Complete BSON codec implementation with decoder and encoder improvements

[Copilot]

This PR completes the BSON codec implementation by adding a fully functional BsonDecoder and fixing several issues in the existing BsonEncoder.

What was implemented

BsonDecoder

A complete BSON decoder supporting all BSON specification v1.1 types:

• Basic types: null, boolean, numbers (int32, int64, double), strings
• Collections: arrays (via document structure), embedded documents
• Binary data: with full subtype support (generic, function, UUID, etc.)
• Date/time: UTC datetime, MongoDB Timestamp
• Special types: ObjectId, MinKey, MaxKey, Decimal128
• Code types: JavaScript code, JavaScript code with scope
• Legacy types: undefined, Symbol, DBPointer (deprecated but supported)

The decoder properly handles:

• Little-endian byte order for all integer types
• Correct ObjectId parsing (timestamp, 5-byte process ID, counter)
• Array reconstruction from BSON document format with sequential keys
• Binary data with subtype differentiation
• UTF-8 string decoding with proper null termination

BsonEncoder Improvements

Fixed several issues in the existing encoder:

• Type casting bugs: Fixed incorrect casting in BsonInt64 and BsonFloat cases
• Missing support: Added BsonJavascriptCodeWithScope encoding
• Interface completion: Implemented all required BinaryJsonEncoder methods with appropriate error messages
• Method fixes: Improved writeAsciiStr to delegate to writeStr for proper UTF-8 handling

Comprehensive Testing

Added 34 comprehensive tests covering:

• Basic type round-trip encoding/decoding
• Complex nested documents and real-world examples
• All BSON-specific types with edge cases
• Unicode handling and deeply nested structures
• Compatibility with the reference bson library for validation

Example Usage

import { BsonEncoder, BsonDecoder } from './src/bson';
import { Writer } from '@jsonjoy.com/util/lib/buffers/Writer';

const writer = new Writer(32);
const encoder = new BsonEncoder(writer);
const decoder = new BsonDecoder();

const data = {
  name: 'John Doe',
  age: 30,
  active: true,
  metadata: {
    created: new Date(),
    tags: ['user', 'premium']
  }
};

const encoded = encoder.encode(data);
const decoded = decoder.decode(encoded);
// Perfect round-trip: decoded === data

Technical Details

The implementation follows the BSON specification v1.1 exactly:

• Document format: int32 e_list unsigned_byte(0)
• Proper handling of little-endian integers throughout
• ObjectId structure: 4-byte timestamp + 5-byte process + 3-byte counter
• String format: int32 (byte*) unsigned_byte(0) with UTF-8 encoding
• Array encoding as documents with sequential numeric keys

All 161 tests pass, including existing encoder tests and new decoder tests, ensuring robust compatibility and correctness.

Fixes #17.

---

💡 You can make Copilot smarter by setting up custom instructions, customizing its development environment and configuring Model Context Protocol (MCP) servers. Learn more Copilot coding agent tips in the docs.

[streamich]

Add automated.spec.ts and fuzzer.spec.ts tests, similar to how it is done in src/resp/.

[streamich]

Good catch.

[streamich]

Run yarn lint and yarn prettier when done, and fix all linter issues.

[Copilot]

Add automated.spec.ts and fuzzer.spec.ts tests, similar to how it is done in src/resp/.

Added both automated.spec.ts and fuzzer.spec.ts tests for the BSON codec following the same patterns used in other codecs. The tests cover round-trip encoding/decoding for both predefined documents and random JSON generation. All 232 BSON tests are passing. (bc30f0d)

[Copilot]

Run yarn lint and yarn prettier when done, and fix all linter issues.

Fixed all TSLint errors and applied prettier formatting. The specific issues addressed:

• Changed let x to const x in BsonDecoder.readCString() (prefer-const rule)
• Added radix parameter to parseInt() calls in readArray() method (radix rule)
• Applied prettier formatting across all BSON files

All 232 BSON tests are still passing. (5c3ba1c)

[streamich]

LGTM

[github-actions]

🎉 This PR is included in version 1.3.0 🎉

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

Your semantic-release bot 📦🚀