command_exercise.py

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from .command_classes import Command_TextObject, Command
 
 
_commandUndoList = []  # type; [Command]
 
 
def Command_Save_And_Execute(text : Command_TextObject, command : Command):
    _commandUndoList.append(command)
    command.Execute()
 
 
 
def Command_Operation_Replace(source : Command_TextObject, searchPattern : str, replaceText : str) -> None:
    source.Text = source.Text.replace(searchPattern, replaceText)
 
 
 
def Command_Operation_Reverse(source : Command_TextObject):
    text_in_list = [c for c in source.Text]
    text_in_list.reverse()
    output = "".join(text_in_list)
    source.Text = output
 
 
 
def Command_Undo(text : Command_TextObject) -> None:
    if _commandUndoList:
        # Reset the text to the starting point.
        text.Reset()
 
        # Get rid of the last command applied and remember it.
        lastCommand = _commandUndoList.pop(len(_commandUndoList) - 1)
 
        # Now apply all remaining commands to the text in order
        # (oldest to newest).
        for command in _commandUndoList:
            command.Execute()
 
        # Show off what we (un)did.
        print("    undoing command {0:<31}==> \"{1}\"".format(lastCommand.ToString(), text.ToString()))
 
 
 
def Command_ApplyReplaceCommand(text : Command_TextObject, searchPattern : str, replaceText : str) -> None:
    command = Command(text, "Replace", Command_Operation_Replace, searchPattern, replaceText)
    Command_Save_And_Execute(text, command)
    print("    command {0:<31}==> \"{1}\"".format(command.ToString(), text.ToString()))
 
 
 
def Command_ApplyReverseCommand(text : Command_TextObject) -> None:
    command = Command(text, "Reverse", Command_Operation_Reverse)
    Command_Save_And_Execute(text, command)
    print("    command {0:<31}==> \"{1}\"".format(command.ToString(), text.ToString()))
 
 
 
 
# ! [Using Command in Python]
def Command_Exercise():
    print()
    print("Command Exercise")
 
    # The base text object to work from.
    text = Command_TextObject("This is a line of text on which to experiment.")
 
    print("  Starting text: \"{0}\"".format(text.ToString()))
 
    # Apply four operations to the text.
    Command_ApplyReplaceCommand(text, "text", "painting")
    Command_ApplyReplaceCommand(text, "on", "off")
    Command_ApplyReverseCommand(text)
    Command_ApplyReplaceCommand(text, "i", "!")
 
    print("  Now perform undo until back to original")
 
    # Now undo the four operations.
    Command_Undo(text)
    Command_Undo(text)
    Command_Undo(text)
    Command_Undo(text)
 
    print("  Final text   : \"{0}\"".format(text.ToString()))
 
    print("  Done.")
# ! [Using Command in Python]