news: new syntax (%gprec and %precr)

3 grammars: one typical, with normal test cases, one to display all the
warnings introduced, and one with the errors introduced.

* tests/conflicts.at: New

NEWS

@@ -2,6 +2,32 @@ GNU Bison NEWS
 
 * Noteworthy changes in release ?.? (????-??-??) [?]
 
+** New syntax: partial-order precedence relationships
+
+  Formerly, the precedence order of tokens was linear, depending only on the
+  order in which they were declared.  With the new syntax, all the tokens are
+  not necessarily comparable.  It is possible to declare a group of tokens with
+  no links outside of the group, and to later on add only those needed.
+  The uncomparability of tokens would allow for more feedback on new conflicts
+  silently resolved via precedence.
+
+  An example of the new syntax applied to arithmetic and boolean operators,
+  with '^' serving as both numerical power and boolean XOR:
+
+  %gprec arith {
+    %left '+' '-'
+    %left '*' '/'
+  }
+  %gprec bool {
+    %left OR
+    %left AND
+  }
+  %gprec { %right '^' }
+
+  %precr '^' > arith
+  %precr OR AND > '^'
+
+  Here, AND is not comparable with '+', but '^' > '+' and AND > '^'
 
 * Noteworthy changes in release 3.0 (2013-07-25) [stable]
 

src/AnnotationList.c

@@ -242,7 +242,7 @@ AnnotationList__computePredecessorAnnotations (AnnotationList *self, state *s,
           {
             symbol_number contribution_token =
               InadequacyList__getContributionToken (self->inadequacyNode, ci)
-                ->number;
+                ->content->number;
             if (AnnotationList__isContributionAlways (self, ci))
               {
                 annotation_node->contributions[ci] = NULL;
@@ -549,7 +549,7 @@ AnnotationList__compute_from_inadequacies (
                    does discard annotations in the simplest case of a S/R
                    conflict with no token precedence.  */
                 aver (!bitset_test (shift_tokens, conflicted_token)
-                      || symbols[conflicted_token]->prec);
+                      || symbols[conflicted_token]->content->prec);
                 ++annotation_counts[s->number];
                 if (contribution_count > *max_contributionsp)
                   *max_contributionsp = contribution_count;
@@ -595,7 +595,7 @@ AnnotationList__debug (AnnotationList const *self, size_t nitems, int spaces)
           {
             symbol_number token =
               InadequacyList__getContributionToken (a->inadequacyNode, ci)
-                ->number;
+                ->content->number;
             {
               int j;
               for (j = 0; j < spaces+2; ++j)
@@ -644,7 +644,7 @@ AnnotationList__computeLookaheadFilter (AnnotationList const *self,
             Sbitset biter;
             symbol_number token =
               InadequacyList__getContributionToken (self->inadequacyNode, ci)
-                ->number;
+                ->content->number;
             SBITSET__FOR_EACH (self->contributions[ci], nitems, biter, item)
               bitset_set (lookahead_filter[item], token);
           }
@@ -679,7 +679,8 @@ AnnotationList__stateMakesContribution (AnnotationList const *self,
     return false;
   {
     symbol_number token =
-      InadequacyList__getContributionToken (self->inadequacyNode, ci)->number;
+      InadequacyList__getContributionToken (self->inadequacyNode, ci)
+      ->content->number;
     Sbitset__Index item;
     Sbitset biter;
     SBITSET__FOR_EACH (self->contributions[ci], nitems, biter, item)
@@ -709,7 +710,7 @@ AnnotationList__computeDominantContribution (AnnotationList const *self,
         ContributionIndex ci;
         int actioni;
         ContributionIndex ci_rr_dominator = ContributionIndex__none;
-        int shift_precedence = token->prec;
+        int shift_precedence = token->content->prec;
 
         /* If the token has no precedence set, shift is always chosen.  */
         if (!shift_precedence)
@@ -739,7 +740,7 @@ AnnotationList__computeDominantContribution (AnnotationList const *self,
             if (reduce_precedence
                 && (reduce_precedence < shift_precedence
                     || (reduce_precedence == shift_precedence
-                        && token->assoc == right_assoc)))
+                        && token->content->prec_node->assoc == right_assoc)))
               continue;
             if (!AnnotationList__stateMakesContribution (self, nitems, ci,
                                                          lookaheads))
@@ -747,7 +748,7 @@ AnnotationList__computeDominantContribution (AnnotationList const *self,
             /* This uneliminated reduction contributes, so see if it can cause
                an error action.  */
             if (reduce_precedence == shift_precedence
-                 && token->assoc == non_assoc)
+                 && token->content->prec_node->assoc == non_assoc)
               {
                 /* It's not possible to find split-stable domination over
                    shift after a potential %nonassoc.  */

src/conflicts.c

@@ -53,7 +53,8 @@ enum conflict_resolution
     reduce_resolution,
     left_resolution,
     right_resolution,
-    nonassoc_resolution
+    nonassoc_resolution,
+    uncomparable_resolution
   };
 
 
@@ -90,6 +91,7 @@ log_resolution (rule *r, symbol_number token,
           break;
 
         case nonassoc_resolution:
+        case uncomparable_resolution:
           obstack_printf (&solved_conflicts_obstack,
                           _("    Conflict between rule %d and token %s"
                             " resolved as an error"),
@@ -104,7 +106,7 @@ log_resolution (rule *r, symbol_number token,
         case shift_resolution:
           obstack_printf (&solved_conflicts_obstack,
                           " (%s < %s)",
-                          r->prec->tag,
+                          r->prec->symbol->tag,
                           symbols[token]->tag);
           break;
 
@@ -112,7 +114,7 @@ log_resolution (rule *r, symbol_number token,
           obstack_printf (&solved_conflicts_obstack,
                           " (%s < %s)",
                           symbols[token]->tag,
-                          r->prec->tag);
+                          r->prec->symbol->tag);
           break;
 
         case left_resolution:
@@ -132,6 +134,12 @@ log_resolution (rule *r, symbol_number token,
                           " (%%nonassoc %s)",
                           symbols[token]->tag);
           break;
+        case uncomparable_resolution:
+          obstack_printf (&solved_conflicts_obstack,
+                          " (%s uncomparable with %s)",
+                          r->prec->symbol->tag,
+                          symbols[token]->tag);
+          break;
         }
 
       obstack_sgrow (&solved_conflicts_obstack, ".\n");
@@ -161,6 +169,7 @@ log_resolution (rule *r, symbol_number token,
                           xml_escape (symbols[token]->tag));
           break;
 
+        case uncomparable_resolution:
         case nonassoc_resolution:
           obstack_printf (&solved_conflicts_xml_obstack,
                           "        <resolution rule=\"%d\" symbol=\"%s\""
@@ -176,7 +185,7 @@ log_resolution (rule *r, symbol_number token,
         case shift_resolution:
           obstack_printf (&solved_conflicts_xml_obstack,
                           "%s &lt; %s",
-                          xml_escape_n (0, r->prec->tag),
+                          xml_escape_n (0, r->prec->symbol->tag),
                           xml_escape_n (1, symbols[token]->tag));
           break;
 
@@ -184,7 +193,7 @@ log_resolution (rule *r, symbol_number token,
           obstack_printf (&solved_conflicts_xml_obstack,
                           "%s &lt; %s",
                           xml_escape_n (0, symbols[token]->tag),
-                          xml_escape_n (1, r->prec->tag));
+                          xml_escape_n (1, r->prec->symbol->tag));
           break;
 
         case left_resolution:
@@ -203,7 +212,13 @@ log_resolution (rule *r, symbol_number token,
           obstack_printf (&solved_conflicts_xml_obstack,
                           "%%nonassoc %s",
                           xml_escape (symbols[token]->tag));
-      break;
+          break;
+        case uncomparable_resolution:
+          obstack_printf (&solved_conflicts_xml_obstack,
+                          "%s uncomparable with %s",
+                          xml_escape_n (0, symbols[token]->tag),
+                          xml_escape_n (1, r->prec->symbol->tag));
+          break;
         }
 
       obstack_sgrow (&solved_conflicts_xml_obstack, "</resolution>\n");
@@ -243,7 +258,6 @@ flush_reduce (bitset lookahead_tokens, int token)
   bitset_reset (lookahead_tokens, token);
 }
 
