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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
package org.python.core;
import java.io.*;
/**
* A wrapper for all python exception. Note that the well-known python exceptions are not
* subclasses of PyException. Instead the python exception class is stored in the type
* field and value or class instance is stored in the value field.
*/
public class PyException extends RuntimeException implements Traverseproc
{
/**
* The python exception class (for class exception) or identifier (for string exception).
*/
public PyObject type;
/**
* The exception instance (for class exception) or exception value (for string exception).
*/
public PyObject value = Py.None;
/** The exception traceback object. */
public PyTraceback traceback;
/**
* Whether the exception was re-raised, such as when a traceback is specified to
* 'raise', or via a 'finally' block.
*/
private boolean isReRaise = false;
private boolean normalized = false;
public PyException() {
this(Py.None, Py.None);
}
public PyException(PyObject type) {
this(type, Py.None);
}
public PyException(PyObject type, PyObject value) {
this(type, value, null);
}
public PyException(PyObject type, PyObject value, PyTraceback traceback) {
this.type = type;
this.value = value;
if (traceback != null) {
this.traceback = traceback;
isReRaise = true;
} else {
PyFrame frame = Py.getFrame();
if (frame != null && frame.tracefunc != null) {
frame.tracefunc = frame.tracefunc.traceException(frame, this);
}
}
}
public PyException(PyObject type, String value) {
this(type, Py.newStringOrUnicode(value));
}
private boolean printingStackTrace = false;
@Override
public void printStackTrace() {
Py.printException(this);
}
@Override
public Throwable fillInStackTrace() {
return Options.includeJavaStackInExceptions ? super.fillInStackTrace() : this;
}
@Override
public String getMessage() {
normalize();
return Py.formatException(type, value);
}
@Override
public synchronized void printStackTrace(PrintStream s) {
if (printingStackTrace) {
super.printStackTrace(s);
} else {
try {
/*
* Ensure that non-ascii characters are made printable. IOne would prefer to emit
* Unicode, but the output stream too often only accepts bytes. (s is not
* necessarily a console, e.g. during a doctest.)
*/
PyFile err = new PyFile(s);
err.setEncoding("ascii", "backslashreplace");
printingStackTrace = true;
Py.displayException(type, value, traceback, err);
} finally {
printingStackTrace = false;
}
}
}
public synchronized void super__printStackTrace(PrintWriter w) {
try {
printingStackTrace = true;
super.printStackTrace(w);
} finally {
printingStackTrace = false;
}
}
@Override
public synchronized String toString() {
return Py.exceptionToString(type, value, traceback);
}
/**
* Instantiates the exception value if it is not already an
* instance.
*
*/
public void normalize() {
if (normalized) {
return;
}
PyObject inClass = null;
if (isExceptionInstance(value)) {
inClass = value.fastGetClass();
}
if (isExceptionClass(type)) {
if (inClass == null || !Py.isSubClass(inClass, type)) {
PyObject[] args;
// Don't decouple a tuple into args when it's a
// KeyError, pass it on through below
if (value == Py.None) {
args = Py.EmptyObjects;
} else if (value instanceof PyTuple && type != Py.KeyError) {
args = ((PyTuple)value).getArray();
} else {
args = new PyObject[] {value};
}
value = type.__call__(args);
} else if (inClass != type) {
type = inClass;
}
}
normalized = true;
}
/**
* Register frame as having been visited in the traceback.
*
* @param here the current PyFrame
*/
public void tracebackHere(PyFrame here) {
tracebackHere(here, false);
}
/**
* Register frame as having been visited in the traceback.
*
* @param here the current PyFrame
* @param isFinally whether caller is a Python finally block
*/
public void tracebackHere(PyFrame here, boolean isFinally) {
if (!isReRaise && here != null) {
// the frame is either inapplicable or already registered (from a finally)
// during a re-raise
traceback = new PyTraceback(traceback, here);
}
// finally blocks immediately tracebackHere: so they toggle isReRaise to skip the
// next tracebackHere hook
isReRaise = isFinally;
}
/**
* Logic for the raise statement
*
* @param type the first arg to raise, a type or an instance
* @param value the second arg, the instance of the class or arguments to its
* constructor
* @param traceback a traceback object
* @return a PyException wrapper
*/
public static PyException doRaise(PyObject type, PyObject value, PyObject traceback) {
if (type == null) {
ThreadState state = Py.getThreadState();
type = state.exception.type;
value = state.exception.value;
traceback = state.exception.traceback;
}
if (traceback == Py.None) {
traceback = null;
} else if (traceback != null && !(traceback instanceof PyTraceback)) {
throw Py.TypeError("raise: arg 3 must be a traceback or None");
}
if (value == null) {
value = Py.None;
}
// Repeatedly, replace a tuple exception with its first item
while (type instanceof PyTuple && ((PyTuple)type).size() > 0) {
type = type.__getitem__(0);
}
if (isExceptionClass(type)) {
PyException pye = new PyException(type, value, (PyTraceback)traceback);
pye.normalize();
if (!isExceptionInstance(pye.value)) {
throw Py.TypeError(String.format(
"calling %s() should have returned an instance of BaseException, not '%s'",
pye.type, pye.value));
}
return pye;
} else if (isExceptionInstance(type)) {
// Raising an instance. The value should be a dummy.
