X-Git-Url: https://ocean-lang.org/code/?a=blobdiff_plain;f=csrc%2Fparsergen.mdc;h=d30275e4e4d383a22905acd1e415c72d89fc56de;hb=f8c00ecff941f5f86b4d54dd73cac3680684a11e;hp=478482e0f6b0512b9fc09946b4b1b5ead04fe7fd;hpb=51ba21ffd913b8eb700699567567560f99a2aa9c;p=ocean

diff --git a/csrc/parsergen.mdc b/csrc/parsergen.mdc
index 478482e..d30275e 100644
--- a/csrc/parsergen.mdc
+++ b/csrc/parsergen.mdc
@@ -277,6 +277,9 @@ declares how it associates.  This level is stored in each symbol
 listed and may be inherited by any production which uses the symbol.  A
 production inherits from the last symbol which has a precedence.
 
+The symbols on the first precedence line have the lowest precedence.
+Subsequent lines introduce symbols with higher precedence.
+
 ###### grammar fields
 	struct text current_type;
 	int type_isref;
@@ -1287,12 +1290,11 @@ When itemsets are created we assign a precedence to the itemset from
 the complete item, if there is one.  We ignore the possibility of
 there being two and don't (currently) handle precedence in such
 grammars.  When completing a grammar we ignore any item where DOT is
-followed by a terminal with a precedence lower (numerically higher)
-than that for the itemset.  Unless the terminal has right
-associativity, we also ignore items where the terminal has the same
-precedence.  The result is that unwanted items are still in the
-itemset, but the terminal doesn't get into the go to set, so the item
-is ineffective.
+followed by a terminal with a precedence lower than that for the
+itemset.  Unless the terminal has right associativity, we also ignore
+items where the terminal has the same precedence.  The result is that
+unwanted items are still in the itemset, but the terminal doesn't get
+into the go to set, so the item is ineffective.
 
 ###### complete itemset
 	for (i = 0; i < is->items.cnt; i++) {
@@ -1311,7 +1313,7 @@ is ineffective.
 			continue;
 		s = pr->body[bs];
 		if (s->precedence && is->precedence &&
-		    is->precedence < s->precedence)
+		    is->precedence > s->precedence)
 			/* This terminal has a low precedence and
 			 * shouldn't be shifted
 			 */
@@ -1404,8 +1406,7 @@ with a pre-existing itemset).
 			pos = symset_find(&newitemset, pr->head->num);
 			if (bp + 1 == pr->body_size &&
 			    pr->precedence > 0 &&
-			    (precedence == 0 ||
-			     pr->precedence < precedence)) {
+			    pr->precedence > precedence) {
 				// new itemset is reducible and has a precedence.
 				precedence = pr->precedence;
 				assoc = pr->assoc;
@@ -1799,14 +1800,20 @@ counted, and are reported as non-critical.  This will not affect a
 				int p = item_prod(itm);
 				int bp = item_index(itm);
 				struct production *pr = g->productions[p];
+				struct symbol *s;
 
-				if (bp < pr->body_size &&
-				    pr->body[bp]->type == Terminal) {
-					/* shiftable */
-					int sym = pr->body[bp]->num;
-					if (symset_find(&shifts, sym) < 0)
-						symset_add(&shifts, sym, itm);
-				}
+				if (bp >= pr->body_size ||
+				    pr->body[bp]->type != Terminal)
+					/* not shiftable */
+					continue;
+
+				s = pr->body[bp];
+				if (s->precedence && is->precedence)
+					/* Precedence resolves this, so no conflict */
+					continue;
+
+				if (symset_find(&shifts, s->num) < 0)
+					symset_add(&shifts, s->num, itm);
 			}
 			/* Now look for reductions and conflicts */
 			for (j = 0; j < is->items.cnt; j++) {
@@ -1900,7 +1907,9 @@ pieces of code provided in the grammar file, so they are generated first.
 ### Known words table
 
 The known words table is simply an array of terminal symbols.
-The table of nonterminals used for tracing is a similar array.
+The table of nonterminals used for tracing is a similar array.  We
+include virtual symbols in the table of non_terminals to keep the
+numbers right.
 
 ###### functions
 
@@ -1925,7 +1934,7 @@ The table of nonterminals used for tracing is a similar array.
 		for (i = TK_reserved;
 		     i < g->num_syms;
 		     i++)
-			if (g->symtab[i]->type == Nonterminal)
+			if (g->symtab[i]->type != Terminal)
 				fprintf(f, "\t\"%.*s\",\n", g->symtab[i]->name.len,
 					g->symtab[i]->name.txt);
 		fprintf(f, "};\n\n");
@@ -2103,10 +2112,13 @@ automatically freed.  This is equivalent to assigning `NULL` to the pointer.
 		fputs("\n", f);
 		for (i = 0; i < p->body_size; i++) {
 			if (p->body[i]->struct_name.txt &&
-			    p->body[i]->isref &&
-			    used[i])
+			    used[i]) {
 				// assume this has been copied out
-				fprintf(f, "\t\t*(void**)body[%d] = NULL;\n", i);
+				if (p->body[i]->isref)
+					fprintf(f, "\t\t*(void**)body[%d] = NULL;\n", i);
+				else
+					fprintf(f, "\t\tmemset(body[%d], 0, sizeof(struct %.*s));\n", i, p->body[i]->struct_name.len, p->body[i]->struct_name.txt);
+			}
 		}
 		free(used);
 	}
@@ -3087,8 +3099,8 @@ an error.
 
 # calc: grammar
 
-	$LEFT * /
 	$LEFT + -
+	$LEFT * /
 
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