week3/Operand.cs


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using System;

namespace ALGA {
	public class Operand : Expression {
		private char operand;
		private Expression left, right;

		public Operand(char operand, Expression left, Expression right) {
			this.operand = operand;
			this.left = left;
			this.right = right;
		}

		public override int evaluate() {
			int a = left.evaluate();
			int b = right.evaluate();

			switch (operand) {
				case '+': return a + b;
				case '*': return a * b;
			}

			throw new NotImplementedException();
		}

		public override string ToString() {
			return $"({left.ToString()}{operand}{right.ToString()})";
		}
	}
}