1 files changed, 30 insertions, 67 deletions

diff --git a/std/encoding/hex.ts b/std/encoding/hex.ts
index c246f7182..729df6c49 100644
--- a/std/encoding/hex.ts
+++ b/std/encoding/hex.ts
@@ -18,17 +18,16 @@ export function errLength(): Error {
   return new Error("encoding/hex: odd length hex string");
 }
 
-// fromHexChar converts a hex character into its value and a success flag.
-function fromHexChar(byte: number): [number, boolean] {
-  switch (true) {
-    case 48 <= byte && byte <= 57: // '0' <= byte && byte <= '9'
-      return [byte - 48, true];
-    case 97 <= byte && byte <= 102: // 'a' <= byte && byte <= 'f'
-      return [byte - 97 + 10, true];
-    case 65 <= byte && byte <= 70: // 'A' <= byte && byte <= 'F'
-      return [byte - 65 + 10, true];
-  }
-  return [0, false];
+// fromHexChar converts a hex character into its value.
+function fromHexChar(byte: number): number {
+  // '0' <= byte && byte <= '9'
+  if (48 <= byte && byte <= 57) return byte - 48;
+  // 'a' <= byte && byte <= 'f'
+  if (97 <= byte && byte <= 102) return byte - 97 + 10;
+  // 'A' <= byte && byte <= 'F'
+  if (65 <= byte && byte <= 70) return byte - 65 + 10;
+
+  throw errInvalidByte(byte);
 }
 
 /**
@@ -41,24 +40,17 @@ export function encodedLen(n: number): number {
 }
 
 /**
- * Encode encodes `src` into `encodedLen(src.length)` bytes of `dst`.
- * As a convenience, it returns the number of bytes written to `dst`
- * but this value is always `encodedLen(src.length)`.
- * Encode implements hexadecimal encoding.
- * @param dst
+ * Encode encodes `src` into `encodedLen(src.length)` bytes.
  * @param src
  */
-export function encode(src: Uint8Array, dst: Uint8Array): number {
-  const srcLength = encodedLen(src.length);
-  if (dst.length !== srcLength) {
-    throw new Error("Out of index.");
-  }
-  for (let i = 0; i < src.length; i++) {
+export function encode(src: Uint8Array): Uint8Array {
+  const dst = new Uint8Array(encodedLen(src.length));
+  for (let i = 0; i < dst.length; i++) {
     const v = src[i];
     dst[i * 2] = hextable[v >> 4];
     dst[i * 2 + 1] = hextable[v & 0x0f];
   }
-  return srcLength;
+  return dst;
 }
 
 /**
@@ -66,78 +58,49 @@ export function encode(src: Uint8Array, dst: Uint8Array): number {
  * @param src
  */
 export function encodeToString(src: Uint8Array): string {
-  const dest = new Uint8Array(encodedLen(src.length));
-  encode(src, dest);
-  return new TextDecoder().decode(dest);
+  return new TextDecoder().decode(encode(src));
 }
 
 /**
  * Decode decodes `src` into `decodedLen(src.length)` bytes
- * returning the actual number of bytes written to `dst`.
- * Decode expects that `src` contains only hexadecimal characters and that `src`
- * has even length.
- * If the input is malformed, Decode returns the number of bytes decoded before
+ * If the input is malformed an error will be thrown
  * the error.
- * @param dst
  * @param src
  */
-export function decode(
-  src: Uint8Array,
-  dst: Uint8Array
-): [number, Error | void] {
-  let i = 0;
-  for (; i < Math.floor(src.length / 2); i++) {
-    const [a, aOK] = fromHexChar(src[i * 2]);
-    if (!aOK) {
-      return [i, errInvalidByte(src[i * 2])];
-    }
-    const [b, bOK] = fromHexChar(src[i * 2 + 1]);
-    if (!bOK) {
-      return [i, errInvalidByte(src[i * 2 + 1])];
-    }
-
+export function decode(src: Uint8Array): Uint8Array {
+  const dst = new Uint8Array(decodedLen(src.length));
+  for (let i = 0; i < dst.length; i++) {
+    const a = fromHexChar(src[i * 2]);
+    const b = fromHexChar(src[i * 2 + 1]);
     dst[i] = (a << 4) | b;
   }
 
   if (src.length % 2 == 1) {
     // Check for invalid char before reporting bad length,
     // since the invalid char (if present) is an earlier problem.
-    const [, ok] = fromHexChar(src[i * 2]);
-    if (!ok) {
-      return [i, errInvalidByte(src[i * 2])];
-    }
-    return [i, errLength()];
+    fromHexChar(src[dst.length * 2]);
+    throw errLength();
   }
 
-  return [i, undefined];
+  return dst;
 }
 
 /**
- * DecodedLen returns the length of a decoding of `x` source bytes.
+ * DecodedLen returns the length of decoding `x` source bytes.
  * Specifically, it returns `x / 2`.
  * @param x
  */
 export function decodedLen(x: number): number {
-  return Math.floor(x / 2);
+  return x >>> 1;
 }
 
 /**
  * DecodeString returns the bytes represented by the hexadecimal string `s`.
  * DecodeString expects that src contains only hexadecimal characters and that
  * src has even length.
- * If the input is malformed, DecodeString will throws an error.
- * @param s the `string` need to decode to `Uint8Array`
+ * If the input is malformed, DecodeString will throw an error.
+ * @param s the `string` to decode to `Uint8Array`
  */
 export function decodeString(s: string): Uint8Array {
-  const src = new TextEncoder().encode(s);
-  // We can use the source slice itself as the destination
-  // because the decode loop increments by one and then the 'seen' byte is not
-  // used anymore.
-  const [n, err] = decode(src, src);
-
-  if (err) {
-    throw err;
-  }
-
-  return src.slice(0, n);
+  return decode(new TextEncoder().encode(s));
 }