parser: use %empty

[bison.git] / src / parse-gram.y

diff --git a/src/parse-gram.y b/src/parse-gram.y
index f0187fb308a7e7f076a703766c132e7dbad61df0..2f66e412a0157908fdaf41a64538449b5ea9fc72 100644 (file)
--- a/src/parse-gram.y
+++ b/src/parse-gram.y
@@ -1,6 +1,6 @@
 %{/* Bison Grammar Parser                             -*- C -*-
 
-   Copyright (C) 2002-2012 Free Software Foundation, Inc.
+   Copyright (C) 2002-2013 Free Software Foundation, Inc.
 
    This file is part of Bison, the GNU Compiler Compiler.
 
@@ -40,17 +40,13 @@
 static YYLTYPE lloc_default (YYLTYPE const *, int);
 
 #define YY_LOCATION_PRINT(File, Loc) \
-          location_print (File, Loc)
+          location_print (Loc, File)
 
 static void version_check (location const *loc, char const *version);
 
-/* Request detailed syntax error messages, and pass them to GRAM_ERROR.
-   FIXME: depends on the undocumented availability of YYLLOC.  */
-#undef  yyerror
-#define yyerror(Msg) \
-        gram_error (&yylloc, Msg)
 static void gram_error (location const *, char const *);
 
+/* A string that describes a char (e.g., 'a' -> "'a'").  */
 static char const *char_name (char);
 %}
 
@@ -68,7 +64,7 @@ static char const *char_name (char);
    */
   static
   void
-  current_lhs(symbol *sym, location loc, named_ref *ref)
+  current_lhs (symbol *sym, location loc, named_ref *ref)
   {
     current_lhs_symbol = sym;
     current_lhs_location = loc;
@@ -87,15 +83,15 @@ static char const *char_name (char);
   #define YYTYPE_UINT8 uint_fast8_t
 }
 
-%verbose
-%defines
+%define api.prefix "gram_"
+%define api.pure full
 %define locations
-%define api.pure
 %define parse.error verbose
 %define parse.lac full
 %define parse.trace
-%name-prefix "gram_"
+%defines
 %expect 0
+%verbose
 
 %initial-action
 {
@@ -254,9 +250,9 @@ static char const *char_name (char);
     {
 #define CASE(In, Out)                                           \
       case param_ ## In: fputs ("%" #Out, stderr); break
-      CASE(lex,   lex-param);
-      CASE(parse, parse-param);
-      CASE(both,  param);
+      CASE (lex,   lex-param);
+      CASE (parse, parse-param);
+      CASE (both,  param);
 #undef CASE
       case param_none: aver (false); break;
     }
@@ -278,7 +274,7 @@ input:
         `------------------------------------*/
 
 prologue_declarations:
-  /* Nothing */
+  %empty
 | prologue_declarations prologue_declaration
 ;
 
@@ -317,7 +313,6 @@ prologue_declaration:
 | "%expect" INT                    { expected_sr_conflicts = $2; }
 | "%expect-rr" INT                 { expected_rr_conflicts = $2; }
 | "%file-prefix" STRING            { spec_file_prefix = $2; }
-| "%file-prefix" "=" STRING        { spec_file_prefix = $3; } /* deprecated */
 | "%glr-parser"
     {
       nondeterministic_parser = true;
@@ -334,11 +329,9 @@ prologue_declaration:
     }
 | "%language" STRING            { language_argmatch ($2, grammar_prio, @1); }
 | "%name-prefix" STRING         { spec_name_prefix = $2; }
-| "%name-prefix" "=" STRING     { spec_name_prefix = $3; } /* deprecated */
 | "%no-lines"                   { no_lines_flag = true; }
 | "%nondeterministic-parser"    { nondeterministic_parser = true; }
 | "%output" STRING              { spec_outfile = $2; }
-| "%output" "=" STRING          { spec_outfile = $3; }  /* deprecated */
 | "%param" { current_param = $1; } params { current_param = param_none; }
 | "%require" STRING             { version_check (&@2, $2); }
 | "%skeleton" STRING
@@ -437,15 +430,15 @@ code_props_type:
 %token PERCENT_UNION "%union";
 
 union_name:
-  /* Nothing. */ {}
-| ID             { muscle_code_grow ("union_name", $1, @1); }
+  %empty {}
+| ID     { muscle_code_grow ("union_name", $1, @1); }
 ;
 
 grammar_declaration:
   "%union" union_name braceless
     {
       union_seen = true;
-      muscle_code_grow ("stype", $3, @3);
+      muscle_code_grow ("union_members", $3, @3);
       code_scanner_last_string_free ();
     }
 ;
@@ -497,8 +490,8 @@ precedence_declarator:
 ;
 
 tag.opt:
-  /* Nothing. */ { current_type = NULL; }
-| TAG            { current_type = $1; tag_seen = true; }
+  %empty { current_type = NULL; }
+| TAG    { current_type = $1; tag_seen = true; }
 ;
 
