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/*
* Copyright (c) 2014, 2024 Oracle and/or its affiliates. All rights reserved.
*
* This program and the accompanying materials are made available under the
* terms of the Eclipse Public License v. 2.0 which is available at
* http://www.eclipse.org/legal/epl-2.0,
* or the Eclipse Distribution License v. 1.0 which is available at
* http://www.eclipse.org/org/documents/edl-v10.php.
*
* SPDX-License-Identifier: EPL-2.0 OR BSD-3-Clause
*/
package org.eclipse.persistence.internal.jaxb;
import java.lang.reflect.Array;
import java.lang.reflect.GenericArrayType;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.lang.reflect.TypeVariable;
import java.util.HashMap;
import java.util.Map;
/**
* Utility class for Generic class hierarchy.
*
*/
public class GenericsClassHelper {
/**
* A tuple consisting of a concrete class, declaring class that declares a
* generic interface type.
*/
private static class DeclaringClassInterfacePair {
public final Class concreteClass;
public final Class declaringClass;
public final Type genericInterface;
private DeclaringClassInterfacePair(Class concreteClass, Class declaringClass, Type genericInteface) {
this.concreteClass = concreteClass;
this.declaringClass = declaringClass;
this.genericInterface = genericInteface;
}
}
/**
* Get the parameterized type arguments for a declaring class that
* declares a generic class or interface type.
*
* @param concrete the concrete class than directly or indirectly
* implements or extends an interface class.
* @param classOrIface the interface or class.
* @return the parameterized type arguments, or null if the generic
* interface type is not a parameterized type.
*/
public static Type[] getParameterizedTypeArguments(Class concrete, Class classOrIface) {
DeclaringClassInterfacePair declaringClassInterfacePair = getClass(concrete, classOrIface);
if (null != declaringClassInterfacePair) {
return getParameterizedTypeArguments(declaringClassInterfacePair);
}
return null;
}
/**
* Get the parameterized type arguments for a declaring class that
* declares a generic interface type.
*
* @param p the declaring class
* @return the parameterized type arguments, or null if the generic
* interface type is not a parameterized type.
*/
private static Type[] getParameterizedTypeArguments(DeclaringClassInterfacePair p) {
if (p.genericInterface instanceof ParameterizedType pt) {
Type[] as = pt.getActualTypeArguments();
Type[] ras = new Type[as.length];
for (int i = 0; i < as.length; i++) {
Type a = as[i];
if (a instanceof Class) {
ras[i] = a;
} else if (a instanceof ParameterizedType) {
pt = (ParameterizedType) a;
ras[i] = a;
} else if (a instanceof TypeVariable) {
ClassTypePair ctp = resolveTypeVariable(p.concreteClass, p.declaringClass, (TypeVariable) a);
if (null != ctp) {
ras[i] = ctp.t;
}
}
}
return ras;
} else {
return null;
}
}
/**
* Find the declaring class that implements or extends an interface or class.
*
* @param concrete the concrete class than directly or indirectly
* implements or extends an interface class.
* @param classOrIface the interface or class.
* @return the tuple of the declaring class and the generic interface or class
* type.
*/
private static DeclaringClassInterfacePair getClass(Class concrete, Class classOrIface) {
return getClass(concrete, classOrIface, concrete);
}
private static DeclaringClassInterfacePair getClass(Class concrete, Class classOrIface, Class c) {
Type[] gis = null;
if (null != c.getGenericSuperclass()) {
gis = new Type[] {c.getGenericSuperclass()};
}
if (null == gis) {
gis = c.getGenericInterfaces();
}
DeclaringClassInterfacePair p = getType(concrete, classOrIface, c, gis);
if (p != null)
return p;
c = c.getSuperclass();
if (c == null || c == Object.class)
return null;
return getClass(concrete, classOrIface, c);
}
private static DeclaringClassInterfacePair getType(Class concrete, Class classOrIface, Class c, Type[] ts) {
for (Type t : ts) {
DeclaringClassInterfacePair p = getType(concrete, classOrIface, c, t);
if (p != null)
return p;
}
return null;
}
private static DeclaringClassInterfacePair getType(Class concrete, Class classOrIface, Class c, Type t) {
if (t instanceof Class) {
if (t == classOrIface) {
return new DeclaringClassInterfacePair(concrete, c, t);
} else {
return getClass(concrete, classOrIface, (Class) t);
}
} else if (t instanceof ParameterizedType pt) {
if (pt.getRawType() == classOrIface) {
return new DeclaringClassInterfacePair(concrete, c, t);
} else {
return getClass(concrete, classOrIface, (Class) pt.getRawType());
}
}
return null;
}
/**
* A tuple consisting of a class and type of the class.
