feat(NODE-7314): export byteUtils & add missing methods

Author: tadjik1

src/bson.ts

@@ -49,7 +49,8 @@ export {
   MaxKey,
   BSONRegExp,
   Decimal128,
-  NumberUtils
+  NumberUtils,
+  ByteUtils
 };
 export { BSONValue, bsonType, type BSONTypeTag } from './bson_value';
 export { BSONError, BSONVersionError, BSONRuntimeError, BSONOffsetError } from './error';

src/utils/byte_utils.ts

@@ -15,6 +15,10 @@ export type ByteUtils = {
   allocate: (size: number) => Uint8Array;
   /** Create empty space of size, use pooled memory when available */
   allocateUnsafe: (size: number) => Uint8Array;
+  /** Compare 2 Uint8Arrays lexicographically */
+  compare: (buffer1: Uint8Array, buffer2: Uint8Array) => -1 | 0 | 1;
+  /** Concatenating all the Uint8Arrays in new Uint8Array. */
+  concat: (list: Uint8Array[]) => Uint8Array;
   /** Check if two Uint8Arrays are deep equal */
   equals: (a: Uint8Array, b: Uint8Array) => boolean;
   /** Check if two Uint8Arrays are deep equal */

src/utils/node_byte_utils.ts

@@ -10,6 +10,7 @@ type NodeJsBuffer = ArrayBufferView &
     toString: (this: Uint8Array, encoding: NodeJsEncoding, start?: number, end?: number) => string;
     equals: (this: Uint8Array, other: Uint8Array) => boolean;
     swap32: (this: NodeJsBuffer) => NodeJsBuffer;
+    compare: (this: Uint8Array, other: Uint8Array) => -1 | 0 | 1;
   };
 type NodeJsBufferConstructor = Omit<Uint8ArrayConstructor, 'from'> & {
   alloc: (size: number) => NodeJsBuffer;
@@ -21,6 +22,7 @@ type NodeJsBufferConstructor = Omit<Uint8ArrayConstructor, 'from'> & {
   from(base64: string, encoding: NodeJsEncoding): NodeJsBuffer;
   byteLength(input: string, encoding: 'utf8'): number;
   isBuffer(value: unknown): value is NodeJsBuffer;
+  concat(list: Uint8Array[]): NodeJsBuffer;
 };
 
 // This can be nullish, but we gate the nodejs functions on being exported whether or not this exists
@@ -88,6 +90,14 @@ export const nodeJsByteUtils = {
     return Buffer.allocUnsafe(size);
   },
 
+  compare(a: Uint8Array, b: Uint8Array) {
+    return nodeJsByteUtils.toLocalBufferType(a).compare(b);
+  },
+
+  concat(list: Uint8Array[]): NodeJsBuffer {
+    return Buffer.concat(list);
+  },
+
   equals(a: Uint8Array, b: Uint8Array): boolean {
     return nodeJsByteUtils.toLocalBufferType(a).equals(b);
   },

src/utils/web_byte_utils.ts

@@ -114,6 +114,42 @@ export const webByteUtils = {
     return webByteUtils.allocate(size);
   },
 
+  compare(a: Uint8Array, b: Uint8Array): -1 | 0 | 1 {
+    if (a === b) return 0;
+
+    const len = Math.min(a.length, b.length);
+
+    for (let i = 0; i < len; i++) {
+      if (a[i] < b[i]) return -1;
+      if (a[i] > b[i]) return 1;
+    }
+
+    if (a.length < b.length) return -1;
+    if (a.length > b.length) return 1;
+
+    return 0;
+  },
+
+  concat(list: Uint8Array[]): Uint8Array {
+    if (list.length === 0) return webByteUtils.allocate(0);
+    if (list.length === 1) return list[0];
+
+    let totalLength = 0;
+    for (const arr of list) {
+      totalLength += arr.length;
+    }
+
+    const result = webByteUtils.allocate(totalLength);
+    let offset = 0;
+
+    for (const arr of list) {
+      result.set(arr, offset);
+      offset += arr.length;
+    }
+
+    return result;
+  },
+
   equals(a: Uint8Array, b: Uint8Array): boolean {
     if (a.byteLength !== b.byteLength) {
       return false;