-
 /*------------------------------------------------------------------.
 | Attempt to resolve shift-reduce conflict for one rule by means of |
 | precedence declarations.  It has already been checked that the    |
@@ -263,66 +277,73 @@ resolve_sr_conflict (state *s, int ruleno, symbol **errors, int *nerrs)
   reductions *reds = s->reductions;
   /* Find the rule to reduce by to get precedence of reduction.  */
   rule *redrule = reds->rules[ruleno];
-  int redprec = redrule->prec->prec;
+  prec_node *redprecsym = redrule->prec->prec_node;
   bitset lookahead_tokens = reds->lookahead_tokens[ruleno];
 
   for (i = 0; i < ntokens; i++)
     if (bitset_test (lookahead_tokens, i)
-        && bitset_test (lookahead_set, i)
-        && symbols[i]->prec)
+        && bitset_test (lookahead_set, i))
       {
-        /* Shift-reduce conflict occurs for token number i
-           and it has a precedence.
-           The precedence of shifting is that of token i.  */
-        if (symbols[i]->prec < redprec)
+        if (redprecsym && symbols[i]->content->prec_node)
           {
-            register_precedence (redrule->prec->number, i);
-            log_resolution (redrule, i, reduce_resolution);
-            flush_shift (s, i);
-          }
-        else if (symbols[i]->prec > redprec)
-          {
-            register_precedence (i, redrule->prec->number);
-            log_resolution (redrule, i, shift_resolution);
-            flush_reduce (lookahead_tokens, i);
+            /* Shift-reduce conflict occurs for token number i
+               and it has a precedence.
+               The precedence of shifting is that of token i.  */
+            if (is_prec_superior (redprecsym, symbols[i]->content->prec_node))
+              {
+                register_precedence (redrule->prec->number, i);
+                log_resolution (redrule, i, reduce_resolution);
+                flush_shift (s, i);
+              }
+            else if (is_prec_superior (symbols[i]->content->prec_node,
+                                       redprecsym))
+              {
+                register_precedence (i, redrule->prec->number);
+                log_resolution (redrule, i, shift_resolution);
+                flush_reduce (lookahead_tokens, i);
+              }
+            else if (is_prec_equal (redprecsym, symbols[i]->content->prec_node))
+              /* Matching precedence levels.
+                 For non-defined associativity, keep both: unexpected
+                 associativity conflict.
+                 For left associativity, keep only the reduction.
+                 For right associativity, keep only the shift.
+                 For nonassociativity, keep neither.  */
+
+              switch (symbols[i]->content->prec_node->assoc)
+                {
+                case undef_assoc:
+                  break;
+
+                case precedence_assoc:
+                  break;
+
+                case right_assoc:
+                  register_assoc (i, redrule->prec->number);
+                  log_resolution (redrule, i, right_resolution);
+                  flush_reduce (lookahead_tokens, i);
+                  break;
+
+                case left_assoc:
+                  register_assoc (i, redrule->prec->number);
+                  log_resolution (redrule, i, left_resolution);
+                  flush_shift (s, i);
+                  break;
+
+                case non_assoc:
+                  register_assoc (i, redrule->prec->number);
+                  log_resolution (redrule, i, nonassoc_resolution);
+                  flush_shift (s, i);
+                  flush_reduce (lookahead_tokens, i);
+                  /* Record an explicit error for this token.  */
+                  errors[(*nerrs)++] = symbols[i];
+                  break;
+                }
+            else
+              log_resolution (redrule, i, uncomparable_resolution);
           }
         else
-          /* Matching precedence levels.
-             For non-defined associativity, keep both: unexpected
-             associativity conflict.
-             For left associativity, keep only the reduction.
-             For right associativity, keep only the shift.
-             For nonassociativity, keep neither.  */
-
-          switch (symbols[i]->assoc)
-            {
-            case undef_assoc:
-              abort ();
-
-            case precedence_assoc:
-              break;
-
-            case right_assoc:
-              register_assoc (i, redrule->prec->number);
-              log_resolution (redrule, i, right_resolution);
-              flush_reduce (lookahead_tokens, i);
-              break;
-
-            case left_assoc:
-              register_assoc (i, redrule->prec->number);
-              log_resolution (redrule, i, left_resolution);
-              flush_shift (s, i);
-              break;
-
-            case non_assoc:
-              register_assoc (i, redrule->prec->number);
-              log_resolution (redrule, i, nonassoc_resolution);
-              flush_shift (s, i);
-              flush_reduce (lookahead_tokens, i);
-              /* Record an explicit error for this token.  */
-              errors[(*nerrs)++] = symbols[i];
-              break;
-            }
+          log_resolution (redrule, i, uncomparable_resolution);
       }
 }
 
@@ -354,7 +375,7 @@ set_conflicts (state *s, symbol **errors)
      check for shift-reduce conflict, and try to resolve using
      precedence.  */
   for (i = 0; i < reds->num; ++i)
-    if (reds->rules[i]->prec && reds->rules[i]->prec->prec
+    if (reds->rules[i]->prec /* && reds->rules[i]->prec->prec */
         && !bitset_disjoint_p (reds->lookahead_tokens[i], lookahead_set))
       resolve_sr_conflict (s, i, errors, &nerrs);
 

src/gram.c

@@ -44,6 +44,8 @@ int nvars = 0;
 
 symbol_number *token_translations = NULL;
 
+enum braces_state prec_braces = 0;
+
 int max_user_token_number = 256;
 
 bool
@@ -65,19 +67,19 @@ rule_useless_in_parser_p (rule const *r)
 }
 
 void
-rule_lhs_print (rule const *r, symbol const *previous_lhs, FILE *out)
+rule_lhs_print (rule const *r, sym_content const *previous_lhs, FILE *out)
 {
   fprintf (out, "  %3d ", r->number);
   if (previous_lhs != r->lhs)
-    fprintf (out, "%s:", r->lhs->tag);
+    fprintf (out, "%s:", r->lhs->symbol->tag);
   else
-    fprintf (out, "%*s|", (int) strlen (previous_lhs->tag), "");
+    fprintf (out, "%*s|", (int) strlen (previous_lhs->symbol->tag), "");
 }
 
 void
 rule_lhs_print_xml (rule const *r, FILE *out, int level)
 {
-  xml_printf (out, level, "<lhs>%s</lhs>", r->lhs->tag);
+  xml_printf (out, level, "<lhs>%s</lhs>", r->lhs->symbol->tag);
 }
 
 size_t
@@ -158,7 +160,7 @@ grammar_rules_partial_print (FILE *out, const char *title,
 {
   rule_number r;
   bool first = true;
-  symbol *previous_lhs = NULL;
+  sym_content *previous_lhs = NULL;
 
   /* rule # : LHS -> RHS */
   for (r = 0; r < nrules + nuseless_productions; r++)
@@ -209,7 +211,7 @@ grammar_rules_print_xml (FILE *out, int level)
                  rules[r].number, usefulness);
         if (rules[r].precsym)
           fprintf (out, " percent_prec=\"%s\"",
-                   xml_escape (rules[r].precsym->tag));
+                   xml_escape (rules[r].precsym->symbol->tag));
         fputs (">\n", out);
       }
       rule_lhs_print_xml (&rules[r], out, level + 3);
@@ -239,7 +241,7 @@ grammar_dump (FILE *out, const char *title)
     for (i = ntokens; i < nsyms; i++)
       fprintf (out, "%5d  %5d   %5d  %s\n",
                i,
-               symbols[i]->prec, symbols[i]->assoc,
+               symbols[i]->content->prec, symbols[i]->content->prec_node->assoc,
                symbols[i]->tag);
     fprintf (out, "\n\n");
   }
@@ -262,7 +264,7 @@ grammar_dump (FILE *out, const char *title)
         fprintf (out, "%3d (%2d, %2d, %2d, %2u-%2u)   %2d ->",
                  i,
                  rule_i->prec ? rule_i->prec->prec : 0,
-                 rule_i->prec ? rule_i->prec->assoc : 0,
+                 rule_i->prec ? rule_i->prec->prec_node->assoc : 0,
                  rule_i->useful,
                  rhs_itemno,
                  rhs_itemno + rhs_count - 1,
@@ -280,7 +282,7 @@ grammar_dump (FILE *out, const char *title)
     rule_number r;
     for (r = 0; r < nrules + nuseless_productions; r++)
       {
-        fprintf (out, "%-5d  %s:", r, rules[r].lhs->tag);
+        fprintf (out, "%-5d  %s:", r, rules[r].lhs->symbol->tag);
         rule_rhs_print (&rules[r], out);
         fprintf (out, "\n");
       }

src/gram.h

@@ -117,6 +117,17 @@ typedef int item_number;
 extern item_number *ritem;
 extern unsigned int nritems;
 
