feat(encoding/unstable): add Uint8Array support to decodeBase64, 32, and hex (#6508)

Author: BlackAsLight

encoding/unstable_base32.ts

@@ -159,7 +159,9 @@ export function encodeRawBase32(
 
 /**
  * `decodeBase32` takes an input source and decodes it into a
- * {@linkcode Uint8Array<ArrayBuffer>} using the specified format.
+ * {@linkcode Uint8Array<ArrayBuffer>} using the specified format. If a
+ * {@linkcode Uint8Array<ArrayBuffer>} is provided as input then a subarray of
+ * the input containing the decoded data is returned.
  *
  * @experimental **UNSTABLE**: New API, yet to be vetted.
  *
@@ -189,15 +191,13 @@ export function encodeRawBase32(
  * ```
  */
 export function decodeBase32(
-  input: string,
+  input: string | Uint8Array_,
   format: Base32Format = "Base32",
 ): Uint8Array_ {
-  const output = new TextEncoder().encode(input) as Uint8Array_;
-  return output
-    .subarray(
-      0,
-      decode(output, 0, 0, rAlphabet[format], padding),
-    );
+  if (typeof input === "string") {
+    input = new TextEncoder().encode(input) as Uint8Array_;
+  }
+  return input.subarray(0, decode(input, 0, 0, rAlphabet[format], padding));
 }
 
 /**

encoding/unstable_base64.ts

@@ -185,15 +185,13 @@ export function encodeRawBase64(
  * ```
  */
 export function decodeBase64(
-  input: string,
+  input: string | Uint8Array_,
   format: Base64Format = "Base64",
 ): Uint8Array_ {
-  const output = new TextEncoder().encode(input) as Uint8Array_;
-  return output
-    .subarray(
-      0,
-      decode(output, 0, 0, rAlphabet[format], padding),
-    );
+  if (typeof input === "string") {
+    input = new TextEncoder().encode(input) as Uint8Array_;
+  }
+  return input.subarray(0, decode(input, 0, 0, rAlphabet[format], padding));
 }
 
 /**

encoding/unstable_hex.ts

@@ -146,11 +146,12 @@ export function encodeRawHex(
  * ```
  */
 export function decodeHex(
-  input: string,
+  input: string | Uint8Array_,
 ): Uint8Array_ {
-  const output = new TextEncoder().encode(input) as Uint8Array_;
-  return output
-    .subarray(0, decode(output, 0, 0, rAlphabet));
+  if (typeof input === "string") {
+    input = new TextEncoder().encode(input) as Uint8Array_;
+  }
+  return input.subarray(0, decode(input, 0, 0, rAlphabet));
 }
 
 /**