if (value != Py.None) {
throw Py.TypeError("instance exception may not have a separate value");
} else {
// Normalize to raise ,
value = type;
type = type.fastGetClass();
}
} else {
// Not something you can raise. You get an exception
// anyway, just not what you specified :-)
throw Py.TypeError("exceptions must be old-style classes or derived from "
+ "BaseException, not " + type.getType().fastGetName());
}
if (Options.py3k_warning && type instanceof PyClass) {
Py.DeprecationWarning("exceptions must derive from BaseException in 3.x");
}
return new PyException(type, value, (PyTraceback)traceback);
}
/**
* Determine if this PyException is a match for exc.
*
* @param exc a PyObject exception type
* @return true if a match
*/
public boolean match(PyObject exc) {
if (exc instanceof PyTuple) {
for (PyObject item : ((PyTuple)exc).getArray()) {
if (match(item)) {
return true;
}
}
return false;
}
if (exc instanceof PyString) {
Py.DeprecationWarning("catching of string exceptions is deprecated");
} else if (Options.py3k_warning && !isPy3kExceptionClass(exc)) {
Py.DeprecationWarning("catching classes that don't inherit from BaseException is not "
+ "allowed in 3.x");
}
normalize();
// FIXME, see bug 737978
//
// A special case for IOError's to allow them to also match
// java.io.IOExceptions. This is a hack for 1.0.x until I can do
// it right in 1.1
if (exc == Py.IOError) {
if (__builtin__.isinstance(value, PyType.fromClass(IOException.class))) {
return true;
}
}
// FIXME too, same approach for OutOfMemoryError
if (exc == Py.MemoryError) {
if (__builtin__.isinstance(value,
PyType.fromClass(OutOfMemoryError.class))) {
return true;
}
}
if (isExceptionClass(type) && isExceptionClass(exc)) {
try {
return Py.isSubClass(type, exc);
} catch (PyException pye) {
// This function must not fail, so print the error here
Py.writeUnraisable(pye, type);
return false;
}
}
return type == exc;
}
/**
* Determine whether obj is a Python exception class
*
* @param obj a PyObject
* @return true if an exception
*/
public static boolean isExceptionClass(PyObject obj) {
if (obj instanceof PyClass) {
return true;
}
return isPy3kExceptionClass(obj);
}
/**
* Determine whether obj is a Python 3 exception class
*
* @param obj a PyObject
* @return true if an exception
*/
private static boolean isPy3kExceptionClass(PyObject obj) {
if (!(obj instanceof PyType)) {
return false;
}
PyType type = ((PyType)obj);
if (type.isSubType(PyBaseException.TYPE)) {
return true;
}
return type.getProxyType() != null
&& Throwable.class.isAssignableFrom(type.getProxyType());
}
/**
* Determine whether obj is an Python exception instance
*
* @param obj a PyObject
* @return true if an exception instance
*/
public static boolean isExceptionInstance(PyObject obj) {
return obj instanceof PyInstance || obj instanceof PyBaseException
|| obj.getJavaProxy() instanceof Throwable;
}
/**
* Get the name of the exception's class
*
* @param obj a PyObject exception
* @return String exception name
*/
public static String exceptionClassName(PyObject obj) {
return obj instanceof PyClass ? ((PyClass)obj).__name__ : ((PyType)obj).fastGetName();
}
/* Traverseproc support */
@Override
public int traverse(Visitproc visit, Object arg) {
int retValue;
if (type != null) {
retValue = visit.visit(type, arg);
if (retValue != 0) {
return retValue;
}
} if (value != null) {
retValue = visit.visit(value, arg);
if (retValue != 0) {
return retValue;
}
} if (traceback != null) {
retValue = visit.visit(traceback, arg);
if (retValue != 0) {
return retValue;
}
}
return 0;
}
@Override
public boolean refersDirectlyTo(PyObject ob) {
return ob != null && (type == ob || value == ob || traceback == ob);
}
}