+enum braces_state
+  {
+    default_braces_state,
+    gprec_seen,
+    group_name_seen,
+    braces_seen
+  };
+
+/* Marker for the lexer and parser, to correctly interpret braces. */
+extern enum braces_state prec_braces;
+
 /* There is weird relationship between OT1H item_number and OTOH
    symbol_number and rule_number: we store the latter in
    item_number.  symbol_number values are stored as-is, while
@@ -180,17 +191,17 @@ typedef struct
      except if some rules are useless.  */
   rule_number number;
 
-  symbol *lhs;
+  sym_content *lhs;
   item_number *rhs;
 
   /* This symbol provides both the associativity, and the precedence. */
-  symbol *prec;
+  sym_content *prec;
 
   int dprec;
   int merger;
 
   /* This symbol was attached to the rule via %prec. */
-  symbol *precsym;
+  sym_content *precsym;
 
   location location;
   bool useful;
@@ -220,7 +231,8 @@ bool rule_useless_in_parser_p (rule const *r);
 /* Print this rule's number and lhs on OUT.  If a PREVIOUS_LHS was
    already displayed (by a previous call for another rule), avoid
    useless repetitions.  */
-void rule_lhs_print (rule const *r, symbol const *previous_lhs, FILE *out);
+void rule_lhs_print (rule const *r, sym_content const *previous_lhs,
+                     FILE *out);
 void rule_lhs_print_xml (rule const *r, FILE *out, int level);
 
 /* Return the length of the RHS.  */

src/graphviz.c

@@ -93,7 +93,7 @@ no_reduce_bitset_init (state const *s, bitset *no_reduce_set)
     bitset_set (*no_reduce_set, TRANSITION_SYMBOL (s->transitions, n));
   for (n = 0; n < s->errs->num; ++n)
     if (s->errs->symbols[n])
-      bitset_set (*no_reduce_set, s->errs->symbols[n]->number);
+      bitset_set (*no_reduce_set, s->errs->symbols[n]->content->number);
 }
 
 static void

src/ielr.c

@@ -424,7 +424,7 @@ ielr_item_has_lookahead (state *s, symbol_number lhs, size_t item,
           if (item_number_is_rule_number (ritem[s->items[item] - 2]))
             {
               state **predecessor;
-              aver (lhs != accept->number);
+              aver (lhs != accept->content->number);
               for (predecessor = predecessors[s->number];
                    *predecessor;
                    ++predecessor)
@@ -580,7 +580,7 @@ typedef struct state_list {
 static void
 ielr_compute_goto_follow_set (bitsetv follow_kernel_items,
                               bitsetv always_follows, state_list *s,
-                              symbol *n, bitset follow_set)
+                              sym_content *n, bitset follow_set)
 {
   goto_number n_goto = map_goto (s->lr0Isocore->state->number, n->number);
   bitset_copy (follow_set, always_follows[n_goto]);

src/output.c

@@ -149,7 +149,7 @@ prepare_symbols (void)
   MUSCLE_INSERT_INT ("tokens_number", ntokens);
   MUSCLE_INSERT_INT ("nterms_number", nvars);
   MUSCLE_INSERT_INT ("symbols_number", nsyms);
-  MUSCLE_INSERT_INT ("undef_token_number", undeftoken->number);
+  MUSCLE_INSERT_INT ("undef_token_number", undeftoken->content->number);
   MUSCLE_INSERT_INT ("user_token_number_max", max_user_token_number);
 
   muscle_insert_symbol_number_table ("translate",
@@ -197,7 +197,7 @@ prepare_symbols (void)
     int i;
     int *values = xnmalloc (ntokens, sizeof *values);
     for (i = 0; i < ntokens; ++i)
-      values[i] = symbols[i]->user_token_number;
+      values[i] = symbols[i]->content->user_token_number;
     muscle_insert_int_table ("toknum", values,
                              values[0], 1, ntokens);
     free (values);
@@ -283,9 +283,9 @@ prepare_states (void)
 static int
 symbol_type_name_cmp (const symbol **lhs, const symbol **rhs)
 {
-  int res = uniqstr_cmp ((*lhs)->type_name, (*rhs)->type_name);
+  int res = uniqstr_cmp ((*lhs)->content->type_name, (*rhs)->content->type_name);
   if (!res)
-    res = (*lhs)->number - (*rhs)->number;
+    res = (*lhs)->content->number - (*rhs)->content->number;
   return res;
 }
 
@@ -320,8 +320,9 @@ type_names_output (FILE *out)
       /* The index of the first symbol of the current type-name.  */
       int i0 = i;
       fputs (i ? ",\n[" : "[", out);
-      for (; i < nsyms && syms[i]->type_name == syms[i0]->type_name; ++i)
-        fprintf (out, "%s%d", i != i0 ? ", " : "", syms[i]->number);
+      for (; i < nsyms
+           && syms[i]->content->type_name == syms[i0]->content->type_name; ++i)
+        fprintf (out, "%s%d", i != i0 ? ", " : "", syms[i]->content->number);
       fputs ("]", out);
     }
   fputs ("])\n\n", out);
@@ -428,20 +429,21 @@ prepare_symbol_definitions (void)
       MUSCLE_INSERT_STRING (key, sym->tag);
 
       SET_KEY ("user_number");
-      MUSCLE_INSERT_INT (key, sym->user_token_number);
+      MUSCLE_INSERT_INT (key, sym->content->user_token_number);
 
       SET_KEY ("is_token");
       MUSCLE_INSERT_INT (key,
                          i < ntokens && sym != errtoken && sym != undeftoken);
 
       SET_KEY ("number");
-      MUSCLE_INSERT_INT (key, sym->number);
+      MUSCLE_INSERT_INT (key, sym->content->number);
 
       SET_KEY ("has_type");
-      MUSCLE_INSERT_INT (key, !!sym->type_name);
+      MUSCLE_INSERT_INT (key, !!sym->content->type_name);
 
       SET_KEY ("type");
-      MUSCLE_INSERT_STRING (key, sym->type_name ? sym->type_name : "");
+      MUSCLE_INSERT_STRING (key, sym->content->type_name
+                            ? sym->content->type_name : "");
 
       {
         int j;

src/parse-gram.h

@@ -52,7 +52,7 @@ extern int gram_debug;
 
   #include "symlist.h"
   #include "symtab.h"
-#line 221 "src/parse-gram.y" /* yacc.c:1909  */
+#line 233 "src/parse-gram.y" /* yacc.c:1909  */
 
   typedef enum
   {
@@ -61,7 +61,7 @@ extern int gram_debug;
     param_parse  = 1 << 1,
     param_both   = param_lex | param_parse
   } param_type;
-#line 645 "src/parse-gram.y" /* yacc.c:1909  */
+#line 723 "src/parse-gram.y" /* yacc.c:1909  */
 #include "muscle-tab.h"
 
