//规则：Robert 和 John 是男性
public static Expression getMaleExpression()
{
Expression robert = new TerminalExpression("Robert");
Expression john = new TerminalExpression("John");
return(new OrExpression(robert, john));
}
//规则：Julie 是一个已婚的女性
public static Expression getMarriedWomanExpression()
{
Expression julie = new TerminalExpression("Julie");
Expression married = new TerminalExpression("Married");
return(new AndExpression(julie, married));
}
public Context()
{
Expression city = new TerminalExpression(citys);
Expression person = new TerminalExpression(persons);
cityPerson = new NonTerminalExpression(city, person);
}