feat(cbor): add encoding/decoding for new Map() instance (#6252)

cbor/_common_decode.ts

@@ -234,29 +234,34 @@ export function decodeFive(
 export function decodeSix(
   source: number[],
   aI: number,
-): Date | CborTag<CborType> {
+): Date | Map<CborType, CborType> | CborTag<CborType> {
   if (aI > 27) {
     throw new RangeError(
       `Cannot decode value (0b110_${aI.toString(2).padStart(5, "0")})`,
     );
   }
   const tagNumber = decodeZero(source, aI);
-  const tagContent = decode(source);
   switch (BigInt(tagNumber)) {
-    case 0n:
+    case 0n: {
+      const tagContent = decode(source);
       if (typeof tagContent !== "string") {
         throw new TypeError('Invalid TagItem: Expected a "text string"');
       }
       return new Date(tagContent);
-    case 1n:
+    }
+    case 1n: {
+      const tagContent = decode(source);
       if (typeof tagContent !== "number" && typeof tagContent !== "bigint") {
         throw new TypeError(
           'Invalid TagItem: Expected a "integer" or "float"',
         );
       }
       return new Date(Number(tagContent) * 1000);
+    }
+    case 259n:
+      return decodeMap(source);
   }
-  return new CborTag(tagNumber, tagContent);
+  return new CborTag(tagNumber, decode(source));
 }
 
 export function decodeSeven(
@@ -285,3 +290,47 @@ export function decodeSeven(
     `Cannot decode value (0b111_${aI.toString(2).padStart(5, "0")})`,
   );
 }
+
+function decodeMap(source: number[]): Map<CborType, CborType> {
+  const byte = source.pop();
+  if (byte == undefined) throw new RangeError("More bytes were expected");
+
+  const majorType = byte >> 5;
+  if (majorType !== 5) throw new TypeError('Invalid TagItem: Expected a "map"');
+  const aI = byte & 0b000_11111;
+  if (aI <= 27) {
+    const map = new Map<CborType, CborType>();
+    // Can safely assume `source.length < 2 ** 53` as JavaScript doesn't support an `Array` being that large.
+    // 2 ** 53 is the tipping point where integers loose precision.
+    const len = Number(decodeZero(source, aI));
+    for (let i = 0; i < len; ++i) {
+      const key = decode(source);
+      if (map.has(key)) {
+        throw new TypeError(
+          `A Map cannot have duplicate keys: Key (${key}) already exists`,
+        ); // https://datatracker.ietf.org/doc/html/rfc8949#name-specifying-keys-for-maps
+      }
+      map.set(key, decode(source));
+    }
+    return map;
+  }
+  if (aI === 31) {
+    const map = new Map<CborType, CborType>();
+    if (!source.length) throw new RangeError("More bytes were expected");
+    while (source[source.length - 1] !== 0b111_11111) {
+      const key = decode(source);
+      if (map.has(key)) {
+        throw new TypeError(
+          `A Map cannot have duplicate keys: Key (${key}) already exists`,
+        ); // https://datatracker.ietf.org/doc/html/rfc8949#name-specifying-keys-for-maps
+      }
+      map.set(key, decode(source));
+      if (!source.length) throw new RangeError("More bytes were expected");
+    }
+    source.pop();
+    return map;
+  }
+  throw new RangeError(
+    `Cannot decode value (0b101_${aI.toString(2).padStart(5, "0")})`,
+  );
+}

cbor/_common_encode.ts

@@ -109,6 +109,37 @@ export function encodeDate(x: Date): Uint8Array {
   return output;
 }
 
+export function encodeMap(x: Map<CborType, CborType>): Uint8Array {
+  const len = x.size;
+  let head: Uint8Array;
+  if (len < 24) head = Uint8Array.from([0b101_00000 + len]);
+  else if (len < 2 ** 8) head = Uint8Array.from([0b101_11000, len]);
+  else {
+    head = new Uint8Array(9);
+    const view = new DataView(head.buffer);
+    if (len < 2 ** 16) {
+      head[0] = 0b101_11001;
+      view.setUint16(1, len);
+      head = head.subarray(0, 3);
+    } else if (len < 2 ** 32) {
+      head[0] = 0b101_11010;
+      view.setUint32(1, len);
+      head = head.subarray(0, 5);
+    } else {
+      head[0] = 0b101_11011;
+      view.setBigUint64(1, BigInt(len));
+    }
+  }
+  return concat([
+    Uint8Array.from([217, 1, 3]), // TagNumber 259
+    head,
+    ...Array.from(x
+      .entries())
+      .map(([k, v]) => [encodeCbor(k), encodeCbor(v)])
+      .flat(),
+  ]);
+}
+
 export function encodeArray(x: CborType[]): Uint8Array {
   let head: number[];
   if (x.length < 24) head = [0b100_00000 + x.length];

