Remove most MINOR_*, MINOR_* BCEL class file versions

in favour of Constants.ClassFileVersion.of(int, int). The few ones
retained are used from production code, the vast majority of removed
ones only from test code.

This gets rid of yet another 'AspectJ_JDK_Update' tag. One less place to
check and update with each newly supported Java version. :-)

Signed-off-by: Alexander Kriegisch <Alexander@Kriegisch.name>

2 files changed, 83 insertions, 54 deletions

diff --git a/bcel-builder/src/main/java/org/aspectj/apache/bcel/Constants.java b/bcel-builder/src/main/java/org/aspectj/apache/bcel/Constants.java
index 5b96bb6d1..566133f17 100644
--- a/bcel-builder/src/main/java/org/aspectj/apache/bcel/Constants.java
+++ b/bcel-builder/src/main/java/org/aspectj/apache/bcel/Constants.java
@@ -2,6 +2,10 @@ package org.aspectj.apache.bcel;
 
 import org.aspectj.apache.bcel.generic.Type;
 
+import java.util.Map;
+import java.util.Objects;
+import java.util.concurrent.ConcurrentHashMap;
+
 /* ====================================================================
  * The Apache Software License, Version 1.1
  *
@@ -63,58 +67,83 @@ import org.aspectj.apache.bcel.generic.Type;
  * @author Andy Clement
  */
 public interface Constants {
-	// Major and minor version of the code
-	short MAJOR_1_1 = 45;
-	short MINOR_1_1 = 3;
-	short MAJOR_1_2 = 46;
-	short MINOR_1_2 = 0;
-	short MAJOR_1_3 = 47;
-	short MINOR_1_3 = 0;
-	short MAJOR_1_4 = 48;
-	short MINOR_1_4 = 0;
-	short MAJOR_1_5 = 49;
-	short MINOR_1_5 = 0;
-	short MAJOR_1_6 = 50;
-	short MINOR_1_6 = 0;
-	short MAJOR_1_7 = 51;
-	short MINOR_1_7 = 0;
-	short MAJOR_1_8 = 52;
-	short MINOR_1_8 = 0;
-	short MAJOR_1_9 = 53;
-	short MINOR_1_9 = 0;
-	short MAJOR_10 = 54;
-	short MINOR_10 = 0;
-	short MAJOR_11 = 55;
-	short MINOR_11 = 0;
-	short MAJOR_12 = 56;
-	short MINOR_12 = 0;
-	short MAJOR_13 = 57;
-	short MINOR_13 = 0;
-	short MAJOR_14 = 58;
-	short MINOR_14 = 0;
-	short MAJOR_15 = 59;
-	short MINOR_15 = 0;
-	short MAJOR_16 = 60;
-	short MINOR_16 = 0;
-	short MAJOR_17 = 61;
-	short MINOR_17 = 0;
-	short MAJOR_18 = 62;
-	short MINOR_18 = 0;
-	short MAJOR_19 = 63;
-	short MINOR_19 = 0;
-	short MAJOR_20 = 64;
-	short MINOR_20 = 0;
-	short MAJOR_21 = 65;
-	short MINOR_21 = 0;
-	// AspectJ_JDK_Update
-//	short MAJOR_22 = 66;
-//	short MINOR_22 = 0;
-
-	int PREVIEW_MINOR_VERSION = 65535;
-
-	// Defaults
-	short MAJOR = MAJOR_1_1;
-	short MINOR = MINOR_1_1;
+	// Selected major/minor class file versions, defined as constants because they are used in production code. Maybe,
+	// there is a slight performance advantage, therefore retain them. When tests need class file version infos, they
+	// should use ClassFileVersion.of(javaMajor) instead, avoiding new constants for every major Java release. In the
+	// past, we had too many of them.
+	int MAJOR_1_1 = 45;
+	int MINOR_1_1 = 3;
+	int MAJOR_1_5 = 49;
+	int MAJOR_1_6 = 50;
+	int MAJOR_1_8 = 52;
+
+	/**
+	 * Carries information about major, minor and preview-minor version byte values found in Java class files for a
+	 * specific Java version. You can obtain instances via {@link #of(int)} and {@link #of(int, int)}, respectively.
+	 */
+	class ClassFileVersion {
+		private static final Map<Integer, ClassFileVersion> cache = new ConcurrentHashMap<>();
+
+		public final int MAJOR;
+		public final int MINOR;
+		public final int PREVIEW_MINOR = 65535;
+
+		private ClassFileVersion(int major, int minor) {
+			MAJOR = major;
+			MINOR = minor;
+		}
+
+		/**
+		 * Obtain a class file version info instance for a specific Java version
+		 *
+		 * @param javaMajor Java major version; must be >= 2; values 2 to 9 are interpreted as Java versions 1.2 to 1.9
+		 *
+		 * @return either a cached or a new instance; result is identical to calling {@code of(javaMajor, 0)}
+		 */
+		public static ClassFileVersion of(int javaMajor) {
+			return of(javaMajor, 0);
+		}
+
+		/**
+		 * Obtain a class file version info instance for a specific Java version
+		 *
+		 * @param javaMajor Java major version; must be >= 1; values 2 to 9 are interpreted as Java versions 1.2 to 1.9
+		 * @param javaMinor Java minor version; is only relevant for Java major 1 and must be in range [1..9]
+		 *
+		 * @return either a cached or a new instance
+		 */
+		public static ClassFileVersion of(int javaMajor, int javaMinor) {
+			if (javaMajor < 1)
+				throw new IllegalArgumentException("Java major version must be >= 1");
+			if (javaMajor == 1) {
+				if (javaMinor < 1 || javaMinor > 9)
+					throw new IllegalArgumentException("Java 1.x versions must be 1.1 to 1.9");
+				// 1.1 -> 1, ..., 1.5 -> 5, ..., 1.9 -> 9
+				javaMajor = javaMinor;
+			}
+			ClassFileVersion classFileVersion = cache.get(javaMajor);
+			if (classFileVersion == null) {
+				classFileVersion = new ClassFileVersion(javaMajor + 44, javaMajor == 1 ? 3 : 0);
+				cache.put(javaMajor, classFileVersion);
+			}
+			return classFileVersion;
+		}
+
+		@Override
+		public boolean equals(Object o) {
+			if (this == o) return true;
+			if (!(o instanceof ClassFileVersion)) return false;
+			ClassFileVersion that = (ClassFileVersion) o;
+			// Include PREVIEW_MINOR, if it ever changes to be non-constant
+			return MAJOR == that.MAJOR && MINOR == that.MINOR /*&& PREVIEW_MINOR == that.PREVIEW_MINOR*/;
+		}
+
+		@Override
+		public int hashCode() {
+			// Include PREVIEW_MINOR, if it ever changes to be non-constant
+			return Objects.hash(MAJOR, MINOR/*, PREVIEW_MINOR*/);
+		}
+	}
 
