Simple way to do BGPs
// ---- Works.
// Treats Constraint like any other not triple pattern
// which it syntactically is.  But it forms part of the BGP.

void GraphPattern(ElementGroup elg) : { Element el = null ; }
{
  BasicGraphPatternTP(elg)
  (
    If anything, loop and try for more.
    ( 
      Extends the BasicGraphPattern
      el = Constraint() { elg.addElement(el) ; }

    |
      el = GraphPatternNotTriples() { elg.addElement(el) ; }
    )
    (<DOT>)?
    GraphPattern(elg)
  )?
}

// Swallow trailing DOT.  May be empty
void BasicGraphPatternTP(ElementGroup elg) : { }
{
  (
    TriplesSameSubject(elg)
    (<DOT> (TriplesSameSubject(elg))?)*
  )?
}

--------------

With trailing dots

// |
//   // #NCCHAR
//   <#NCCHAR: (<NCCHAR1> | "_" | "-" | "." | ["0"-"9"] | "\u00B7" |
//               ["\u0300"-"\u036F"] | ["\u203F"-"\u2040"] ) >
// |
//   // NCNAME but no leading "_"
//   <#NCNAME_PREFIX: <NCCHAR1> (<NCCHAR>)*  >
// |
//   // With a leading "_"
//   <#NCNAME: ("_"|<NCCHAR1>) (<NCCHAR>)*>

---------------------------

// June 28 DAWG grammar

// Notes for the tail form:
// javacc will not know that RBRACE is always the terminating token.
// This confuses GroupOrUnionPattern

Element GroupGraphPattern() : {}
{
    { ElementGroup elg = new ElementGroup() ; }
  <LBRACE> 
    GraphPattern(elg)
  <RBRACE>
    {return elg ; }
}

void GraphPattern(ElementGroup elg) : { Element el = null ; }
{
  (Triples(elg) (<DOT>)? )?
  (
    el = GraphPatternNotTriples() { elg.addElement(el) ; }
    (<DOT>)?
    GraphPattern(elg)
  )?
}

// -----------------------------------------------
// Version in which DOT is NOT optional after a triples, 
// if anything else occurs.

Element GroupGraphPattern() : {}
{
    { ElementGroup elg = new ElementGroup() ; }
  <LBRACE> 
    GroupGraphPatternTail(elg)
  <RBRACE> 
    { return elg ; }
   
}

// Does not end in a DOT
void GroupGraphPatternTail(ElementGroup elg) : { Element el = null ;}
{
  ( 
    Triples1(elg) 
//     ( el = GraphPatternNotTriples() { elg.addElement(el) ; }
//       GroupGraphPatternTail(elg) 
//     | <DOT> GroupGraphPatternTail(elg) 
//     )?
    // Fixed DOT after triples if there is more
    (<DOT> GroupGraphPatternTail(elg) )?
  | 
    el = GraphPatternNotTriples() { elg.addElement(el) ; }
    GroupGraphPatternTail(elg)
  )?
}


// Bare patterns
// -----------------------------------------------

void WhereClause() : { Element el ; }
{
   LOOKAHEAD(2)
   <WHERE> el = QueryPattern() { getQuery().setQueryElement(el) ; }
 |
   el = GroupGraphPattern() { getQuery().setQueryElement(el) ; }
}

. . . .

Element QueryPattern() : { Element el ; }
{
//   el = GroupGraphPattern() { return el ; }

    { ElementGroup elg = new ElementGroup() ; }
    (
      el = GraphPatternNotTriples() { elg.addElement(el) ; }
      (<DOT>)?
      QueryPatternTail(elg)
    |
      Triples(elg)
      (<DOT>)?
      ( el = GraphPatternNotTriples() { elg.addElement(el) ; }
        (<DOT>)?
        QueryPatternTail(elg)
      )?
    )

    { return compressGroupOfOneGroup(elg) ; }
}