org.openide.util.NbCollections Maven / Gradle / Ivy
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package org.openide.util;
import java.io.Serializable;
import java.util.AbstractMap;
import java.util.AbstractSet;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.NoSuchElementException;
import java.util.RandomAccess;
import java.util.Set;
import java.util.logging.Level;
import java.util.logging.Logger;
/**
* Utilities for working with generics.
* Note that there is no checkedListByFilter method currently.
* If constant-time operation is important (e.g. your raw list is large and {@link RandomAccess})
* you can use {@link #checkedListByCopy}, assuming you do not need to modify the underlying list.
* If you are only interested in an iterator anyway, try {@link #checkedIteratorByFilter}.
* @author Jesse Glick
* @since org.openide.util 7.1
*/
public class NbCollections {
private NbCollections() {}
private static final Logger LOG = Logger.getLogger(NbCollections.class.getName());
/**
* Create a typesafe copy of a raw set.
* @param rawSet an unchecked set
* @param type the desired supertype of the entries
* @param strict true to throw a ClassCastException if the raw set has an invalid entry,
* false to skip over such entries (warnings may be logged)
* @return a typed set guaranteed to contain only entries assignable
* to the named type (or they may be null)
* @throws ClassCastException if some entry in the raw set was not well-typed, and only if strict was true
*/
public static Set checkedSetByCopy(Set rawSet, Class type, boolean strict) throws ClassCastException {
Set s = new HashSet(rawSet.size() * 4 / 3 + 1);
Iterator it = rawSet.iterator();
while (it.hasNext()) {
Object e = it.next();
try {
s.add(type.cast(e));
} catch (ClassCastException x) {
if (strict) {
throw x;
} else {
LOG.log(Level.WARNING, "Element {0} not assignable to {1}", new Object[] {e, type});
}
}
}
return s;
}
/**
* Create a typesafe copy of a raw list.
* @param rawList an unchecked list
* @param type the desired supertype of the entries
* @param strict true to throw a ClassCastException if the raw list has an invalid entry,
* false to skip over such entries (warnings may be logged)
* @return a typed list guaranteed to contain only entries assignable
* to the named type (or they may be null)
* @throws ClassCastException if some entry in the raw list was not well-typed, and only if strict was true
*/
public static List checkedListByCopy(List rawList, Class type, boolean strict) throws ClassCastException {
List l = (rawList instanceof RandomAccess) ? new ArrayList(rawList.size()) : new LinkedList();
Iterator it = rawList.iterator();
while (it.hasNext()) {
Object e = it.next();
try {
l.add(type.cast(e));
} catch (ClassCastException x) {
if (strict) {
throw x;
} else {
LOG.log(Level.WARNING, "Element {0} not assignable to {1}", new Object[] {e, type});
}
}
}
return l;
}
/**
* Create a typesafe copy of a raw map.
* @param rawMap an unchecked map
* @param keyType the desired supertype of the keys
* @param valueType the desired supertype of the values
* @param strict true to throw a ClassCastException if the raw map has an invalid key or value,
* false to skip over such map entries (warnings may be logged)
* @return a typed map guaranteed to contain only keys and values assignable
* to the named types (or they may be null)
* @throws ClassCastException if some key or value in the raw map was not well-typed, and only if strict was true
*/
public static Map checkedMapByCopy(Map rawMap, Class keyType, Class valueType, boolean strict) throws ClassCastException {
Map m2 = new HashMap(rawMap.size() * 4 / 3 + 1);
Iterator it = rawMap.entrySet().iterator();
while (it.hasNext()) {
Map.Entry e = (Map.Entry) it.next();
try {
m2.put(keyType.cast(e.getKey()), valueType.cast(e.getValue()));
} catch (ClassCastException x) {
if (strict) {
throw x;
} else {
LOG.log(Level.WARNING, "Entry {0} not assignable to <{1},{2}>", new Object[] {e, keyType, valueType});
}
}
}
return m2;
}
private static abstract class CheckedIterator implements Iterator {
private static final Object WAITING = new Object();
private final Iterator it;
private Object next = WAITING;
public CheckedIterator(Iterator it) {
this.it = it;
}
protected abstract boolean accept(Object o);
public boolean hasNext() {
if (next != WAITING) {
return true;
}
while (it.hasNext()) {
next = it.next();
if (accept(next)) {
return true;
}
}
next = WAITING;
return false;
}
public E next() {
if (next == WAITING && !hasNext()) {
throw new NoSuchElementException();
}
assert next != WAITING;
@SuppressWarnings("unchecked") // type-checking is done by accept()
E x = (E) next;
next = WAITING;
return x;
}
public void remove() {
it.remove();
}
}
/**
* Create a typesafe filter of an unchecked iterator.
