This directory contains the implementation of MongoDB Extended JSON v2 codec, providing high-performance encoding and decoding functionality for BSON types in JSON format.

High-Performance Binary Encoding: The implementation uses Writer and Reader directly to output raw bytes without intermediate JSON representations, following the same pattern as JsonEncoder and JsonDecoder for optimal performance.

EjsonEncoder - Supports both encoding modes:

• Canonical Mode: Preserves all type information using explicit type wrappers like {"$numberInt": "42"}
• Relaxed Mode: Uses native JSON types where possible for better readability (e.g., 42 instead of {"$numberInt": "42"})

EjsonDecoder - Strict parsing with comprehensive validation:

• Validates exact key matches for type wrappers
• Throws descriptive errors for malformed input
• Supports both canonical and relaxed format parsing

import {EjsonEncoder, EjsonDecoder} from '@jsonjoy.com/json-pack/lib/ejson';

const encoder = new EjsonEncoder();
const decoder = new EjsonDecoder();

const data = {
  _id: new BsonObjectId(0x507f1f77, 0xbcf86cd799, 0x439011),
  count: new BsonInt64(9223372036854775807),
  created: new Date('2023-01-15T10:30:00.000Z')
};

const encoded = encoder.encode(data);
const decoded = decoder.decode(encoded);

console.log(decoded); // Original data with BSON types preserved

import {EjsonEncoder, EjsonDecoder} from '@jsonjoy.com/json-pack/lib/ejson';
import {Writer} from '@jsonjoy.com/buffers/lib/Writer';

const writer = new Writer();
const encoder = new EjsonEncoder(writer, { canonical: true });
const decoder = new EjsonDecoder();

// Encode to bytes
const bytes = encoder.encode(data);

// Decode from bytes
const result = decoder.decode(bytes);

import {createEjsonEncoder, createEjsonDecoder} from '@jsonjoy.com/json-pack/lib/ejson';

const encoder = createEjsonEncoder({ canonical: true });
const decoder = createEjsonDecoder();

// Encode to string
const jsonString = encoder.encodeToString(data);

// Decode from string
const result = decoder.decodeFromString(jsonString);

The implementation supports all BSON types as per the MongoDB specification:

• ObjectId: {"$oid": "507f1f77bcf86cd799439011"}
• Numbers: Int32, Int64, Double with proper canonical/relaxed handling
• Decimal128: {"$numberDecimal": "123.456"}
• Binary & UUID: Full base64 encoding with subtype support
• Code & CodeWScope: JavaScript code with optional scope
• Dates: ISO-8601 format (relaxed) or timestamp (canonical)
• RegExp: Pattern and options preservation
• Special types: MinKey, MaxKey, Undefined, DBPointer, Symbol, Timestamp

import { createEjsonEncoder, createEjsonDecoder, BsonObjectId, BsonInt64 } from '@jsonjoy.com/json-pack/ejson2';

const data = {
  _id: new BsonObjectId(0x507f1f77, 0xbcf86cd799, 0x439011),
  count: new BsonInt64(9223372036854775807),
  created: new Date('2023-01-15T10:30:00.000Z')
};

// Canonical mode (preserves all type info)
const canonical = createEjsonEncoder({ canonical: true });
console.log(canonical.encodeToString(data));
// {"_id":{"$oid":"507f1f77bcf86cd799439011"},"count":{"$numberLong":"9223372036854775807"},"created":{"$date":{"$numberLong":"1673778600000"}}}

// Relaxed mode (more readable)
const relaxed = createEjsonEncoder({ canonical: false });
console.log(relaxed.encodeToString(data));
// {"_id":{"$oid":"507f1f77bcf86cd799439011"},"count":9223372036854775807,"created":{"$date":"2023-01-15T10:30:00.000Z"}}

// Decoding with validation
const decoder = createEjsonDecoder();
const decoded = decoder.decodeFromString(canonical.encodeToString(data));
console.log(decoded._id instanceof BsonObjectId); // true

• High-Performance Binary Encoding: Uses Writer and Reader directly to eliminate intermediate JSON string representations
• Shared Value Classes: Reuses existing BSON value classes from src/bson/values.ts
• Strict Validation: Prevents type wrappers with extra fields (e.g., {"$oid": "...", "extra": "field"} throws error)
• Round-trip Compatibility: Ensures encoding → decoding preserves data integrity
• Error Handling: Comprehensive error messages for debugging
• Specification Compliant: Follows MongoDB Extended JSON v2 specification exactly

Added 54 comprehensive tests covering:

• All BSON type encoding/decoding in both modes
• Round-trip compatibility testing
• Error handling and edge cases
• Special numeric values (Infinity, NaN)
• Date handling for different year ranges
• Malformed input validation

All existing tests continue to pass, ensuring no breaking changes.