 #line 68 "src/parse-gram.h" /* yacc.c:1909  */
@@ -84,49 +84,54 @@ extern int gram_debug;
     PERCENT_PRECEDENCE = 267,
     PERCENT_PREC = 268,
     PERCENT_DPREC = 269,
-    PERCENT_MERGE = 270,
-    PERCENT_CODE = 271,
-    PERCENT_DEFAULT_PREC = 272,
-    PERCENT_DEFINE = 273,
-    PERCENT_DEFINES = 274,
-    PERCENT_ERROR_VERBOSE = 275,
-    PERCENT_EXPECT = 276,
-    PERCENT_EXPECT_RR = 277,
-    PERCENT_FLAG = 278,
-    PERCENT_FILE_PREFIX = 279,
-    PERCENT_GLR_PARSER = 280,
-    PERCENT_INITIAL_ACTION = 281,
-    PERCENT_LANGUAGE = 282,
-    PERCENT_NAME_PREFIX = 283,
-    PERCENT_NO_DEFAULT_PREC = 284,
-    PERCENT_NO_LINES = 285,
-    PERCENT_NONDETERMINISTIC_PARSER = 286,
-    PERCENT_OUTPUT = 287,
-    PERCENT_REQUIRE = 288,
-    PERCENT_SKELETON = 289,
-    PERCENT_START = 290,
-    PERCENT_TOKEN_TABLE = 291,
-    PERCENT_VERBOSE = 292,
-    PERCENT_YACC = 293,
-    BRACED_CODE = 294,
-    BRACED_PREDICATE = 295,
-    BRACKETED_ID = 296,
-    CHAR = 297,
-    EPILOGUE = 298,
-    EQUAL = 299,
-    ID = 300,
-    ID_COLON = 301,
-    PERCENT_PERCENT = 302,
-    PIPE = 303,
-    PROLOGUE = 304,
-    SEMICOLON = 305,
-    TAG = 306,
-    TAG_ANY = 307,
-    TAG_NONE = 308,
-    INT = 309,
-    PERCENT_PARAM = 310,
-    PERCENT_UNION = 311,
-    PERCENT_EMPTY = 312
+    PERCENT_GPREC = 270,
+    PERCENT_PRECR = 271,
+    PERCENT_MERGE = 272,
+    PERCENT_CODE = 273,
+    PERCENT_DEFAULT_PREC = 274,
+    PERCENT_DEFINE = 275,
+    PERCENT_DEFINES = 276,
+    PERCENT_ERROR_VERBOSE = 277,
+    PERCENT_EXPECT = 278,
+    PERCENT_EXPECT_RR = 279,
+    PERCENT_FLAG = 280,
+    PERCENT_FILE_PREFIX = 281,
+    PERCENT_GLR_PARSER = 282,
+    PERCENT_INITIAL_ACTION = 283,
+    PERCENT_LANGUAGE = 284,
+    PERCENT_NAME_PREFIX = 285,
+    PERCENT_NO_DEFAULT_PREC = 286,
+    PERCENT_NO_LINES = 287,
+    PERCENT_NONDETERMINISTIC_PARSER = 288,
+    PERCENT_OUTPUT = 289,
+    PERCENT_REQUIRE = 290,
+    PERCENT_SKELETON = 291,
+    PERCENT_START = 292,
+    PERCENT_TOKEN_TABLE = 293,
+    PERCENT_VERBOSE = 294,
+    PERCENT_YACC = 295,
+    BRACED_CODE = 296,
+    BRACED_PREDICATE = 297,
+    BRACKETED_ID = 298,
+    CHAR = 299,
+    EPILOGUE = 300,
+    EQUAL = 301,
+    ID = 302,
+    ID_COLON = 303,
+    PERCENT_PERCENT = 304,
+    PIPE = 305,
+    PROLOGUE = 306,
+    SEMICOLON = 307,
+    GT = 308,
+    TAG = 309,
+    TAG_ANY = 310,
+    TAG_NONE = 311,
+    LBRACE = 312,
+    RBRACE = 313,
+    INT = 314,
+    PERCENT_PARAM = 315,
+    PERCENT_UNION = 316,
+    PERCENT_EMPTY = 317
   };
 #endif
 
@@ -135,27 +140,29 @@ extern int gram_debug;
 typedef union GRAM_STYPE GRAM_STYPE;
 union GRAM_STYPE
 {
-#line 182 "src/parse-gram.y" /* yacc.c:1909  */
+#line 187 "src/parse-gram.y" /* yacc.c:1909  */
 unsigned char character;
-#line 186 "src/parse-gram.y" /* yacc.c:1909  */
-char *code;
 #line 191 "src/parse-gram.y" /* yacc.c:1909  */
+char *code;
+#line 196 "src/parse-gram.y" /* yacc.c:1909  */
 uniqstr uniqstr;
-#line 199 "src/parse-gram.y" /* yacc.c:1909  */
+#line 204 "src/parse-gram.y" /* yacc.c:1909  */
 int integer;
-#line 203 "src/parse-gram.y" /* yacc.c:1909  */
-symbol *symbol;
 #line 208 "src/parse-gram.y" /* yacc.c:1909  */
+symbol *symbol;
+#line 213 "src/parse-gram.y" /* yacc.c:1909  */
 assoc assoc;
-#line 211 "src/parse-gram.y" /* yacc.c:1909  */
+#line 216 "src/parse-gram.y" /* yacc.c:1909  */
 symbol_list *list;
-#line 214 "src/parse-gram.y" /* yacc.c:1909  */
+#line 219 "src/parse-gram.y" /* yacc.c:1909  */
 named_ref *named_ref;
-#line 241 "src/parse-gram.y" /* yacc.c:1909  */
+#line 224 "src/parse-gram.y" /* yacc.c:1909  */
+prec_rel_comparator prec_rel_comparator;
+#line 253 "src/parse-gram.y" /* yacc.c:1909  */
 param_type param;
-#line 409 "src/parse-gram.y" /* yacc.c:1909  */
+#line 423 "src/parse-gram.y" /* yacc.c:1909  */
 code_props_type code_type;
-#line 647 "src/parse-gram.y" /* yacc.c:1909  */
+#line 725 "src/parse-gram.y" /* yacc.c:1909  */
 
   struct
   {
@@ -163,7 +170,7 @@ code_props_type code_type;
     muscle_kind kind;
   } value;
 
-#line 167 "src/parse-gram.h" /* yacc.c:1909  */
+#line 174 "src/parse-gram.h" /* yacc.c:1909  */
 };
 # define GRAM_STYPE_IS_TRIVIAL 1
 # define GRAM_STYPE_IS_DECLARED 1

src/parse-gram.y

@@ -130,6 +130,8 @@
 
 %token PERCENT_PREC          "%prec"
 %token PERCENT_DPREC         "%dprec"
+%token PERCENT_GPREC         "%gprec"
+%token PERCENT_PRECR         "%precr"
 %token PERCENT_MERGE         "%merge"
 
 /*----------------------.
@@ -175,9 +177,12 @@
 %token PIPE            "|"
 %token PROLOGUE        "%{...%}"
 %token SEMICOLON       ";"
+%token GT              ">"
 %token TAG             "<tag>"
 %token TAG_ANY         "<*>"
 %token TAG_NONE        "<>"
+%token LBRACE          "{"
+%token RBRACE          "}"
 
 %union {unsigned char character;}
 %type <character> CHAR
@@ -214,6 +219,13 @@
 %union {named_ref *named_ref;}
 %type <named_ref> named_ref.opt
 
+%type <uniqstr> prec_group_name.opt string_or_id
+
+%union {prec_rel_comparator prec_rel_comparator;}
+%type <prec_rel_comparator> prec_rel_comparator
+
+%type <list> precedence_relation_symbols precedence_symbol
+
 /*---------.
 | %param.  |
 `---------*/
@@ -365,6 +377,8 @@ params:
 
 grammar_declaration:
   precedence_declaration
+| precedence_group_declaration
+| precedence_relation_declaration
 | symbol_declaration
 | "%start" symbol
     {
@@ -457,6 +471,30 @@ symbol_declaration:
     }
 ;
 
+/* A group of symbols for precedence declaration */
+precedence_group_declaration:
+  "%gprec" prec_group_name.opt
+  {
+    set_current_group ($2, &@2);
+  }
+  "{"  precedence_declarations "}"
+  {
+    set_current_group (DEFAULT_GROUP_NAME, NULL);
+  }
+;
+
+/* Name for the precedence group. If none is present a new unique one is
+   generated. */
+prec_group_name.opt:
+  %empty { $$ = new_anonymous_group_name (); }
+| variable /* Just a string, maybe there's a better way? */
+;
+
+precedence_declarations:
+  precedence_declaration
+| precedence_declarations precedence_declaration
+;
+
 precedence_declaration:
   precedence_declarator tag.opt symbols.prec
     {
@@ -484,6 +522,46 @@ tag.opt:
 | TAG    { current_type = $1; tag_seen = true; }
 ;
 
