ENH: Stdin can optionally be redirected to a custom callback

Since the original 'stdin' is backed up,
it's also possible to enable/disable the custom callback using
setRedirectStdInCallBackEnabled

Author: jcfr

CMakeLists.txt

@@ -110,6 +110,7 @@ set(sources
     src/PythonQtSignalReceiver.cpp
     src/PythonQtSlot.cpp
     src/PythonQtStdDecorators.cpp
+    src/PythonQtStdIn.cpp
     src/PythonQtStdOut.cpp
     src/gui/PythonQtScriptingConsole.cpp
 
@@ -141,6 +142,7 @@ set(headers
     src/PythonQtSignalReceiver.h
     src/PythonQtSlot.h
     src/PythonQtStdDecorators.h
+    src/PythonQtStdIn.h
     src/PythonQtStdOut.h
     src/PythonQtSystem.h
     src/PythonQtVariants.h

src/PythonQt.cpp

@@ -45,6 +45,7 @@
 #include "PythonQtMethodInfo.h"
 #include "PythonQtSignalReceiver.h"
 #include "PythonQtConversion.h"
+#include "PythonQtStdIn.h"
 #include "PythonQtStdOut.h"
 #include "PythonQtCppWrapperFactory.h"
 #include "PythonQtVariants.h"
@@ -192,6 +193,12 @@ PythonQt::PythonQt(int flags, const QByteArray& pythonQtModuleName)
   }
   Py_INCREF(&PythonQtStdOutRedirectType);
 
+  // add our own python object types for redirection of stdin
+  if (PyType_Ready(&PythonQtStdInRedirectType) < 0) {
+    std::cerr << "could not initialize PythonQtStdInRedirectType" << ", in " << __FILE__ << ":" << __LINE__ << std::endl;
+  }
+  Py_INCREF(&PythonQtStdInRedirectType);
+
   initPythonQtModule(flags & RedirectStdOut, pythonQtModuleName);
 
   _p->setupSharedLibrarySuffixes();
@@ -220,6 +227,46 @@ PythonQtPrivate::~PythonQtPrivate() {
   PythonQtMethodInfo::cleanupCachedMethodInfos();
 }
 
+void PythonQt::setRedirectStdInCallBack(PythonQtInputChangedCB* callback, void * callbackData)
+{
+  if (!callback)
+    {
+    std::cerr << "PythonQt::setRedirectStdInCallBack - callback parameter is NULL !" << std::endl;
+    return;
+    }
+
+  PythonQtObjectPtr sys;
+  PythonQtObjectPtr in;
+  sys.setNewRef(PyImport_ImportModule("sys"));
+
+  // Backup original 'sys.stdin' if not yet done
+  PyRun_SimpleString("if not hasattr(sys, 'pythonqt_original_stdin'):"
+                     "sys.pythonqt_original_stdin = sys.stdin");
+
+  in = PythonQtStdInRedirectType.tp_new(&PythonQtStdInRedirectType, NULL, NULL);
+  ((PythonQtStdInRedirect*)in.object())->_cb = callback;
+  ((PythonQtStdInRedirect*)in.object())->_callData = callbackData;
+  // replace the built in file objects with our own objects
+  PyModule_AddObject(sys, "stdin", in);
+
+  // Backup custom 'stdin' into 'pythonqt_stdin'
+  PyRun_SimpleString("sys.pythonqt_stdin = sys.stdin");
+}
+
+void PythonQt::setRedirectStdInCallBackEnabled(bool enabled)
+{
+  if (enabled)
+    {
+    PyRun_SimpleString("if hasattr(sys, 'pythonqt_stdin'):"
+                       "sys.stdin = sys.pythonqt_stdin");
+    }
+  else
+    {
+    PyRun_SimpleString("if hasattr(sys,'pythonqt_original_stdin'):"
+                       "sys.stdin = sys.pythonqt_original_stdin");
+    }
+}
+
 PythonQtImportFileInterface* PythonQt::importInterface()
 {
   return _self->_p->_importInterface?_self->_p->_importInterface:_self->_p->_defaultImporter;

src/PythonQt.h

@@ -47,6 +47,7 @@
 #include "PythonQtClassWrapper.h"
 #include "PythonQtSlot.h"
 #include "PythonQtObjectPtr.h"
+#include "PythonQtStdIn.h"
 #include <QObject>
 #include <QVariant>
 #include <QList>
@@ -173,6 +174,21 @@ class PYTHONQT_EXPORT PythonQt : public QObject {
     CallOverloads
   };
 
