namespace DesignPattern.Interpreter
   {
 public abstract class Expression
  {
public abstract bool Interpret();
 }
 public class Constant : Expression
{
private bool m_val;
public Constant(bool val)
{
this.m_val=val;
}
public override bool Interpret()
{
return this.m_val;
}
public override string ToString()
{
return this.m_val.ToString();
}
}
public class And : Expression
{
public Expression left,right;
public And(Expression left,Expression right)
{
this.left=left;
this.right=right;
}
public override bool Interpret()
{
return left.Interpret()&&right.Interpret();
}
public override string ToString()
{
return "("+this.left.ToString()+" && "+this.right.ToString()+")";
}
}
public class Or : Expression
{
public Expression left,right;
public Or(Expression left,Expression right)
{
this.left=left;
this.right=right;
}
public override bool Interpret()
{
return left.Interpret()||right.Interpret();
}
public override string ToString()
{
return "("+this.left.ToString()+" || "+this.right.ToString()+")";
}
}
public class Not : Expression
{
private Expression exp;
public Not(Expression exp)
{
this.exp=exp;
}
public override bool Interpret()
{
return !exp.Interpret();
}
public override string ToString()
{
return "(! "+exp.ToString()+")";
}
}
public class Client
{
public static void Main()
{
Expression exp=new Or(new And(new Constant(true),new Constant(false)),
new And(new Constant(true),new Not(new Constant(false))));
Console.WriteLine(exp.ToString()+"="+exp.Interpret());
}
}
}
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