+/* Declaration of a precedence relation between two (lists of) tokens */
+precedence_relation_declaration:
+  "%precr" precedence_relation_symbols
+    { prec_braces = default_braces_state; }
+    prec_rel_comparator
+    precedence_relation_symbols
+    { declare_precedence_relation ($2, $5, $4, @4); }
+;
+
+precedence_relation_symbols:
+  precedence_symbol { $$ = $1; }
+| precedence_relation_symbols precedence_symbol
+    { $$ = symbol_list_append ($1, $2); }
+;
+
+precedence_symbol:
+  string_or_id
+  {
+    if (is_prec_group ($1))
+      $$ = expand_symbol_group (symgroup_from_uniqstr($1, &@1), @1);
+    else
+      $$ = symbol_list_sym_new (symbol_from_uniqstr ($1, @1), @1);
+  }
+| CHAR
+  {
+    $$ = symbol_list_sym_new (symbol_from_uniqstr (uniqstr_new (char_name ($1)), @1), @1);
+  }
+;
+
+string_or_id:
+  STRING { $$ = uniqstr_new (quotearg_style (c_quoting_style, $1)); }
+| ID { $$ = $1; }
+;
+
+prec_rel_comparator:
+  ">"     { $$ = prec_superior; }
+| "="     { $$ = prec_equal; }
+| ">" ">" { $$ = prec_superior_strict; }
+;
+
 /* Just like symbols.1 but accept INT for the sake of POSIX.  */
 symbols.prec:
   symbol.prec

src/print-xml.c

@@ -260,7 +260,7 @@ print_reductions (FILE *out, int level, state *s)
     bitset_set (no_reduce_set, TRANSITION_SYMBOL (trans, i));
   for (i = 0; i < s->errs->num; ++i)
     if (s->errs->symbols[i])
-      bitset_set (no_reduce_set, s->errs->symbols[i]->number);
+      bitset_set (no_reduce_set, s->errs->symbols[i]->content->number);
 
   if (default_reduction)
     report = true;
@@ -388,11 +388,12 @@ print_grammar (FILE *out, int level)
   /* Terminals */
   xml_puts (out, level + 1, "<terminals>");
   for (i = 0; i < max_user_token_number + 1; i++)
-    if (token_translations[i] != undeftoken->number)
+    if (token_translations[i] != undeftoken->content->number)
       {
         char const *tag = symbols[token_translations[i]]->tag;
-        int precedence = symbols[token_translations[i]]->prec;
-        assoc associativity = symbols[token_translations[i]]->assoc;
+        int precedence = symbols[token_translations[i]]->content->prec;
+        assoc associativity = symbols[token_translations[i]]->content->prec_node
+          ->assoc;
         xml_indent (out, level + 2);
         fprintf (out,
                  "<terminal symbol-number=\"%d\" token-number=\"%d\""

src/print.c

@@ -72,7 +72,7 @@ print_core (FILE *out, state *s)
   size_t i;
   item_number *sitems = s->items;
   size_t snritems = s->nitems;
-  symbol *previous_lhs = NULL;
+  sym_content *previous_lhs = NULL;
 
   /* Output all the items of a state, not only its kernel.  */
   if (report_flag & report_itemsets)
@@ -223,7 +223,8 @@ print_reduction (FILE *out, size_t width,
   if (!enabled)
     fputc ('[', out);
   if (r->number)
-    fprintf (out, _("reduce using rule %d (%s)"), r->number, r->lhs->tag);
+    fprintf (out, _("reduce using rule %d (%s)"), r->number,
+             r->lhs->symbol->tag);
   else
     fprintf (out, _("accept"));
   if (!enabled)
@@ -257,7 +258,7 @@ print_reductions (FILE *out, state *s)
     bitset_set (no_reduce_set, TRANSITION_SYMBOL (trans, i));
   for (i = 0; i < s->errs->num; ++i)
     if (s->errs->symbols[i])
-      bitset_set (no_reduce_set, s->errs->symbols[i]->number);
+      bitset_set (no_reduce_set, s->errs->symbols[i]->content->number);
 
   /* Compute the width of the lookahead token column.  */
   if (default_reduction)
@@ -408,7 +409,7 @@ print_grammar (FILE *out)
   /* TERMINAL (type #) : rule #s terminal is on RHS */
   fprintf (out, "%s\n\n", _("Terminals, with rules where they appear"));
   for (i = 0; i < max_user_token_number + 1; i++)
-    if (token_translations[i] != undeftoken->number)
+    if (token_translations[i] != undeftoken->content->number)
       {
         const char *tag = symbols[token_translations[i]]->tag;
         rule_number r;

src/print_graph.c

@@ -46,7 +46,7 @@ static void
 print_core (struct obstack *oout, state *s)
 {
   item_number const *sitems = s->items;
-  symbol *previous_lhs = NULL;
+  sym_content *previous_lhs = NULL;
   size_t i;
   size_t snritems = s->nitems;
 
@@ -72,11 +72,12 @@ print_core (struct obstack *oout, state *s)
       r = &rules[item_number_as_rule_number (*sp)];
 
       obstack_printf (oout, "%3d ", r->number);
-      if (previous_lhs && UNIQSTR_EQ (previous_lhs->tag, r->lhs->tag))
+      if (previous_lhs && UNIQSTR_EQ (previous_lhs->symbol->tag,
+                                      r->lhs->symbol->tag))
         obstack_printf (oout, "%*s| ",
-                        (int) strlen (previous_lhs->tag), "");
+                        (int) strlen (previous_lhs->symbol->tag), "");
       else
-        obstack_printf (oout, "%s: ", escape (r->lhs->tag));
+        obstack_printf (oout, "%s: ", escape (r->lhs->symbol->tag));
       previous_lhs = r->lhs;
 
       for (sp = r->rhs; sp < sp1; sp++)

src/reader.c

@@ -240,13 +240,13 @@ grammar_current_rule_begin (symbol *lhs, location loc,
   current_rule = grammar_end;
 
   /* Mark the rule's lhs as a nonterminal if not already so.  */
-  if (lhs->class == unknown_sym)
+  if (lhs->content->class == unknown_sym)
     {
-      lhs->class = nterm_sym;
-      lhs->number = nvars;
+      lhs->content->class = nterm_sym;
+      lhs->content->number = nvars;
       ++nvars;
     }
-  else if (lhs->class == token_sym)
+  else if (lhs->content->class == token_sym)
     complain (&loc, complaint, _("rule given for %s, which is a token"),
               lhs->tag);
 }
@@ -292,15 +292,15 @@ grammar_rule_check (const symbol_list *r)
 
      Don't worry about the default action if $$ is untyped, since $$'s
      value can't be used.  */
-  if (!r->action_props.code && r->content.sym->type_name)
+  if (!r->action_props.code && r->content.sym->content->type_name)
     {
       symbol *first_rhs = r->next->content.sym;
       /* If $$ is being set in default way, report if any type mismatch.  */
       if (first_rhs)
         {
-          char const *lhs_type = r->content.sym->type_name;
+          char const *lhs_type = r->content.sym->content->type_name;
           const char *rhs_type =
-            first_rhs->type_name ? first_rhs->type_name : "";
+            first_rhs->content->type_name ? first_rhs->content->type_name : "";
           if (!UNIQSTR_EQ (lhs_type, rhs_type))
             complain (&r->location, Wother,
                       _("type clash on default action: <%s> != <%s>"),
@@ -350,7 +350,8 @@ grammar_rule_check (const symbol_list *r)
      it for char literals and strings, which are always tokens.  */
   if (r->ruleprec
       && r->ruleprec->tag[0] != '\'' && r->ruleprec->tag[0] != '"'
-      && r->ruleprec->status != declared && !r->ruleprec->prec)
+      && r->ruleprec->content->status != declared
+      && !r->ruleprec->content->prec)
     complain (&r->location, Wother,
               _("token for %%prec is not defined: %s"), r->ruleprec->tag);
 }
@@ -517,8 +518,8 @@ grammar_current_rule_symbol_append (symbol *sym, location loc,
   p = grammar_symbol_append (sym, loc);
   if (name)
     assign_named_ref (p, name);
-  if (sym->status == undeclared || sym->status == used)
-    sym->status = needed;
+  if (sym->content->status == undeclared || sym->content->status == used)
+    sym->content->status = needed;
 }
 