 	/** Maximum value for an unsigned short */
 	int MAX_SHORT = 65535; // 2^16 - 1
diff --git a/bcel-builder/src/test/java/org/aspectj/apache/bcel/classfile/tests/ModuleTest.java b/bcel-builder/src/test/java/org/aspectj/apache/bcel/classfile/tests/ModuleTest.java
index f8012a983..b52c89e4f 100644
--- a/bcel-builder/src/test/java/org/aspectj/apache/bcel/classfile/tests/ModuleTest.java
+++ b/bcel-builder/src/test/java/org/aspectj/apache/bcel/classfile/tests/ModuleTest.java
@@ -36,8 +36,8 @@ public class ModuleTest extends BcelTestCase {
 		ClassParser classParser = new ClassParser(moduleFilename);
 		JavaClass javaClass = classParser.parse();
 		assertNotNull(javaClass);
-		assertEquals(Constants.MAJOR_1_9,javaClass.getMajor());
-		assertEquals(Constants.MINOR_1_9,javaClass.getMinor());
+		assertEquals(Constants.ClassFileVersion.of(9).MAJOR, javaClass.getMajor());
+		assertEquals(Constants.ClassFileVersion.of(9).MINOR, javaClass.getMinor());
 		assertEquals(Constants.ACC_MODULE,javaClass.getModifiers());
 		assertEquals(0,javaClass.getSuperclassNameIndex());
 		assertEquals(0,javaClass.getInterfaceIndices().length);