* {@link Iterator#remove} will work if it does in the unchecked iterator.
* @param rawIterator an unchecked iterator
* @param type the desired enumeration type
* @param strict if false, elements which are not null but not assignable to the requested type are omitted;
* if true, {@link ClassCastException} may be thrown from an iterator operation
* @return an iterator guaranteed to contain only objects of the requested type (or null)
*/
public static Iterator checkedIteratorByFilter(Iterator rawIterator, final Class type, final boolean strict) {
return new CheckedIterator(rawIterator) {
protected boolean accept(Object o) {
if (o == null) {
return true;
} else if (type.isInstance(o)) {
return true;
} else if (strict) {
throw new ClassCastException(o + " was not a " + type.getName()); // NOI18N
} else {
return false;
}
}
};
}
/**
* Create a typesafe view over an underlying raw set.
* Mutations affect the underlying set (this is not a copy).
* {@link Set#clear} will make the view empty but may not clear the underlying set.
* You may add elements only of the requested type.
* {@link Set#contains} also performs a type check and will throw {@link ClassCastException}
* for an illegal argument.
* The view is serializable if the underlying set is.
* @param rawSet an unchecked set
* @param type the desired element type
* @param strict if false, elements in the underlying set which are not null and which are not assignable
* to the requested type are omitted from the view;
* if true, a {@link ClassCastException} may arise during some set operation
* @return a view over the raw set guaranteed to match the specified type
*/
public static Set checkedSetByFilter(Set rawSet, Class type, boolean strict) {
return new CheckedSet(rawSet, type, strict);
}
private static final class CheckedSet extends AbstractSet implements Serializable {
private static final long serialVersionUID = 1L;
private final Set rawSet;
private final Class type;
private final boolean strict;
public CheckedSet(Set rawSet, Class type, boolean strict) {
this.rawSet = rawSet;
this.type = type;
this.strict = strict;
}
private boolean acceptEntry(Object o) {
if (o == null) {
return true;
} else if (type.isInstance(o)) {
return true;
} else if (strict) {
throw new ClassCastException(o + " was not a " + type.getName()); // NOI18N
} else {
return false;
}
}
@Override
public Iterator iterator() {
return new CheckedIterator(rawSet.iterator()) {
@Override
protected boolean accept(Object o) {
return acceptEntry(o);
}
};
}
@Override
public int size() {
int c = 0;
Iterator it = rawSet.iterator();
while (it.hasNext()) {
if (acceptEntry(it.next())) {
c++;
}
}
return c;
}
@Override
@SuppressWarnings("unchecked") // complains about usage of raw set
public boolean add(E o) {
return rawSet.add(type.cast(o));
}
@Override
public boolean contains(Object o) {
return rawSet.contains(type.cast(o));
}
}
/**
* Create a typesafe view over an underlying raw map.
* Mutations affect the underlying map (this is not a copy).
* {@link Map#clear} will make the view empty but may not clear the underlying map.
* You may add entries only of the requested type pair.
* {@link Map#get}, {@link Map#containsKey}, and {@link Map#containsValue} also perform a type check
* and will throw {@link ClassCastException} for an illegal argument.
* The view is serializable if the underlying map is.