 /* Attach an ACTION to the current rule.  */
@@ -558,11 +559,11 @@ packgram (void)
   for (p = grammar; p; p = p->next)
     {
       symbol *ruleprec = p->ruleprec;
-      record_merge_function_type (p->merger, p->content.sym->type_name,
+      record_merge_function_type (p->merger, p->content.sym->content->type_name,
                                   p->merger_declaration_location);
       rules[ruleno].user_number = ruleno;
       rules[ruleno].number = ruleno;
-      rules[ruleno].lhs = p->content.sym;
+      rules[ruleno].lhs = p->content.sym->content;
       rules[ruleno].rhs = ritem + itemno;
       rules[ruleno].prec = NULL;
       rules[ruleno].dprec = p->dprec;
@@ -604,11 +605,11 @@ packgram (void)
             /* item_number = symbol_number.
                But the former needs to contain more: negative rule numbers. */
             ritem[itemno++] =
-              symbol_number_as_item_number (p->content.sym->number);
+              symbol_number_as_item_number (p->content.sym->content->number);
             /* A rule gets by default the precedence and associativity
                of its last token.  */
-            if (p->content.sym->class == token_sym && default_prec)
-              rules[ruleno].prec = p->content.sym;
+            if (p->content.sym->content->class == token_sym && default_prec)
+              rules[ruleno].prec = p->content.sym->content;
           }
       }
 
@@ -616,8 +617,8 @@ packgram (void)
          the specified symbol's precedence replaces the default.  */
       if (ruleprec)
         {
-          rules[ruleno].precsym = ruleprec;
-          rules[ruleno].prec = ruleprec;
+          rules[ruleno].precsym = ruleprec->content;
+          rules[ruleno].prec = ruleprec->content;
         }
       /* An item ends by the rule number (negated).  */
       ritem[itemno++] = rule_number_as_item_number (ruleno);
@@ -647,19 +648,19 @@ reader (void)
 
   /* Construct the accept symbol. */
   accept = symbol_get ("$accept", empty_location);
-  accept->class = nterm_sym;
-  accept->number = nvars++;
+  accept->content->class = nterm_sym;
+  accept->content->number = nvars++;
 
   /* Construct the error token */
   errtoken = symbol_get ("error", empty_location);
-  errtoken->class = token_sym;
-  errtoken->number = ntokens++;
+  errtoken->content->class = token_sym;
+  errtoken->content->number = ntokens++;
 
   /* Construct a token that represents all undefined literal tokens.
      It is always token number 2.  */
   undeftoken = symbol_get ("$undefined", empty_location);
-  undeftoken->class = token_sym;
-  undeftoken->number = ntokens++;
+  undeftoken->content->class = token_sym;
+  undeftoken->content->number = ntokens++;
 
   gram_in = xfopen (grammar_file, "r");
 
@@ -721,10 +722,10 @@ check_and_convert_grammar (void)
   if (!endtoken)
     {
       endtoken = symbol_get ("$end", empty_location);
-      endtoken->class = token_sym;
-      endtoken->number = 0;
+      endtoken->content->class = token_sym;
+      endtoken->content->number = 0;
       /* Value specified by POSIX.  */
-      endtoken->user_token_number = 0;
+      endtoken->content->user_token_number = 0;
     }
 
   /* Report any undefined symbols and consider them nonterminals.  */

src/reduce.c

@@ -163,9 +163,9 @@ inaccessable_symbols (void)
   Pp = bitset_create (nrules, BITSET_FIXED);
 
   /* If the start symbol isn't useful, then nothing will be useful. */
-  if (bitset_test (N, accept->number - ntokens))
+  if (bitset_test (N, accept->content->number - ntokens))
     {
-      bitset_set (V, accept->number);
+      bitset_set (V, accept->content->number);
 
       while (1)
         {
@@ -196,9 +196,9 @@ inaccessable_symbols (void)
   V = Vp;
 
   /* Tokens 0, 1, and 2 are internal to Bison.  Consider them useful. */
-  bitset_set (V, endtoken->number);             /* end-of-input token */
-  bitset_set (V, errtoken->number);             /* error token */
-  bitset_set (V, undeftoken->number);           /* some undefined token */
+  bitset_set (V, endtoken->content->number);   /* end-of-input token */
+  bitset_set (V, errtoken->content->number);   /* error token */
+  bitset_set (V, undeftoken->content->number); /* some undefined token */
 
   bitset_free (P);
   P = Pp;
@@ -298,7 +298,7 @@ nonterminals_reduce (void)
     if (!bitset_test (V, i))
       {
         nontermmap[i - ntokens] = n++;
-        if (symbols[i]->status != used)
+        if (symbols[i]->content->status != used)
           complain (&symbols[i]->location, Wother,
                     _("nonterminal useless in grammar: %s"),
                     symbols[i]->tag);
@@ -310,7 +310,7 @@ nonterminals_reduce (void)
     symbol **symbols_sorted = xnmalloc (nvars, sizeof *symbols_sorted);
 
     for (i = ntokens; i < nsyms; i++)
-      symbols[i]->number = nontermmap[i - ntokens];
+      symbols[i]->content->number = nontermmap[i - ntokens];
     for (i = ntokens; i < nsyms; i++)
       symbols_sorted[nontermmap[i - ntokens] - ntokens] = symbols[i];
     for (i = ntokens; i < nsyms; i++)
@@ -328,7 +328,7 @@ nonterminals_reduce (void)
             *rhsp =  symbol_number_as_item_number (nontermmap[*rhsp
                                                               - ntokens]);
       }
-    accept->number = nontermmap[accept->number - ntokens];
+    accept->content->number = nontermmap[accept->content->number - ntokens];
   }
 
   nsyms -= nuseless_nonterminals;
@@ -415,7 +415,7 @@ reduce_grammar (void)
 
   reduce_print ();
 
-  if (!bitset_test (N, accept->number - ntokens))
+  if (!bitset_test (N, accept->content->number - ntokens))
     complain (&startsymbol_location, fatal,
               _("start symbol %s does not derive any sentence"),
               startsymbol->tag);

src/scan-gram.l

@@ -223,6 +223,10 @@ eqopt    ([[:space:]]*=)?
   "%fixed-output-files"             return PERCENT_YACC;
   "%initial-action"                 return PERCENT_INITIAL_ACTION;
   "%glr-parser"                     return PERCENT_GLR_PARSER;
+  "%gprec"                          {
+                                      prec_braces = gprec_seen;
+                                      return PERCENT_GPREC;
+                                    }
   "%language"                       return PERCENT_LANGUAGE;
   "%left"                           return PERCENT_LEFT;
   "%lex-param"                      RETURN_PERCENT_PARAM(lex);
@@ -239,6 +243,7 @@ eqopt    ([[:space:]]*=)?
   "%parse-param"                    RETURN_PERCENT_PARAM(parse);
   "%prec"                           return PERCENT_PREC;
   "%precedence"                     return PERCENT_PRECEDENCE;
+  "%precr"                          return PERCENT_PRECR;
   "%printer"                        return PERCENT_PRINTER;
   "%pure-parser"                    RETURN_PERCENT_FLAG("api.pure");
   "%require"                        return PERCENT_REQUIRE;
@@ -273,10 +278,17 @@ eqopt    ([[:space:]]*=)?
   "="                     return EQUAL;
   "|"                     return PIPE;
   ";"                     return SEMICOLON;
+  "}"                     return RBRACE;
+  ">"                     return GT;
 
   {id} {
     val->uniqstr = uniqstr_new (yytext);
     id_loc = *loc;
+    if (prec_braces == gprec_seen)
+    {
+      prec_braces = group_name_seen;
+      return ID;
+    }
     bracketed_id_str = NULL;
     BEGIN SC_AFTER_IDENTIFIER;
   }
@@ -307,6 +319,11 @@ eqopt    ([[:space:]]*=)?
 
