Move everything into std subdir

1 files changed, 143 insertions, 0 deletions

diff --git a/std/encoding/hex.ts b/std/encoding/hex.ts
new file mode 100644
index 000000000..de3d76869
--- /dev/null
+++ b/std/encoding/hex.ts
@@ -0,0 +1,143 @@
+// Ported from Go
+// https://github.com/golang/go/blob/go1.12.5/src/encoding/hex/hex.go
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+const hextable = new TextEncoder().encode("0123456789abcdef");
+
+export function errInvalidByte(byte: number): Error {
+  return new Error(
+    "encoding/hex: invalid byte: " +
+      new TextDecoder().decode(new Uint8Array([byte]))
+  );
+}
+
+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];
+}
+
+/**
+ * EncodedLen returns the length of an encoding of n source bytes. Specifically,
+ * it returns n * 2.
+ * @param n
+ */
+export function encodedLen(n: number): number {
+  return n * 2;
+}
+
+/**
+ * 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
+ * @param src
+ */
+export function encode(dst: Uint8Array, src: 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++) {
+    const v = src[i];
+    dst[i * 2] = hextable[v >> 4];
+    dst[i * 2 + 1] = hextable[v & 0x0f];
+  }
+  return srcLength;
+}
+
+/**
+ * EncodeToString returns the hexadecimal encoding of `src`.
+ * @param src
+ */
+export function encodeToString(src: Uint8Array): string {
+  const dest = new Uint8Array(encodedLen(src.length));
+  encode(dest, src);
+  return new TextDecoder().decode(dest);
+}
+
+/**
+ * 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
+ * the error.
+ * @param dst
+ * @param src
+ */
+export function decode(
+  dst: Uint8Array,
+  src: 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])];
+    }
+
+    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()];
+  }
+
+  return [i, undefined];
+}
+
+/**
+ * DecodedLen returns the length of a decoding of `x` source bytes.
+ * Specifically, it returns `x / 2`.
+ * @param x
+ */
+export function decodedLen(x: number): number {
+  return Math.floor(x / 2);
+}
+
+/**
+ * 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`
+ */
+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);
+}