--- lemon.c.orig	2020-01-10 14:08:19.181711107 +0100
+++ lemon.c	2020-01-10 14:12:00.621402133 +0100
@@ -406,6 +406,7 @@
   struct symbol *errsym;   /* The error symbol */
   struct symbol *wildcard; /* Token that matches anything */
   char *name;              /* Name of the generated parser */
+  char *namesp;            /* Surrounding namespace for generated parser */
   char *arg;               /* Declaration of the 3th argument to parser */
   char *ctx;               /* Declaration of 2nd argument to constructor */
   char *tokentype;         /* Type of terminal symbols in the parser stack */
@@ -1559,6 +1560,23 @@
   lemon_strcpy(outputDir, z);
 }
 
+/* Remember the name of the code extension (automatically prefix '.')
+*/
+static char *code_ext = NULL;
+static void handle_e_option(char *z){
+  code_ext = (char *) malloc( lemonStrlen(z)+2 );
+  if( code_ext==0 ){
+    fprintf(stderr,"out of memory\n");
+    exit(1);
+  }
+  if(*z == '.'){
+    lemon_strcpy(code_ext, z);
+  } else {
+    code_ext[0] = '.';
+    lemon_strcpy(&(code_ext[1]), z);
+  }
+}
+
 static char *user_templatename = NULL;
 static void handle_T_option(char *z){
   user_templatename = (char *) malloc( lemonStrlen(z)+1 );
@@ -1647,6 +1665,7 @@
     {OPT_FLAG, "c", (char*)&compress, "Don't compress the action table."},
     {OPT_FSTR, "d", (char*)&handle_d_option, "Output directory.  Default '.'"},
     {OPT_FSTR, "D", (char*)handle_D_option, "Define an %ifdef macro."},
+    {OPT_FSTR, "e", (char*)&handle_e_option, "Output code extension.  Default 'c'"},
     {OPT_FSTR, "f", 0, "Ignored.  (Placeholder for -f compiler options.)"},
     {OPT_FLAG, "g", (char*)&rpflag, "Print grammar without actions."},
     {OPT_FSTR, "I", 0, "Ignored.  (Placeholder for '-I' compiler options.)"},
@@ -2490,6 +2509,9 @@
         if( strcmp(x,"name")==0 ){
           psp->declargslot = &(psp->gp->name);
           psp->insertLineMacro = 0;
+        }else if( strcmp(x,"namespace")==0 ){
+          psp->declargslot = &(psp->gp->namesp);
+          psp->insertLineMacro = 0;
         }else if( strcmp(x,"include")==0 ){
           psp->declargslot = &(psp->gp->include);
         }else if( strcmp(x,"code")==0 ){
@@ -3477,20 +3499,83 @@
 #define LINESIZE 1000
 /* The next cluster of routines are for reading the template file
 ** and writing the results to the generated parser */
+
+/* Helper function to emit begin of namespace when namesp!=0
+** Converts "ns1::ns2" to "namespace ns1 { namespace ns2 {"
+*/
+PRIVATE void tplt_namespace_begin(char *namesp, FILE *out)
+{
+  if(!namesp) return;
+  while (ISSPACE(*namesp)) ++namesp;
+
+  char *cp = namesp;
+  do {
+      fprintf(out,"namespace ");
+      cp = strchr(namesp, ':');
+      if (cp) {
+          while (namesp != cp) {
+              fputc(*namesp,out);
+              ++namesp;
+          }
+          while(*namesp == ':') ++namesp;
+      }
+      else {
+          while (*namesp && !ISSPACE(*namesp)) {
+              fputc(*namesp,out);
+              ++namesp;
+          }
+      }
+      fprintf(out, " {");
+  } while (cp);
+  fputc('\n',out);
+}
+
+/* Helper function to emit end of namespace when namesp!=0
+** Converts "ns1::ns2" to "}} // End namespace"
+*/
+PRIVATE void tplt_namespace_end(char *namesp, FILE *out)
+{
+  if(!namesp) return;
+  while (ISSPACE(*namesp)) ++namesp;
+
+  char *cp = namesp;
+  do {
+      cp = strchr(cp, ':');
+      if (cp) {
+          while(*cp == ':') ++cp;
+      }
+      fputc('}',out);
+  } while (cp);
+
+  fprintf(out," // End namespace %s\n", namesp);
+}
+
 /* The first function transfers data from "in" to "out" until
 ** a line is seen which begins with "%%".  The line number is
 ** tracked.
 **
 ** if name!=0, then any word that begin with "Parse" is changed to
 ** begin with *name instead.
+**
+** if namesp!=0, then replace %namespace_begin / %namespace_end
 */
-PRIVATE void tplt_xfer(char *name, FILE *in, FILE *out, int *lineno)
+PRIVATE void tplt_xfer(char *name, char *namesp, FILE *in, FILE *out, int *lineno)
 {
   int i, iStart;
   char line[LINESIZE];
   while( fgets(line,LINESIZE,in) && (line[0]!='%' || line[1]!='%') ){
     (*lineno)++;
     iStart = 0;
+    if(line[0]=='%' && line[1]=='n'){
+      if(strncmp(&line[1],"namespace_begin",15)==0){
+        tplt_namespace_begin(namesp, out);
+        continue;
+      }else if(strncmp(&line[1],"namespace_end",13)==0){
+        tplt_namespace_end(namesp, out);
+        continue;
+      }
+    }
+
     if( name ){
       for(i=0; line[i]; i++){
         if( line[i]=='P' && strncmp(&line[i],"Parse",5)==0
@@ -4187,7 +4272,8 @@
 