   /* Code in between braces.  */
   "{" {
+    if (prec_braces == gprec_seen || prec_braces == group_name_seen)
+    {
+      prec_braces = braces_seen;
+      return LBRACE;
+    }
     STRING_GROW;
     nesting = 0;
     code_start = loc->start;

src/state.h

@@ -135,7 +135,7 @@ typedef struct
 /* Is the TRANSITIONS->states[Num] labelled by the error token?  */
 
 # define TRANSITION_IS_ERROR(Transitions, Num) \
-  (TRANSITION_SYMBOL (Transitions, Num) == errtoken->number)
+  (TRANSITION_SYMBOL (Transitions, Num) == errtoken->content->number)
 
 /* When resolving a SR conflicts, if the reduction wins, the shift is
    disabled.  */

src/symlist.c

@@ -205,7 +205,7 @@ symbol_list_n_type_name_get (symbol_list *l, location loc, int n)
       return NULL;
     }
   aver (l->content_type == SYMLIST_SYMBOL);
-  return l->content.sym->type_name;
+  return l->content.sym->content->type_name;
 }
 
 bool
@@ -223,8 +223,8 @@ symbol_list_code_props_set (symbol_list *node, code_props_type kind,
     {
     case SYMLIST_SYMBOL:
       symbol_code_props_set (node->content.sym, kind, cprops);
-      if (node->content.sym->status == undeclared)
-        node->content.sym->status = used;
+      if (node->content.sym->content->status == undeclared)
+        node->content.sym->content->status = used;
       break;
     case SYMLIST_TYPE:
       semantic_type_code_props_set

src/symtab.h

@@ -31,6 +31,8 @@
 # include "scan-code.h"
 # include "uniqstr.h"
 
+typedef struct symbol_list symbol_list;
+
 /*----------.
 | Symbols.  |
 `----------*/
@@ -50,6 +52,7 @@ typedef int symbol_number;
 
 
 typedef struct symbol symbol;
+typedef struct sym_content sym_content;
 
 /* Declaration status of a symbol.
 
@@ -61,6 +64,8 @@ typedef struct symbol symbol;
    When status are checked at the end, "declared" symbols are fine,
    "used" symbols trigger warnings, otherwise it's an error.  */
 
+typedef struct prec_node prec_node;
+
 typedef enum
   {
     /** Used in the input file for an unknown reason (error).  */
@@ -82,8 +87,6 @@ enum code_props_type
 
 enum { CODE_PROPS_SIZE = 2 };
 
-/* When extending this structure, be sure to complete
-   symbol_check_alias_consistency.  */
 struct symbol
 {
   /** The key, name of the symbol.  */
@@ -91,6 +94,20 @@ struct symbol
   /** The location of its first occurrence.  */
   location location;
 
+  /* Points to the other in the symbol-string pair for an alias. */
+  symbol *alias;
+
+  /** Whether this symbol is the alias of another or not. */
+  bool is_alias;
+
+  /** All the info about the pointed symbol is there. */
+  sym_content *content;
+};
+
+struct sym_content
+{
+  symbol *symbol;
+
   /** Its \c \%type.
 
       Beware that this is the type_name as was entered by the user,
@@ -112,17 +129,21 @@ struct symbol
   code_props props[CODE_PROPS_SIZE];
 
   symbol_number number;
-  location prec_location;
+
+  /* Not used anymore, to remove. */
   int prec;
-  assoc assoc;
+
   int user_token_number;
 
-  /* Points to the other in the symbol-string pair for an alias.
-     Special value USER_NUMBER_HAS_STRING_ALIAS in the symbol half of the
-     symbol-string pair for an alias.  */
-  symbol *alias;
   symbol_class class;
   status status;
+
+  /* The next element in the symbol precedence group. */
+  sym_content *group_next;
+
+  /* The graph node containing all the precedence information for this
+     symbol. */
+  prec_node *prec_node;
 };
 
 /** Undefined user number.  */
@@ -277,6 +298,91 @@ void print_precedence_warnings (void);
 
 void register_assoc (graphid i, graphid j);
 
+
+/*------------------.
+| Groups of symbols |
+`------------------*/
+
+#define DEFAULT_GROUP_NAME uniqstr_new ("__default__")
+
+typedef struct symgroup symgroup;
+
+struct symgroup
+{
+    /** The name of the group. */
+    uniqstr tag;
+
+    /** The list of symbols in the group. */
+    sym_content * symbol_list;
+
+    location location;
+} ;
+
+/** Get a dummy name for an anonymous group. */
+uniqstr new_anonymous_group_name (void);
+
+/** Set the current group in the token precedence declaration to a new group
+ * with this name */
+void set_current_group (const uniqstr name, location *loc);
+
+/** Get or create the group by that name. The location information is used for
+ *  creation when available. */
+symgroup *
+symgroup_from_uniqstr (const uniqstr key, location *loc);
+
+/** Check if there is a symbol precedence group by that name. */
+bool
+is_prec_group (const uniqstr key);
+
+
+/*----------------------------------.
+| Graph of precedence relationships |
+`----------------------------------*/
+
+typedef struct prec_link prec_link;
+
+struct prec_link
+{
+    prec_node *target;
+    bool transitive;
+    prec_link *next;
+};
+
+struct prec_node
+{
+    symbol *symbol;
+    /** Associativity for the symbol. */
+    assoc assoc;
+    location prec_location;
+    prec_link *sons;
+    prec_link *equals;
+};
+
+typedef enum prec_rel_comparator prec_rel_comparator;
+
+enum prec_rel_comparator
+{
+    prec_equal,
+    prec_superior,
+    prec_superior_strict,
+};
+
+/** Declare a precedence relationship between the symbols of the two lists,
+ *  as defined by the operator. */
+void
+declare_precedence_relation (symbol_list *l1, symbol_list *l2,
+                             prec_rel_comparator c, location loc);
+/** Return the list of symbols contained in the group. */
+symbol_list *
+expand_symbol_group (symgroup * group, location loc);
+
+/** Check if s1 and s2 have the same precedence level. */
+bool is_prec_equal (prec_node * s1, prec_node * s2);
+
+/** Check if from > to . */
+bool is_prec_superior (prec_node * from, prec_node * to);
+
+
 /*-----------------.
 | Semantic types.  |
 `-----------------*/

src/tables.c

@@ -290,7 +290,7 @@ action_row (state *s)
 
       /* Do not use any default reduction if there is a shift for
          error */
-      if (sym == errtoken->number)
+      if (sym == errtoken->content->number)
         nodefault = true;
     }
 
@@ -300,7 +300,7 @@ action_row (state *s)
   for (i = 0; i < errp->num; i++)
     {
       symbol *sym = errp->symbols[i];
-      actrow[sym->number] = ACTION_NUMBER_MINIMUM;
+      actrow[sym->content->number] = ACTION_NUMBER_MINIMUM;
     }
 
   /* Turn off default reductions where requested by the user.  See

tests/conflicts.at

@@ -17,6 +17,152 @@
 
 AT_BANNER([[Conflicts.]])
 
