XML API

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Transaction System ​

The Transaction system is the heart of xml-api's state management. It allows for atomic, predictable updates to the editor state.

Concept ​

Instead of mutating the state directly, you create a Transaction that describes the changes you want to make. The SyncEngine then processes this transaction to produce a new state.

typescript
// 1. Create a transaction from the current state
const tr = new Transaction(api.engine.state);

// 2. Add changes (e.g. text replacement)
tr.replace(start, end, "New Text");

// 3. Dispatch the transaction
api.engine.dispatch(tr);

Immutable State ​

The EditorState is immutable. When a transaction is dispatched:

  1. A new source string is calculated.
  2. The Parser updates the CST (incrementally if possible).
  3. The Binder reconciles the Model.
  4. A new EditorState instance is created and stored in the engine.

Advanced Usage ​

Since transactions are objects, they can be:

  • Queued
  • Transformed (for collaboration)
  • Inspected (for logging or undo/redo)

Batch Updates ​

You can perform multiple updates in a single transaction, ensuring they are applied atomically and trigger only one re-parse/re-render cycle.

typescript
const tr = new Transaction(api.engine.state);
tr.replace(0, 5, "Hello");
tr.replace(10, 15, "World");
api.engine.dispatch(tr);