Fix peg.ebnf unit test failures

extra/peg/ebnf/ebnf.factor

@@ -49,6 +49,10 @@ C: <ebnf-var> ebnf-var
 C: <ebnf-semantic> ebnf-semantic
 C: <ebnf> ebnf
 
+: filter-hidden ( seq -- seq )
+  #! Remove elements that produce no AST from sequence
+  [ ebnf-ensure-not? not ] filter [ ebnf-ensure? not ] filter ;
+
 : syntax ( string -- parser )
   #! Parses the string, ignoring white space, and
   #! does not put the result in the AST.
@@ -139,6 +143,7 @@ C: <ebnf> ebnf
   #! non-terminal but must not be followed by a "=". 
   #! The latter indicates that it is the beginning of a
   #! new rule.
+  [
     [
       [ 
         'non-terminal' ,
@@ -146,6 +151,11 @@ C: <ebnf> ebnf
         'foreign' ,
         'range-parser' ,
         'any-character' ,
+      ] choice* 
+      [ dup , "*" token hide , ] seq* [ first <ebnf-repeat0> ] action ,
+      [ dup , "+" token hide , ] seq* [ first <ebnf-repeat1> ] action ,
+      [ dup , "?[" token ensure-not , "?" token hide , ] seq* [ first <ebnf-optional> ] action ,
+      ,
     ] choice* ,
     [
       "=" syntax ensure-not ,
@@ -153,6 +163,8 @@ C: <ebnf> ebnf
     ] choice* ,
   ] seq* [ first ] action ;
 
+DEFER: 'action'
+
 : 'element' ( -- parser )
   [
     [ ('element') , ":" syntax , "a-zA-Z" range-pattern repeat1 [ >string ] action , ] seq* [ first2 <ebnf-var> ] action ,
@@ -256,7 +268,7 @@ DEFER: 'choice'
   ] choice* ;
   
 : 'choice' ( -- parser )
-  'actioned-sequence' sp "|" token sp list-of [ 
+  'actioned-sequence' sp repeat1 [ dup length 1 = [ first ] [ <ebnf-sequence> ] if  ] action "|" token sp list-of [ 
     dup length 1 = [ first ] [ <ebnf-choice> ] if
   ] action ;
  
@@ -337,7 +349,12 @@ M: ebnf-whitespace (transform) ( ast -- parser )
 GENERIC: build-locals ( code ast -- code )
 
 M: ebnf-sequence build-locals ( code ast -- code )
-  elements>> dup [ ebnf-var? ] filter empty? [
+  #! Note the need to filter out this ebnf items that
+  #! leave nothing in the AST
+  elements>> filter-hidden dup length 1 = [ 
+    first build-locals 
+  ]  [
+    dup [ ebnf-var? ] filter empty? [
       drop 
     ] [ 
       [
@@ -354,6 +371,7 @@ M: ebnf-sequence build-locals ( code ast -- code )
           %  
           " nip ]" %     
       ] "" make 
+    ] if
   ] if ;
 
 M: ebnf-var build-locals ( code ast -- )