+## ----------------- ##
+## Precedence groups ##
+## ----------------- ##
+
+# Sample use case of precedence groups and relations, working.
+
+AT_SETUP([Precedence groups])
+
+AT_DATA_GRAMMAR([[input.y]],
+[[%token CARET "^"
+%token NUM BOOL '^' OR AND
+
+%left '+' '-'
+%gprec {
+  %right CARET
+}
+%gprec boolean {
+  %left OR
+  %left AND
+}
+%left '*' '/'
+
+%precr boolean >> "^"
+%precr CARET > '*' '/' '-' '+'
+
+%%
+
+stmt:
+  exp
+| bool_exp
+
+exp:
+  NUM
+| exp '+' exp
+| exp '-' exp
+| exp '*' exp
+| exp '/' exp
+| exp "^" exp
+
+bool_exp:
+  BOOL
+| bool_exp AND bool_exp
+| bool_exp OR bool_exp
+| bool_exp CARET bool_exp
+]])
+
+AT_BISON_CHECK([[--report=all -o input.c input.y]], 0, [])
+
+AT_CLEANUP
+
+## -------------------------------- ##
+## Conflicting precedence relations ##
+## -------------------------------- ##
+
+AT_SETUP([Conflicting precedence relations])
+
+AT_DATA_GRAMMAR([[input.y]],
+[[%token TOKEN
+%precedence A
+%precedence B
+%precedence C
+%precedence D E
+
+%gprec group {
+  %precedence F
+  %precedence G
+}
+
+%precr B = C
+%precr A > B
+%precr C > B
+%precr F > G
+%precr F > A
+%%
+exp:
+  TOKEN
+| exp A exp
+| exp B exp
+| exp C exp
+| exp D exp
+| exp E exp
+| exp F exp
+| exp G exp
+]])
+
+AT_BISON_CHECK([[-Wall -o input.c input.y]], 0, [],
+[[input.y:20.10: warning: contradicting declaration: B = C is in conflict with the previous declaration: B > C [-Wprecedence]
+input.y:21.10: warning: contradicting declaration: A > B is in conflict with the previous declaration: A < B [-Wprecedence]
+input.y:22.10: warning: contradicting declaration: C > B is in conflict with the previous declaration: C = B [-Wprecedence]
+input.y:23.10: warning: contradicting declaration: F > G is in conflict with the previous declaration: F < G [-Wprecedence]
+input.y: warning: 27 shift/reduce conflicts [-Wconflicts-sr]
+]])
+
+AT_CLEANUP
+
+## ------------------------------ ##
+## Duplicate precedence relations ##
+## ------------------------------ ##
+
+AT_SETUP([Duplicate precedence relations])
+
+AT_DATA_GRAMMAR([[input.y]],
+[[%token TOKEN
+%precedence A
+%precedence B
+%precedence C
+%precedence D E
+
+%gprec group {
+  %precedence F
+  %precedence G
+}
+
+%precr D = E
+%precr B > A
+%precr C > B
+%precr G > F
+%precr F > A
+%precr C > group
+%precr C > F
+%%
+exp:
+  TOKEN
+| exp A exp
+| exp B exp
+| exp C exp
+| exp D exp
+| exp E exp
+| exp F exp
+| exp G exp
+]])
+
+AT_BISON_CHECK([[-Wall -o input.c input.y]], 0, [],
+[[input.y:20.10: warning: duplicate declaration of the precedence relationship D = E [-Wprecedence]
+input.y:20.10: warning: duplicate declaration of the precedence relationship E = D [-Wprecedence]
+input.y:21.10: warning: duplicate declaration of the precedence relationship B > A [-Wprecedence]
+input.y:22.10: warning: duplicate declaration of the precedence relationship C > B [-Wprecedence]
+input.y:23.10: warning: duplicate declaration of the precedence relationship G > F [-Wprecedence]
+input.y:26.10: warning: duplicate declaration of the precedence relationship C > F [-Wprecedence]
+input.y: warning: 23 shift/reduce conflicts [-Wconflicts-sr]
+]])
+
+AT_CLEANUP
+
+
+
 ## ------------------------- ##
 ## Token declaration order.  ##
 ## ------------------------- ##

tests/existing.at

@@ -484,7 +484,7 @@ dnl   - 61 -> 328: reduce -> shift on '*', '/', and '%'
 
      NAME      [reduce using rule 152 (opt_variable)]
      '$'       [reduce using rule 152 (opt_variable)]
-@@ -5379,7 +5379,7 @@
+@@ -5385,7 +5385,7 @@
    156         | . '$' non_post_simp_exp
 
      NAME  shift, and go to state 9
@@ -493,7 +493,7 @@ dnl   - 61 -> 328: reduce -> shift on '*', '/', and '%'
 
      NAME      [reduce using rule 152 (opt_variable)]
      '$'       [reduce using rule 152 (opt_variable)]
-@@ -5399,7 +5399,7 @@
+@@ -5405,7 +5405,7 @@
    156         | . '$' non_post_simp_exp
 
      NAME  shift, and go to state 9
@@ -502,7 +502,7 @@ dnl   - 61 -> 328: reduce -> shift on '*', '/', and '%'
 
      NAME      [reduce using rule 152 (opt_variable)]
      '$'       [reduce using rule 152 (opt_variable)]
-@@ -6214,7 +6214,7 @@
+@@ -6220,7 +6220,7 @@
    156         | . '$' non_post_simp_exp
 
      NAME  shift, and go to state 9
@@ -511,7 +511,7 @@ dnl   - 61 -> 328: reduce -> shift on '*', '/', and '%'
 
      NAME      [reduce using rule 152 (opt_variable)]
      '$'       [reduce using rule 152 (opt_variable)]
-@@ -11099,3 +11099,274 @@
+@@ -11117,3 +11117,274 @@
     45 statement: LEX_FOR '(' opt_exp semi opt_nls exp semi opt_nls opt_exp r_paren opt_nls statement .
 
      $default  reduce using rule 45 (statement)

tests/input.at

@@ -64,14 +64,13 @@ AT_CHECK([[$PERL -pi -e 's/\\(\d{3})/chr(oct($1))/ge' input.y || exit 77]])
 AT_BISON_CHECK([input.y], [1], [],
 [[input.y:1.1-2: error: invalid characters: '\0\001\002\377?'
 input.y:3.1: error: invalid character: '?'
-input.y:4.14: error: invalid character: '}'
+input.y:4.14: error: syntax error, unexpected }
 input.y:5.1: error: invalid character: '%'
 input.y:5.2: error: invalid character: '&'
 input.y:6.1-17: error: invalid directive: '%a-does-not-exist'
 input.y:7.1: error: invalid character: '%'
 input.y:7.2: error: invalid character: '-'
 input.y:8.1-9.0: error: missing '%}' at end of file
-input.y:8.1-9.0: error: syntax error, unexpected %{...%}
 ]])
 
 AT_CLEANUP
@@ -672,25 +671,25 @@ exp: foo;
 ]])
 
 AT_BISON_CHECK([-fcaret input.y], [1], [],
-[[input.y:8.7-11: error: %type redeclaration for foo
+[[input.y:8.7-11: error: %type redeclaration for "foo"
  %type <baz>       "foo"
        ^^^^^
 input.y:3.7-11:     previous declaration
  %type <bar>       foo
        ^^^^^
-input.y:10.13-17: error: %destructor redeclaration for foo
- %destructor {baz} "foo"
-             ^^^^^
-input.y:5.13-17:      previous declaration
- %destructor {bar} foo
-             ^^^^^
-input.y:9.10-14: error: %printer redeclaration for foo
+input.y:9.10-14: error: %printer redeclaration for "foo"
  %printer {baz}    "foo"
           ^^^^^
 input.y:4.10-14:     previous declaration
  %printer {bar}    foo
           ^^^^^
-input.y:11.1-5: error: %left redeclaration for foo
+input.y:10.13-17: error: %destructor redeclaration for "foo"
+ %destructor {baz} "foo"
+             ^^^^^
+input.y:5.13-17:      previous declaration
+ %destructor {bar} foo
+             ^^^^^
+input.y:11.1-5: error: %left redeclaration for "foo"
  %left             "foo"
  ^^^^^
 input.y:6.1-5:      previous declaration

tests/regression.at

@@ -405,14 +405,13 @@ default: 'a' }
 
 AT_BISON_CHECK([input.y], [1], [],
 [[input.y:2.1: error: invalid character: '?'
-input.y:3.14: error: invalid character: '}'
+input.y:3.14: error: syntax error, unexpected }
 input.y:4.1: error: invalid character: '%'
 input.y:4.2: error: invalid character: '&'
 input.y:5.1-17: error: invalid directive: '%a-does-not-exist'
 input.y:6.1: error: invalid character: '%'
 input.y:6.2: error: invalid character: '-'
 input.y:7.1-8.0: error: missing '%}' at end of file
-input.y:7.1-8.0: error: syntax error, unexpected %{...%}
 ]])
 
 AT_CLEANUP