*/
private static class ClassTypePair {
/**
* The type of the class.
*/
public final Type t;
public ClassTypePair(Class c) {
this(c, c);
}
public ClassTypePair(Class c, Type t) {
this.t = t;
}
}
/**
* Given a type variable resolve the Java class of that variable.
*
* @param c the concrete class from which all type variables are resolved
* @param dc the declaring class where the type variable was defined
* @param tv the type variable
* @return the resolved Java class and type, otherwise null if the type variable
* could not be resolved
*/
private static ClassTypePair resolveTypeVariable(Class c, Class dc, TypeVariable tv) {
return resolveTypeVariable(c, dc, tv, new HashMap<>());
}
private static ClassTypePair resolveTypeVariable(Class c, Class dc, TypeVariable tv,
Map map) {
Type[] gis = c.getGenericInterfaces();
for (Type gi : gis) {
if (gi instanceof ParameterizedType pt) {
// process pt of interface
ClassTypePair ctp = resolveTypeVariable(pt, (Class) pt.getRawType(), dc, tv, map);
if (ctp != null)
return ctp;
}
}
Type gsc = c.getGenericSuperclass();
if (gsc instanceof ParameterizedType pt) {
// process pt of class
return resolveTypeVariable(pt, c.getSuperclass(), dc, tv, map);
} else if (gsc instanceof Class) {
return resolveTypeVariable(c.getSuperclass(), dc, tv, map);
}
return null;
}
private static ClassTypePair resolveTypeVariable(ParameterizedType pt, Class c, Class dc, TypeVariable tv,
Map map) {
Type[] typeArguments = pt.getActualTypeArguments();
TypeVariable[] typeParameters = c.getTypeParameters();
Map submap = new HashMap<>();
for (int i = 0; i < typeArguments.length; i++) {
// Substitute a type variable with the Java class
if (typeArguments[i] instanceof TypeVariable) {
Type t = map.get(typeArguments[i]);
submap.put(typeParameters[i], t);
} else {
submap.put(typeParameters[i], typeArguments[i]);
}
}
if (c == dc) {
Type t = submap.get(tv);
if (t instanceof Class) {
return new ClassTypePair((Class) t);
} else if (t instanceof GenericArrayType) {
t = ((GenericArrayType) t).getGenericComponentType();
if (t instanceof Class) {
c = (Class) t;
try {
return new ClassTypePair(getArrayClass(c));
} catch (Exception e) {
}
return null;
} else if (t instanceof ParameterizedType) {
Type rt = ((ParameterizedType) t).getRawType();
if (rt instanceof Class) {
c = (Class) rt;
} else {
return null;
}
try {
return new ClassTypePair(getArrayClass(c), t);
} catch (Exception e) {
return null;
}
} else {
return null;
}
} else if (t instanceof ParameterizedType) {
pt = (ParameterizedType) t;
if (pt.getRawType() instanceof Class) {
return new ClassTypePair((Class) pt.getRawType(), pt);
} else
return null;
} else {
return null;
}
} else {
return resolveTypeVariable(c, dc, tv, submap);
}
}
protected static Class getClassOfType(Type type) {
if (type instanceof Class) {
return (Class) type;
} else if (type instanceof GenericArrayType arrayType) {
Type t = arrayType.getGenericComponentType();
if (t instanceof Class) {
return getArrayClass((Class) t);
}
} else if (type instanceof ParameterizedType subType) {
Type t = subType.getRawType();
if (t instanceof Class) {
return (Class) t;
}
}
return null;
}
/**
* Get Array class of component class.
*
* @param c the component class of the array
* @return the array class.
*/
private static Class getArrayClass(Class c) {
try {
Object o = Array.newInstance(c, 0);
return o.getClass();
} catch (Exception e) {
throw new IllegalArgumentException(e);
}
}
}