Implement author-constructible ReadableStream using V8 extras

third_party/WebKit/LayoutTests/http/tests/streams/resources/rs-utils.js

+'use strict';
+(function () {
+
+  class RandomPushSource {
+    constructor(toPush) {
+      this.pushed = 0;
+      this.toPush = toPush;
+      this.started = false;
+      this.paused = false;
+      this.closed = false;
+
+      this._intervalHandle = null;
+    }
+
+    readStart() {
+      if (this.closed) {
+        return;
+      }
+
+      if (!this.started) {
+        this._intervalHandle = setInterval(writeChunk, 2);
+        this.started = true;
+      }
+
+      if (this.paused) {
+        this._intervalHandle = setInterval(writeChunk, 2);
+        this.paused = false;
+      }
+
+      const source = this;
+      function writeChunk() {
+        if (source.paused) {
+          return;
+        }
+
+        source.pushed++;
+
+        if (source.toPush > 0 && source.pushed > source.toPush) {
+          if (source._intervalHandle) {
+            clearInterval(source._intervalHandle);
+            source._intervalHandle = undefined;
+          }
+          source.closed = true;
+          source.onend();
+        } else {
+          source.ondata(randomChunk(128));
+        }
+      }
+    }
+
+    readStop() {
+      if (this.paused) {
+        return;
+      }
+
+      if (this.started) {
+        this.paused = true;
+        clearInterval(this._intervalHandle);
+        this._intervalHandle = undefined;
+      } else {
+        throw new Error('Can\'t pause reading an unstarted source.');
+      }
+    }
+  }
+
+  function randomChunk(size) {
+    let chunk = '';
+
+    for (let i = 0; i < size; ++i) {
+      // Add a random character from the basic printable ASCII set.
+      chunk += String.fromCharCode(Math.round(Math.random() * 84) + 32);
+    }
+
+    return chunk;
+  }
+
+  function readableStreamToArray(readable, reader) {
+    if (reader === undefined) {
+      reader = readable.getReader();
+    }
+
+    const chunks = [];
+
+    return pump();
+
+    function pump() {
+      return reader.read().then(result => {
+        if (result.done) {
+          return chunks;
+        }
+
+        chunks.push(result.value);
+        return pump();
+      });
+    }
+  }
+
+  class SequentialPullSource {
+    constructor(limit, options) {
+      const async = options && options.async;
+
+      this.current = 0;
+      this.limit = limit;
+      this.opened = false;
+      this.closed = false;
+
+      this._exec = f => f();
+      if (async) {
+        this._exec = f => setTimeout(f, 0);
+      }
+    }
+
+    open(cb) {
+      this._exec(() => {
+        this.opened = true;
+        cb();
+      });
+    }
+
+    read(cb) {
+      this._exec(() => {
+        if (++this.current <= this.limit) {
+          cb(null, false, this.current);
+        } else {
+          cb(null, true, null);
+        }
+      });
+    }
+
+    close(cb) {
+      this._exec(() => {
+        this.closed = true;
+        cb();
+      });
+    }
+  }
+
+  function sequentialReadableStream(limit, options) {
+    const sequentialSource = new SequentialPullSource(limit, options);
+
+    const stream = new ReadableStream({
+      start() {
+        return new Promise((resolve, reject) => {
+          sequentialSource.open(err => {
+            if (err) {
+              reject(err);
+            }
+            resolve();
+          });
+        });
+      },
+
+      pull(c) {
+        return new Promise((resolve, reject) => {
+          sequentialSource.read((err, done, chunk) => {
+            if (err) {
+              reject(err);
+            } else if (done) {
+              sequentialSource.close(err2 => {
+                if (err2) {
+                  reject(err2);
+                }
+                c.close();
+                resolve();
+              });
+            } else {
+              c.enqueue(chunk);
+              resolve();
+            }
+          });
+        });
+      }
+    });
+
+    stream.source = sequentialSource;
+
+    return stream;
+  }
+
+
+  self.RandomPushSource = RandomPushSource;
+  self.readableStreamToArray = readableStreamToArray;
+  self.sequentialReadableStream = sequentialReadableStream;
+
+}());