more %define front-end support

[Joel E. Denny]

I committed the following.  I'm using it in my LR(1) work, and I believe 
it'll prove useful in general.

Index: ChangeLog
===================================================================
RCS file: /sources/bison/bison/ChangeLog,v
retrieving revision 1.1698
diff -p -u -r1.1698 ChangeLog
--- ChangeLog   8 May 2007 05:03:53 -0000       1.1698
+++ ChangeLog   20 May 2007 03:24:51 -0000
@@ -1,3 +1,24 @@
+2007-05-20  Joel E. Denny  <address@hidden>
+
+       Extend the front-end API for %define variables to more completely
+       mirror the back-end.  This will be useful in the future.
+       * data/bison.m4 (b4_percent_define_get, b4_percent_define_ifdef):
+       Update comments to mention the new front-end counterparts of these
+       macros.
+       * src/muscle_tab.c (MUSCLE_COMMON_DECODE): New macro with common code
+       for muscle_string_decode and muscle_location_decode.
+       (muscle_string_decode): New static function.
+       (muscle_location_decode): Use MUSCLE_COMMON_DECODE.
+       (muscle_percent_define_get, muscle_percent_define_ifdef): New
+       functions.
+       (muscle_percent_define_flag_if): Use muscle_percent_define_ifdef and
+       muscle_percent_define_get to mimic the b4_percent_define_flag_if
+       implementation more closely.
+       (muscle_percent_define_invalid_value): New function.
+       * src/muscle_tab.h (muscle_percent_define_get,
+       muscle_percent_define_ifdef, muscle_percent_define_invalid_value):
+       Prototype.
+
 2007-05-07  Joel E. Denny  <address@hidden>
 
        * NEWS (2.3a+): Mention yesterday's state-removal change.
Index: data/bison.m4
===================================================================
RCS file: /sources/bison/bison/data/bison.m4,v
retrieving revision 1.17
diff -p -u -r1.17 bison.m4
--- data/bison.m4       2 Mar 2007 06:26:28 -0000       1.17
+++ data/bison.m4       20 May 2007 03:24:51 -0000
@@ -338,7 +338,8 @@ m4_popdef([b4_end])dnl
 
 # b4_percent_define_get(VARIABLE)
 # -------------------------------
-# If the %define variable VARIABLE is defined, emit its value.  Also, record
+# Mimic muscle_percent_define_get in ../src/muscle_tab.h exactly.  That is, if
+# the %define variable VARIABLE is defined, emit its value.  Also, record
 # Bison's usage of VARIABLE by defining
 # b4_percent_define_bison_variables(VARIABLE).
 #
@@ -351,7 +352,8 @@ m4_ifdef([b4_percent_define(]$1[)], [m4_
 
 # b4_percent_define_ifdef(VARIABLE, IF-TRUE, [IF-FALSE])
 # ------------------------------------------------------
-# If the %define variable VARIABLE is defined, expand IF-TRUE, else expand
+# Mimic muscle_percent_define_ifdef in ../src/muscle_tab.h exactly.  That is,
+# if the %define variable VARIABLE is defined, expand IF-TRUE, else expand
 # IF-FALSE.  Also, record Bison's usage of VARIABLE by defining
 # b4_percent_define_bison_variables(VARIABLE).
 #
Index: src/muscle_tab.c
===================================================================
RCS file: /sources/bison/bison/src/muscle_tab.c,v
retrieving revision 1.47
diff -p -u -r1.47 muscle_tab.c
--- src/muscle_tab.c    2 Mar 2007 06:26:28 -0000       1.47
+++ src/muscle_tab.c    20 May 2007 03:24:52 -0000
@@ -275,6 +275,52 @@ muscle_location_grow (char const *key, l
   muscle_grow (key, "]]", "");
 }
 
+#define MUSCLE_COMMON_DECODE(Value)                                           \
+  case '$':                                                                   \
+    aver (*++(Value) == ']');                                                 \
+    aver (*++(Value) == '[');                                                 \
+    obstack_sgrow (&muscle_obstack, "$");                                     \
+    break;                                                                    \
+  case '@':                                                                   \
+    switch (*++(Value))                                                       \
+      {                                                                       \
+        case '@': obstack_sgrow (&muscle_obstack, "@" ); break;               \
+        case '{': obstack_sgrow (&muscle_obstack, "[" ); break;               \
+        case '}': obstack_sgrow (&muscle_obstack, "]" ); break;               \
+        default: aver (false); break;                                         \
+      }                                                                       \
+    break;                                                                    \
+  default:                                                                    \
+    obstack_1grow (&muscle_obstack, *(Value));                                \
+    break;
+
+/* Reverse of MUSCLE_OBSTACK_SGROW.  */
+static char *
+muscle_string_decode (char const *key)
+{
+  char const *value;
+  char *value_decoded;
+  char *result;
+
+  value = muscle_find_const (key);
+  if (!value)
+    return NULL;
+  do {
+    switch (*value)
+      {
+        MUSCLE_COMMON_DECODE (value)
+        case '[':
+        case ']':
+          aver (false);
+          break;
+      }
+  } while (*value++);
+  value_decoded = obstack_finish (&muscle_obstack);
+  result = xstrdup (value_decoded);
+  obstack_free (&muscle_obstack, value_decoded);
+  return result;
+}
+
 /* Reverse of muscle_location_grow.  */
 static location
 muscle_location_decode (char const *key)
@@ -287,20 +333,7 @@ muscle_location_decode (char const *key)
   while (*++value)
     switch (*value)
       {
-        case '$':
-          aver (*++value == ']');
-          aver (*++value == '[');
-          obstack_sgrow (&muscle_obstack, "$");
-          break;
-        case '@':
-          switch (*++value)
-            {
-              case '@': obstack_sgrow (&muscle_obstack, "@" ); break;
-              case '{': obstack_sgrow (&muscle_obstack, "[" ); break;
-              case '}': obstack_sgrow (&muscle_obstack, "]" ); break;
-              default: aver (false); break;
-            }
-          break;
+        MUSCLE_COMMON_DECODE (value)
         case '[':
           aver (false);
           break;
@@ -330,9 +363,6 @@ muscle_location_decode (char const *key)
               }
           }
           break;
-        default:
-          obstack_1grow (&muscle_obstack, *value);
-          break;
       }
   aver (false);
   return loc;
@@ -385,13 +415,51 @@ muscle_percent_define_insert (char const
                               variable_loc);
 }
 
