refactor: add deno_file op crate (#10019)

Also enables WPT for FileReader.

1 files changed, 334 insertions, 0 deletions

diff --git a/op_crates/file/02_filereader.js b/op_crates/file/02_filereader.js
new file mode 100644
index 000000000..e398b23df
--- /dev/null
+++ b/op_crates/file/02_filereader.js
@@ -0,0 +1,334 @@
+// Copyright 2018-2021 the Deno authors. All rights reserved. MIT license.
+
+// @ts-check
+/// <reference no-default-lib="true" />
+/// <reference path="../../core/lib.deno_core.d.ts" />
+/// <reference path="../webidl/internal.d.ts" />
+/// <reference path="../web/internal.d.ts" />
+/// <reference path="../web/lib.deno_web.d.ts" />
+/// <reference path="./internal.d.ts" />
+/// <reference path="./lib.deno_file.d.ts" />
+/// <reference lib="esnext" />
+
+"use strict";
+
+((window) => {
+  const webidl = window.__bootstrap.webidl;
+  const base64 = window.__bootstrap.base64;
+
+  const state = Symbol("[[state]]");
+  const result = Symbol("[[result]]");
+  const error = Symbol("[[error]]");
+  const aborted = Symbol("[[aborted]]");
+
+  class FileReader extends EventTarget {
+    /** @type {"empty" | "loading" | "done"} */
+    [state] = "empty";
+    /** @type {null | string | ArrayBuffer} */
+    [result] = null;
+    /** @type {null | DOMException} */
+    [error] = null;
+
+    [aborted] = false;
+
+    /** 
+     * @param {Blob} blob
+     * @param {{kind: "ArrayBuffer" | "Text" | "DataUrl", encoding?: string}} readtype
+     */
+    #readOperation = async (blob, readtype) => {
+      // 1. If fr’s state is "loading", throw an InvalidStateError DOMException.
+      if (this[state] === "loading") {
+        throw new DOMException(
+          "Invalid FileReader state.",
+          "InvalidStateError",
+        );
+      }
+      // 2. Set fr’s state to "loading".
+      this[state] = "loading";
+      // 3. Set fr’s result to null.
+      this[result] = null;
+      // 4. Set fr’s error to null.
+      this[error] = null;
+
+      // 5. Let stream be the result of calling get stream on blob.
+      const stream /*: ReadableStream<ArrayBufferView>*/ = blob.stream();
+
+      // 6. Let reader be the result of getting a reader from stream.
+      const reader = stream.getReader();
+
+      // 7. Let bytes be an empty byte sequence.
+      /** @type {Uint8Array[]} */
+      const chunks = [];
+
+      // 8. Let chunkPromise be the result of reading a chunk from stream with reader.
+      let chunkPromise = reader.read();
+
+      // 9. Let isFirstChunk be true.
+      let isFirstChunk = true;
+
+      // 10 in parallel while true
+      while (!this[aborted]) {
+        // 1. Wait for chunkPromise to be fulfilled or rejected.
+        try {
+          const chunk = await chunkPromise;
+          if (this[aborted]) return;
+
+          // 2. If chunkPromise is fulfilled, and isFirstChunk is true, queue a task to fire a progress event called loadstart at fr.
+          if (isFirstChunk) {
+            queueMicrotask(() => {
+              // fire a progress event for loadstart
+              const ev = new ProgressEvent("loadstart", {});
+              this.dispatchEvent(ev);
+            });
+          }
+          // 3. Set isFirstChunk to false.
+          isFirstChunk = false;
+
+          // 4. If chunkPromise is fulfilled with an object whose done property is false
+          // and whose value property is a Uint8Array object, run these steps:
+          if (!chunk.done && chunk.value instanceof Uint8Array) {
+            chunks.push(chunk.value);
+
+            // TODO(bartlomieju): (only) If roughly 50ms have passed since last progress
+            {
+              const size = chunks.reduce((p, i) => p + i.byteLength, 0);
+              const ev = new ProgressEvent("progress", {
+                loaded: size,
+              });
+              this.dispatchEvent(ev);
+            }
+
+            chunkPromise = reader.read();
+          } // 5 Otherwise, if chunkPromise is fulfilled with an object whose done property is true, queue a task to run the following steps and abort this algorithm:
+          else if (chunk.done === true) {
+            queueMicrotask(() => {
+              // 1. Set fr’s state to "done".
+              this[state] = "done";
+              // 2. Let result be the result of package data given bytes, type, blob’s type, and encodingName.
+              const size = chunks.reduce((p, i) => p + i.byteLength, 0);
+              const bytes = new Uint8Array(size);
+              let offs = 0;
+              for (const chunk of chunks) {
+                bytes.set(chunk, offs);
+                offs += chunk.byteLength;
+              }
+              switch (readtype.kind) {
+                case "ArrayBuffer": {
+                  this[result] = bytes.buffer;
+                  break;
+                }
+                case "Text": {
+                  const decoder = new TextDecoder(readtype.encoding);
+                  this[result] = decoder.decode(bytes.buffer);
+                  break;
+                }
+                case "DataUrl": {
+                  this[result] = "data:application/octet-stream;base64," +
+                    base64.fromByteArray(bytes);
+                  break;
+                }
+              }
+              // 4.2 Fire a progress event called load at the fr.
+              {
+                const ev = new ProgressEvent("load", {
+                  lengthComputable: true,
+                  loaded: size,
+                  total: size,
+                });
+                this.dispatchEvent(ev);
