Improve C++ namespace support. Discussed starting at

<http://lists.gnu.org/archive/html/help-bison/2007-09/msg00016.html>. * data/c++.m4: (b4_namespace_ref, b4_namespace_open, b4_namespace_close): New macros that interpret the %define variable "namespace" so its value can contain "::" to indicate nested namespaces. * data/glr.cc (b4_namespace): Don't define, and replace all uses with the above macros. * data/lalr1.cc (b4_namespace): Likewise. * data/location.cc (b4_namespace): Likewise. * doc/bison.texinfo (Decl Summary): Move `%define push_pull' entry inside a new table in the general %define entry. Document `%define namespace' there as well. Point the %name-prefix entry to it since it explains it more completely in the case of C++. (C++ Bison Interface): Mention `%define namespace' instead of %name-prefix. (Table of Symbols): Remove the `%define push_pull' entry. The %define entry suffices. * tests/c++.at (Relative namespace references): New test case. (Absolute namespace references): New test case. (Syntactically invalid namespace references): New test case. * tests/input.at (C++ namespace reference errors): New test case.
2026-03-10 21:03:04 +00:00 · 2007-10-08 10:09:07 +00:00
parent 35b8730d01
commit 793fbca50a
8 changed files with 309 additions and 63 deletions
--- a/data/c++.m4
+++ b/data/c++.m4
@@ -35,6 +35,51 @@ b4_percent_define_default([[define_location_comparison]],
                                 [std::string], [[true]], [[false]])])


+## ----------- ##
+## Namespace.  ##
+## ----------- ##
+
+m4_define([b4_namespace_ref], [b4_percent_define_get([[namespace]])])
+
+# Don't permit an empty b4_namespace_ref.  Any `::parser::foo' appended to it
+# would compile as an absolute reference with `parser' in the global namespace.
+# b4_namespace_open would open an anonymous namespace and thus establish
+# internal linkage.  This would compile.  However, it's cryptic, and internal
+# linkage for the parser would be specified in all translation units that
+# include the header, which is always generated.  If we ever need to permit
+# internal linkage somehow, surely we can find a cleaner approach.
+m4_if(m4_bregexp(b4_namespace_ref, [^[	 ]*$]), [-1], [],
+[b4_complain_at(b4_percent_define_get_loc([[namespace]]),
+                [[namespace reference is empty]])])
+
+# Instead of assuming the C++ compiler will do it, Bison should reject any
+# invalid b4_namepsace_ref that would be converted to a valid
+# b4_namespace_open.  The problem is that Bison doesn't always output
+# b4_namespace_ref to uncommented code but should reserve the ability to do so
+# in future releases without risking breaking any existing user grammars.
+# Specifically, don't allow empty names as b4_namespace_open would just convert
+# those into anonymous namespaces, and that might tempt some users.
+m4_if(m4_bregexp(b4_namespace_ref, [::[	 ]*::]), [-1], [],
+[b4_complain_at(b4_percent_define_get_loc([[namespace]]),
+                [[namespace reference has consecutive "::"]])])
+m4_if(m4_bregexp(b4_namespace_ref, [::[	 ]*$]), [-1], [],
+[b4_complain_at(b4_percent_define_get_loc([[namespace]]),
+                [[namespace reference has a trailing "::"]])])
+
+m4_define([b4_namespace_open],
+[b4_user_code([b4_percent_define_get_syncline([[namespace]])
+[namespace ]m4_bpatsubst(m4_dquote(m4_bpatsubst(m4_dquote(b4_namespace_ref),
+                                                [^\(.\)[	 ]*::], [\1])),
+                         [::], [ { namespace ])[ {]])])
+
+m4_define([b4_namespace_close],
+[b4_user_code([b4_percent_define_get_syncline([[namespace]])
+m4_bpatsubst(m4_dquote(m4_bpatsubst(m4_dquote(b4_namespace_ref),
+                                    [^\(.\)[	 ]*\(::\)?\([^][:]\|:[^][:]\)*],
+                                    [\1])),
+             [::\([^][:]\|:[^][:]\)*], [} ])[} // ]b4_namespace_ref])])
+
+
 # b4_token_enums(LIST-OF-PAIRS-TOKEN-NAME-TOKEN-NUMBER)
 # -----------------------------------------------------
 # Output the definition of the tokens as enums.
--- a/data/glr.cc
+++ b/data/glr.cc
@@ -58,8 +58,6 @@ m4_include(b4_pkgdatadir/[location.cc])

 m4_define([b4_parser_class_name],
          [b4_percent_define_get([[parser_class_name]])])
-m4_define([b4_namespace],
-          [b4_percent_define_get([[namespace]])])

