derive.java

symbman（大学作业）

public class Derive extends Expression {

	private Expression e;
	private Symbol s;
	
	public Derive(Expression e, Symbol s) {
		this.e = (Expression)e.clone();
		this.s = (Symbol)s.clone();
	}
	
	public Expression getExpression() { return e; }
	
	public Symbol getSymbol() { return s; }
	
	public Object clone() {
		return new Derive(e, s);
	}

	public Expression eval() {
		return (e.eval()).derive(s);
	}

	public String toString() {
		StringBuffer res = new StringBuffer("(D(");
		res.append(e);
		res.append(",");
		res.append(s);
		res.append("))");
		return res.toString();
	}
	
	public Expression derive(Symbol s) {
		return e.derive(this.s).derive(s);
	}
	
	public Expression simplify() {
		return new Derive(e.simplify(), s);
	}
	
	public boolean equals(Expression ex) {
		if(!(ex instanceof Derive)) return false;
		Derive d = (Derive)ex;
		if(!((d.getExpression()).equals(e))) return false;
		if(!((d.getSymbol()).equals(s))) return false;
		return true;
	}

}