[#625] Instead of '31' as a prime number for hashCode(), use something else. 31, probably owing to its inclusion in Effective Java, is overused, as proven by Maaartinus in issue 625. Switching to 277 instead. Also, 1231/1237 pair used for booleans has been replaced by 2591/2609.

3 files changed, 20 insertions, 13 deletions

diff --git a/src/core/lombok/core/handlers/HandlerUtil.java b/src/core/lombok/core/handlers/HandlerUtil.java
index 3d386054..c8076ab6 100644
--- a/src/core/lombok/core/handlers/HandlerUtil.java
+++ b/src/core/lombok/core/handlers/HandlerUtil.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2013 The Project Lombok Authors.
+ * Copyright (C) 2013-2014 The Project Lombok Authors.
  * 
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
@@ -27,6 +27,10 @@ import lombok.core.LombokNode;
 public class HandlerUtil {
 	private HandlerUtil() {}
 	
+	public static final int PRIME_FOR_HASHCODE = 277;
+	public static final int PRIME_FOR_TRUE = 2591;
+	public static final int PRIME_FOR_FALSE = 2609;
+	
 	/** Checks if the given name is a valid identifier.
 	 * 
 	 * If it is, this returns {@code true} and does nothing else.
diff --git a/src/core/lombok/eclipse/handlers/HandleEqualsAndHashCode.java b/src/core/lombok/eclipse/handlers/HandleEqualsAndHashCode.java
index 3c8a7039..0b054159 100644
--- a/src/core/lombok/eclipse/handlers/HandleEqualsAndHashCode.java
+++ b/src/core/lombok/eclipse/handlers/HandleEqualsAndHashCode.java
@@ -35,6 +35,7 @@ import java.util.Set;
 import lombok.AccessLevel;
 import lombok.EqualsAndHashCode;
 import lombok.core.AST.Kind;
+import lombok.core.handlers.HandlerUtil;
 import lombok.core.AnnotationValues;
 import lombok.eclipse.Eclipse;
 import lombok.eclipse.EclipseAnnotationHandler;
@@ -271,7 +272,7 @@ public class HandleEqualsAndHashCode extends EclipseAnnotationHandler<EqualsAndH
 		
 		final boolean isEmpty = fields.isEmpty();
 		
-		/* final int PRIME = 31; */ {
+		/* final int PRIME = 277; */ {
 			/* Without fields, PRIME isn't used, and that would trigger a 'local variable not used' warning. */
 			if (!isEmpty || callSuper) {
 				LocalDeclaration primeDecl = new LocalDeclaration(PRIME, pS, pE);
@@ -280,7 +281,7 @@ public class HandleEqualsAndHashCode extends EclipseAnnotationHandler<EqualsAndH
 				primeDecl.type = TypeReference.baseTypeReference(TypeIds.T_int, 0);
 				primeDecl.type.sourceStart = pS; primeDecl.type.sourceEnd = pE;
 				setGeneratedBy(primeDecl.type, source);
-				primeDecl.initialization = makeIntLiteral("31".toCharArray(), source);
+				primeDecl.initialization = makeIntLiteral(String.valueOf(HandlerUtil.PRIME_FOR_HASHCODE).toCharArray(), source);
 				statements.add(primeDecl);
 			}
 		}
@@ -312,12 +313,12 @@ public class HandleEqualsAndHashCode extends EclipseAnnotationHandler<EqualsAndH
 			Expression fieldAccessor = createFieldAccessor(field, fieldAccess, source);
 			if (fType.dimensions() == 0 && token != null) {
 				if (Arrays.equals(TypeConstants.BOOLEAN, token)) {
-					/* booleanField ? 1231 : 1237 */
-					IntLiteral int1231 = makeIntLiteral("1231".toCharArray(), source);
-					IntLiteral int1237 = makeIntLiteral("1237".toCharArray(), source);
-					ConditionalExpression int1231or1237 = new ConditionalExpression(fieldAccessor, int1231, int1237);
-					setGeneratedBy(int1231or1237, source);
-					statements.add(createResultCalculation(source, int1231or1237));
+					/* booleanField ? 2591 : 2609 */
+					IntLiteral intFalse = makeIntLiteral(String.valueOf(HandlerUtil.PRIME_FOR_FALSE).toCharArray(), source);
+					IntLiteral intTrue = makeIntLiteral(String.valueOf(HandlerUtil.PRIME_FOR_TRUE).toCharArray(), source);
+					ConditionalExpression intForBool = new ConditionalExpression(fieldAccessor, intFalse, intTrue);
+					setGeneratedBy(intForBool, source);
+					statements.add(createResultCalculation(source, intForBool));
 				} else if (Arrays.equals(TypeConstants.LONG, token)) {
 					statements.add(createLocalDeclaration(source, dollarFieldName, TypeReference.baseTypeReference(TypeIds.T_long, 0), fieldAccessor));
 					SingleNameReference copy1 = new SingleNameReference(dollarFieldName, p);
diff --git a/src/core/lombok/javac/handlers/HandleEqualsAndHashCode.java b/src/core/lombok/javac/handlers/HandleEqualsAndHashCode.java
index f3641f7f..3f72f8a1 100644
--- a/src/core/lombok/javac/handlers/HandleEqualsAndHashCode.java
+++ b/src/core/lombok/javac/handlers/HandleEqualsAndHashCode.java
@@ -31,6 +31,7 @@ import java.util.Collections;
 import lombok.EqualsAndHashCode;
 import lombok.core.AST.Kind;
 import lombok.core.AnnotationValues;
+import lombok.core.handlers.HandlerUtil;
 import lombok.javac.Javac;
 import lombok.javac.JavacAnnotationHandler;
 import lombok.javac.JavacNode;
@@ -230,9 +231,9 @@ public class HandleEqualsAndHashCode extends JavacAnnotationHandler<EqualsAndHas
 		Name resultName = typeNode.toName(RESULT_NAME);
 		long finalFlag = JavacHandlerUtil.addFinalIfNeeded(0L, typeNode.getContext());
 		
-		/* final int PRIME = 31; */ {
+		/* final int PRIME = 277; */ {
 			if (!fields.isEmpty() || callSuper) {
-				statements.append(maker.VarDef(maker.Modifiers(finalFlag), primeName, maker.TypeIdent(CTC_INT), maker.Literal(31)));
+				statements.append(maker.VarDef(maker.Modifiers(finalFlag), primeName, maker.TypeIdent(CTC_INT), maker.Literal(HandlerUtil.PRIME_FOR_HASHCODE)));
 			}
 		}
 		
@@ -254,8 +255,9 @@ public class HandleEqualsAndHashCode extends JavacAnnotationHandler<EqualsAndHas
 			if (fType instanceof JCPrimitiveTypeTree) {
 				switch (((JCPrimitiveTypeTree)fType).getPrimitiveTypeKind()) {
 				case BOOLEAN:
-					/* this.fieldName ? 1231 : 1237 */
-					statements.append(createResultCalculation(typeNode, maker.Conditional(fieldAccessor, maker.Literal(1231), maker.Literal(1237))));
+					/* this.fieldName ? 2591 : 2609 */
+					statements.append(createResultCalculation(typeNode, maker.Conditional(fieldAccessor, 
+							maker.Literal(HandlerUtil.PRIME_FOR_FALSE), maker.Literal(HandlerUtil.PRIME_FOR_TRUE))));
 					break;
 				case LONG: {
 						Name dollarFieldName = dollar.append(((JCVariableDecl)fieldNode.get()).name);