+char *
+muscle_percent_define_get (char const *variable)
+{
+  char const *name;
+  char const *usage_name;
+  char *value;
+
+  MUSCLE_USER_NAME_CONVERT (name, "percent_define(", variable, ")");
+  MUSCLE_USER_NAME_CONVERT (usage_name, "percent_define_bison_variables(",
+                            variable, ")");
+
+  muscle_insert (usage_name, "");
+  value = muscle_string_decode (name);
+  if (!value)
+    value = xstrdup ("");
+  return value;
+}
+
+bool
+muscle_percent_define_ifdef (char const *variable)
+{
+  char const *name;
+  char const *usage_name;
+  char const *value;
+
+  MUSCLE_USER_NAME_CONVERT (name, "percent_define(", variable, ")");
+  MUSCLE_USER_NAME_CONVERT (usage_name, "percent_define_bison_variables(",
+                            variable, ")");
+
+  value = muscle_find_const (name);
+  if (value)
+    {
+      muscle_insert (usage_name, "");
+      return true;
+    }
+
+  return false;
+}
+
 bool
 muscle_percent_define_flag_if (char const *variable)
 {
   char const *name;
   char const *loc_name;
   char const *usage_name;
-  char const *value;
   bool result = false;
 
   MUSCLE_USER_NAME_CONVERT (name, "percent_define(", variable, ")");
@@ -399,9 +467,9 @@ muscle_percent_define_flag_if (char cons
   MUSCLE_USER_NAME_CONVERT (usage_name, "percent_define_bison_variables(",
                             variable, ")");
 
-  value = muscle_find_const (name);
-  if (value)
+  if (muscle_percent_define_ifdef (variable))
     {
+      char *value = muscle_percent_define_get (variable);
       if (value[0] == '\0' || 0 == strcmp (value, "true"))
         result = true;
       else if (0 == strcmp (value, "false"))
@@ -410,13 +478,12 @@ muscle_percent_define_flag_if (char cons
         complain_at(muscle_location_decode (loc_name),
                     _("invalid value for %%define boolean variable `%s'"),
                     variable);
+      free (value);
     }
   else
     fatal(_("undefined %%define variable `%s' passed to 
muscle_percent_define_flag_if"),
           variable);
 
-  muscle_insert (usage_name, "");
-
   return result;
 }
 
@@ -440,6 +507,16 @@ muscle_percent_define_default (char cons
 }
 
 void
+muscle_percent_define_invalid_value (char const *variable)
+{
+  char const *loc_name;
+  MUSCLE_USER_NAME_CONVERT (loc_name, "percent_define_loc(", variable, ")");
+  complain_at(muscle_location_decode (loc_name),
+              _("invalid value for %%define variable `%s'"), variable);
+}
+
+
+void
 muscle_percent_code_grow (char const *qualifier, location qualifier_loc,
                           char const *code, location code_loc)
 {
Index: src/muscle_tab.h
===================================================================
RCS file: /sources/bison/bison/src/muscle_tab.h,v
retrieving revision 1.25
diff -p -u -r1.25 muscle_tab.h
--- src/muscle_tab.h    2 Mar 2007 06:26:28 -0000       1.25
+++ src/muscle_tab.h    20 May 2007 03:24:52 -0000
@@ -131,6 +131,19 @@ void muscle_user_name_list_grow (char co
 void muscle_percent_define_insert (char const *variable, location variable_loc,
                                    char const *value);
 
+/* Mimic b4_percent_define_get in ../data/bison.m4 exactly.  That is, if the
+   %define variable VARIABLE is defined, return its value.  Otherwise, return
+   the empty string.  Also, record Bison's usage of VARIABLE by defining
+   b4_percent_define_bison_variables(VARIABLE).  The caller is responsible for
+   freeing the memory of the returned string.  */
+char *muscle_percent_define_get (char const *variable);
+
+/* Mimic b4_percent_define_ifdef in ../data/bison.m4 exactly.  That is, if the
+   %define variable VARIABLE is defined, return true.  Otherwise, return false.
+   Also, record Bison's usage of VARIABLE by defining
+   b4_percent_define_bison_variables(VARIABLE).  */
+bool muscle_percent_define_ifdef (char const *variable);
+
 /* Mimic b4_percent_define_flag_if in ../data/bison.m4 exactly.  That is, if
    the %define variable VARIABLE is defined to "" or "true", return true.  If
    it is defined to "false", return false.  Complain if it is undefined (a
@@ -145,6 +158,10 @@ bool muscle_percent_define_flag_if (char
    suspect that the value has yet influenced the output.  */
 void muscle_percent_define_default (char const *variable, char const *value);
 
+/* Complain that the value set for the %define variable VARIABLE is
+   invalid.  */
+void muscle_percent_define_invalid_value (char const *variable);
+
 /* Grow the muscle for the %code qualifier QUALIFIER appearing at QUALIFIER_LOC
    in the grammar file with code CODE appearing at CODE_LOC.  Record this as a
    grammar occurrence of VARIABLE by invoking muscle_user_name_list_grow.  */