121 lines
3.8 KiB
Python
121 lines
3.8 KiB
Python
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"""
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Menu class to help with drawing menus on screen
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"""
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class Menu:
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"""
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Menu class. Creates a menu with text to display and options
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"""
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def __init__(self, menu_text=''):
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self._menu_text = menu_text
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self._options = []
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self._selection = 0
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def add_option(self, option):
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"""
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Adds an option to the menu. Only allows instances of Menu.Option
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:param option:
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"""
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if not isinstance(option, Menu.Option):
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raise TypeError('option must be an instance of Menu.Option')
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else:
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self._options.append(option)
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def get_option(self, index):
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"""
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Gets an option object given the index of the option. Raises IndexError if given
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index is out of bounds.
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:param index: the index of the option
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:return: the option object
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"""
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try:
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return self._options[index]
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except IndexError as ex:
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raise IndexError('option index out of range') from ex
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def select_next(self):
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"""
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Selects the next option in the list. Wraps around to the first option if
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the last option is currently selected.
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"""
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self._selection += 1
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if self._selection >= len(self._options):
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self._selection = 0
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def select_prev(self):
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"""
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Selects the previous option in the list. Wraps around to the last option if
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the first option is currently selected.
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"""
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self._selection -= 1
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if self._selection < 0:
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if len(self._options) > 0:
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self._selection = len(self._options) - 1
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else:
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self._selection = 0
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def run_selection(self, *args, **kwargs):
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"""
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Runs the function that the currently selected option object points to.
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:param args: arguments to be passed to the function
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:param kwargs: keyword arguments to be passed to the function
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"""
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try:
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return self._options[self._selection].run(*args, **kwargs)
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except IndexError as ex:
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raise Exception('menu has no options, cannot run a non-existent option') from ex
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def draw_menu(self):
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"""
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Draws the menu on screen with a leading 20 blank lines.
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"""
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print('\n' * 20)
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print(self._menu_text + '\n')
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for option in self._options:
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selection_char = '>'
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if self._options.index(option) != self._selection:
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selection_char = ' '
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print('{0} {1}'.format(selection_char, option.get_text()))
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class Option:
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"""
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Class that defines options for the Menu class.
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"""
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def __init__(self, option_text='', function=None, *args, **kwargs):
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self._option_text = option_text
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self._function = function
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self._default_args = args
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self._default_kwargs = kwargs
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def get_text(self):
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"""
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Returns the text to be displayed by the option
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:return: the option text
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"""
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return self._option_text
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def run(self, *args, **kwargs):
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"""
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Runs the function that the option object points to. Returns None if
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there is no function or the given function is not valid.
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:param args: arguments to be passed to the function
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:param kwargs: keyword arguments to be passed to the function
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:return: the return value of the function (if any)
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"""
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if len(args) == 0:
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args = self._default_args
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if len(kwargs) == 0:
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kwargs = self._default_kwargs
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try:
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return self._function(*args, **kwargs)
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except TypeError:
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return None
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