Struct design_pattern_examples_rust::command::CommandContext

struct CommandContext {
    command_list: Vec<Box<dyn ICommand>>,
}

This struct creates a context around the undo list that the command_exercise() executes within. This gets around the problem of needing a static undo list (or passing the undo list to all functions) as all the methods on this context have ready access to the undo list in the context.

Fields

command_list: Vec<Box<dyn ICommand>>

The list of command objects that describe the changes made to the text object.

Implementations

impl CommandContext

fn new() -> CommandContext

Constructor.

fn execute_and_save( &mut self, command: Box<dyn ICommand>, text: &mut CommandTextObject )

Execute the given command on the given text object then save the command on the given undo list.

Parameters

• command_list

  The list that holds the commands for later undoing.

• command

  The command to apply to the text.

• text

  The CommandTextObject to affect.

fn apply_replace_command( &mut self, text: &mut CommandTextObject, search_pattern: &str, replace_text: &str )

Helper method to create a Command object that replaces text in the given CommandTextObject, applies the command to the CommandTextObject, and then adds the command to the given undo list. Finally, it shows off what was done.

Parameters

• command_list

  The list that holds the commands for later undoing.

• text

  The CommandTextObject to affect.

• search_pattern

  What to look for in the CommandTextObject.

• replace_text

  What to replace search_pattern with.

fn apply_reverse_command(&mut self, text: &mut CommandTextObject)

Helper method to create a Command object that reverses the order of the characters in the given CommandTextObject, applies the command to the CommandTextObject, and then adds the command to the given undo list. Finally, it shows what was done.

Parameters

• command_list

  The list that holds the commands for later undoing.

• text

  The CommandTextObject to affect.

fn undo(&mut self, text: &mut CommandTextObject)

Perform an undo on the given CommandTextObject, using the commands in the given undo list. If the undo list is empty, nothing happens.

Parameters

• command_list

  The list that holds the commands for later undoing.

• text

  The CommandTextObject to affect.