undo

Documentation

Index

• func CannotRedoTitle() string
• func CannotUndoTitle() string
• type Edit
• type Manager
  • func NewManager(costLimit int, recoveryHandler errs.RecoveryHandler) *Manager
  • func (m *Manager) Add(edit Edit)
  • func (m *Manager) CanRedo() bool
  • func (m *Manager) CanUndo() bool
  • func (m *Manager) Clear()
  • func (m *Manager) CostLimit() int
  • func (m *Manager) Redo()
  • func (m *Manager) RedoTitle() string
  • func (m *Manager) SetCostLimit(limit int)
  • func (m *Manager) Undo()
  • func (m *Manager) UndoTitle() string

Functions

func CannotRedoTitle

func CannotRedoTitle() string

CannotRedoTitle returns the Cannot Redo title.

func CannotUndoTitle

func CannotUndoTitle() string

CannotUndoTitle returns the Cannot Undo title.

Types

type Edit

type Edit interface {
	// Name returns the localized name of the edit, suitable for displaying in
	// a user interface menu. Note that no leading "Undo " or "Redo " should
	// be part of this name, as the Manager will add this.
	Name() string
	// Cost returns a cost factor for this edit. When the cost values of the
	// edits within a given Manager exceed the Manager's defined cost limit,
	// the oldest edits will be discarded until the cost values are less than
	// or equal to the Manager's defined limit. Note that if this method
	// returns a value less than 1, it will be set to 1 for purposes of this
	// calculation.
	Cost() int
	// Undo the state.
	Undo()
	// Redo the state.
	Redo()
	// Absorb gives this edit a chance to absorb a new edit that is about to
	// be added to the manager. If this method returns true, it is assumed
	// this edit has incorporated any necessary state into itself to perform
	// an undo/redo and the other edit will be discarded.
	Absorb(other Edit) bool
	// Release is called when this edit is no longer needed by the Manager.
	Release()
}

Edit defines the required methods an undoable edit must implement.

type Manager

type Manager struct {
	// contains filtered or unexported fields
}

Manager provides management of an undo/redo stack.

func NewManager

func NewManager(costLimit int, recoveryHandler errs.RecoveryHandler) *Manager

NewManager creates a new undo/redo manager.

func (*Manager) Add

func (m *Manager) Add(edit Edit)

Add an edit. If one or more undos have been performed, this will cause any redo capability beyond this point to be lost.

func (*Manager) CanRedo

func (m *Manager) CanRedo() bool

CanRedo returns true if Redo() can be called successfully.

func (*Manager) CanUndo

func (m *Manager) CanUndo() bool

CanUndo returns true if Undo() can be called successfully.

func (*Manager) Clear

func (m *Manager) Clear()

Clear removes all edits from this Manager.

func (*Manager) CostLimit

func (m *Manager) CostLimit() int

CostLimit returns the current cost limit permitted by this undo manager.

func (*Manager) Redo

func (m *Manager) Redo()

Redo re-applies the current state by one edit.

func (*Manager) RedoTitle

func (m *Manager) RedoTitle() string

RedoTitle returns the title for the current redo state.

func (*Manager) SetCostLimit

func (m *Manager) SetCostLimit(limit int)

SetCostLimit sets a new cost limit, potentially trimming existing edits to fit within the new limit. Note that if the most recent edit has a cost larger than the new limit, that last edit (and only that last edit) will still be retained.

func (*Manager) Undo

func (m *Manager) Undo()

Undo rewinds the current state by one edit.

func (*Manager) UndoTitle

func (m *Manager) UndoTitle() string

UndoTitle returns the title for the current undo state.