add bi and side variance

Author: FelixAnthonisen

src/main/java/io/github/bldl/annotationProcessing/VarianceProcessor.java

@@ -127,6 +127,10 @@ private void checkVariance(String className, MyVariance annotation, String packa
             cu.accept(new ReturnTypeCollector(), types);
         else if (annotation.variance() == VarianceType.COVARIANT)
             cu.accept(new ParameterTypeCollector(), types);
+        else if (annotation.variance() == VarianceType.BIVARIANT) {
+            cu.accept(new ReturnTypeCollector(), types);
+            cu.accept(new ParameterTypeCollector(), types);
+        }
 
         for (Type type : types) {
             if (TypeHandler.containsType(type, typeOfInterest)) {
@@ -136,7 +140,8 @@ else if (annotation.variance() == VarianceType.COVARIANT)
                                 "%s is declared as %s, but does not conform to constraints: contains T in %s position",
                                 className,
                                 annotation.variance(),
-                                annotation.variance() == VarianceType.COVARIANT ? "IN" : "OUT"));
+                                annotation.variance() == VarianceType.COVARIANT ? "IN"
+                                        : annotation.variance() == VarianceType.BIVARIANT ? "OUT" : "IN/OUT"));
             }
         }
     }

src/main/java/io/github/bldl/annotationProcessing/VarianceType.java

@@ -4,5 +4,6 @@ public enum VarianceType {
     INVARIANT,
     COVARIANT,
     CONTRAVARIANT,
-    SIDE
+    BIVARIANT,
+    SIDEVARIANT
 }

src/main/java/io/github/bldl/astParsing/visitors/SubtypingCheckVisitor.java

@@ -197,7 +197,15 @@ private boolean isValidSubtype(ClassOrInterfaceType assigneeType, ClassOrInterfa
                         return classHierarchy.isDescendant(
                                 ((ClassOrInterfaceType) assignedArgs.get(i)).getNameAsString(),
                                 ((ClassOrInterfaceType) assigneeArgs.get(i)).getNameAsString(), mp.get(i).depth());
-                    case SIDE:
+                    case BIVARIANT:
+                        return classHierarchy.isDescendant(
+                                ((ClassOrInterfaceType) assigneeArgs.get(i)).getNameAsString(),
+                                ((ClassOrInterfaceType) assignedArgs.get(i)).getNameAsString(), mp.get(i).depth())
+                                || classHierarchy.isDescendant(
+                                        ((ClassOrInterfaceType) assignedArgs.get(i)).getNameAsString(),
+                                        ((ClassOrInterfaceType) assigneeArgs.get(i)).getNameAsString(),
+                                        mp.get(i).depth());
+                    case SIDEVARIANT:
                         return classHierarchy.sameLevel(((ClassOrInterfaceType) assignedArgs.get(i)).getNameAsString(),
                                 ((ClassOrInterfaceType) assigneeArgs.get(i)).getNameAsString());
                     default: