Move to 1.20.4

Refactored the calculator code for clarity.

Added Jacoco line to prvent issues with the bigger Material class.

pom.xml

@@ -58,7 +58,7 @@
         <!-- Non-minecraft related dependencies -->
         <powermock.version>2.0.9</powermock.version>
         <!-- More visible way how to change dependency versions -->
-        <spigot.version>1.19.4-R0.1-SNAPSHOT</spigot.version>
+        <spigot.version>1.20.4-R0.1-SNAPSHOT</spigot.version>
         <bentobox.version>2.0.0-SNAPSHOT</bentobox.version>
         <!-- Warps addon version -->
         <warps.version>1.12.0</warps.version>
@@ -410,6 +410,8 @@
                         <!-- This is required to prevent Jacoco from adding 
                             synthetic fields to a JavaBean class (causes errors in testing) -->
                         <exclude>**/*Names*</exclude>
+                        <!-- Prevents the Material is too large to mock error -->
+                        <exclude>org/bukkit/Material*</exclude>
                     </excludes>
                 </configuration>
                 <executions>

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

@@ -0,0 +1,121 @@
+package world.bentobox.level.calculators;
+
+import java.text.ParseException;
+
+/**
+ * @author tastybento
+ */
+public class EquationEvaluator {
+
+    private static class Parser {
+	private final String input;
+	private int pos = -1;
+	private int currentChar;
+
+	public Parser(String input) {
+	    this.input = input;
+	    moveToNextChar();
+	}
+
+	private void moveToNextChar() {
+	    currentChar = (++pos < input.length()) ? input.charAt(pos) : -1;
+	}
+
+	private boolean tryToEat(int charToEat) {
+	    while (currentChar == ' ')
+		moveToNextChar();
+	    if (currentChar == charToEat) {
+		moveToNextChar();
+		return true;
+	    }
+	    return false;
+	}
+
+	public double evaluate() throws ParseException {
+	    double result = parseExpression();
+	    if (pos < input.length()) {
+		throw new ParseException("Unexpected character: " + (char) currentChar, pos);
+	    }
+	    return result;
+	}
+
+	private double parseExpression() throws ParseException {
+	    double result = parseTerm();
+	    while (true) {
+		if (tryToEat('+'))
+		    result += parseTerm();
+		else if (tryToEat('-'))
+		    result -= parseTerm();
+		else
+		    return result;
+	    }
+	}
+
+	private double parseFactor() throws ParseException {
+	    if (tryToEat('+'))
+		return parseFactor(); // unary plus
+	    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 == '.')
+		    moveToNextChar();
+		x = Double.parseDouble(input.substring(startPos, this.pos));
+	    } else if (currentChar >= 'a' && currentChar <= 'z') { // functions
+		while (currentChar >= 'a' && currentChar <= 'z')
+		    moveToNextChar();
+		String func = input.substring(startPos, this.pos);
+		x = parseFactor();
+		switch (func) {
+		case "sqrt":
+		    x = Math.sqrt(x);
+		    break;
+		case "sin":
+		    x = Math.sin(Math.toRadians(x));
+		    break;
+		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('^'))
+		x = Math.pow(x, parseFactor()); // exponentiation
+
+	    return x;
+	}
+
+	private double parseTerm() throws ParseException {
+	    double x = parseFactor();
+	    for (;;) {
+		if (tryToEat('*'))
+		    x *= parseFactor(); // multiplication
+		else if (tryToEat('/'))
+		    x /= parseFactor(); // division
+		else
+		    return x;
+	    }
+	}
+
+    }
+
+    public static double eval(final String equation) throws ParseException {
+	return new Parser(equation).evaluate();
+    }
+
+}