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Jython is an implementation of the high-level, dynamic, object-oriented
language Python written in 100% Pure Java, and seamlessly integrated with
the Java platform. It thus allows you to run Python on any Java platform.
/* Copyright (c) Jython Developers */
package org.python.modules._collections;
import java.util.Map;
import java.util.concurrent.ConcurrentMap;
import com.google.common.cache.CacheBuilder;
import com.google.common.cache.CacheLoader;
import com.google.common.cache.LoadingCache;
import org.python.core.BuiltinDocs;
import org.python.core.Py;
import org.python.core.PyDictionary;
import org.python.core.PyException;
import org.python.core.PyObject;
import org.python.core.PyTuple;
import org.python.core.PyType;
import org.python.core.Traverseproc;
import org.python.core.Visitproc;
import org.python.expose.ExposedDelete;
import org.python.expose.ExposedGet;
import org.python.expose.ExposedMethod;
import org.python.expose.ExposedNew;
import org.python.expose.ExposedSet;
import org.python.expose.ExposedType;
/**
* PyDefaultDict - This is a subclass of the builtin dict(PyDictionary) class. It supports
* one additional method __missing__ and adds one writable instance variable
* defaultFactory. The remaining functionality is the same as for the dict class.
*
* collections.defaultdict([defaultFactory[, ...]]) - returns a new dictionary-like
* object. The first argument provides the initial value for the defaultFactory attribute;
* it defaults to None. All remaining arguments are treated the same as if they were
* passed to the dict constructor, including keyword arguments.
*/
@ExposedType(name = "collections.defaultdict")
public class PyDefaultDict extends PyDictionary implements Traverseproc {
public static final PyType TYPE = PyType.fromClass(PyDefaultDict.class);
/**
* This attribute is used by the __missing__ method; it is initialized from the first
* argument to the constructor, if present, or to None, if absent.
*/
private PyObject defaultFactory = Py.None;
private final LoadingCache backingMap;
public ConcurrentMap getMap() {
return backingMap.asMap();
}
public PyDefaultDict() {
this(TYPE);
}
public PyDefaultDict(PyType subtype) {
super(subtype, false);
backingMap = CacheBuilder.newBuilder().build(
new CacheLoader() {
public PyObject load(PyObject key) {
try {
return __missing__(key);
} catch (RuntimeException ex) {
throw new MissingThrownException(ex);
}
}
});
}
public PyDefaultDict(PyType subtype, Map map) {
this(subtype);
getMap().putAll(map);
}
@ExposedMethod
@ExposedNew
final void defaultdict___init__(PyObject[] args, String[] kwds) {
int nargs = args.length - kwds.length;
if (nargs != 0) {
defaultFactory = args[0];
if (!(defaultFactory == Py.None || defaultFactory.isCallable())) {
throw Py.TypeError("first argument must be callable");
}
PyObject newargs[] = new PyObject[args.length - 1];
System.arraycopy(args, 1, newargs, 0, newargs.length);
dict___init__(newargs, kwds);
}
}
public PyObject __missing__(PyObject key) {
return defaultdict___missing__(key);
}
/**
* This method does NOT call __setitem__ instead it relies on the fact that it is
* called within the context of `CacheLoader#load` to actually insert the value
* into the dict.
*/
@ExposedMethod
final PyObject defaultdict___missing__(PyObject key) {
if (defaultFactory == Py.None) {
throw Py.KeyError(key);
}
return defaultFactory.__call__();
}
@Override
public PyObject __reduce__() {
return defaultdict___reduce__();
}
@ExposedMethod
final PyObject defaultdict___reduce__() {
PyTuple args = null;
if (defaultFactory == Py.None) {
args = new PyTuple();
} else {
PyObject[] ob = {defaultFactory};
args = new PyTuple(ob);
}
return new PyTuple(getType(), args, Py.None, Py.None, iteritems());
}
@Override
public PyDictionary copy() {
return defaultdict_copy();
}
@ExposedMethod(names = {"copy", "__copy__"})
final PyDefaultDict defaultdict_copy() {
PyDefaultDict ob = new PyDefaultDict(TYPE, getMap());
ob.defaultFactory = defaultFactory;
return ob;
}
@Override
public String toString() {
return defaultdict_toString();
}
@ExposedMethod(names = "__repr__")
final String defaultdict_toString() {
return String.format("defaultdict(%s, %s)", defaultFactory, super.toString());
}
@ExposedGet(name = "default_factory")
public PyObject getDefaultFactory() {
return defaultFactory;
}
@ExposedSet(name = "default_factory")
public void setDefaultFactory(PyObject value) {
defaultFactory = value;
}
@ExposedDelete(name = "default_factory")
public void delDefaultFactory() {
defaultFactory = Py.None;
}
@Override
public PyObject __finditem__(PyObject key) {
return defaultdict___getitem__(key);
}
@ExposedMethod(doc = BuiltinDocs.dict___getitem___doc)
protected final PyObject defaultdict___getitem__(PyObject key) {
try {
return backingMap.get(key);
} catch (PyException pe) {
/* LoadingCache#get() don't throw any PyException itself and it
* prevents those raised in CacheLoader#load() to get through
* without being wrapped in UncheckedExecutionException, so this
* PyException must be from key#hashCode(). We can propagated it to
* caller as it is. */
throw pe;
} catch (Exception ex) {
Throwable cause = ex.getCause();
if (cause != null && cause instanceof MissingThrownException) {
throw ((MissingThrownException) cause).thrownByMissing;
}
throw Py.KeyError(key);
}
}
public PyObject get(PyObject key, PyObject defaultObj) {
PyObject value = getMap().get(key);
if (value != null) {
return value;
} else {
return defaultObj;
}
}
/* Traverseproc implementation */
@Override
public int traverse(Visitproc visit, Object arg) {
int retVal = super.traverse(visit, arg);
if (retVal != 0) {
return retVal;
}
retVal = visit.visit(defaultFactory, arg);
if (retVal != 0) {
return retVal;
}
if (backingMap != null) {
for (Map.Entry ent: backingMap.asMap().entrySet()) {
retVal = visit.visit(ent.getKey(), arg);
if (retVal != 0) {
return retVal;
}
if (ent.getValue() != null) {
retVal = visit.visit(ent.getValue(), arg);
if (retVal != 0) {
return retVal;
}
}
}
}
return 0;
}
@Override
public boolean refersDirectlyTo(PyObject ob) {
if (ob == null) {
return false;
} else if (super.refersDirectlyTo(ob)) {
return true;
}
if (backingMap == null) {
return false;
}
return backingMap.asMap().containsKey(ob) || backingMap.asMap().containsValue(ob);
}
private static class MissingThrownException extends RuntimeException {
final RuntimeException thrownByMissing;
MissingThrownException(RuntimeException thrownByMissing) {
super(thrownByMissing);
this.thrownByMissing = thrownByMissing;
}
}
}