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The Adobe Experience Manager SDK
/**
* Copyright (c) 2012-2015 Edgar Espina
*
* This file is part of Handlebars.java.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.github.jknack.handlebars.context;
import static org.apache.commons.lang3.Validate.notNull;
import java.lang.reflect.AccessibleObject;
import java.lang.reflect.Member;
import java.lang.reflect.Modifier;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;
import com.github.jknack.handlebars.ValueResolver;
/**
* A specialization of {@link ValueResolver} that is built on top of reflections
* API. It use an internal cache for saving {@link Member members}.
*
* @author edgar.espina
* @param The member type.
* @since 0.1.1
*
* @deprecated com.github.jknack.handlebars.context package is deprecated and marked for removal in subsequent releases which will involve removal of the handlebars dependency in AEM.
*/
@Deprecated(since = "2024-07-10")
public abstract class MemberValueResolver implements ValueResolver {
/**
* A concurrent and thread-safe cache for {@link Member}.
*/
private final Map, Map> cache = new ConcurrentHashMap<>();
@Override
public final Object resolve(final Object context, final String name) {
Class key = context.getClass();
Map mcache = cache(key);
M member = mcache.get(name);
if (member == null) {
return UNRESOLVED;
} else {
return invokeMember(member, context);
}
}
@Override
public Object resolve(final Object context) {
return UNRESOLVED;
}
/**
* Get or build a class member cache.
*
* @param clazz Owner/key.
* @return A class cache.
*/
private Map cache(final Class clazz) {
Map mcache = this.cache.get(clazz);
if (mcache == null) {
mcache = new HashMap<>();
Set members = members(clazz);
for (M m : members) {
// Mark as accessible.
if (isUseSetAccessible(m) && m instanceof AccessibleObject) {
((AccessibleObject) m).setAccessible(true);
}
mcache.put(memberName(m), m);
}
this.cache.put(clazz, mcache);
}
return mcache;
}
/**
* Determines whether or not to call
* {@link AccessibleObject#setAccessible(boolean)} on members before they are
* cached.
*
* Calling setAccessible on JDK 9 or later on private or protected declaring
* classes in modules will result in errors so the default implementation checks
* to see if the declared class cannonical name starts with "java." or "sun." to
* prevent most of these errors.
*
* Modular applications should create their own resolvers and override this
* method to prevent encapsulation violation errors.
*
* @param member Not null.
* @return true will cause setAccessible(true) to be called.
*/
protected boolean isUseSetAccessible(final M member) {
Class dc = member.getDeclaringClass();
String dn = dc == null ? null : dc.getCanonicalName();
if (dn != null && (dn.startsWith("java.") || dn.startsWith("sun."))) {
return false;
}
return true;
}
/**
* Invoke the member in the given context.
*
* @param member The class member.
* @param context The context object.
* @return The resulting value.
*/
protected abstract Object invokeMember(M member, Object context);
/**
* True, if the member matches the one we look for.
*
* @param member The class {@link Member}.
* @param name The attribute's name.
* @return True, if the member matches the one we look for.
*/
public abstract boolean matches(M member, String name);
/**
* True if the member is public.
*
* @param member The member object.
* @return True if the member is public.
*/
protected boolean isPublic(final M member) {
return Modifier.isPublic(member.getModifiers());
}
/**
* True if the member is private.
*
* @param member The member object.
* @return True if the member is private.
*/
protected boolean isPrivate(final M member) {
return Modifier.isPrivate(member.getModifiers());
}
/**
* True if the member is protected.
*
* @param member The member object.
* @return True if the member is protected.
*/
protected boolean isProtected(final M member) {
return Modifier.isProtected(member.getModifiers());
}
/**
* True if the member is static.
*
* @param member The member object.
* @return True if the member is static.
*/
protected boolean isStatic(final M member) {
return Modifier.isStatic(member.getModifiers());
}
/**
* List all the possible members for the given class.
*
* @param clazz The base class.
* @return All the possible members for the given class.
*/
protected abstract Set members(Class clazz);
@Override
public Set> propertySet(final Object context) {
notNull(context, "The context is required.");
if (context instanceof Map) {
return Collections.emptySet();
} else if (context instanceof Collection) {
return Collections.emptySet();
}
Collection members = cache(context.getClass()).values();
Map propertySet = new LinkedHashMap<>();
for (M member : members) {
String name = memberName(member);
propertySet.put(name, resolve(context, name));
}
return propertySet.entrySet();
}
/**
* Get the name for the given member.
*
* @param member A class member.
* @return The member's name.
*/
protected abstract String memberName(M member);
}
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