   in = tplt_open(lemp);
   if( in==0 ) return;
-  out = file_open(lemp,".c","wb");
+  if(code_ext) out = file_open(lemp,code_ext,"wb");
+  else out = file_open(lemp,".c","wb");
   if( out==0 ){
     fclose(in);
     return;
@@ -4265,7 +4351,7 @@
     fprintf(sql, "COMMIT;\n");
   }
   lineno = 1;
-  tplt_xfer(lemp->name,in,out,&lineno);
+  tplt_xfer(lemp->name,lemp->namesp,in,out,&lineno);
 
   /* Generate the include code, if any */
   tplt_print(out,lemp,lemp->include,&lineno);
@@ -4274,7 +4360,7 @@
     fprintf(out,"#include \"%s\"\n", incName); lineno++;
     free(incName);
   }
-  tplt_xfer(lemp->name,in,out,&lineno);
+  tplt_xfer(lemp->name,lemp->namesp,in,out,&lineno);
 
   /* Generate #defines for all tokens */
   if( mhflag ){
@@ -4288,7 +4374,7 @@
     }
     fprintf(out,"#endif\n"); lineno++;
   }
-  tplt_xfer(lemp->name,in,out,&lineno);
+  tplt_xfer(lemp->name,lemp->namesp,in,out,&lineno);
 
   /* Generate the defines */
   fprintf(out,"#define YYCODETYPE %s\n",
@@ -4453,7 +4539,7 @@
   fprintf(out,"#define YY_MIN_REDUCE        %d\n", lemp->minReduce); lineno++;
   i = lemp->minReduce + lemp->nrule;
   fprintf(out,"#define YY_MAX_REDUCE        %d\n", i-1); lineno++;
-  tplt_xfer(lemp->name,in,out,&lineno);
+  tplt_xfer(lemp->name,lemp->namesp,in,out,&lineno);
 
   /* Now output the action table and its associates:
   **
@@ -4591,7 +4677,7 @@
     }
   }
   fprintf(out, "};\n"); lineno++;
-  tplt_xfer(lemp->name,in,out,&lineno);
+  tplt_xfer(lemp->name,lemp->namesp,in,out,&lineno);
 
