Bitmap-Index Library

This TypeScript library provides a bitmap implementation (Bitmap) that allows efficient manipulation of a bitmap data structure, useful for various indexing and set operations.

Features

• Set Operations: set, remove, contains, and clear operations on the bitmap.
• Logical Operations: and, andNot, or, and xor operations between bitmaps.
• Iteration and Filtering: range iteration, generator-based iteration via [Symbol.iterator], and filter based on user-defined conditions.
• Count and Extremes: Methods to count set bits (count), find the minimum and maximum set bit (min, max), as well as the minimum and maximum unset bit (minZero, maxZero).
• Cloning: Supports cloning of the bitmap instance.
• Iterable Support: Can be used directly in for...of loops and spread syntax ([...bitmap]) for convenient iteration over set bits.

Installation

You can install the library via npm:

npm install bitmap-index

Usage Example

import { Bitmap } from 'bitmap-index';

// Create a new Bitmap with a size of 32 bits
const bitmap = new Bitmap(32);

// Set bits
bitmap.set(2);
bitmap.set(5);
bitmap.set(10);

// Check if a bit is set
console.log(bitmap.contains(5)); // true
console.log(bitmap.contains(3)); // false

// Perform logical operations with another bitmap
const otherBitmap = new Bitmap(32);
otherBitmap.set(5);
otherBitmap.set(10);

const andResult = bitmap.and(otherBitmap); // Bitmap with bits [5, 10]
const orResult = bitmap.or(otherBitmap);   // Bitmap with bits [2, 5, 10]
const xorResult = bitmap.xor(otherBitmap); // Bitmap with bits [2]

// Iterate over set bits using range
bitmap.range((x) => {
  console.log(`Bit ${x} is set`);
  return true; // Continue iterating
});

// Iterate using for...of (generator)
for (const bit of bitmap) {
  console.log(`Iterated bit: ${bit}`);
}

// Spread operator
const bitsArray = [...bitmap]; // [2, 5, 10]

// Filter based on a condition
bitmap.filter((x) => x % 2 === 0); // Remove odd-numbered bits

// Count the number of set bits
console.log(bitmap.count()); // 1

// Find the minimum and maximum set bits
console.log(bitmap.min()); // 2
console.log(bitmap.max()); // 10

// Clear all bits
bitmap.clear();

// Clone the bitmap
const clonedBitmap = bitmap.clone();

API Documentation

• Bitmap Class

  • Constructor: new Bitmap(size: number = 32)
  • Set Operations: set(x: number), remove(x: number), contains(x: number), clear()
  • Logical Operations: and(bitmap: Bitmap), andNot(bitmap: Bitmap), or(bitmap: Bitmap), xor(bitmap: Bitmap)
  • Iteration and Filtering: range(fn: (x: number) => boolean), filter(fn: (x: number) => boolean), [Symbol.iterator](): Iterator<number>
  • Count and Extremes: count(), min(), max(), minZero(), maxZero()
  • Cloning: clone(): Bitmap

Note

This library is designed for bitmap indexing operations and is not related to image processing. For more information on bitmap indexing, please refer to Bitmap Index Wiki.

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Feel free to contribute, report issues, or suggest improvements on GitHub.