+              }
+
+              // 5. If fr’s state is not "loading", fire a progress event called loadend at the fr.
+              //Note: Event handler for the load or error events could have started another load, if that happens the loadend event for this load is not fired.
+              if (this[state] !== "loading") {
+                const ev = new ProgressEvent("loadend", {
+                  lengthComputable: true,
+                  loaded: size,
+                  total: size,
+                });
+                this.dispatchEvent(ev);
+              }
+            });
+
+            break;
+          }
+        } catch (err) {
+          if (this[aborted]) return;
+
+          // chunkPromise rejected
+          this[state] = "done";
+          this[error] = err;
+
+          {
+            const ev = new ProgressEvent("error", {});
+            this.dispatchEvent(ev);
+          }
+
+          //If fr’s state is not "loading", fire a progress event called loadend at fr.
+          //Note: Event handler for the error event could have started another load, if that happens the loadend event for this load is not fired.
+          if (this[state] !== "loading") {
+            const ev = new ProgressEvent("loadend", {});
+            this.dispatchEvent(ev);
+          }
+
+          break;
+        }
+      }
+    };
+
+    static EMPTY = 0;
+    static LOADING = 1;
+    static DONE = 2;
+
+    constructor() {
+      super();
+      this[webidl.brand] = webidl.brand;
+    }
+
+    /** @returns {number} */
+    get readyState() {
+      webidl.assertBranded(this, FileReader);
+      switch (this[state]) {
+        case "empty":
+          return FileReader.EMPTY;
+        case "loading":
+          return FileReader.LOADING;
+        case "done":
+          return FileReader.DONE;
+        default:
+          throw new TypeError("Invalid state");
+      }
+    }
+
+    get result() {
+      webidl.assertBranded(this, FileReader);
+      return this[result];
+    }
+
+    get error() {
+      webidl.assertBranded(this, FileReader);
+      return this[error];
+    }
+
+    abort() {
+      webidl.assertBranded(this, FileReader);
+      // If context object's state is "empty" or if context object's state is "done" set context object's result to null and terminate this algorithm.
+      if (
+        this[state] === "empty" ||
+        this[state] === "done"
+      ) {
+        this[result] = null;
+        return;
+      }
+      // If context object's state is "loading" set context object's state to "done" and set context object's result to null.
+      if (this[state] === "loading") {
+        this[state] = "done";
+        this[result] = null;
+      }
+      // If there are any tasks from the context object on the file reading task source in an affiliated task queue, then remove those tasks from that task queue.
+      // Terminate the algorithm for the read method being processed.
+      this[aborted] = true;
+
+      // Fire a progress event called abort at the context object.
+      const ev = new ProgressEvent("abort", {});
+      this.dispatchEvent(ev);
+
+      // If context object's state is not "loading", fire a progress event called loadend at the context object.
+      if (this[state] !== "loading") {
+        const ev = new ProgressEvent("loadend", {});
+        this.dispatchEvent(ev);
+      }
+    }
+
+    /** @param {Blob} blob */
+    readAsArrayBuffer(blob) {
+      webidl.assertBranded(this, FileReader);
+      const prefix = "Failed to execute 'readAsArrayBuffer' on 'FileReader'";
+      webidl.requiredArguments(arguments.length, 1, { prefix });
+      this.#readOperation(blob, { kind: "ArrayBuffer" });
+    }
+
+    /** @param {Blob} blob */
+    readAsBinaryString(blob) {
+      webidl.assertBranded(this, FileReader);
+      const prefix = "Failed to execute 'readAsBinaryString' on 'FileReader'";
+      webidl.requiredArguments(arguments.length, 1, { prefix });
+      // alias for readAsArrayBuffer
+      this.#readOperation(blob, { kind: "ArrayBuffer" });
+    }
+
+    /** @param {Blob} blob */
+    readAsDataURL(blob) {
+      webidl.assertBranded(this, FileReader);
+      const prefix = "Failed to execute 'readAsBinaryString' on 'FileReader'";
+      webidl.requiredArguments(arguments.length, 1, { prefix });
+      // alias for readAsArrayBuffer
+      this.#readOperation(blob, { kind: "DataUrl" });
+    }
+
+    /** 
+     * @param {Blob} blob
+     * @param {string} [encoding]
+    */
+    readAsText(blob, encoding) {
+      webidl.assertBranded(this, FileReader);
+      const prefix = "Failed to execute 'readAsBinaryString' on 'FileReader'";
+      webidl.requiredArguments(arguments.length, 1, { prefix });
+      if (encoding !== undefined) {
+        encoding = webidl.converters["DOMString"](encoding, {
+          prefix,
+          context: "Argument 2",
+        });
+      }
+      // alias for readAsArrayBuffer
+      this.#readOperation(blob, { kind: "Text", encoding });
+    }
+  }
+
+  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 when we can reuse code between web crates
+  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,
+    });
+  }
+  defineEventHandler(FileReader.prototype, "error");
+  defineEventHandler(FileReader.prototype, "loadstart");
+  defineEventHandler(FileReader.prototype, "load");
+  defineEventHandler(FileReader.prototype, "loadend");
+  defineEventHandler(FileReader.prototype, "progress");
+  defineEventHandler(FileReader.prototype, "abort");
+
+  window.__bootstrap.fileReader = {
+    FileReader,
+  };
+})(this);