test/node/byte_utils.test.ts

@@ -517,6 +517,123 @@ const swap32Tests: ByteUtilTest<'swap32'>[] = [
     }
   }
 ];
+const compareTests: ByteUtilTest<'compare'>[] = [
+  {
+    name: 'returns 0 for two equal arrays (same content)',
+    inputs: [new Uint8Array([1, 2, 3]), new Uint8Array([1, 2, 3])],
+    expectation({ output }) {
+      expect(output).to.equal(0);
+    }
+  },
+  {
+    name: 'returns 0 when comparing the same buffer by reference',
+    inputs: (() => {
+      const buf = new Uint8Array([5, 6, 7]);
+      return [buf, buf];
+    })(),
+    expectation({ output }) {
+      expect(output).to.equal(0);
+    }
+  },
+  {
+    name: 'array a is lexicographically less than array b (first differing byte)',
+    inputs: [new Uint8Array([1, 2, 3]), new Uint8Array([1, 2, 4])],
+    expectation({ output }) {
+      expect(output).to.equal(-1);
+    }
+  },
+  {
+    name: 'array a is lexicographically greater than array b (first differing byte)',
+    inputs: [new Uint8Array([1, 2, 4]), new Uint8Array([1, 2, 3])],
+    expectation({ output }) {
+      expect(output).to.equal(1);
+    }
+  },
+  {
+    name: 'a is a strict prefix of b (a shorter, same starting bytes) -> a < b',
+    inputs: [new Uint8Array([1, 2]), new Uint8Array([1, 2, 3])],
+    expectation({ output }) {
+      expect(output).to.equal(-1);
+    }
+  },
+  {
+    name: 'b is a strict prefix of a (b shorter, same starting bytes) -> a > b',
+    inputs: [new Uint8Array([1, 2, 3]), new Uint8Array([1, 2])],
+    expectation({ output }) {
+      expect(output).to.equal(1);
+    }
+  },
+  {
+    name: 'handles empty arrays',
+    inputs: [new Uint8Array([]), new Uint8Array([])],
+    expectation({ output }) {
+      expect(output).to.equal(0);
+    }
+  }
+];
+const concatTests: ByteUtilTest<'concat'>[] = [
+  {
+    name: 'concatenates two non-empty arrays',
+    inputs: [[new Uint8Array([1, 2]), new Uint8Array([3, 4])]],
+    expectation({ output, error }) {
+      expect(error).to.be.null;
+      expect(output).to.deep.equal(Buffer.from([1, 2, 3, 4]));
+    }
+  },
+  {
+    name: 'concatenates multiple arrays in order',
+    inputs: [[new Uint8Array([1]), new Uint8Array([2, 3]), new Uint8Array([4, 5, 6])]],
+    expectation({ output, error }) {
+      expect(error).to.be.null;
+      expect(output).to.deep.equal(Buffer.from([1, 2, 3, 4, 5, 6]));
+    }
+  },
+  {
+    name: 'returns an empty Uint8Array when given an empty list',
+    inputs: [[]],
+    expectation({ output, error }) {
+      expect(error).to.be.null;
+      expect(output).to.have.property('byteLength', 0);
+      expect(output).to.deep.equal(Buffer.from([]));
+    }
+  },
+  {
+    name: 'returns the same contents when given a single array',
+    inputs: [[new Uint8Array([7, 8, 9])]],
+    expectation({ output, error }) {
+      expect(error).to.be.null;
+      expect(output).to.deep.equal(Buffer.from([7, 8, 9]));
+    }
+  },
+  {
+    name: 'handles concatenation with empty arrays inside the list',
+    inputs: [
+      [new Uint8Array([]), new Uint8Array([1, 2, 3]), new Uint8Array([]), new Uint8Array([4])]
+    ],
+    expectation({ output, error }) {
+      expect(error).to.be.null;
+      expect(output).to.deep.equal(Buffer.from([1, 2, 3, 4]));
+    }
+  },
+  {
+    name: 'result has correct total byteLength',
+    inputs: [[new Uint8Array([1, 2]), new Uint8Array([3]), new Uint8Array([4, 5, 6])]],
+    expectation({ output, error }) {
+      expect(error).to.be.null;
+      // 2 + 1 + 3 = 6
+      expect(output).to.have.property('byteLength', 6);
+      expect(output).to.deep.equal(Buffer.from([1, 2, 3, 4, 5, 6]));
+    }
+  },
+  {
+    name: 'concatenates arrays with overlapping contents correctly',
+    inputs: [[new Uint8Array([0, 0, 1]), new Uint8Array([1, 0, 0])]],
+    expectation({ output, error }) {
+      expect(error).to.be.null;
+      expect(output).to.deep.equal(Buffer.from([0, 0, 1, 1, 0, 0]));
+    }
+  }
+];
 
 const utils = new Map([
   ['nodeJsByteUtils', nodeJsByteUtils],
@@ -538,7 +655,9 @@ const table = new Map<keyof ByteUtils, ByteUtilTest<keyof ByteUtils>[]>([
   ['toUTF8', toUTF8Tests],
   ['utf8ByteLength', utf8ByteLengthTests],
   ['randomBytes', randomBytesTests],
-  ['swap32', swap32Tests]
+  ['swap32', swap32Tests],
+  ['compare', compareTests],
+  ['concat', concatTests]
 ]);
 
 describe('ByteUtils', () => {

test/node/exports.test.ts

@@ -39,7 +39,8 @@ const EXPECTED_EXPORTS = [
   'deserializeStream',
   'BSON',
   'bsonType',
-  'NumberUtils'
+  'NumberUtils',
+  'ByteUtils'
 ];
 
 const EXPECTED_EJSON_EXPORTS = ['parse', 'stringify', 'serialize', 'deserialize'];