Class: Fidgit::History

Inherits:

Object

• Object
• Fidgit::History

show all

Defined in:

lib/fidgit/history.rb

Overview

Defined Under Namespace

Classes: Action

Constant Summary

DEFAULT_MAX_SIZE =

Maximum number of actions in the History before Actions are deleted.

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Instance Method Summary (collapse)

• - (Boolean) can_redo?

  Is there an action that has been undone that can now be redone?.

• - (Boolean) can_undo?

  Is there an action that can be undone?.

• - (Object) do(action)

  Perform a History::Action, adding it to the history.

• - (History) initialize(max_size = DEFAULT_MAX_SIZE) constructor

  A new instance of History.

• - (Object) redo

  Redo the last action that was undone.

• - (Object) replace_last(action)

  Perform a History::Action, replacing the last action that was performed.

• - (Object) undo

  Undo the last action that was performed.

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# File 'lib/fidgit/history.rb', line 24

def initialize(max_size = DEFAULT_MAX_SIZE)
  @max_size = max_size
  @actions = []
  @last_done = -1 # Last command that was performed.
end

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# File 'lib/fidgit/history.rb', line 22

def can_redo?; @last_done < (@actions.size - 1); end

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# File 'lib/fidgit/history.rb', line 19

def can_undo?; @last_done >= 0; end

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# File 'lib/fidgit/history.rb', line 34

def do(action)
  raise ArgumentError, "Parameter, 'action', expected to be a #{Action}, but received: #{action}" unless action.is_a? Action

  # Remove all undone actions when a new one is performed.
  if can_redo?
    if @last_done == -1
      @actions.clear
    else
      @actions = @actions[0..@last_done]
    end
  end

  # If history is too big, remove the oldest action.
  if @actions.size >= @max_size
    @actions.shift
  end

  @last_done = @actions.size
  @actions << action
  action.do

  nil
end

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# File 'lib/fidgit/history.rb', line 82

def redo
  raise "Can't redo if there are no commands in the future" unless can_redo?

  @last_done += 1
  @actions[@last_done].do

  nil
end

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# File 'lib/fidgit/history.rb', line 61

def replace_last(action)
  raise ArgumentError, "Parameter, 'action', expected to be a #{Action}, but received: #{action}" unless action.is_a? Action

  @actions[@last_done].undo
  @actions[@last_done] = action
  action.do

  nil
end

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# File 'lib/fidgit/history.rb', line 72

def undo
  raise "Can't undo unless there are commands in past" unless can_undo?

  @actions[@last_done].undo
  @last_done -= 1

  nil
end