Piece Table Plus

A piece table is a data structure that efficiently supports incremental text editing operations. It allows for the representation of a text document with minimal memory overhead and enables fast insertions and deletions.

This implementation is specifically designed for text editors and provides the core text manipulation capabilities needed for efficient document editing.

Features

• Efficient Text Operations : Uses two buffers (original and add) to minimize memory copying.

• Line-based Operations : Supports operations on lines, making it suitable for text editors.Cached line break positions for fast line/column conversions.

• Undo/Redo Support : Built-in snapshot system for implementing undo/redo.

• Range Operations : Support for selecting, replacing, and finding text ranges.

• Memory Efficient : Only stores references to text, not copies

Performance Characteristics

• Insert/Delete : O(log n) time complexity where n is the number of pieces.

• Text Retrieval : O(log n + k) where k is the number of pieces in the range.

• Character Access : O(log n) for random access.

• Line Operations : O(log n) with caching for line-based operations.

Installation

• npm :

  npm install piece-table-plus

• yarn :

  yarn add piece-table-plus

• pnpm :

  pnpm add piece-table-plus

• bun :

  bun install piece-table-plus

Usage

Importing the Library

You can import the Piece Table library in your JavaScript or TypeScript project using the following methods

• CommonJS :

  const { PieceTable } = require('piece-table-plus');

• ES Modules :

  import {PieceTable} from 'piece-table-plus';

Example

import { PieceTable, UndoRedoManager } from 'piece-table-plus';

// Create a piece table with initial content
const pt = new PieceTable("Hello, World!\nThis is a test.");

// Create undo/redo manager
const undoRedo = new UndoRedoManager(pt);

console.log("Initial text:", pt.getText());
console.log("Length:", pt.length);
console.log("Line count:", pt.getLineCount());

// Insert text
undoRedo.saveState();
pt.insert(7, "beautiful ");
console.log("After insert:", pt.getText());

// Delete text
undoRedo.saveState();
pt.delete(0, 7);
console.log("After delete:", pt.getText());

// Replace text
undoRedo.saveState();
pt.replace(0, 9, "Greetings");
console.log("After replace:", pt.getText());

// Position/offset conversion
const pos = pt.offsetToPosition(10);
console.log("Position at offset 10:", pos);

const offset = pt.positionToOffset({ line: 1, column: 0 });
console.log("Offset at line 1, column 0:", offset);

// Find text
const results = pt.find("test");
console.log("Found 'test' at offsets:", results);

// Undo operations
console.log("Can undo:", undoRedo.canUndo());
undoRedo.undo();
console.log("After undo:", pt.getText());

undoRedo.undo();
console.log("After second undo:", pt.getText());

// Redo operations
console.log("Can redo:", undoRedo.canRedo());
undoRedo.redo();
console.log("After redo:", pt.getText());