cbor/decode_cbor.ts

@@ -21,7 +21,7 @@ import type { CborType } from "./types.ts";
  * @example Usage
  * ```ts
  * import { assert, assertEquals } from "@std/assert";
- * import { decodeCbor, encodeCbor } from "@std/cbor";
+ * import { type CborType, decodeCbor, encodeCbor } from "@std/cbor";
  *
  * const rawMessage = [
  *   "Hello World",
@@ -31,6 +31,8 @@ import type { CborType } from "./types.ts";
  *   -1,
  *   null,
  *   Uint8Array.from([0, 1, 2, 3]),
+ *   new Date(),
+ *   new Map<CborType, CborType>([[1, 2], ['3', 4], [[5], { a: 6 }]]),
  * ];
  *
  * const encodedMessage = encodeCbor(rawMessage);

cbor/decode_cbor_sequence.ts

@@ -20,7 +20,7 @@ import type { CborType } from "./types.ts";
  * @example Usage
  * ```ts
  * import { assertEquals } from "@std/assert";
- * import { decodeCborSequence, encodeCborSequence } from "@std/cbor";
+ * import { type CborType, decodeCborSequence, encodeCborSequence } from "@std/cbor";
  *
  * const rawMessage = [
  *   "Hello World",
@@ -30,6 +30,8 @@ import type { CborType } from "./types.ts";
  *   -1,
  *   null,
  *   Uint8Array.from([0, 1, 2, 3]),
+ *   new Date(),
+ *   new Map<CborType, CborType>([[1, 2], ['3', 4], [[5], { a: 6 }]]),
  * ];
  *
  * const encodedMessage = encodeCborSequence(rawMessage);

cbor/decode_cbor_test.ts

@@ -5,6 +5,7 @@ import { random } from "./_common_test.ts";
 import { decodeCbor } from "./decode_cbor.ts";
 import { encodeCbor } from "./encode_cbor.ts";
 import { CborTag } from "./tag.ts";
+import type { CborType } from "./types.ts";
 
 Deno.test("decodeCbor() decoding undefined", () => {
   assertEquals(decodeCbor(encodeCbor(undefined)), undefined);
@@ -111,6 +112,47 @@ Deno.test("decodeCbor() decoding Dates", () => {
   assertEquals(decodeCbor(encodeCbor(date)), date);
 });
 
