Changed ExpandRule 1 and 2

src/main/resources/rules/ExpandRule1.js

@@ -25,7 +25,7 @@ var rule = {
 	},
 	// Rule type
 	getRuleType: function() {
-		return RuleType.EXPANSION;
+		return RuleType.REDUCTION;
 	},
 	/* Rule function
 	   Returns:

src/main/resources/rules/ExpandRule2.js

@@ -0,0 +1,127 @@
+// Imports
+var ObjectArrayList = Java.type("it.unimi.dsi.fastutil.objects.ObjectArrayList");
+var ScriptUtils = org.warp.picalculator.ScriptUtils;
+var Rule = org.warp.picalculator.math.rules.Rule;
+var RuleType = org.warp.picalculator.math.rules.RuleType;
+var RulesManager = org.warp.picalculator.math.rules.RulesManager;
+var Multiplication = org.warp.picalculator.math.functions.Multiplication;
+var Sum = org.warp.picalculator.math.functions.Sum;
+var Subtraction = org.warp.picalculator.math.functions.Subtraction;
+var SumSubtraction = org.warp.picalculator.math.functions.SumSubtraction;
+var Number = org.warp.picalculator.math.functions.Number;
+
+/**
+ * Expand rule
+ * -(-a) = a
+ * 
+ * @author Andrea Cavalli
+ *
+ */
+var rule = {
+	// Rule name
+	getRuleName: function() {
+		return "ExpandRule2";
+	},
+	// Rule type
+	getRuleType: function() {
+		return RuleType.REDUCTION;
+	},
+	/* Rule function
+	   Returns:
+	     - null if it's not executable on the function "f"
+	     - An ObjectArrayList<Function> if it did something
+	*/
+	execute: function(f) {
+		var isExecutable;
+		if (ScriptUtils.instanceOf(f, Multiplication.class)) {
+			var fnc = f;
+			if (fnc.getParameter1().equals(new Number(fnc.getMathContext(), -1))) {
+				var expr = fnc.getParameter2();
+				if (expr instanceof Sum) {
+					isExecutable = true;
+				} else if (expr instanceof Subtraction) {
+					isExecutable = true;
+				} else if (expr instanceof SumSubtraction) {
+					isExecutable = true;
+				}
+			}
+		} else if (ScriptUtils.instanceOf(f,Subtraction.class) || ScriptUtils.instanceOf(f,SumSubtraction.class)) {
+			var fnc = f;
+			var expr = fnc.getParameter2();
+			if (ScriptUtils.instanceOf(expr,Sum.class)) {
+				isExecutable = true;
+			} else if (ScriptUtils.instanceOf(expr,Subtraction.class)) {
+				isExecutable = true;
+			} else if (ScriptUtils.instanceOf(expr,SumSubtraction.class)) {
+				isExecutable = true;
+			}
+		}
+		if (isExecutable) {
+			var result = new ObjectArrayList();
+			var root = f.getMathContext();
+
+			var expr = null;
+			var fromSubtraction = 0;
+			var subtraction = null;
+			if (ScriptUtils.instanceOf(f,Multiplication.class)) {
+				expr = f.getParameter2();
+			} else if (f instanceof Subtraction || f instanceof SumSubtraction) {
+				expr = f.getParameter2();
+				if (f instanceof Subtraction) {
+					fromSubtraction = 1;
+				} else {
+					fromSubtraction = 2;
+				}
+			}
+
+			if (f instanceof SumSubtraction) {
+				
+			}
+
+			var fnc = expr;
+			if (fnc instanceof Sum) {
+				var a = fnc.getParameter1();
+				var b = fnc.getParameter2();
+				var fnc2 = new Subtraction(root, new Multiplication(root, new Number(root, -1), a), b);
+				if (fromSubtraction > 0) {
+					subtraction = new Subtraction(root, f.getParameter1(), fnc2);
+					result.add(subtraction);
+				} else {
+					result.add(fnc2);
+				}
+			} else if (fnc instanceof Subtraction) {
+				var a = fnc.getParameter1();
+				var b = fnc.getParameter2();
+				var fnc2 = new Sum(root, new Multiplication(root, new Number(root, -1), a), b);
+				if (fromSubtraction > 0) {
+					subtraction = new Subtraction(root, f.getParameter1(), fnc2);
+					result.add(subtraction);
+				} else {
+					result.add(fnc2);
+				}
+			} else if (fnc instanceof SumSubtraction) {
+				var a = fnc.getParameter1();
+				var b = fnc.getParameter2();
+				var fnc2 = new Sum(root, new Multiplication(root, new Number(root, -1), a), b);
+				var fnc3 = new Subtraction(root, new Multiplication(root, new Number(root, -1), a), b);
+				if (fromSubtraction > 0) {
+					subtraction = new SumSubtraction(root, f.getParameter1(), fnc2);
+					result.add(subtraction);
+					subtraction = new SumSubtraction(root, f.getParameter1(), fnc3);
+					result.add(subtraction);
+					result.add(subtraction);
+				} else {
+					result.add(fnc2);
+					result.add(fnc2);
+				}
+			}
+			return result;
+		} else {
+			return null;
+		}
+		
+	}
+}
+
+//Add this rule to the list of rules
+RulesManager.addRule(engine.getInterface(rule, Rule.class));