/* SetExpr.java */ /** A class to represent assignment statements in the expression language. */ public class SetExpr extends Expression { /* Constructs a SetExpr object in which var is being assigned the * Value val. (We might write such assignments as "var = val" in * some langauges, although ours will use "(set var val)". * @param var is the variable to be assigned. * @param val is a value to which var is assigned. Note that * val is an arbitrary Expression, not necessary a ValueExpr. */ public SetExpr(Expression var, Expression val) { /* Fill in for part 2. */ } public int arity() { return 2; } public String oper() { return "set"; } public Expression operand(int i) { /* Fill in for part 2. */ } public Value eval() { /* Fill in for part 2. */ } }