+Deno.test("decodeCbor() decoding Map<CborType, CborType>", () => {
+  const map = new Map<CborType, CborType>([[1, 2], ["3", 4], [[5], { a: 6 }]]);
+  assertEquals(decodeCbor(encodeCbor(map)), map);
+});
+
+Deno.test("decodeCbor() decoding Maps", () => {
+  let pairs = random(0, 24);
+  let map = new Map(
+    new Array(pairs)
+      .fill(0)
+      .map((_, i) => [i, i]),
+  );
+  assertEquals(decodeCbor(encodeCbor(map)), map);
+
+  pairs = random(24, 2 ** 8);
+  map = new Map(
+    new Array(pairs)
+      .fill(0)
+      .map((_, i) => [i, i]),
+  );
+  assertEquals(decodeCbor(encodeCbor(map)), map);
+
+  pairs = random(2 ** 8, 2 ** 16);
+  map = new Map(
+    new Array(pairs)
+      .fill(0)
+      .map((_, i) => [i, i]),
+  );
+  assertEquals(decodeCbor(encodeCbor(map)), map);
+
+  pairs = random(2 ** 16, 2 ** 17);
+  map = new Map(
+    new Array(pairs)
+      .fill(0)
+      .map((_, i) => [i, i]),
+  );
+  assertEquals(decodeCbor(encodeCbor(map)), map);
+
+  // Can't test the next bracket up due to JavaScript limitations.
+});
+
 Deno.test("decodeCbor() decoding arrays", () => {
   let array = new Array(random(0, 24)).fill(0).map((_) => random(0, 2 ** 32));
   assertEquals(decodeCbor(encodeCbor(array)), array);
@@ -653,3 +695,122 @@ Deno.test("decodeCbor() rejecting majorType 7 due to additional information", ()
     "Cannot decode value (0b111_11110)",
   );
 });
+
+Deno.test("decodeCbor() rejecting tagNumber 259 due to additional information", () => {
+  assertThrows(
+    () => {
+      decodeCbor(
+        Uint8Array.from([
+          217,
+          1,
+          3,
+          0b101_11100,
+          ...new Array(random(0, 64)).fill(0).map((_) => random(0, 256)),
+        ]),
+      );
+    },
+    RangeError,
+    "Cannot decode value (0b101_11100)",
+  );
+  assertThrows(
+    () => {
+      decodeCbor(
+        Uint8Array.from([
+          217,
+          1,
+          3,
+          0b101_11101,
+          ...new Array(random(0, 64)).fill(0).map((_) => random(0, 256)),
+        ]),
+      );
+    },
+    RangeError,
+    "Cannot decode value (0b101_11101)",
+  );
+  assertThrows(
+    () => {
+      decodeCbor(
+        Uint8Array.from([
+          217,
+          1,
+          3,
+          0b101_11110,
+          ...new Array(random(0, 64)).fill(0).map((_) => random(0, 256)),
+        ]),
+      );
+    },
+    RangeError,
+    "Cannot decode value (0b101_11110)",
+  );
+});
+
+Deno.test("decodeCbor() rejecting TagNumber 259 due to maps having invalid keys", () => {
+  assertThrows(
+    () => {
+      decodeCbor(
+        Uint8Array.from([
+          217,
+          1,
+          3,
+          0b101_00010,
+          0b011_00001,
+          48,
+          0b000_00000,
+          0b011_00001,
+          48,
+          0b000_00001,
+        ]),
+      );
+    },
+    TypeError,
+    "A Map cannot have duplicate keys: Key (0) already exists",
+  );
+});
+
+Deno.test("decodeCbor() rejecting tagNumber 259 due to invalid indefinite length maps", () => {
+  assertThrows(
+    () => {
+      decodeCbor(Uint8Array.from([217, 1, 3, 0b101_11111]));
+    },
+    RangeError,
+    "More bytes were expected",
+  );
+  assertThrows(
+    () => {
+      decodeCbor(
+        Uint8Array.from([
+          217,
+          1,
+          3,
+          0b101_11111,
+          0b011_00001,
+          48,
+          0b000_00000,
+          0b011_00001,
+          48,
+          0b000_00001,
+          0b111_11111,
+        ]),
+      );
+    },
+    TypeError,
+    "A Map cannot have duplicate keys: Key (0) already exists",
+  );
+  assertThrows(
+    () => {
+      decodeCbor(
+        Uint8Array.from([
+          217,
+          1,
+          3,
+          0b101_11111,
+          0b011_00001,
+          48,
+          0b000_00000,
+        ]),
+      );
+    },
+    RangeError,
+    "More bytes were expected",
+  );
+});

cbor/encode_cbor.ts

@@ -4,6 +4,7 @@ import {
   encodeArray,
   encodeBigInt,
   encodeDate,
+  encodeMap,
   encodeNumber,
   encodeObject,
   encodeString,
@@ -21,7 +22,7 @@ import type { CborType } from "./types.ts";
  * @example Usage
  * ```ts
  * import { assert, assertEquals } from "@std/assert";
- * import { decodeCbor, encodeCbor } from "@std/cbor";
+ * import { type CborType, decodeCbor, encodeCbor } from "@std/cbor";
  *
  * const rawMessage = [
  *   "Hello World",
@@ -31,6 +32,8 @@ import type { CborType } from "./types.ts";
  *   -1,
  *   null,
  *   Uint8Array.from([0, 1, 2, 3]),
+ *   new Date(),
+ *   new Map<CborType, CborType>([[1, 2], ['3', 4], [[5], { a: 6 }]]),
  * ];
  *
  * const encodedMessage = encodeCbor(rawMessage);
@@ -61,5 +64,6 @@ export function encodeCbor(value: CborType): Uint8Array {
   if (value instanceof Uint8Array) return encodeUint8Array(value);
   if (value instanceof Array) return encodeArray(value);
   if (value instanceof CborTag) return encodeTag(value);
+  if (value instanceof Map) return encodeMap(value);
   return encodeObject(value);
 }

cbor/encode_cbor_sequence.ts

@@ -12,7 +12,7 @@ import type { CborType } from "./types.ts";
  * @example Usage
  * ```ts
  * import { assertEquals } from "@std/assert";
- * import { decodeCborSequence, encodeCborSequence } from "@std/cbor";
+ * import { type CborType, decodeCborSequence, encodeCborSequence } from "@std/cbor";
  *
  * const rawMessage = [
  *   "Hello World",
@@ -22,6 +22,8 @@ import type { CborType } from "./types.ts";
  *   -1,
  *   null,
  *   Uint8Array.from([0, 1, 2, 3]),
+ *   new Date(),
+ *   new Map<CborType, CborType>([[1, 2], ['3', 4], [[5], { a: 6 }]]),
  * ];
  *
  * const encodedMessage = encodeCborSequence(rawMessage);