[PATCH 5/5] glr.cc: support syntax_error exceptions

[Akim Demaille]

Kindly requested by Аскар Сафин (Askar Safin).
http://lists.gnu.org/archive/html/bug-bison/2018-12/msg00033.html

* data/skeletons/glr.c (b4_glr_cc_if): New.
Use it.
(yygetToken): Catch syntax_errors.
* data/skeletons/glr.cc (YY_EXCEPTIONS): New.
* tests/c++.at: Check it.
---
 NEWS                  |  5 +++++
 THANKS                |  1 -
 TODO                  |  5 +++++
 data/skeletons/glr.c  | 41 +++++++++++++++++++++++++++++++++++++----
 data/skeletons/glr.cc | 12 ++++++++++--
 tests/c++.at          |  1 +
 6 files changed, 58 insertions(+), 7 deletions(-)

diff --git a/NEWS b/NEWS
index 49cc24c8..1e253c0f 100644
--- a/NEWS
+++ b/NEWS
@@ -147,6 +147,11 @@ GNU Bison NEWS
       return parser::token::PAIR;
     }
 
+*** C++: Syntax error exceptions in GLR
+
+  The glr.cc skeleton now supports syntax_error exceptions thrown from user
+  actions, or from the scanner.
+
 *** More POSIX Yacc compatibility warnings
 
   More Bison specific directives are now reported with -y or -Wyacc.  This
diff --git a/TODO b/TODO
index 342d2917..a5c068a8 100644
--- a/TODO
+++ b/TODO
@@ -108,6 +108,11 @@ since it is no longer bound to a particular parser, it's 
just a
 as lr0.cc, why upper case?
 
 * Various
+** Rewrite glr.cc in C++
+As a matter of fact, it would be very interesting to see how much we can
+share between lalr1.cc and glr.cc.  Most of the skeletons should be common.
+It would be a very nice source of inspiration for the other languages.
+
 ** YYERRCODE
 Defined to 256, but not used, not documented.  Probably the token
 number for the error token, which POSIX wants to be 256, but which
diff --git a/data/skeletons/glr.c b/data/skeletons/glr.c
index 868e96f0..4c97f806 100644
--- a/data/skeletons/glr.c
+++ b/data/skeletons/glr.c
@@ -23,6 +23,10 @@
 m4_if(b4_skeleton, ["glr.c"],
       [m4_include(b4_skeletonsdir/[c.m4])])
 
+m4_define([b4_glr_cc_if],
+          [m4_if(b4_skeleton, ["glr.cc"], [$1], [$2])])
+
+
 ## ---------------- ##
 ## Default values.  ##
 ## ---------------- ##
@@ -193,7 +197,7 @@ m4_if(b4_skeleton, ["glr.c"],
 # ----------------- #
 
 # glr.cc produces its own header.
-m4_if(b4_skeleton, ["glr.c"],
+b4_glr_cc_if([],
 [b4_defines_if(
 [b4_output_begin([b4_spec_defines_file])
 b4_copyright([Skeleton interface for Bison GLR parsers in C],
@@ -769,8 +773,23 @@ yygetToken (int *yycharp][]b4_pure_if([, yyGLRStack* 
yystackp])[]b4_user_formals
 ]b4_parse_param_use()dnl
 [  if (*yycharp == YYEMPTY)
     {
-      YYDPRINTF ((stderr, "Reading a token: "));
-      *yycharp = ]b4_lex[;
+      YYDPRINTF ((stderr, "Reading a token: "));]b4_glr_cc_if([[
+#if YY_EXCEPTIONS
+      try
+        {
+#endif // YY_EXCEPTIONS
+          *yycharp = ]b4_lex[;
+#if YY_EXCEPTIONS
+        }
+      catch (const ]b4_namespace_ref[::]b4_parser_class_name[::syntax_error& 
yyexc)
+        {]b4_locations_if([
+          yylloc = yyexc.location;])[
+          yyerror (]b4_lyyerror_args[yyexc.what ());
+          // Map to the undef token.
+          *yycharp = YYMAXUTOK + 1;
+        }
+#endif // YY_EXCEPTIONS]], [[
+      *yycharp = ]b4_lex[;]])[
     }
   if (*yycharp <= YYEOF)
     {
@@ -842,12 +861,26 @@ yyuserAction (yyRuleNum yyn, int yyrhslen, 
yyGLRStackItem* yyvsp,
   /* Default location. */
   YYLLOC_DEFAULT ((*yylocp), (yyvsp - yyrhslen), yyrhslen);
   yystackp->yyerror_range[1].yystate.yyloc = *yylocp;
-]])[
+]])[]b4_glr_cc_if([[
+#if YY_EXCEPTIONS
+  typedef ]b4_namespace_ref[::]b4_parser_class_name[::syntax_error 
syntax_error;
+  try
+  {
+#endif // YY_EXCEPTIONS]])[
   switch (yyn)
     {
 ]b4_user_actions[
       default: break;
+    }]b4_glr_cc_if([[
+#if YY_EXCEPTIONS
+  }
+  catch (const syntax_error& yyexc)
+    {]b4_locations_if([
+      *yylocp = yyexc.location;])[
+      yyerror (]b4_yyerror_args[yyexc.what ());
+      YYERROR;
     }
+#endif // YY_EXCEPTIONS]])[
 
   return yyok;
 # undef yyerrok
diff --git a/data/skeletons/glr.cc b/data/skeletons/glr.cc
index c9c4acda..b5b0dba2 100644
--- a/data/skeletons/glr.cc
+++ b/data/skeletons/glr.cc
@@ -163,8 +163,7 @@ m4_pushdef([b4_parse_param], 
m4_defn([b4_parse_param_orig]))dnl
   }
 
   ]b4_parser_class_name::~b4_parser_class_name[ ()
-  {
-  }
+  {}
 
   int
   ]b4_parser_class_name[::operator() ()
@@ -257,6 +256,15 @@ b4_percent_code_get([[requires]])[
 
 ]b4_null_define[
 
+// Whether we are compiled with exception support.
+#ifndef YY_EXCEPTIONS
+# if defined __GNUC__ && !defined __EXCEPTIONS
+#  define YY_EXCEPTIONS 0
+# else
+#  define YY_EXCEPTIONS 1
+# endif
+#endif
+
 ]b4_YYDEBUG_define[
 
 ]b4_namespace_open[
diff --git a/tests/c++.at b/tests/c++.at
index 4dd39bc7..c2b892bc 100644
--- a/tests/c++.at
+++ b/tests/c++.at
@@ -1020,6 +1020,7 @@ AT_CLEANUP
 ])
 
 AT_TEST([%skeleton "lalr1.cc"])
+AT_TEST([%skeleton "glr.cc"])
 
 m4_popdef([AT_TEST])
 
-- 
2.20.0