org.springframework.binding.collection.StringKeyedMapAdapter Maven / Gradle / Ivy
/*
* Copyright 2004-2012 the original author or authors.
*
* 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 org.springframework.binding.collection;
import java.util.Collection;
import java.util.Iterator;
import java.util.Map;
import java.util.NoSuchElementException;
import java.util.Set;
/**
* Base class for map adapters whose keys are String values. Concrete classes need only implement the abstract hook
* methods defined by this class.
*
* @author Keith Donald
*/
public abstract class StringKeyedMapAdapter implements Map {
private Set keySet;
private Collection values;
private Set> entrySet;
// implementing Map
public void clear() {
for (Iterator it = getAttributeNames(); it.hasNext();) {
removeAttribute(it.next());
}
}
public boolean containsKey(Object key) {
return getAttribute(key.toString()) != null;
}
public boolean containsValue(Object value) {
if (value == null) {
return false;
}
for (Iterator it = getAttributeNames(); it.hasNext();) {
Object aValue = getAttribute(it.next());
if (value.equals(aValue)) {
return true;
}
}
return false;
}
public Set> entrySet() {
return (entrySet != null) ? entrySet : (entrySet = new EntrySet());
}
public V get(Object key) {
return getAttribute(key.toString());
}
public boolean isEmpty() {
return !getAttributeNames().hasNext();
}
public Set keySet() {
return (keySet != null) ? keySet : (keySet = new KeySet());
}
public V put(String key, V value) {
String stringKey = String.valueOf(key);
V previousValue = getAttribute(stringKey);
setAttribute(stringKey, value);
return previousValue;
}
public void putAll(Map map) {
for (Entry entry : map.entrySet()) {
setAttribute(entry.getKey(), entry.getValue());
}
}
public V remove(Object key) {
String stringKey = key.toString();
V retval = getAttribute(stringKey);
removeAttribute(stringKey);
return retval;
}
public int size() {
int size = 0;
for (Iterator it = getAttributeNames(); it.hasNext();) {
size++;
it.next();
}
return size;
}
public Collection values() {
return (values != null) ? values : (values = new Values());
}
// hook methods
/**
* Hook method that needs to be implemented by concrete subclasses. Gets a value associated with a key.
* @param key the key to lookup
* @return the associated value, or null if none
*/
protected abstract V getAttribute(String key);
/**
* Hook method that needs to be implemented by concrete subclasses. Puts a key-value pair in the map, overwriting
* any possible earlier value associated with the same key.
* @param key the key to associate the value with
* @param value the value to associate with the key
*/
protected abstract void setAttribute(String key, V value);
/**
* Hook method that needs to be implemented by concrete subclasses. Removes a key and its associated value from the
* map.
* @param key the key to remove
*/
protected abstract void removeAttribute(String key);
/**
* Hook method that needs to be implemented by concrete subclasses. Returns an enumeration listing all keys known to
* the map.
* @return the key enumeration
*/
protected abstract Iterator getAttributeNames();
// internal helper classes
private abstract class AbstractSet extends java.util.AbstractSet {
public boolean isEmpty() {
return StringKeyedMapAdapter.this.isEmpty();
}
public int size() {
return StringKeyedMapAdapter.this.size();
}
public void clear() {
StringKeyedMapAdapter.this.clear();
}
}
private class KeySet extends AbstractSet {
public Iterator iterator() {
return new KeyIterator();
}
public boolean contains(Object o) {
return StringKeyedMapAdapter.this.containsKey(o);
}
public boolean remove(Object o) {
return StringKeyedMapAdapter.this.remove(o) != null;
}
}
private abstract class AbstractKeyIterator {
private final Iterator it = getAttributeNames();
private String currentKey;
public void remove() {
if (currentKey == null) {
throw new NoSuchElementException("You must call next() at least once");
}
StringKeyedMapAdapter.this.remove(currentKey);
}
public boolean hasNext() {
return it.hasNext();
}
protected String nextKey() {
return currentKey = it.next();
}
}
private class KeyIterator extends AbstractKeyIterator implements Iterator {
public String next() {
return nextKey();
}
}
private class Values extends AbstractSet {
public Iterator iterator() {
return new ValuesIterator();
}
public boolean contains(Object o) {
return StringKeyedMapAdapter.this.containsValue(o);
}
public boolean remove(Object o) {
if (o == null) {
return false;
}
for (Iterator it = iterator(); it.hasNext();) {
if (o.equals(it.next())) {
it.remove();
return true;
}
}
return false;
}
}
private class ValuesIterator extends AbstractKeyIterator implements Iterator {
public V next() {
return StringKeyedMapAdapter.this.get(nextKey());
}
}
private class EntrySet extends AbstractSet> {
public Iterator> iterator() {
return new EntryIterator();
}
public boolean contains(Object o) {
Entry entry = getAsEntry(o);
if (entry == null || entry.getKey() == null || entry.getValue() == null) {
return false;
}
V valueFromThisMap = StringKeyedMapAdapter.this.get(entry.getKey());
return entry.getValue().equals(valueFromThisMap);
}
public boolean remove(Object o) {
Entry entry = getAsEntry(o);
if (entry == null || entry.getKey() == null || entry.getValue() == null) {
return false;
}
V valueFromThisMap = StringKeyedMapAdapter.this.get(entry.getKey());
if (!entry.getValue().equals(valueFromThisMap)) {
return false;
}
return StringKeyedMapAdapter.this.remove(entry.getKey()) != null;
}
@SuppressWarnings("unchecked")
private Entry getAsEntry(Object o) {
if (o instanceof Entry) {
return (Entry) o;
}
return null;
}
}
private class EntryIterator extends AbstractKeyIterator implements Iterator> {
public Entry next() {
return new EntrySetEntry(nextKey());
}
}
private class EntrySetEntry implements Entry {
private final String currentKey;
public EntrySetEntry(String currentKey) {
this.currentKey = currentKey;
}
public String getKey() {
return currentKey;
}
public V getValue() {
return StringKeyedMapAdapter.this.get(currentKey);
}
public V setValue(V value) {
return StringKeyedMapAdapter.this.put(currentKey, value);
}
}
}