ap = Action_sort(stp->ap);
-    for(ap=stp->ap; ap && ap->next; ap=nap){
+    for(ap=stp->ap; ap && ap->next; ap=ap->next){
       for(nap=ap->next; nap && nap->sp==ap->sp; nap=nap->next){
          /* The two actions "ap" and "nap" have the same lookahead.
          ** Figure out which one should be used */
@@ -848,9 +848,17 @@ struct symbol *errsym;   /* The error symbol (if defined.  NULL otherwise) */
       apx->type = RD_RESOLVED;
     }
   }else{
-    /* Can't happen.  Shifts have to come before Reduces on the
+    assert( 
-    ** list because the reduces were added last.  Hence, if apx->type==REDUCE
+      apx->type==SH_RESOLVED ||
-    ** then it is impossible for apy->type==SHIFT */
+      apx->type==RD_RESOLVED ||
+      apx->type==CONFLICT ||
+      apy->type==SH_RESOLVED ||
+      apy->type==RD_RESOLVED ||
+      apy->type==CONFLICT
+    );
+    /* The REDUCE/SHIFT case cannot happen because SHIFTs come before
+    ** REDUCEs on the list.  If we reach this point it must be because
+    ** the parser conflict had already been resolved. */
   }
   return errcnt;
 }
@@ -3256,48 +3264,59 @@ struct lemon *lemp;
 /* Reduce the size of the action tables, if possible, by making use
 ** of defaults.
 **
-** In this version, if all REDUCE actions use the same rule, make
+** In this version, we take the most frequent REDUCE action and make
-** them the default.  Only default them if there are more than one.
+** it the default.  Only default a reduce if there are more than one.
 */
 void CompressTables(lemp)
 struct lemon *lemp;
 {
   struct state *stp;
-  struct action *ap;
+  struct action *ap, *ap2;
-  struct rule *rp;
+  struct rule *rp, *rp2, *rbest;
+  int nbest, n;
   int i;
   int cnt;
 
   for(i=0; i<lemp->nstate; i++){
     stp = lemp->sorted[i];
+    nbest = 0;
+    rbest = 0;
 
-    /* Find the first REDUCE action */
+    for(ap=stp->ap; ap; ap=ap->next){
-    for(ap=stp->ap; ap && ap->type!=REDUCE; ap=ap->next);
+      if( ap->type!=REDUCE ) continue;
-    if( ap==0 ) continue;
+      rp = ap->x.rp;
-
+      if( rp==rbest ) continue;
-    /* Remember the rule used */
+      n = 1;
-    rp = ap->x.rp;
+      for(ap2=ap->next; ap2; ap2=ap2->next){
-
+        if( ap2->type!=REDUCE ) continue;
-    /* See if all other REDUCE acitons use the same rule */
+        rp2 = ap2->x.rp;
-    cnt = 1;
+        if( rp2==rbest ) continue;
-    for(ap=ap->next; ap; ap=ap->next){
+        if( rp2==rp ) n++;
-      if( ap->type==REDUCE ){
+      }
-        if( ap->x.rp!=rp ) break;
+      if( n>nbest ){
-        cnt++;
+        nbest = n;
+        rbest = rp;
       }
     }
-    if( ap || cnt==1 ) continue;
+ 
+    /* Do not make a default if the number of rules to default
+    ** is not at least 2 */
+    if( nbest<2 ) continue;
 
-    /* Combine all REDUCE actions into a single default */
+
-    for(ap=stp->ap; ap && ap->type!=REDUCE; ap=ap->next);
+    /* Combine matching REDUCE actions into a single default */
+    for(ap=stp->ap; ap; ap=ap->next){
+      if( ap->type==REDUCE && ap->x.rp==rbest ) break;
+    }
     assert( ap );
     ap->sp = Symbol_new("{default}");
     for(ap=ap->next; ap; ap=ap->next){
-      if( ap->type==REDUCE ) ap->type = NOT_USED;
+      if( ap->type==REDUCE && ap->x.rp==rbest ) ap->type = NOT_USED;
     }
     stp->ap = Action_sort(stp->ap);
   }
 }
+
 /***************** From the file "set.c" ************************************/
 /*
 ** Set manipulation routines for the LEMON parser generator.