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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) Corporation for National Research Initiatives
// Copyright (c) Jython Developers
package org.python.core;
import java.io.Serializable;
import org.python.expose.ExposedMethod;
import org.python.expose.ExposedType;
/**
* The singleton None object.
*/
@Untraversable
@ExposedType(name = "NoneType", isBaseType = false)
public class PyNone extends PyObject implements Serializable {
public static final PyType TYPE = PyType.fromClass(PyNone.class);
private PyNone() {/* Not super(TYPE): TYPE is null until too late in bootstrapping. */}
private static class Holder {
/** The unique instance of PyNone. */
static final PyNone INSTANCE = new PyNone();
}
static PyNone getInstance() {
return Holder.INSTANCE;
}
@Override
public boolean __nonzero__() {
return false;
}
@Override
public Object __tojava__(Class c) {
if (c == PyObject.class) {
return this;
}
if (c.isPrimitive()) {
return Py.NoConversion;
}
// Java gets null
return null;
}
@Override
public String toString() {
return NoneType_toString();
}
@ExposedMethod(names = "__repr__")
final String NoneType_toString() {
return "None";
}
@Override
public String asStringOrNull(int index) {
return null;
}
@Override
public String asStringOrNull() {
return null;
}
private Object writeReplace() {
return new Py.SingletonResolver("None");
}
}