/*
 * Copyright (c) 2005, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
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 *
 */

package javax.script;

import java.util.Map;
import java.util.HashMap;
import java.util.Collection;
import java.util.Set;

/**
 * A simple implementation of Bindings backed by
 * a <code>HashMap</code> or some other specified <code>Map</code>.
 *
 * @author Mike Grogan
 * @since 1.6
 */
public class SimpleBindings implements Bindings {

 /**
 * The <code>Map</code> field stores the attributes.
 */
 private Map<String,Object> map;

 /**
 * Constructor uses an existing <code>Map</code> to store the values.
 * @param m The <code>Map</code> backing this <code>SimpleBindings</code>.
 * @throws NullPointerException if m is null
 */
 public SimpleBindings(Map<String,Object> m) {
 if (m == null) {
 throw new NullPointerException();
 }
 this.map = m;
 }

 /**
 * Default constructor uses a <code>HashMap</code>.
 */
 public SimpleBindings() {
 this(new HashMap<String,Object>());
 }

 /**
 * Sets the specified key/value in the underlying <code>map</code> field.
 *
 * @param name Name of value
 * @param value Value to set.
 *
 * @return Previous value for the specified key. Returns null if key was previously
 * unset.
 *
 * @throws NullPointerException if the name is null.
 * @throws IllegalArgumentException if the name is empty.
 */
 public Object put(String name, Object value) {
 checkKey(name);
 return map.put(name,value);
 }

 /**
 * <code>putAll</code> is implemented using <code>Map.putAll</code>.
 *
 * @param toMerge The <code>Map</code> of values to add.
 *
 * @throws NullPointerException
 * if toMerge map is null or if some key in the map is null.
 * @throws IllegalArgumentException
 * if some key in the map is an empty String.
 */
 public void putAll(Map<? extends String, ? extends Object> toMerge) {
 if (toMerge == null) {
 throw new NullPointerException("toMerge map is null");
 }
 for (Map.Entry<? extends String, ? extends Object> entry : toMerge.entrySet()) {
 String key = entry.getKey();
 checkKey(key);
 put(key, entry.getValue());
 }
 }

 /** {@inheritDoc} */
 public void clear() {
 map.clear();
 }

 /**
 * Returns <tt>true</tt> if this map contains a mapping for the specified
 * key. More formally, returns <tt>true</tt> if and only if
 * this map contains a mapping for a key <tt>k</tt> such that
 * <tt>(key==null ? k==null : key.equals(k))</tt>. (There can be
 * at most one such mapping.)
 *
 * @param key key whose presence in this map is to be tested.
 * @return <tt>true</tt> if this map contains a mapping for the specified
 * key.
 *
 * @throws NullPointerException if key is null
 * @throws ClassCastException if key is not String
 * @throws IllegalArgumentException if key is empty String
 */
 public boolean containsKey(Object key) {
 checkKey(key);
 return map.containsKey(key);
 }

 /** {@inheritDoc} */
 public boolean containsValue(Object value) {
 return map.containsValue(value);
 }

 /** {@inheritDoc} */
 public Set<Map.Entry<String, Object>> entrySet() {
 return map.entrySet();
 }

 /**
 * Returns the value to which this map maps the specified key. Returns
 * <tt>null</tt> if the map contains no mapping for this key. A return
 * value of <tt>null</tt> does not <i>necessarily</i> indicate that the
 * map contains no mapping for the key; it's also possible that the map
 * explicitly maps the key to <tt>null</tt>. The <tt>containsKey</tt>
 * operation may be used to distinguish these two cases.
 *
 * <p>More formally, if this map contains a mapping from a key
 * <tt>k</tt> to a value <tt>v</tt> such that <tt>(key==null ? k==null :
 * key.equals(k))</tt>, then this method returns <tt>v</tt>; otherwise
 * it returns <tt>null</tt>. (There can be at most one such mapping.)
 *
 * @param key key whose associated value is to be returned.
 * @return the value to which this map maps the specified key, or
 * <tt>null</tt> if the map contains no mapping for this key.
 *
 * @throws NullPointerException if key is null
 * @throws ClassCastException if key is not String
 * @throws IllegalArgumentException if key is empty String
 */
 public Object get(Object key) {
 checkKey(key);
 return map.get(key);
 }

 /** {@inheritDoc} */
 public boolean isEmpty() {
 return map.isEmpty();
 }

 /** {@inheritDoc} */
 public Set<String> keySet() {
 return map.keySet();
 }

 /**
 * Removes the mapping for this key from this map if it is present
 * (optional operation). More formally, if this map contains a mapping
 * from key <tt>k</tt> to value <tt>v</tt> such that
 * <code>(key==null ? k==null : key.equals(k))</code>, that mapping
 * is removed. (The map can contain at most one such mapping.)
 *
 * <p>Returns the value to which the map previously associated the key, or
 * <tt>null</tt> if the map contained no mapping for this key. (A
 * <tt>null</tt> return can also indicate that the map previously
 * associated <tt>null</tt> with the specified key if the implementation
 * supports <tt>null</tt> values.) The map will not contain a mapping for
 * the specified key once the call returns.
 *
 * @param key key whose mapping is to be removed from the map.
 * @return previous value associated with specified key, or <tt>null</tt>
 * if there was no mapping for key.
 *
 * @throws NullPointerException if key is null
 * @throws ClassCastException if key is not String
 * @throws IllegalArgumentException if key is empty String
 */
 public Object remove(Object key) {
 checkKey(key);
 return map.remove(key);
 }

 /** {@inheritDoc} */
 public int size() {
 return map.size();
 }

 /** {@inheritDoc} */
 public Collection<Object> values() {
 return map.values();
 }

 private void checkKey(Object key) {
 if (key == null) {
 throw new NullPointerException("key can not be null");
 }
 if (!(key instanceof String)) {
 throw new ClassCastException("key should be a String");
 }
 if (key.equals("")) {
 throw new IllegalArgumentException("key can not be empty");
 }
 }
}