private BooleanExpression ParseSimpleExpression()
{
BooleanExpression expression = null;
switch (this.token)
{
case TokenType.LeftParenthesis:
this.MoveNext();
BooleanExpression c = this.ParseOrOperator();
this.AssertTokenType(TokenType.RightParenthesis);
expression = c;
break;
case TokenType.Identity:
this.MoveNext();
expression = new IdentityExpression(this.ParseWordExpression());
break;
case TokenType.Role:
this.MoveNext();
expression = new RoleExpression(this.ParseWordExpression());
break;
case TokenType.Not:
this.MoveNext();
expression = new NotOperator(this.ParseOrOperator());
break;
default:
TokenType[] types = new TokenType[]
{
TokenType.LeftParenthesis,
TokenType.Identity,
TokenType.Role,
TokenType.Not
};
throw new SyntaxException(
SR.UnexpectedTokenMessage(
ConcatTokenNames(types),
this.lexer.Current,
this.GetIndex()),
this.GetIndex());
}
return expression;
}