package bsh;
import javax.script.ScriptContext;
import java.util.Collection;
import java.util.Collections;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import static javax.script.ScriptContext.ENGINE_SCOPE;
// Adopted from http://ikayzo.org/svn/beanshell/BeanShell/engine/src/bsh/engine/ScriptContextEngineView.java
/**
* This class implements an ENGINE_SCOPE centric Map view of the ScriptContext
* for engine implementations. This class can be used to simplify engine
* implementations which have the capability to bind their namespaces to Maps
* or other external interfaces.
* <p/>
* Get operations on this view delegate to the
* ScriptContext inheriting get() method that automatically traverses the
* binding scopes in order or precedence. Put operations on this view always
* store values in the ENGINE_SCOPE bindings. Other operations such as
* size() and contains() are implemented appropriately, but perhaps not as
* efficiently as possible.
*/
public class ScriptContextEngineView implements Map<String, Object> {
ScriptContext context;
public ScriptContextEngineView(ScriptContext context) {
this.context = context;
}
/**
* Returns the number of unique object bindings in all scopes.
* (duplicate, shadowed, bindings count as a single binging).
*/
public int size() {
return totalKeySet().size();
}
/**
* Returns true if no bindings are present in any scope of the context.
*/
public boolean isEmpty() {
return totalKeySet().size() == 0;
}
/**
* Returns true if the key name is bound in any scope in the context.
* The key must be a String.
*
* @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 ClassCastException if the key is of an inappropriate type for this
* map (optional).
* @throws NullPointerException if the key is <tt>null</tt> and this map does
* not permit <tt>null</tt> keys (optional).
*/
public boolean containsKey(Object key) {
if (key instanceof String) {
return context.getAttributesScope((String) key) != -1;
}
return false;
}
/**
* Returns <tt>true</tt> if this map maps one or more keys to the specified
* value. More formally, returns <tt>true</tt> if and only if this map
* contains at least one mapping to a value <tt>v</tt> such that
* <tt>(value==null ? v==null : value.equals(v))</tt>. This operation will
* probably require time linear in the map size for most implementations of the
* <tt>Map</tt> interface.
*
* @param value value whose presence in this map is to be tested.
* @return <tt>true</tt> if this map maps one or more keys to the specified
* value.
* @throws ClassCastException if the value is of an inappropriate type for this
* map (optional).
* @throws NullPointerException if the value is <tt>null</tt> and this map does
* not permit <tt>null</tt> values (optional).
*/
public boolean containsValue(Object value) {
Set values = totalValueSet();
return values.contains(value);
}
/**
* Returns the value bound in the most specific (lowest numbered)
* bindings space for this key.
* key must be a String.
*
* @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 ClassCastException if the key is of an inappropriate type for this
* map (optional).
* @throws NullPointerException if the key is <tt>null</tt> and this map does
* not permit <tt>null</tt> keys (optional).
* @see #containsKey(Object)
*/
public Object get(Object key) {
return context.getAttribute((String) key);
}
/**
* Set the key, value binding in the ENGINE_SCOPE of the context.
*
* @param key key with which the specified value is to be associated.
* @param value value to be associated with the specified key.
* @return previous value associated with specified key, or <tt>null</tt> if
* there was no mapping for 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.
* @throws UnsupportedOperationException if the <tt>put</tt> operation is not
* supported by this map.
* @throws ClassCastException if the class of the specified key or value
* prevents it from being stored in this map.
* @throws IllegalArgumentException if some aspect of this key or value
* prevents it from being stored in this map.
* @throws NullPointerException if this map does not permit <tt>null</tt> keys
* or values, and the specified key or value is <tt>null</tt>.
*/
public Object put(String key, Object value) {
Object oldValue = context.getAttribute(key, ENGINE_SCOPE);
context.setAttribute(key, value, ENGINE_SCOPE);
return oldValue;
}
/**
* Put the bindings into the ENGINE_SCOPE of the context.
*
* @param t Mappings to be stored in this map.
* @throws UnsupportedOperationException if the <tt>putAll</tt> method is not
* supported by this map.
* @throws ClassCastException if the class of a key or value in the specified
* map prevents it from being stored in this map.
* @throws IllegalArgumentException some aspect of a key or value in the
* specified map prevents it from being stored in this map.
* @throws NullPointerException if the specified map is <tt>null</tt>, or if
* this map does not permit <tt>null</tt> keys or values, and the specified map
* contains <tt>null</tt> keys or values.
*/
public void putAll(Map<? extends String, ? extends Object> t) {
context.getBindings(ENGINE_SCOPE).putAll(t);
}
/**
* Removes the mapping from the engine scope.
* <p/>
* <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 okey 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 ClassCastException if the key is of an inappropriate type for this
* map (optional).
* @throws NullPointerException if the key is <tt>null</tt> and this map does
* not permit <tt>null</tt> keys (optional).
* @throws UnsupportedOperationException if the <tt>remove</tt> method is not
* supported by this map.
*/
// Why is the compiler complaining about this?
//public Object remove( String key )
public Object remove(Object okey) {
// This shouldn't be necessary... we don't map Objects, Strings.
String key = (String) okey;
Object oldValue = context.getAttribute(key, ENGINE_SCOPE);
context.removeAttribute(key, ENGINE_SCOPE);
return oldValue;
}
/**
* Removes all mappings from this map (optional operation).
*
* @throws UnsupportedOperationException clear is not supported by this map.
*/
public void clear() {
context.getBindings(ENGINE_SCOPE).clear();
}
/**
* Returns the total key set of all scopes.
* This method violates the Map contract by returning an unmodifiable set.
*
* @return a set view of the keys contained in this map.
*/
public Set<String> keySet() {
return totalKeySet();
}
/**
* Returns the total values set of all scopes.
* This method violates the Map contract by returning an unmodifiable set.
*
* @return a collection view of the values contained in this map.
*/
public Collection<Object> values() {
return totalValueSet();
}
/**
* Returns a set view of the mappings contained in this map. Each element in
* the returned set is a {@link java.util.Map.Entry}. The set is backed by the
* map, so changes to the map are reflected in the set, and vice-versa. If the
* map is modified while an iteration over the set is in progress (except
* through the iterator's own <tt>remove</tt> operation, or through the
* <tt>setValue</tt> operation on a map entry returned by the iterator) the
* results of the iteration are undefined. The set supports element removal,
* which removes the corresponding mapping from the map, via the
* <tt>Iterator.remove</tt>, <tt>Set.remove</tt>, <tt>removeAll</tt>,
* <tt>retainAll</tt> and <tt>clear</tt> operations. It does not support the
* <tt>add</tt> or <tt>addAll</tt> operations.
*
* @return a set view of the mappings contained in this map.
*/
public Set<Entry<String, Object>> entrySet() {
throw new Error("unimplemented");
}
private Set<String> totalKeySet() {
Set<String> keys = new HashSet<String>();
List<Integer> scopes = context.getScopes();
for (int i : scopes) {
keys.addAll(context.getBindings(i).keySet());
}
return Collections.unmodifiableSet(keys);
}
private Set<Object> totalValueSet() {
Set<Object> values = new HashSet<Object>();
List<Integer> scopes = context.getScopes();
for (int i : scopes) {
values.addAll(context.getBindings(i).values());
}
return Collections.unmodifiableSet(values);
}
}