1 files changed, 116 insertions, 0 deletions
diff --git a/op_crates/web/03_abort_signal.js b/op_crates/web/03_abort_signal.js
new file mode 100644
index 000000000..3090513eb
--- /dev/null
+++ b/op_crates/web/03_abort_signal.js
@@ -0,0 +1,116 @@
+// Copyright 2018-2021 the Deno authors. All rights reserved. MIT license.
+"use strict";
+
+((window) => {
+  const { setIsTrusted } = window.__bootstrap.event;
+
+  const add = Symbol("add");
+  const signalAbort = Symbol("signalAbort");
+  const remove = Symbol("remove");
+
+  const illegalConstructorKey = Symbol("illegalConstructorKey");
+
+  class AbortSignal extends EventTarget {
+    #aborted = false;
+    #abortAlgorithms = new Set();
+
+    [add](algorithm) {
+      this.#abortAlgorithms.add(algorithm);
+    }
+
+    [signalAbort]() {
+      if (this.#aborted) {
+        return;
+      }
+      this.#aborted = true;
+      for (const algorithm of this.#abortAlgorithms) {
+        algorithm();
+      }
+      this.#abortAlgorithms.clear();
+      const event = new Event("abort");
+      setIsTrusted(event, true);
+      this.dispatchEvent(event);
+    }
+
+    [remove](algorithm) {
+      this.#abortAlgorithms.delete(algorithm);
+    }
+
+    constructor(key = null) {
+      if (key != illegalConstructorKey) {
+        throw new TypeError("Illegal constructor.");
+      }
+      super();
+    }
+
+    get aborted() {
+      return Boolean(this.#aborted);
+    }
+
+    get [Symbol.toStringTag]() {
+      return "AbortSignal";
+    }
+  }
+  defineEventHandler(AbortSignal.prototype, "abort");
+  class AbortController {
+    #signal = new AbortSignal(illegalConstructorKey);
+
+    get signal() {
+      return this.#signal;
+    }
+
+    abort() {
+      this.#signal[signalAbort]();
+    }
+
+    get [Symbol.toStringTag]() {
+      return "AbortController";
+    }
+  }
+
+  const handlerSymbol = Symbol("eventHandlers");
+
+  function makeWrappedHandler(handler) {
+    function wrappedHandler(...args) {
+      if (typeof wrappedHandler.handler !== "function") {
+        return;
+      }
+      return wrappedHandler.handler.call(this, ...args);
+    }
+    wrappedHandler.handler = handler;
+    return wrappedHandler;
+  }
+  // TODO(benjamingr) reuse this here and websocket where possible
+  function defineEventHandler(emitter, name) {
+    // HTML specification section 8.1.5.1
+    Object.defineProperty(emitter, `on${name}`, {
+      get() {
+        return this[handlerSymbol]?.get(name)?.handler;
+      },
+      set(value) {
+        if (!this[handlerSymbol]) {
+          this[handlerSymbol] = new Map();
+        }
+        let handlerWrapper = this[handlerSymbol]?.get(name);
+        if (handlerWrapper) {
+          handlerWrapper.handler = value;
+        } else {
+          handlerWrapper = makeWrappedHandler(value);
+          this.addEventListener(name, handlerWrapper);
+        }
+        this[handlerSymbol].set(name, handlerWrapper);
+      },
+      configurable: true,
+      enumerable: true,
+    });
+  }
+
+  window.AbortSignal = AbortSignal;
+  window.AbortController = AbortController;
+  window.__bootstrap = window.__bootstrap || {};
+  window.__bootstrap.abortSignal = {
+    add,
+    signalAbort,
+    remove,
+  };
+})(this);