Created the Expression class

Advanced Software Engineering/Advanced Software Engineering/Verbs/Value/Expression.cs

@@ -0,0 +1,121 @@
+using System;
+using System.Drawing;
+
+namespace Advanced_Software_Engineering.Verbs.Value {
+
+    public class Expression : IValue {
+        private const int ADD = 0;
+        private const int SUBTRACT = 1;
+        private const int MULTIPLY = 2;
+        private const int DIVIDE = 3;
+
+        private Drawer drawer;
+        private string variable1;
+        private string variable2;
+        private int operation;
+
+        private bool evaluated = false;
+        private IValue evaluatedValue;
+
+        public Expression(Drawer drawer, string variable1, string variable2, int operation) {
+            this.drawer = drawer;
+            this.variable1 = variable1;
+            this.variable2 = variable2;
+            this.operation = operation;
+
+            //Check for bad input
+            if (operation > 3 && operation < 0) throw new Exception("Bad operation");
+            if(variable1.)
+        }
+
+        private IValue Evaluate() {
+            if (evaluated) return evaluatedValue;
+            IValue value1 = drawer.GetVariable(variable1);
+            IValue value2 = drawer.GetVariable(variable2);
+
+            string value1type = value1.GetOriginalType();
+
+            switch (value1type) {
+                case "bool":
+                    //operations as standard for bool expressions eg
+                    // (a + b) => a or b, (a * b) => a and b, (a ^ b) => a xor b
+                    if (operation == ADD) evaluatedValue = ValueFactory.CreateValue(value1.ToBool() || value2.ToBool());
+                    else if (operation == SUBTRACT) evaluatedValue = ValueFactory.CreateValue(value1.ToBool() ^ value2.ToBool());
+                    else if (operation == MULTIPLY) evaluatedValue = ValueFactory.CreateValue(value1.ToBool() && value2.ToBool());
+                    else if (operation == DIVIDE) throw new Exception("Bool cannot be divided");
+                    else throw new Exception("Bad operation");
+                    break;
+
+                case "int":
+                    if (operation == ADD) evaluatedValue = ValueFactory.CreateValue(value1.ToInt() + value2.ToInt());
+                    else if (operation == SUBTRACT) evaluatedValue = ValueFactory.CreateValue(value1.ToInt() - value2.ToInt());
+                    else if (operation == MULTIPLY) evaluatedValue = ValueFactory.CreateValue(value1.ToInt() * value2.ToInt());
+                    else if (operation == DIVIDE) evaluatedValue = ValueFactory.CreateValue(value1.ToInt() / value2.ToInt());
+                    else throw new Exception("Bad operation");
+                    break;
+
+                case "double":
+                    if (operation == ADD) evaluatedValue = ValueFactory.CreateValue(value1.ToDouble() + value2.ToDouble());
+                    else if (operation == SUBTRACT) evaluatedValue = ValueFactory.CreateValue(value1.ToDouble() - value2.ToDouble());
+                    else if (operation == MULTIPLY) evaluatedValue = ValueFactory.CreateValue(value1.ToDouble() * value2.ToDouble());
+                    else if (operation == DIVIDE) evaluatedValue = ValueFactory.CreateValue(value1.ToDouble() / value2.ToDouble());
+                    else throw new Exception("Bad operation");
+                    break;
+
+                case "color":
+                    throw new Exception("Colors are immutable");
+            }
+            evaluated = true;
+            return evaluatedValue;
+        }
+
+        public string GetDescription() {
+            string operation;
+            switch (this.operation) {
+                case ADD:
+                    operation = "added";
+                    break;
+
+                case SUBTRACT:
+                    operation = "subtracted";
+                    break;
+
+                case MULTIPLY:
+                    operation = "multiplied";
+                    break;
+
+                case DIVIDE:
+                    operation = "divided";
+                    break;
+
+                default:
+                    throw new Exception("Bad operation");
+            }
+            return "Expression of the variables " + variable1 + " and " + variable2 + " being " + operation;
+        }
+
+        public string GetOriginalType() {
+            return evaluatedValue.GetOriginalType();
+        }
+
+        public bool isInitialised() {
+            return true;
+        }
+
+        public bool ToBool() {
+            return evaluatedValue.ToBool();
+        }
+
+        public Color ToColor() {
+            return evaluatedValue.ToColor();
+        }
+
+        public double ToDouble() {
+            return evaluatedValue.ToDouble();
+        }
+
+        public int ToInt() {
+            return evaluatedValue.ToInt();
+        }
+    }
+}