Added test class for EquationEvaluator

src/main/java/world/bentobox/level/calculators/EquationEvaluator.java

@@ -3,7 +3,7 @@ package world.bentobox.level.calculators;
 import java.text.ParseException;
 
 /**
- * @author tastybento
+ * Utility class to evaluate equations
  */
 public class EquationEvaluator {
 
@@ -12,6 +12,11 @@ public class EquationEvaluator {
         private int pos = -1;
         private int currentChar;
 
+        @SuppressWarnings("unused")
+        private Parser() {
+            throw new IllegalStateException("Utility class");
+        }
+
         public Parser(String input) {
             this.input = input;
             moveToNextChar();
@@ -22,8 +27,9 @@ public class EquationEvaluator {
         }
 
         private boolean tryToEat(int charToEat) {
-	    while (currentChar == ' ')
+            while (currentChar == ' ') {
                 moveToNextChar();
+            }
             if (currentChar == charToEat) {
                 moveToNextChar();
                 return true;
@@ -42,60 +48,54 @@ public class EquationEvaluator {
         private double parseExpression() throws ParseException {
             double result = parseTerm();
             while (true) {
-		if (tryToEat('+'))
+                if (tryToEat('+')) {
                     result += parseTerm();
-		else if (tryToEat('-'))
+                } else if (tryToEat('-')) {
                     result -= parseTerm();
-		else
+                } else {
                     return result;
                 }
             }
+        }
 
         private double parseFactor() throws ParseException {
-	    if (tryToEat('+'))
+            if (tryToEat('+')) {
                 return parseFactor(); // unary plus
-	    if (tryToEat('-'))
+            }
+            if (tryToEat('-')) {
                 return -parseFactor(); // unary minus
-
+            }
             double x;
             int startPos = this.pos;
             if (tryToEat('(')) { // parentheses
                 x = parseExpression();
                 tryToEat(')');
             } else if ((currentChar >= '0' && currentChar <= '9') || currentChar == '.') { // numbers
-		while ((currentChar >= '0' && currentChar <= '9') || currentChar == '.')
+                while ((currentChar >= '0' && currentChar <= '9') || currentChar == '.') {
                     moveToNextChar();
+                }
                 x = Double.parseDouble(input.substring(startPos, this.pos));
             } else if (currentChar >= 'a' && currentChar <= 'z') { // functions
-		while (currentChar >= 'a' && currentChar <= 'z')
+                while (currentChar >= 'a' && currentChar <= 'z') {
                     moveToNextChar();
+                }
                 String func = input.substring(startPos, this.pos);
                 x = parseFactor();
-		switch (func) {
+                x = switch (func) {
-		case "sqrt":
+                case "sqrt" -> Math.sqrt(x);
-		    x = Math.sqrt(x);
+                case "sin" -> Math.sin(Math.toRadians(x));
-		    break;
+                case "cos" -> Math.cos(Math.toRadians(x));
-		case "sin":
+                case "tan" -> Math.tan(Math.toRadians(x));
-		    x = Math.sin(Math.toRadians(x));
+                case "log" -> Math.log(x);
-		    break;
+                default -> throw new ParseException("Unknown function: " + func, startPos);
-		case "cos":
+                };
-		    x = Math.cos(Math.toRadians(x));
-		    break;
-		case "tan":
-		    x = Math.tan(Math.toRadians(x));
-		    break;
-		case "log":
-		    x = Math.log(x);
-		    break;
-		default:
-		    throw new ParseException("Unknown function: " + func, startPos);
-		}
             } else {
                 throw new ParseException("Unexpected: " + (char) currentChar, startPos);
             }
 
-	    if (tryToEat('^'))
+            if (tryToEat('^')) {
                 x = Math.pow(x, parseFactor()); // exponentiation
+            }
 
             return x;
         }

src/test/java/world/bentobox/level/calculators/EquationEvaluatorTest.java

@@ -0,0 +1,37 @@
+package world.bentobox.level.calculators;
+
+import static org.junit.Assert.assertEquals;
+
+import java.text.ParseException;
+
+import org.junit.Test;
+
+/**
+ * Test the equation evaluation
+ */
+public class EquationEvaluatorTest {
+
+    /**
+     * Test method for {@link world.bentobox.level.calculators.EquationEvaluator#eval(java.lang.String)}.
+     * @throws ParseException 
+     */
+    @Test
+    public void testEval() throws ParseException {
+        assertEquals(4D, EquationEvaluator.eval("2+2"), 0D);
+        assertEquals(0D, EquationEvaluator.eval("2-2"), 0D);
+        assertEquals(1D, EquationEvaluator.eval("2/2"), 0D);
+        assertEquals(4D, EquationEvaluator.eval("2*2"), 0D);
+        assertEquals(8D, EquationEvaluator.eval("2+2+2+2"), 0D);
+        assertEquals(5D, EquationEvaluator.eval("2.5+2.5"), 0D);
+        assertEquals(1.414, EquationEvaluator.eval("sqrt(2)"), 0.001D);
+        assertEquals(3.414, EquationEvaluator.eval("2 + sqrt(2)"), 0.001D);
+        assertEquals(0D, EquationEvaluator.eval("sin(0)"), 0.1D);
+        assertEquals(1D, EquationEvaluator.eval("cos(0)"), 0.1D);
+        assertEquals(0D, EquationEvaluator.eval("tan(0)"), 0.1D);
+        assertEquals(0D, EquationEvaluator.eval("log(1)"), 0.1D);
+        assertEquals(27D, EquationEvaluator.eval("3^3"), 0.D);
+        assertEquals(84.70332D, EquationEvaluator.eval("3^3 + 2 + 2.65 * (3 / 4) - sin(45) * log(10) + 55.344"),
+                0.0001D);
+    
+    }
+}