C++ comparison operators for location

[Joel E. Denny]

Akim, what do you think of this (uncommitted) patch?

Index: ChangeLog
===================================================================
RCS file: /sources/bison/bison/ChangeLog,v
retrieving revision 1.1510
diff -p -u -r1.1510 ChangeLog
--- ChangeLog   21 Jun 2006 01:37:00 -0000      1.1510
+++ ChangeLog   21 Jun 2006 05:43:10 -0000
@@ -1,3 +1,9 @@
+2006-06-21  Joel E. Denny  <address@hidden>
+
+       data/location.cc: If filename_type is std::string so that the filename
+       member of class position can be compared, add operator== and
+       operator!= to class position and to class location.
+
 2006-06-20  Joel E. Denny  <address@hidden>
 
        Don't put the pre-prologue in the header file.  For the yacc.c code
Index: data/location.cc
===================================================================
RCS file: /sources/bison/bison/data/location.cc,v
retrieving revision 1.11
diff -p -u -r1.11 location.cc
--- data/location.cc    20 Jun 2006 11:32:19 -0000      1.11
+++ data/location.cc    21 Jun 2006 05:43:12 -0000
@@ -119,7 +119,24 @@ namespace ]b4_namespace[
   {
     return begin + -width;
   }
+]m4_if(b4_filename_type, [std::string], [[
+  /// Compare two position objects.
+  inline bool
+  operator== (const position& pos1, const position& pos2)
+  {
+    return
+      (pos1.filename == pos2.filename
+       || pos1.filename && pos2.filename && *pos1.filename == *pos2.filename)
+      && pos1.line == pos2.line && pos1.column == pos2.column;
+  }
 
+  /// Compare two position objects.
+  inline bool
+  operator!= (const position& pos1, const position& pos2)
+  {
+    return !(pos1 == pos2);
+  }
+]])[
   /** \brief Intercept output stream redirection.
    ** \param ostr the destination output stream
    ** \param pos a reference to the position to redirect
@@ -224,7 +241,21 @@ namespace ]b4_namespace[
     res.columns (width);
     return res;
   }
+]m4_if(b4_filename_type, [std::string], [[
+  /// Compare two location objects.
+  inline bool
+  operator== (const location& loc1, const location& loc2)
+  {
+    return loc1.begin == loc2.begin && loc1.end == loc2.end;
+  }
 
+  /// Compare two location objects.
+  inline bool
+  operator!= (const location& loc1, const location& loc2)
+  {
+    return !(loc1 == loc2);
+  }
+]])[
   /** \brief Intercept output stream redirection.
    ** \param ostr the destination output stream
    ** \param loc a reference to the location to redirect