Added a very complicated AsyncIterableReader class.

The class was already implemented in
"https://deno.land/std@0.144.0/streams/conversion.ts".  So, I litterally
lost 1 day of work!  I hate myself.

vendor/deno.land/x/oak@v12.5.0/content_disposition.ts

@@ -0,0 +1,143 @@
+/**
+ * Adapted directly from content-disposition.js at
+ * https://github.com/Rob--W/open-in-browser/blob/master/extension/content-disposition.js
+ * which is licensed as:
+ *
+ * (c) 2017 Rob Wu <rob@robwu.nl> (https://robwu.nl)
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+
+import { toParamRegExp, unquote } from "./headers.ts";
+
+let needsEncodingFixup = false;
+
+function fixupEncoding(value: string): string {
+  if (needsEncodingFixup && /[\x80-\xff]/.test(value)) {
+    value = textDecode("utf-8", value);
+    if (needsEncodingFixup) {
+      value = textDecode("iso-8859-1", value);
+    }
+  }
+  return value;
+}
+
+const FILENAME_STAR_REGEX = toParamRegExp("filename\\*", "i");
+const FILENAME_START_ITER_REGEX = toParamRegExp(
+  "filename\\*((?!0\\d)\\d+)(\\*?)",
+  "ig",
+);
+const FILENAME_REGEX = toParamRegExp("filename", "i");
+
+function rfc2047decode(value: string): string {
+  // deno-lint-ignore no-control-regex
+  if (!value.startsWith("=?") || /[\x00-\x19\x80-\xff]/.test(value)) {
+    return value;
+  }
+  return value.replace(
+    /=\?([\w-]*)\?([QqBb])\?((?:[^?]|\?(?!=))*)\?=/g,
+    (_: string, charset: string, encoding: string, text: string) => {
+      if (encoding === "q" || encoding === "Q") {
+        text = text.replace(/_/g, " ");
+        text = text.replace(
+          /=([0-9a-fA-F]{2})/g,
+          (_, hex) => String.fromCharCode(parseInt(hex, 16)),
+        );
+        return textDecode(charset, text);
+      }
+      try {
+        text = atob(text);
+        // deno-lint-ignore no-empty
+      } catch {}
+      return textDecode(charset, text);
+    },
+  );
+}
+
+function rfc2231getParam(header: string): string {
+  const matches: [string, string][] = [];
+  let match: RegExpExecArray | null;
+  while ((match = FILENAME_START_ITER_REGEX.exec(header))) {
+    const [, ns, quote, part] = match;
+    const n = parseInt(ns, 10);
+    if (n in matches) {
+      if (n === 0) {
+        break;
+      }
+      continue;
+    }
+    matches[n] = [quote, part];
+  }
+  const parts: string[] = [];
+  for (let n = 0; n < matches.length; ++n) {
+    if (!(n in matches)) {
+      break;
+    }
+    let [quote, part] = matches[n];
+    part = unquote(part);
+    if (quote) {
+      part = unescape(part);
+      if (n === 0) {
+        part = rfc5987decode(part);
+      }
+    }
+    parts.push(part);
+  }
+  return parts.join("");
+}
+
+function rfc5987decode(value: string): string {
+  const encodingEnd = value.indexOf(`'`);
+  if (encodingEnd === -1) {
+    return value;
+  }
+  const encoding = value.slice(0, encodingEnd);
+  const langValue = value.slice(encodingEnd + 1);
+  return textDecode(encoding, langValue.replace(/^[^']*'/, ""));
+}
+
+function textDecode(encoding: string, value: string): string {
+  if (encoding) {
+    try {
+      const decoder = new TextDecoder(encoding, { fatal: true });
+      const bytes = Array.from(value, (c) => c.charCodeAt(0));
+      if (bytes.every((code) => code <= 0xFF)) {
+        value = decoder.decode(new Uint8Array(bytes));
+        needsEncodingFixup = false;
+      }
+      // deno-lint-ignore no-empty
+    } catch {}
+  }
+  return value;
+}
+
+export function getFilename(header: string): string {
+  needsEncodingFixup = true;
+
+  // filename*=ext-value ("ext-value" from RFC 5987, referenced by RFC 6266).
+  let matches = FILENAME_STAR_REGEX.exec(header);
+  if (matches) {
+    const [, filename] = matches;
+    return fixupEncoding(
+      rfc2047decode(rfc5987decode(unescape(unquote(filename)))),
+    );
+  }
+
+  // Continuations (RFC 2231 section 3, referenced by RFC 5987 section 3.1).
+  // filename*n*=part
+  // filename*n=part
+  const filename = rfc2231getParam(header);
+  if (filename) {
+    return fixupEncoding(rfc2047decode(filename));
+  }
+
+  // filename=value (RFC 5987, section 4.1).
+  matches = FILENAME_REGEX.exec(header);
+  if (matches) {
+    const [, filename] = matches;
+    return fixupEncoding(rfc2047decode(unquote(filename)));
+  }
+
+  return "";
+}