don't compromise with precision

uses Math.xExact code to catch overflows instead of relying on doubles.
SkriptLang · Nov 10, 2024 · 771b09a · 771b09a
1 parent 87cc25d
commit 771b09a
Showing 1 changed file with 34 additions and 11 deletions.
diff --git a/src/main/java/ch/njol/skript/classes/data/DefaultOperations.java b/src/main/java/ch/njol/skript/classes/data/DefaultOperations.java
@@ -32,21 +32,44 @@ public class DefaultOperations {
 	static {
 		// Number - Number
 		Arithmetics.registerOperation(Operator.ADDITION, Number.class, (left, right) -> {
-			double result = left.doubleValue() + right.doubleValue();
-			if (Utils.isInteger(left, right) && result < Long.MAX_VALUE && result > Long.MIN_VALUE)
-				return (long) result;
-			return result;
+			if (Utils.isInteger(left, right)) {
+				long result = left.longValue() + right.longValue();
+				// catches overflow, from Math.addExact(long, long)
+				if (((left.longValue() ^ result) & (right.longValue() ^ result)) >= 0)
+					return (result);
+			}
+			return left.doubleValue() + right.doubleValue();
 		});
 		Arithmetics.registerOperation(Operator.SUBTRACTION, Number.class, (left, right) -> {
-			double result = left.doubleValue() - right.doubleValue();
-			if (Utils.isInteger(left, right) && result < Long.MAX_VALUE && result > Long.MIN_VALUE)
-				return (long) result;
-			return result;
+			if (Utils.isInteger(left, right)) {
+				long result = left.longValue() - right.longValue();
+				// catches overflow, from Math.addExact(long, long)
+				if (((left.longValue() ^ result) & (right.longValue() ^ result)) >= 0)
+					return (result);
+			}
+			return left.doubleValue() - right.doubleValue();
 		});
 		Arithmetics.registerOperation(Operator.MULTIPLICATION, Number.class, (left, right) -> {
-			double result = left.doubleValue() * right.doubleValue();
-			if (Utils.isInteger(left, right) && result < Long.MAX_VALUE && result > Long.MIN_VALUE)
-				return (long) result;
+			if (!Utils.isInteger(left, right))
+				return left.doubleValue() * right.doubleValue();
+
+			// catch overflow, from Math.multiplyExact(long, long)
+			long longLeft = left.longValue();
+			long longRight = right.longValue();
+			long ax = Math.abs(longLeft);
+			long ay = Math.abs(longRight);
+
+			long result = left.longValue() * right.longValue();
+
+			if (((ax | ay) >>> 31 != 0)) {
+				// Some bits greater than 2^31 that might cause overflow
+				// Check the result using the divide operator
+				// and check for the special case of Long.MIN_VALUE * -1
+				if (((longRight != 0) && (result / longRight != longLeft)) ||
+					(longLeft == Long.MIN_VALUE && longRight == -1)) {
+					return left.doubleValue() * right.doubleValue();
+				}
+			}
 			return result;
 		});
 		Arithmetics.registerOperation(Operator.DIVISION, Number.class, (left, right) -> left.doubleValue() / right.doubleValue());