Improve DataSize to support negative values

Issue: SPR-17154

spring-core/src/main/java/org/springframework/util/unit/DataSize.java

@@ -36,7 +36,7 @@ public final class DataSize implements Comparable<DataSize> {
 	/**
 	 * The pattern for parsing.
 	 */
-	private static final Pattern PATTERN = Pattern.compile("^(\\d+)([a-zA-Z]{0,2})$");
+	private static final Pattern PATTERN = Pattern.compile("^([+\\-]?\\d+)([a-zA-Z]{0,2})$");
 
 	/**
 	 * Bytes per KiloByte.
@@ -68,7 +68,7 @@ public final class DataSize implements Comparable<DataSize> {
 
 	/**
 	 * Obtain a {@link DataSize} representing the specified number of bytes.
-	 * @param bytes the number of bytes
+	 * @param bytes the number of bytes, positive or negative
 	 * @return a {@link DataSize}
 	 */
 	public static DataSize ofBytes(long bytes) {
@@ -77,7 +77,7 @@ public final class DataSize implements Comparable<DataSize> {
 
 	/**
 	 * Obtain a {@link DataSize} representing the specified number of kilobytes.
-	 * @param kiloBytes the number of kilobytes
+	 * @param kiloBytes the number of kilobytes, positive or negative
 	 * @return a {@link DataSize}
 	 */
 	public static DataSize ofKiloBytes(long kiloBytes) {
@@ -86,7 +86,7 @@ public final class DataSize implements Comparable<DataSize> {
 
 	/**
 	 * Obtain a {@link DataSize} representing the specified number of megabytes.
-	 * @param megaBytes the number of megabytes
+	 * @param megaBytes the number of megabytes, positive or negative
 	 * @return a {@link DataSize}
 	 */
 	public static DataSize ofMegaBytes(long megaBytes) {
@@ -95,7 +95,7 @@ public final class DataSize implements Comparable<DataSize> {
 
 	/**
 	 * Obtain a {@link DataSize} representing the specified number of gigabytes.
-	 * @param gigaBytes the number of gigabytes
+	 * @param gigaBytes the number of gigabytes, positive or negative
 	 * @return a {@link DataSize}
 	 */
 	public static DataSize ofGigaBytes(long gigaBytes) {
@@ -104,7 +104,7 @@ public final class DataSize implements Comparable<DataSize> {
 
 	/**
 	 * Obtain a {@link DataSize} representing the specified number of terabytes.
-	 * @param teraBytes the number of terabytes
+	 * @param teraBytes the number of terabytes, positive or negative
 	 * @return a {@link DataSize}
 	 */
 	public static DataSize ofTeraBytes(long teraBytes) {
@@ -113,7 +113,8 @@ public final class DataSize implements Comparable<DataSize> {
 
 	/**
 	 * Obtain a {@link DataSize} representing an amount in the specified {@link DataUnit}.
-	 * @param amount the amount of the size, measured in terms of the unit
+	 * @param amount the amount of the size, measured in terms of the unit, positive or
+	 * negative
 	 * @return a {@link DataSize}
 	 */
 	public static DataSize of(long amount, DataUnit unit) {
@@ -177,6 +178,14 @@ public final class DataSize implements Comparable<DataSize> {
 				: defaultUnit);
 	}
 
+	/**
+	 * Checks if this size is negative, excluding zero.
+	 * @return true if this size has a size less than zero bytes
+	 */
+	public boolean isNegative() {
+		return this.bytes < 0;
+	}
+
 	/**
 	 * Return the number of bytes in this instance.
 	 * @return the number of bytes

spring-core/src/test/java/org/springframework/util/unit/DataSizeTests.java

@@ -107,46 +107,111 @@ public class DataSizeTests {
 		assertEquals(DataSize.ofKiloBytes(1), DataSize.parse("1024"));
 	}
 
+	@Test
+	public void parseNegativeNumberWithDefaultUnitUsesBytes() {
+		assertEquals(DataSize.ofBytes(-1), DataSize.parse("-1"));
+	}
+
 	@Test
 	public void parseWithNullDefaultUnitUsesBytes() {
 		assertEquals(DataSize.ofKiloBytes(1), DataSize.parse("1024", null));
 	}
 
+	@Test
+	public void parseNegativeNumberWithNullDefaultUnitUsesBytes() {
+		assertEquals(DataSize.ofKiloBytes(-1), DataSize.parse("-1024", null));
+	}
+
 	@Test
 	public void parseWithCustomDefaultUnit() {
 		assertEquals(DataSize.ofKiloBytes(1), DataSize.parse("1", DataUnit.KILOBYTES));
 	}
 
+	@Test
+	public void parseNegativeNumberWithCustomDefaultUnit() {
+		assertEquals(DataSize.ofKiloBytes(-1), DataSize.parse("-1", DataUnit.KILOBYTES));
+	}
+
 	@Test
 	public void parseWithBytes() {
 		assertEquals(DataSize.ofKiloBytes(1), DataSize.parse("1024B"));
 	}
 
+	@Test
+	public void parseWithNegativeBytes() {
+		assertEquals(DataSize.ofKiloBytes(-1), DataSize.parse("-1024B"));
+	}
+
+	@Test
+	public void parseWithPostivieBytes() {
+		assertEquals(DataSize.ofKiloBytes(1), DataSize.parse("+1024B"));
+	}
+
 	@Test
 	public void parseWithKiloBytes() {
 		assertEquals(DataSize.ofBytes(1024), DataSize.parse("1KB"));
 	}
 
+	@Test
+	public void parseWithNegativeKiloBytes() {
+		assertEquals(DataSize.ofBytes(-1024), DataSize.parse("-1KB"));
+	}
+
 	@Test
 	public void parseWithMegaBytes() {
 		assertEquals(DataSize.ofMegaBytes(4), DataSize.parse("4MB"));
 	}
 
+	@Test
+	public void parseWithNegativeMegaBytes() {
+		assertEquals(DataSize.ofMegaBytes(-4), DataSize.parse("-4MB"));
+	}
+
 	@Test
 	public void parseWithGigaBytes() {
 		assertEquals(DataSize.ofMegaBytes(1024), DataSize.parse("1GB"));
 	}
 
+	@Test
+	public void parseWithNegativeGigaBytes() {
+		assertEquals(DataSize.ofMegaBytes(-1024), DataSize.parse("-1GB"));
+	}
+
 	@Test
 	public void parseWithTeraBytes() {
 		assertEquals(DataSize.ofTeraBytes(1), DataSize.parse("1TB"));
 	}
 
+	@Test
+	public void parseWithNegativeTeraBytes() {
+		assertEquals(DataSize.ofTeraBytes(-1), DataSize.parse("-1TB"));
+	}
+
+	@Test
+	public void isNegativeWithPositive() {
+		assertFalse(DataSize.ofBytes(50).isNegative());
+	}
+
+	@Test
+	public void isNegativeWithZero() {
+		assertFalse(DataSize.ofBytes(0).isNegative());
+	}
+
+	@Test
+	public void isNegativeWithNegative() {
+		assertTrue(DataSize.ofBytes(-1).isNegative());
+	}
+
 	@Test
 	public void toStringUsesBytes() {
 		assertEquals("1024B", DataSize.ofKiloBytes(1).toString());
 	}
 
+	@Test
+	public void toStringWithNegativeBytes() {
+		assertEquals("-1024B", DataSize.ofKiloBytes(-1).toString());
+	}
+
 	@Test
 	public void parseWithUnsupportedUnit() {
 		this.thrown.expect(IllegalArgumentException.class);