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# Source code for pyqtgraph.console.Console

    import os
    import sys
    import pickle
    import subprocess

    from .. import getConfigOption
    from ..Qt import QtCore, QtWidgets
    from .repl_widget import ReplWidget
    from .exception_widget import ExceptionHandlerWidget

    class ConsoleWidget(QtWidgets.QWidget):
        """
        Widget displaying console output and accepting command input.
        Implements:

          - eval python expressions / exec python statements
          - storable history of commands
          - exception handling allowing commands to be interpreted in the context of any level in the exception stack frame

        Why not just use python in an interactive shell (or ipython) ? There are a few reasons:

          - pyside does not yet allow Qt event processing and interactive shell at the same time
          - on some systems, typing in the console _blocks_ the qt event loop until the user presses enter. This can
            be baffling and frustrating to users since it would appear the program has frozen.
          - some terminals (eg windows cmd.exe) have notoriously unfriendly interfaces
          - ability to add extra features like exception stack introspection
          - ability to have multiple interactive prompts, including for spawned sub-processes
        """

        def __init__(self, parent=None, namespace=None, historyFile=None, text=None, editor=None):
            """
            ==============  =============================================================================
            **Arguments:**
            namespace       dictionary containing the initial variables present in the default namespace
            historyFile     optional file for storing command history
            text            initial text to display in the console window
            editor          optional string for invoking code editor (called when stack trace entries are
                            double-clicked). May contain {fileName} and {lineNum} format keys. Example::

                                editorCommand --loadfile {fileName} --gotoline {lineNum}
            ==============  =============================================================================
            """
            QtWidgets.QWidget.__init__(self, parent)

            self._setupUi()

            if namespace is None:
                namespace = {}
            namespace['__console__'] = self

            self.localNamespace = namespace
            self.editor = editor

            self.output = self.repl.output
            self.input = self.repl.input
            self.input.setFocus()

            if text is not None:
                self.output.setPlainText(text)

            self.historyFile = historyFile

            try:
                history = self.loadHistory()
            except Exception as exc:
                sys.excepthook(*sys.exc_info())
                history = None
            if history is not None:
                self.input.history = [""] + history
                self.historyList.addItems(history[::-1])

            self.currentTraceback = None

        def _setupUi(self):
            self.layout = QtWidgets.QGridLayout(self)
            self.setLayout(self.layout)
            self.layout.setContentsMargins(0, 0, 0, 0)
            self.layout.setSpacing(0)

            self.splitter = QtWidgets.QSplitter(QtCore.Qt.Orientation.Vertical, self)
            self.layout.addWidget(self.splitter, 0, 0)

            self.repl = ReplWidget(self.globals, self.locals, self)
            self.splitter.addWidget(self.repl)

            self.historyList = QtWidgets.QListWidget(self)
            self.historyList.hide()
            self.splitter.addWidget(self.historyList)

            self.historyBtn = QtWidgets.QPushButton('History', self)
            self.historyBtn.setCheckable(True)
            self.repl.inputLayout.addWidget(self.historyBtn)

            self.repl.sigCommandEntered.connect(self._commandEntered)
            self.repl.sigCommandRaisedException.connect(self._commandRaisedException)

            self.excHandler = ExceptionHandlerWidget(self)
            self.excHandler.hide()
            self.splitter.addWidget(self.excHandler)

            self.exceptionBtn = QtWidgets.QPushButton("Exceptions..", self)
            self.exceptionBtn.setCheckable(True)
            self.repl.inputLayout.addWidget(self.exceptionBtn)

            self.excHandler.sigStackItemDblClicked.connect(self._stackItemDblClicked)
            self.exceptionBtn.toggled.connect(self.excHandler.setVisible)
            self.historyBtn.toggled.connect(self.historyList.setVisible)
            self.historyList.itemClicked.connect(self.cmdSelected)
            self.historyList.itemDoubleClicked.connect(self.cmdDblClicked)

        def catchAllExceptions(self, catch=True):
            if catch:
                self.exceptionBtn.setChecked(True)
            self.excHandler.catchAllExceptions(catch)

        def catchNextException(self, catch=True):
            if catch:
                self.exceptionBtn.setChecked(True)
            self.excHandler.catchNextException(catch)

        def setStack(self, frame=None):
            self.excHandler.setStack(frame)

        def loadHistory(self):
            """Return the list of previously-invoked command strings (or None)."""
            if self.historyFile is not None and os.path.exists(self.historyFile):
                with open(self.historyFile, 'rb') as pf:
                    return pickle.load(pf)

        def saveHistory(self, history):
            """Store the list of previously-invoked command strings."""
            if self.historyFile is not None:
                with open(self.historyFile, 'wb') as pf:
                    pickle.dump(history, pf)

        def _commandEntered(self, repl, cmd):
            self.historyList.addItem(cmd)
            self.saveHistory(self.input.history[1:100])
            sb = self.historyList.verticalScrollBar()
            sb.setValue(sb.maximum())

        def _commandRaisedException(self, repl, exc):
            self.excHandler.exceptionHandler(exc)

        def globals(self):
            frame = self.excHandler.selectedFrame()
            if frame is not None and self.excHandler.runSelectedFrameCheck.isChecked():
                return frame.f_globals
            else:
                return self.localNamespace

        def locals(self):
            frame = self.excHandler.selectedFrame()
            if frame is not None and self.excHandler.runSelectedFrameCheck.isChecked():
                return frame.f_locals
            else:
                return self.localNamespace

        def cmdSelected(self, item):
            index = -(self.historyList.row(item)+1)
            self.input.setHistory(index)
            self.input.setFocus()

        def cmdDblClicked(self, item):
            index = -(self.historyList.row(item)+1)
            self.input.setHistory(index)
            self.input.execCmd()

        def _stackItemDblClicked(self, handler, item):
            editor = self.editor
            if editor is None:
                editor = getConfigOption('editorCommand')
            if editor is None:
                return
            tb = self.excHandler.selectedFrame()
            lineNum = tb.f_lineno
            fileName = tb.f_code.co_filename
            subprocess.Popen(self.editor.format(fileName=fileName, lineNum=lineNum), shell=True)