 /* Just like symbols.1 but accept INT for the sake of POSIX.  */
@@ -506,7 +499,7 @@ symbols.prec:
   symbol.prec
     { $$ = symbol_list_sym_new ($1, @1); }
 | symbols.prec symbol.prec
-    { $$ = symbol_list_prepend ($1, symbol_list_sym_new ($2, @2)); }
+    { $$ = symbol_list_append ($1, symbol_list_sym_new ($2, @2)); }
 ;
 
 symbol.prec:
@@ -519,12 +512,12 @@ symbols.1:
   symbol
     { $$ = symbol_list_sym_new ($1, @1); }
 | symbols.1 symbol
-    { $$ = symbol_list_prepend ($1, symbol_list_sym_new ($2, @2)); }
+    { $$ = symbol_list_append ($1, symbol_list_sym_new ($2, @2)); }
 ;
 
 generic_symlist:
   generic_symlist_item { $$ = $1; }
-| generic_symlist generic_symlist_item { $$ = symbol_list_prepend ($1, $2); }
+| generic_symlist generic_symlist_item { $$ = symbol_list_append ($1, $2); }
 ;
 
 generic_symlist_item:
@@ -541,15 +534,15 @@ tag:
 /* One token definition.  */
 symbol_def:
   TAG
-     {
-       current_type = $1;
-       tag_seen = true;
-     }
+    {
+      current_type = $1;
+      tag_seen = true;
+    }
 | id
-     {
-       symbol_class_set ($1, current_class, @1, true);
-       symbol_type_set ($1, current_type, @1);
-     }
+    {
+      symbol_class_set ($1, current_class, @1, true);
+      symbol_type_set ($1, current_type, @1);
+    }
 | id INT
     {
       symbol_class_set ($1, current_class, @1, true);
@@ -612,8 +605,9 @@ rhses.1:
 | rhses.1 ";"
 ;
 
+%token PERCENT_EMPTY "%empty";
 rhs:
-  /* Nothing.  */
+  %empty
     { grammar_current_rule_begin (current_lhs_symbol, current_lhs_location,
                                   current_lhs_named_ref); }
 | rhs symbol named_ref.opt
@@ -622,6 +616,8 @@ rhs:
     { grammar_current_rule_action_append ($2, @2, $3, false); }
 | rhs "%?{...}"
     { grammar_current_rule_action_append ($2, @2, NULL, true); }
+| rhs "%empty"
+    { grammar_current_rule_empty_set (@2); }
 | rhs "%prec" symbol
     { grammar_current_rule_prec_set ($3, @3); }
 | rhs "%dprec" INT
@@ -631,9 +627,8 @@ rhs:
 ;
 
 named_ref.opt:
-  /* Nothing. */ { $$ = 0; }
-|
-  BRACKETED_ID   { $$ = named_ref_new($1, @1); }
+  %empty         { $$ = 0; }
+| BRACKETED_ID   { $$ = named_ref_new($1, @1); }
 ;
 
 /*---------------------------.
@@ -649,9 +644,9 @@ variable:
 
 /* Some content or empty by default. */
 content.opt:
-  /* Nothing. */   { $$ = ""; }
-| ID { $$ = $1; }
-| STRING
+  %empty    { $$ = ""; }
+| ID        { $$ = $1; }
+| STRING    { $$ = $1; }
 ;
 
 
@@ -710,7 +705,7 @@ string_as_id:
 ;
 
 epilogue.opt:
-  /* Nothing.  */
+  %empty
 | "%%" EPILOGUE
     {
       code_props plain_code;
@@ -724,7 +719,6 @@ epilogue.opt:
 
 %%
 
-
 /* Return the location of the left-hand side of a rule whose
    right-hand side is RHS[1] ... RHS[N].  Ignore empty nonterminals in
    the right-hand side, and return an empty location equal to the end