// <Expression> ::= <Term> { "|" <Term> } .
private void ParseExpression()
{
ParseAction();
_astBuilder.BeginExpression(_scanner.CurrentToken);
ParseTerm();
while (_scanner.CurrentToken.TokenKind == TokenKind.Or)
{
_scanner.Advance();
ParseTerm();
}
ParseAction();
_astBuilder.EndExpression();
}