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/*****************************************************************************
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* This file is part of the BeanShell Java Scripting distribution. *
* Documentation and updates may be found at http://www.beanshell.org/ *
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* Sun Public License Notice: *
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* The contents of this file are subject to the Sun Public License Version *
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* Code is Pat Niemeyer. Portions created by Pat Niemeyer are Copyright *
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*****************************************************************************/
package bsh;
import java.lang.reflect.Array;
import java.util.Enumeration;
import java.util.Hashtable;
import java.util.Vector;
/**
* The default CollectionManager (which remains Java 1.1 compatible) supports
* iteration over objects of type: Enumeration, Vector, String, StringBuffer and
* array. The dynamically loaded CollectionManagerImpl supports additional types
* when it is present.
*/
public class CollectionManager {
private static CollectionManager manager;
public synchronized static CollectionManager getCollectionManager() {
if (manager == null && Capabilities.classExists("java.util.Collection")) {
Class clas;
try {
clas = Class.forName("bsh.collection.CollectionManagerImpl");
manager = (CollectionManager) clas.newInstance();
} catch (Exception e) {
Interpreter.debug("unable to load CollectionManagerImpl: " + e);
}
}
if (manager == null)
manager = new CollectionManager(); // default impl
return manager;
}
public boolean isBshIterable(Object obj) {
// This could be smarter...
try {
getBshIterator(obj);
return true;
} catch (IllegalArgumentException e) {
return false;
}
}
public BshIterator getBshIterator(Object obj) throws IllegalArgumentException {
return new BasicBshIterator(obj);
}
public boolean isMap(Object obj) {
return obj instanceof Hashtable;
}
public Object getFromMap(Object map, Object key) {
return ((Hashtable) map).get(key);
}
public Object putInMap(Object map, Object key, Object value) {
return ((Hashtable) map).put(key, value);
}
/**
* Determine dynamically if the target is an iterator by the presence of a
* pair of next() and hasNext() methods. public static boolean isIterator()
* { }
*
* An implementation that works with JDK 1.1
*/
public static class BasicBshIterator implements BshIterator {
Enumeration enumeration;
/**
* Construct a basic BasicBshIterator
*
* @param iterateOverMe
* the object over which we are iterating
*
* @throws java.lang.IllegalArgumentException
* If the argument is not a supported (i.e. iterable) type.
*
* @throws java.lang.NullPointerException
* If the argument is null
*/
public BasicBshIterator(Object iterateOverMe) {
enumeration = createEnumeration(iterateOverMe);
}
/**
* Create an enumeration over the given object.
*
* @param iterateOverMe
* Object of type Enumeration, Vector, String, StringBuffer
* or an array
* @return an enumeration
* @throws java.lang.IllegalArgumentException
* If the argument is not a supported (i.e. iterable) type.
* @throws java.lang.NullPointerException
* If the argument is null
*/
protected Enumeration createEnumeration(Object iterateOverMe) {
if (iterateOverMe == null)
throw new NullPointerException("Object arguments passed to " + "the BasicBshIterator constructor cannot be null.");
if (iterateOverMe instanceof Enumeration)
return (Enumeration) iterateOverMe;
if (iterateOverMe instanceof Vector)
return ((Vector) iterateOverMe).elements();
if (iterateOverMe.getClass().isArray()) {
final Object array = iterateOverMe;
return new Enumeration() {
int index = 0,
length = Array.getLength(array);
public Object nextElement() {
return Array.get(array, index++);
}
public boolean hasMoreElements() {
return index < length;
}
};
}
if (iterateOverMe instanceof String)
return createEnumeration(((String) iterateOverMe).toCharArray());
if (iterateOverMe instanceof StringBuffer)
return createEnumeration(iterateOverMe.toString().toCharArray());
throw new IllegalArgumentException("Cannot enumerate object of type " + iterateOverMe.getClass());
}
/**
* Fetch the next object in the iteration
*
* @return The next object
*/
public Object next() {
return enumeration.nextElement();
}
/**
* Returns true if and only if there are more objects available via the
* next() method
*
* @return The next object
*/
public boolean hasNext() {
return enumeration.hasMoreElements();
}
}
}
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