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package javax.faces;
import java.util.Collection;
import java.util.List;
import java.util.Map;
import java.util.Set;
class TypedCollections {
/**
* Dynamically check that the members of the collection are all
* instances of the given type (or null).
*/
private static boolean checkCollectionMembers(Collection c, Class type) {
for (Object element : c) {
if (element != null && !type.isInstance(element)) {
return false;
}
}
return true;
}
/**
* Dynamically check that the members of the collection are all
* instances of the given type (or null), and that the collection
* itself is of the given collection type.
*
* @param
* the collection's element type
* @param c
* the collection to cast
* @param type
* the class of the collection's element type.
* @return the dynamically-type checked collection.
* @throws java.lang.ClassCastException
*/
@SuppressWarnings("unchecked")
static > TypedC dynamicallyCastCollection(Collection c,
Class type,
Class collectionType) {
if (c == null)
return null;
if (!collectionType.isInstance(c))
throw new ClassCastException(c.getClass().getName());
assert checkCollectionMembers(c, type) :
"The collection contains members with a type other than " + type.getName();
return collectionType.cast(c);
}
/**
* Dynamically check that the members of the list are all instances of
* the given type (or null).
*
* @param
* the list's element type
* @param list
* the list to cast
* @param type
* the class of the list's element type.
* @return the dynamically-type checked list.
* @throws java.lang.ClassCastException
*/
@SuppressWarnings("unchecked")
static List dynamicallyCastList(List list, Class type) {
return dynamicallyCastCollection(list, type, List.class);
}
/**
* Dynamically check that the members of the set are all instances of
* the given type (or null).
*
* @param
* the set's element type
* @param set
* the set to cast
* @param type
* the class of the set's element type.
* @return the dynamically-type checked set.
* @throws java.lang.ClassCastException
*/
@SuppressWarnings("unchecked")
static Set dynamicallyCastSet(Set set,
Class type) {
return dynamicallyCastCollection(set, type, Set.class);
}
/**
* Dynamically check that the keys and values in the map are all
* instances of the correct types (or null).
*
* @param
* the map's key type
* @param
* the map's value type
* @param map
* the map to cast
* @param keyType
* the class of the map's key type.
* @param keyType
* the class of the map's key type.
* @return the dynamically-type checked map.
* @throws java.lang.ClassCastException
*/
@SuppressWarnings("unchecked")
static Map dynamicallyCastMap(Map map,
Class keyType,
Class valueType) {
if (map == null) {
return null;
}
assert checkCollectionMembers(map.keySet(), keyType) :
"The map contains keys with a type other than " + keyType.getName();
assert checkCollectionMembers(map.values(), valueType) :
"The map contains values with a type other than " + valueType.getName();
return (Map) map;
}
}