   /* Generate the table of fallback tokens.
   */
@@ -4612,7 +4698,7 @@
       lineno++;
     }
   }
-  tplt_xfer(lemp->name, in, out, &lineno);
+  tplt_xfer(lemp->name,lemp->namesp, in, out, &lineno);
 
   /* Generate a table containing the symbolic name of every symbol
   */
@@ -4620,7 +4706,7 @@
     lemon_sprintf(line,"\"%s\",",lemp->symbols[i]->name);
     fprintf(out,"  /* %4d */ \"%s\",\n",i, lemp->symbols[i]->name); lineno++;
   }
-  tplt_xfer(lemp->name,in,out,&lineno);
+  tplt_xfer(lemp->name,lemp->namesp,in,out,&lineno);
 
   /* Generate a table containing a text string that describes every
   ** rule in the rule set of the grammar.  This information is used
@@ -4632,7 +4718,7 @@
     writeRuleText(out, rp);
     fprintf(out,"\",\n"); lineno++;
   }
-  tplt_xfer(lemp->name,in,out,&lineno);
+  tplt_xfer(lemp->name,lemp->namesp,in,out,&lineno);
 
   /* Generate code which executes every time a symbol is popped from
   ** the stack while processing errors or while destroying the parser.
@@ -4695,11 +4781,11 @@
     emit_destructor_code(out,lemp->symbols[i],lemp,&lineno);
     fprintf(out,"      break;\n"); lineno++;
   }
-  tplt_xfer(lemp->name,in,out,&lineno);
+  tplt_xfer(lemp->name,lemp->namesp,in,out,&lineno);
 
   /* Generate code which executes whenever the parser stack overflows */
   tplt_print(out,lemp,lemp->overflow,&lineno);
-  tplt_xfer(lemp->name,in,out,&lineno);
+  tplt_xfer(lemp->name,lemp->namesp,in,out,&lineno);
 
   /* Generate the tables of rule information.  yyRuleInfoLhs[] and
   ** yyRuleInfoNRhs[].
@@ -4712,13 +4798,13 @@
      rule_print(out, rp);
     fprintf(out," */\n"); lineno++;
   }
-  tplt_xfer(lemp->name,in,out,&lineno);
+  tplt_xfer(lemp->name,lemp->namesp,in,out,&lineno);
   for(i=0, rp=lemp->rule; rp; rp=rp->next, i++){
     fprintf(out,"  %3d,  /* (%d) ", -rp->nrhs, i);
     rule_print(out, rp);
     fprintf(out," */\n"); lineno++;
   }
-  tplt_xfer(lemp->name,in,out,&lineno);
+  tplt_xfer(lemp->name,lemp->namesp,in,out,&lineno);
 
   /* Generate code which execution during each REDUCE action */
   i = 0;
@@ -4771,19 +4857,19 @@
     }
   }
   fprintf(out,"        break;\n"); lineno++;
-  tplt_xfer(lemp->name,in,out,&lineno);
+  tplt_xfer(lemp->name,lemp->namesp,in,out,&lineno);
 
   /* Generate code which executes if a parse fails */
   tplt_print(out,lemp,lemp->failure,&lineno);
-  tplt_xfer(lemp->name,in,out,&lineno);
+  tplt_xfer(lemp->name,lemp->namesp,in,out,&lineno);
 
   /* Generate code which executes when a syntax error occurs */
   tplt_print(out,lemp,lemp->error,&lineno);
-  tplt_xfer(lemp->name,in,out,&lineno);
+  tplt_xfer(lemp->name,lemp->namesp,in,out,&lineno);
 
   /* Generate code which executes when the parser accepts its input */
   tplt_print(out,lemp,lemp->accept,&lineno);
-  tplt_xfer(lemp->name,in,out,&lineno);
+  tplt_xfer(lemp->name,lemp->namesp,in,out,&lineno);
 
   /* Append any addition code the user desires */
   tplt_print(out,lemp,lemp->extracode,&lineno);