+
+  //---------------------------------------------------------------------------
+  //! \name Standard input handling
+  //@{
+
+  //! Overwrite default handling of stdin using a custom callback. It internally backup
+  //! the original 'sys.stdin' into 'sys.pythonqt_original_stdin'
+  void setRedirectStdInCallBack(PythonQtInputChangedCB* callback, void * callbackData = 0);
+
+  //! Enable or disable stdin custom callback. It resets 'sys.stdin' using either 'sys.pythonqt_stdin'
+  //! or 'sys.pythonqt_original_stdin'
+  void setRedirectStdInCallBackEnabled(bool enabled);
+
+  //@}
+
   //---------------------------------------------------------------------------
   //! \name Modules
   //@{

src/PythonQtStdIn.cpp

@@ -0,0 +1,102 @@
+/*=========================================================================
+
+  Library:   CTK
+
+  Copyright (c) Kitware Inc.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+      http://www.commontk.org/LICENSE
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+=========================================================================*/
+
+//----------------------------------------------------------------------------------
+/*!
+// \file    PythonQtStdIn.cpp
+// \author  Jean-Christophe Fillion-Robin
+// \author  Last changed by $Author: jcfr $
+// \date    2011
+*/
+//----------------------------------------------------------------------------------
+
+#include "PythonQtStdIn.h"
+
+static PyObject *PythonQtStdInRedirect_new(PyTypeObject *type, PyObject * /*args*/, PyObject * /*kwds*/)
+{
+  PythonQtStdInRedirect *self;
+  self = (PythonQtStdInRedirect *)type->tp_alloc(type, 0);
+  self->_cb = NULL;
+  self->_callData = NULL;
+
+  return (PyObject *)self;
+}
+
+static PyObject *PythonQtStdInRedirect_readline(PyObject * self, PyObject * args)
+{
+  PythonQtStdInRedirect*  s = (PythonQtStdInRedirect*)self;
+  QString string;
+  if (s->_cb) {
+    string =  (*s->_cb)(s->_callData);
+    }
+  return Py_BuildValue(const_cast<char*>("s"), const_cast<char*>(string.toAscii().data()));
+}
+
+static PyMethodDef PythonQtStdInRedirect_methods[] = {
+  {"readline", (PyCFunction)PythonQtStdInRedirect_readline, METH_VARARGS,
+   "read input line"},
+  {NULL,    NULL, 0 , NULL} /* sentinel */
+};
+
+static PyMemberDef PythonQtStdInRedirect_members[] = {
+  {NULL}  /* Sentinel */
+};
+
+PyTypeObject PythonQtStdInRedirectType = {
+    PyObject_HEAD_INIT(NULL)
+    0,                         /*ob_size*/
+    "PythonQtStdInRedirect",             /*tp_name*/
+    sizeof(PythonQtStdInRedirect),             /*tp_basicsize*/
+    0,                         /*tp_itemsize*/
+    0, /*tp_dealloc*/
+    0,                         /*tp_print*/
+    0,                         /*tp_getattr*/
+    0,                         /*tp_setattr*/
+    0,           /*tp_compare*/
+    0,              /*tp_repr*/
+    0,                         /*tp_as_number*/
+    0,                         /*tp_as_sequence*/
+    0,                         /*tp_as_mapping*/
+    0,                         /*tp_hash */
+    0,                         /*tp_call*/
+    0,                         /*tp_str*/
+    0,                         /*tp_getattro*/
+    0,                         /*tp_setattro*/
+    0,                         /*tp_as_buffer*/
+    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE, /*tp_flags*/
+    "PythonQtStdInRedirect",           /* tp_doc */
+    0,                   /* tp_traverse */
+    0,                   /* tp_clear */
+    0,                   /* tp_richcompare */
+    0,                   /* tp_weaklistoffset */
+    0,                   /* tp_iter */
+    0,                   /* tp_iternext */
+    PythonQtStdInRedirect_methods,                   /* tp_methods */
+    PythonQtStdInRedirect_members,                   /* tp_members */
+    0,                   /* tp_getset */
+    0,                         /* tp_base */
+    0,                         /* tp_dict */
+    0,                         /* tp_descr_get */
+    0,                         /* tp_descr_set */
+    0,                         /* tp_dictoffset */
+    0,                         /* tp_init */
+    0,                         /* tp_alloc */
+    PythonQtStdInRedirect_new,                 /* tp_new */
+};

src/PythonQtStdIn.h

@@ -0,0 +1,51 @@
+#ifndef _PYTHONQTSTDIN_H
+#define _PYTHONQTSTDIN_H
+
+/*=========================================================================
+
+  Library:   CTK
+
+  Copyright (c) Kitware Inc.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+      http://www.commontk.org/LICENSE
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+=========================================================================*/
+
+//----------------------------------------------------------------------------------
+/*!
+// \file    PythonQtStdIn.h
+// \author  Jean-Christophe Fillion-Robin
+// \author  Last changed by $Author: jcfr $
+// \date    2011
+*/
+//----------------------------------------------------------------------------------
+
+
+#include <dPython.h>
+#include "structmember.h"
+#include <QString>
+
+//! declares the type of the stdout redirection class
+extern PyTypeObject PythonQtStdInRedirectType;
+
+//! declares the callback that is called from the write() function
+typedef QString PythonQtInputChangedCB(void* callData);
+
+//! declares the stdin redirection class
+typedef struct {
+  PyObject_HEAD
+  PythonQtInputChangedCB* _cb;
+  void * _callData;
+} PythonQtStdInRedirect;
+
+#endif