🚀 Add number format expression

src/main/java/ch/njol/skript/classes/data/DefaultFunctions.java

@@ -42,6 +42,7 @@
 
 import java.math.BigDecimal;
 import java.math.RoundingMode;
+import java.text.DecimalFormat;
 import java.util.Calendar;
 import java.util.UUID;
 
@@ -50,6 +51,10 @@ public class DefaultFunctions {
 	private static String str(double n) {
 		return StringUtils.toString(n, 4);
 	}
+	private static final String DEFAULT_NUMBER_FORMAT_STRING = "###,###";
+	private static final DecimalFormat DEFAULT_NUMBER_FORMAT = new DecimalFormat(DEFAULT_NUMBER_FORMAT_STRING);
+	private static final ThreadLocal<DecimalFormat> NUMBER_FORMAT = ThreadLocal.withInitial(DecimalFormat::new);
+
 
 	static {
 		Parameter<?>[] numberParam = new Parameter[] {new Parameter<>("n", DefaultClasses.NUMBER, true, null)};
@@ -568,6 +573,36 @@ public Boolean[] executeSimple(Object[][] params) {
 		}).description("Returns true if the input is NaN (not a number).")
 			.examples("isNaN(0) # false", "isNaN(0/0) # true", "isNaN(sqrt(-1)) # true")
 			.since("2.8.0");
+
+		Functions.registerFunction(new SimpleJavaFunction<String>("formatNumber", new Parameter[] {
+			new Parameter<>("number", DefaultClasses.NUMBER, true, null),
+			new Parameter<>("format", DefaultClasses.STRING, true, new SimpleLiteral<String>(DEFAULT_NUMBER_FORMAT_STRING, true))
+		}, DefaultClasses.STRING, true) {
+			@Override
+			public String[] executeSimple(Object[][] params) {
+				Number number = (Number) params[0][0];
+				String format = (String) params[1][0];
+
+				if (DEFAULT_NUMBER_FORMAT_STRING.equals(format)) // shortcut
+					return CollectionUtils.array(DEFAULT_NUMBER_FORMAT.format(number));
+
+				try {
+					DecimalFormat numberFormat = NUMBER_FORMAT.get();
+					numberFormat.applyPattern(format);
+					return CollectionUtils.array(numberFormat.format(number));
+				} catch (IllegalArgumentException e) {
+//					Skript.warning("Invalid number format: " + format); // TODO find a better solution for such warnings/errors that doesn't spam the console
+					return null;
+				}
+			}
+		}).description("Converts numbers to human-readable format. By default, '###,###' (e.g. '123,456,789') will be used. For reference, see this "
+		+ "<a href=\"https://docs.oracle.com/javase/7/docs/api/java/text/DecimalFormat.html\" target=\"_blank\">article</a>.")
+			.examples(
+					"command /formatnumber <number>:",
+						"\taliases: fn",
+						"\ttrigger:",
+							"\t\tsend \"Formatted: %formatNumber(arg-1)%\" to sender"
+			).since("INSERT VERSION");
 	}
 
 }

src/test/skript/tests/regressions/4663-formatted numbers.sk

@@ -0,0 +1,17 @@
+test "formatted numbers function":
+	set {_num1} to formatNumber(123456789)
+	assert {_num1} = "123,456,789" with "default number format failed ##1"
+
+	set {_num2} to formatNumber(1234567)
+	assert {_num2} = "1,234,567" with "default number format failed ##2"
+
+	set {_num3} to formatNumber(12345678, "##,##.00")
+	assert {_num3} = "1,2,3,4,5,6,7,8.00" with "custom number format failed ##1"
+
+	set {_cFormat} to "####,####"
+	set {_num4} to formatNumber(12345678, {_cFormat})
+	assert {_num4} = "12,34,56,78" with "custom number format failed ##2"
+
+	set {_cFormat2} to "##,.##"
+	set {_num5} to formatNumber(12345678, {_cFormat2})
+	assert {_num5} is not set with "custom number format failed ##3"