 # Save the parse parameters.
 m4_define([b4_parse_param_orig], m4_defn([b4_parse_param]))
@@ -79,9 +77,9 @@ m4_define([b4_yy_symbol_print_generate],
    [static void],
    [[FILE *],               []],
    [[int yytype],           [yytype]],
-    [[const b4_namespace::b4_parser_class_name::semantic_type *yyvaluep],
+    [[const b4_namespace_ref::b4_parser_class_name::semantic_type *yyvaluep],
 			     [yyvaluep]],
-    [[const b4_namespace::b4_parser_class_name::location_type *yylocationp],
+    [[const b4_namespace_ref::b4_parser_class_name::location_type *yylocationp],
 			     [yylocationp]],
    b4_parse_param)[
 {
@@ -97,7 +95,7 @@ m4_append([b4_post_prologue],

 b4_c_ansi_function_decl([yyerror],
    [static void],
-    [[b4_namespace::b4_parser_class_name::location_type *yylocationp], [yylocationp]],
+    [[b4_namespace_ref::b4_parser_class_name::location_type *yylocationp], [yylocationp]],
    b4_parse_param,
    [[const char* msg], [msg]])])

@@ -111,7 +109,7 @@ m4_append([b4_epilogue],

 ]b4_c_ansi_function_def([yyerror],
    [static void],
-    [[b4_namespace::b4_parser_class_name::location_type *yylocationp], [yylocationp]],
+    [[b4_namespace_ref::b4_parser_class_name::location_type *yylocationp], [yylocationp]],
    b4_parse_param,
    [[const char* msg], [msg]])[
 {
@@ -120,8 +118,7 @@ m4_append([b4_epilogue],
 }


-namespace ]b4_namespace[
-{
+]b4_namespace_open[
 ]dnl In this section, the parse param are the original parse_params.
 m4_pushdef([b4_parse_param], m4_defn([b4_parse_param_orig]))dnl
 [  /// Build a parser object.
@@ -203,7 +200,7 @@ m4_pushdef([b4_parse_param], m4_defn([b4_parse_param_orig]))dnl

 #endif
 ]m4_popdef([b4_parse_param])dnl
-[} // namespace ]b4_namespace[
+b4_namespace_close[

 ]])

@@ -211,10 +208,10 @@ m4_pushdef([b4_parse_param], m4_defn([b4_parse_param_orig]))dnl
 # Let glr.c believe that the user arguments include the parser itself.
 m4_ifset([b4_parse_param],
 [m4_pushdef([b4_parse_param],
-	    m4_dquote([[[b4_namespace::b4_parser_class_name& yyparser], [[yyparser]]],]
+	    m4_dquote([[[b4_namespace_ref::b4_parser_class_name& yyparser], [[yyparser]]],]
 m4_defn([b4_parse_param])))],
 [m4_pushdef([b4_parse_param],
-	    [[[[b4_namespace::b4_parser_class_name& yyparser], [[yyparser]]]]])
+	    [[[[b4_namespace_ref::b4_parser_class_name& yyparser], [[yyparser]]]]])
 ])
 m4_include(b4_pkgdatadir/[glr.c])
 m4_popdef([b4_parse_param])
@@ -237,11 +234,10 @@ b4_copyright([Skeleton interface for Bison GLR parsers in C++],
 /* Using locations.  */
 #define YYLSP_NEEDED ]b4_locations_flag[

-namespace ]b4_namespace[
-{
+]b4_namespace_open[
  class position;
  class location;
-}
+]b4_namespace_close[

 #include "location.hh"

@@ -269,8 +265,7 @@ namespace ]b4_namespace[
    while (/*CONSTCOND*/ 0)
 #endif

-namespace ]b4_namespace[
-{
+]b4_namespace_open[
  /// A Bison parser.
  class ]b4_parser_class_name[
  {
@@ -368,13 +363,13 @@ b4_percent_define_flag_if([[global_tokens_and_yystype]],
 [b4_token_defines(b4_tokens)])
 [
 #ifndef YYSTYPE
-# define YYSTYPE ]b4_namespace[::]b4_parser_class_name[::semantic_type
+# define YYSTYPE ]b4_namespace_ref[::]b4_parser_class_name[::semantic_type
 #endif
 #ifndef YYLTYPE
-# define YYLTYPE ]b4_namespace[::]b4_parser_class_name[::location_type
+# define YYLTYPE ]b4_namespace_ref[::]b4_parser_class_name[::location_type
 #endif

