Undo

A simple undo / redo manager. This was designed to work well with Replicache, but can be used entirely independently. From this library's perspective, undo/redo actions are just functions and this library doesn't care what those functions do. Please use Replidraw as a reference on how to use the library.

Installation

``
npm install @rocicorp/undo
`

Replicache Usage Example

`tsx
import { Replicache } from "replicache";
import { useSubscribe } from "replicache-react";
...
import {UndoManager} from '@rocicorp/undo';

// Replicache and UndoManager are initialized outside of the initial component render.
// undoManager = new UndoManager()
const App = ({ rep }: { rep: Replicache, undoManager: UndoManager }) => {
const todos = useSubscribe(rep, listTodos, [], [rep]);

// new item with undo
const handleNewItem = (text: string) => {
const id = nanoid();
//function that will redo and execute
const putTodo = () => {
rep.mutate.putTodo({
id,
text: text,
sort: todos.length > 0 ? todos[todos.length - 1].sort + 1 : 0,
completed: false,
});
};

//undo function
const removeTodo = () => rep.mutate.deleteTodos([id]);

undoManager.add({
execute: putTodo,
undo: removeTodo,
});
};

return (



);
}
`

Basic Usage Example

`ts
import {UndoManager} from '@rocicorp/undo';

const undoManager = new UndoManager();
const modifiedValue = 0;
undoManager.add({
undo: () => {
modifiedValue--;
},
execute: () => {
modifiedValue++;
},
});
`

API

constructor

Constructor for UndoManager

| Param | Type | Description |
| ------- | -------------------------------- | ------------------------------------------- |
| options | UnderManagerOptions | Options passed for undo manager constructor |

UnderManagerOptions

| Param | Type | Description |
| -------- | ------------------------------------------------------ | --------------------------------------------------------------------------------- |
| maxSize | Object | The maximum number of entries in the stack. Default is 10000. |
| onChange | (undoManager: UndoRedoStackState) => void | A callback function to be called when the stack canUndo or canRedo values change. |

Example

`ts
const undoManager = new UndoManager({ 10, (e: UndoRedoStackState) => {
console.log('undo manager canUndo or canRedo values changed -- ', e.canUndo, e.canRedo);
}});
`

---

canUndo

Determines if a user can perform the undo operation on the undoRedo stack.

---

canRedo

Determines if a user can perform the redo operation on the undoRedo stack.

---

add

Adds an entry to the undoRedo stack.

| Param | Type | Description |
| ------- | ----------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| options | AddOptions | A UndoRedo or ExecuteUndo object that can is added to the stack. If it is an ExecuteUndo it will run the execute function immediately after adding to the stack. |

$3

`ts
type AddOptions = UndoRedo | ExecuteUndo;

type UndoRedo = {
redo: () => MaybePromise;
undo: () => MaybePromise;
};

type ExecuteUndo = {
execute: () => MaybePromise;
undo: () => MaybePromise;
};
`

---

undo

Executes the undo function of the current entry in the undoRedo stack. If the current entry has groupID it will check the upcoming undo entry. If the upcoming undo entry also has the same groupID the function will recursively call undo until it runs into a entry that has has a different groupID or is undefined.

---

redo

Executes the redo function of the current entry in the undoRedo stack. If the current entry has groupID it will check the upcoming redo entry. If the upcoming redo entry also has the same groupID the function will recursively call redo until it runs into a entry that has has a different groupID or is undefined.

---

startGroup

Sets the undo manager to add groupID to all subsequent entries. Sets the isGrouping internal state of the stack to true

---

endGroup

Sets the undo manager to mark all subsequent added entries groupID to undefined. Sets the isGrouping internal state of the stack to false`

---