* @param rawMap an unchecked map
* @param keyType the desired entry key type
* @param valueType the desired entry value type
* @param strict if false, entries in the underlying map for which the key is not null but not assignable
* to the requested key type, and/or the value is not null but not assignable to
* the requested value type, are omitted from the view;
* if true, a {@link ClassCastException} may arise during some map operation
* @return a view over the raw map guaranteed to match the specified type
*/
public static Map checkedMapByFilter(Map rawMap, Class keyType, Class valueType, boolean strict) {
return new CheckedMap(rawMap, keyType, valueType, strict);
}
private static final class CheckedMap extends AbstractMap implements Serializable {
private static final long serialVersionUID = 1L;
private final Map rawMap;
private final Class keyType;
private final Class valueType;
private final boolean strict;
public CheckedMap(Map rawMap, Class keyType, Class valueType, boolean strict) {
this.rawMap = rawMap;
this.keyType = keyType;
this.valueType = valueType;
this.strict = strict;
}
private boolean acceptKey(Object o) {
if (o == null) {
return true;
} else if (keyType.isInstance(o)) {
return true;
} else if (strict) {
throw new ClassCastException(o + " was not a " + keyType.getName()); // NOI18N
} else {
return false;
}
}
private boolean acceptValue(Object o) {
if (o == null) {
return true;
} else if (valueType.isInstance(o)) {
return true;
} else if (strict) {
throw new ClassCastException(o + " was not a " + valueType.getName()); // NOI18N
} else {
return false;
}
}
private boolean acceptEntry(Map.Entry e) {
return acceptKey(e.getKey()) && acceptValue(e.getValue());
}
private final class EntrySet extends AbstractSet> {
@Override
public Iterator> iterator() {
return new CheckedIterator>(rawMap.entrySet().iterator()) {
@Override
protected boolean accept(Object o) {
return acceptEntry((Map.Entry) o);
}
};
}
@Override
public int size() {
int c = 0;
Iterator it = rawMap.entrySet().iterator();
while (it.hasNext()) {
if (acceptEntry((Map.Entry) it.next())) {
c++;
}
}
return c;
}
}
@Override
public Set> entrySet() {
return new EntrySet();
}
@Override
public V get(Object key) {
Object o = rawMap.get(keyType.cast(key));
if (acceptValue(o)) {
@SuppressWarnings("unchecked")
V v = (V) o;
return v;
} else {
return null;
}
}
@SuppressWarnings("unchecked")
@Override
public V put(K key, V value) {
Object old = rawMap.put(keyType.cast(key), valueType.cast(value));
if (acceptValue(old)) {
return (V) old;
} else {
return null;
}
}
@Override
public V remove(Object key) {
Object old = rawMap.remove(keyType.cast(key));
if (acceptValue(old)) {
@SuppressWarnings("unchecked")
V v = (V) old;
return v;
} else {
return null;
}
}
@Override
public boolean containsKey(Object key) {
return rawMap.containsKey(keyType.cast(key)) &&
acceptValue(rawMap.get(key));
}
@Override
public boolean containsValue(Object value) {
// Cannot just ask rawMap since we could not check type of key.
return super.containsValue(valueType.cast(value));
}
@Override
public int size() {
int c = 0;
Iterator it = rawMap.entrySet().iterator();
while (it.hasNext()) {
if (acceptEntry((Map.Entry) it.next())) {
c++;
}
}
return c;
}
// keySet, values cannot be so easily overridden because we type-check whole entries
}
/**
* Create a typesafe filter of an unchecked enumeration.
* @param rawEnum an unchecked enumeration
* @param type the desired enumeration type
* @param strict if false, elements which are not null but not assignable to the requested type are omitted;
* if true, {@link ClassCastException} may be thrown from an enumeration operation
* @return an enumeration guaranteed to contain only objects of the requested type (or null)
*/
public static Enumeration checkedEnumerationByFilter(Enumeration rawEnum, final Class type, final boolean strict) {
@SuppressWarnings("unchecked")
Enumeration