-}
+]b4_namespace_close[

 ]b4_percent_code_get([[provides]])[]dnl

--- a/data/lalr1.cc
+++ b/data/lalr1.cc
@@ -20,8 +20,6 @@ m4_include(b4_pkgdatadir/[c++.m4])

 m4_define([b4_parser_class_name],
          [b4_percent_define_get([[parser_class_name]])])
-m4_define([b4_namespace],
-          [b4_percent_define_get([[namespace]])])

 # The header is mandatory.
 b4_defines_if([],
@@ -51,11 +49,10 @@ dnl FIXME: This is wrong, we want computed header guards.
 #include <iostream>
 #include "stack.hh"

-namespace ]b4_namespace[
-{
+]b4_namespace_open[
  class position;
  class location;
-}
+]b4_namespace_close[

 #include "location.hh"

@@ -96,8 +93,7 @@ do {							\
 } while (false)
 #endif

-namespace ]b4_namespace[
-{
+]b4_namespace_open[

  /// A Bison parser.
  class ]b4_parser_class_name[
@@ -286,14 +282,14 @@ b4_error_verbose_if([, int tok])[);
    static const token_number_type yyundef_token_;
 ]b4_parse_param_vars[
  };
-}
+]b4_namespace_close[

 ]b4_percent_define_flag_if([[global_tokens_and_yystype]],
 [b4_token_defines(b4_tokens)

 #ifndef YYSTYPE
 /* Redirection for backward compatibility.  */
-# define YYSTYPE b4_namespace::b4_parser_class_name::semantic_type
+# define YYSTYPE b4_namespace_ref::b4_parser_class_name::semantic_type
 #endif
 ])
 b4_percent_code_get([[provides]])[]dnl
@@ -375,8 +371,7 @@ do {					\
 #define YYABORT		goto yyabortlab
 #define YYERROR		goto yyerrorlab

-namespace ]b4_namespace[
-{
+]b4_namespace_open[
 #if YYERROR_VERBOSE

  /* Return YYSTR after stripping away unnecessary quotes and
@@ -1049,7 +1044,7 @@ b4_error_verbose_if([, int tok])[)
  const unsigned int ]b4_parser_class_name[::yyuser_token_number_max_ = ]b4_user_token_number_max[;
  const ]b4_parser_class_name[::token_number_type ]b4_parser_class_name[::yyundef_token_ = ]b4_undef_token_number[;

-} // namespace ]b4_namespace[
+]b4_namespace_close[

 ]b4_epilogue
 dnl
@@ -1062,8 +1057,7 @@ b4_copyright([Stack handling for Bison parsers in C++],

 #include <deque>

-namespace ]b4_namespace[
-{
+]b4_namespace_open[
  template <class T, class S = std::deque<T> >
  class stack
  {
@@ -1149,7 +1143,7 @@ namespace ]b4_namespace[
    const S& stack_;
    unsigned int range_;
  };
-}
+]b4_namespace_close[

 #endif // not BISON_STACK_HH]
 m4_divert_pop(0)
--- a/data/location.cc
+++ b/data/location.cc
@@ -25,7 +25,7 @@ b4_copyright([Positions for Bison parsers in C++],

 /**
 ** \file position.hh
- ** Define the ]b4_percent_define_get([[namespace]])[::position class.
+ ** Define the ]b4_namespace_ref[::position class.
 */

 #ifndef BISON_POSITION_HH
@@ -35,8 +35,7 @@ b4_copyright([Positions for Bison parsers in C++],
 # include <string>
 # include <algorithm>

-namespace ]b4_percent_define_get([[namespace]])[
-{
+]b4_namespace_open[
  /// Abstract a position.
  class position
  {
@@ -142,7 +141,7 @@ namespace ]b4_percent_define_get([[namespace]])[
    return ostr << pos.line << '.' << pos.column;
  }

-}
+]b4_namespace_close[
 #endif // not BISON_POSITION_HH]
@output(b4_dir_prefix[]location.hh@)
 b4_copyright([Locations for Bison parsers in C++],
@@ -150,7 +149,7 @@ b4_copyright([Locations for Bison parsers in C++],

 /**
 ** \file location.hh
- ** Define the ]b4_percent_define_get([[namespace]])[::location class.
+ ** Define the ]b4_namespace_ref[::location class.
 */

 #ifndef BISON_LOCATION_HH
@@ -160,8 +159,7 @@ b4_copyright([Locations for Bison parsers in C++],
 # include <string>
 # include "position.hh"

-namespace ]b4_percent_define_get([[namespace]])[
-{
+]b4_namespace_open[

  /// Abstract a location.
  class location
@@ -270,7 +268,7 @@ namespace ]b4_percent_define_get([[namespace]])[
    return ostr;
  }

-}
+]b4_namespace_close[

 #endif // not BISON_LOCATION_HH]
 m4_divert_pop(0)