fix: comments

Author: nbbeeken

src/parser/on_demand/parse_to_elements.ts

@@ -13,8 +13,16 @@ export type BSONElement = [
   length: number
 ];
 
+/** Parses a int32 little-endian at offset, throws if it is negative */
+function getSize(source: Uint8Array, offset: number): number {
+  if (source[offset + 3] > 127) {
+    throw new BSONOffsetError('BSON size cannot be negative', offset);
+  }
+  return NumberUtils.getInt32LE(source, offset);
+}
+
 /**
- * Searches for null terminator.
+ * Searches for null terminator of a BSON element's value (Never the document null terminator)
  * **Does not** bounds check since this should **ONLY** be used within parseToElements which has asserted that `bytes` ends with a `0x00`.
  * So this will at most iterate to the document's terminator and error if that is the offset reached.
  */
@@ -24,6 +32,7 @@ function findNull(bytes: Uint8Array, offset: number): number {
   for (; bytes[nullTerminatorOffset] !== 0x00; nullTerminatorOffset++);
 
   if (nullTerminatorOffset === bytes.length - 1) {
+    // We reached the null terminator of the document, not a value's
     throw new BSONOffsetError('Null terminator not found', offset);
   }
 
@@ -42,7 +51,7 @@ export function parseToElements(bytes: Uint8Array, startOffset = 0): Iterable<BS
     );
   }
 
-  const documentSize = NumberUtils.getSize(bytes, startOffset);
+  const documentSize = getSize(bytes, startOffset);
 
   if (documentSize > bytes.length - startOffset) {
     throw new BSONOffsetError(
@@ -75,6 +84,7 @@ export function parseToElements(bytes: Uint8Array, startOffset = 0): Iterable<BS
 
     let length: number;
 
+    // The following values are left as literals intentionally
     if (type === 1 || type === 18 || type === 9 || type === 17) {
       // double, long, date, timestamp
       length = 8;
@@ -100,10 +110,10 @@ export function parseToElements(bytes: Uint8Array, startOffset = 0): Iterable<BS
       length = findNull(bytes, findNull(bytes, offset) + 1) + 1 - offset;
     } else if (type === 3 || type === 4 || type === 15) {
       // object, array, code_w_scope
-      length = NumberUtils.getSize(bytes, offset);
+      length = getSize(bytes, offset);
     } else if (type === 2 || type === 5 || type === 12 || type === 13 || type === 14) {
       // string, binary, dbpointer, code, symbol
-      length = NumberUtils.getSize(bytes, offset) + 4;
+      length = getSize(bytes, offset) + 4;
       if (type === 5) {
         // binary subtype
         length += 1;

src/utils/number_utils.ts

@@ -1,5 +1,3 @@
-import { BSONOffsetError } from '../error';
-
 const FLOAT = new Float64Array(1);
 const FLOAT_BYTES = new Uint8Array(FLOAT.buffer, 0, 8);
 
@@ -9,13 +7,6 @@ const FLOAT_BYTES = new Uint8Array(FLOAT.buffer, 0, 8);
  * @internal
  */
 export const NumberUtils = {
-  getSize(source: Uint8Array, offset: number): number {
-    if (source[offset + 3] > 127) {
-      throw new BSONOffsetError('BSON size cannot be negative', offset);
-    }
-    return NumberUtils.getInt32LE(source, offset);
-  },
-
   /** Reads a little-endian 32-bit integer from source */
   getInt32LE(source: Uint8Array, offset: number): number {
     return (

test/node/utils/number_utils.test.ts

@@ -5,30 +5,6 @@ describe('NumberUtils', () => {
   /** Make a Uint8Array in a less verbose way */
   const b = (...values) => new Uint8Array(values);
 
-  context('getSize()', () => {
-    it('parses an int32 little endian', () => {
-      expect(NumberUtils.getSize(b(0, 0, 0, 1), 0)).to.equal(1 << 24);
-    });
-
-    it('throws on a signed int32 little endian that is negative', () => {
-      let thrownError: Error | undefined;
-      try {
-        NumberUtils.getSize(b(255, 255, 255, 255), 0);
-      } catch (error) {
-        thrownError = error;
-      }
-      expect(thrownError).to.match(/BSON size cannot be negative/i);
-    });
-
-    it('parses an int32 little endian at offset', () => {
-      expect(NumberUtils.getSize(b(0, 0, 0, 0, 0, 1), 2)).to.equal(1 << 24);
-    });
-
-    it('does not check bounds of offset', () => {
-      expect(NumberUtils.getSize(b(0, 0, 0, 1), 4)).to.equal(0);
-    });
-  });
-
   context('getInt32LE()', () => {
     it('parses an int32 little endian', () => {
       expect(NumberUtils.getInt32LE(b(0, 0, 0, 1), 0)).to.equal(1 << 24);