feat(std/node) - Add util.promisify (#5540)

1 files changed, 105 insertions, 0 deletions

diff --git a/std/node/_util/_util_promisify.ts b/std/node/_util/_util_promisify.ts
new file mode 100644
index 000000000..d7ca55be8
--- /dev/null
+++ b/std/node/_util/_util_promisify.ts
@@ -0,0 +1,105 @@
+// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
+//
+// Adapted from Node.js. Copyright Joyent, Inc. and other Node contributors.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a
+// copy of this software and associated documentation files (the
+// "Software"), to deal in the Software without restriction, including
+// without limitation the rights to use, copy, modify, merge, publish,
+// distribute, sublicense, and/or sell copies of the Software, and to permit
+// persons to whom the Software is furnished to do so, subject to the
+// following conditions:
+//
+// The above copyright notice and this permission notice shall be included
+// in all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
+// NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
+// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
+// USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+// In addition to being accessible through util.promisify.custom,
+// this symbol is registered globally and can be accessed in any environment as Symbol.for('nodejs.util.promisify.custom')
+const kCustomPromisifiedSymbol = Symbol.for("nodejs.util.promisify.custom");
+// This is an internal Node symbol used by functions returning multiple arguments
+// e.g. ['bytesRead', 'buffer'] for fs.read.
+const kCustomPromisifyArgsSymbol = Symbol.for(
+  "deno.nodejs.util.promisify.customArgs"
+);
+
+class NodeInvalidArgTypeError extends TypeError {
+  public code = "ERR_INVALID_ARG_TYPE";
+  constructor(argumentName: string, type: string, received: unknown) {
+    super(
+      `The "${argumentName}" argument must be of type ${type}. Received ${typeof received}`
+    );
+  }
+}
+
+export function promisify(original: Function): Function {
+  if (typeof original !== "function")
+    throw new NodeInvalidArgTypeError("original", "Function", original);
+
+  // @ts-ignore TypeScript (as of 3.7) does not support indexing namespaces by symbol
+  if (original[kCustomPromisifiedSymbol]) {
+    // @ts-ignore TypeScript (as of 3.7) does not support indexing namespaces by symbol
+    const fn = original[kCustomPromisifiedSymbol];
+    if (typeof fn !== "function") {
+      throw new NodeInvalidArgTypeError(
+        "util.promisify.custom",
+        "Function",
+        fn
+      );
+    }
+    return Object.defineProperty(fn, kCustomPromisifiedSymbol, {
+      value: fn,
+      enumerable: false,
+      writable: false,
+      configurable: true,
+    });
+  }
+
+  // Names to create an object from in case the callback receives multiple
+  // arguments, e.g. ['bytesRead', 'buffer'] for fs.read.
+  // @ts-ignore TypeScript (as of 3.7) does not support indexing namespaces by symbol
+  const argumentNames = original[kCustomPromisifyArgsSymbol];
+
+  function fn(...args: unknown[]): Promise<unknown> {
+    return new Promise((resolve, reject) => {
+      // @ts-ignore
+      original.call(this, ...args, (err: Error, ...values: unknown[]) => {
+        if (err) {
+          return reject(err);
+        }
+        if (argumentNames !== undefined && values.length > 1) {
+          const obj = {};
+          for (let i = 0; i < argumentNames.length; i++) {
+            // @ts-ignore TypeScript
+            obj[argumentNames[i]] = values[i];
+          }
+          resolve(obj);
+        } else {
+          resolve(values[0]);
+        }
+      });
+    });
+  }
+
+  Object.setPrototypeOf(fn, Object.getPrototypeOf(original));
+
+  Object.defineProperty(fn, kCustomPromisifiedSymbol, {
+    value: fn,
+    enumerable: false,
+    writable: false,
+    configurable: true,
+  });
+  return Object.defineProperties(
+    fn,
+    Object.getOwnPropertyDescriptors(original)
+  );
+}
+
+promisify.custom = kCustomPromisifiedSymbol;