Split performStream into functions handling stream of futures

Author: paldepind

.travis.yml

@@ -1,7 +1,6 @@
 language: node_js
 node_js:
   - "node"
-  - "8"
 
 after_success:
-  - "npm run codecov"
+  - "npm run codecov"

src/behavior.ts

@@ -3,7 +3,12 @@ import { combine, isPlaceholder } from "./index";
 import { State, Reactive, Time, BListener, Parent, SListener } from "./common";
 import { Future, BehaviorFuture } from "./future";
 import * as F from "./future";
-import { Stream } from "./stream";
+import {
+  Stream,
+  FlatFutureOrdered,
+  FlatFutureLatest,
+  FlatFuture
+} from "./stream";
 import { tick, getTime } from "./clock";
 import { sample, Now } from "./now";
 
@@ -732,3 +737,29 @@ export function format(
 ): Behavior<string> {
   return new FormatBehavior(strings, behaviors);
 }
+
+export const flatFutureFrom = <A>(
+  stream: Stream<Future<A>>
+): Behavior<Stream<A>> => fromFunction(() => new FlatFuture(stream));
+
+export function flatFuture<A>(stream: Stream<Future<A>>): Now<Stream<A>> {
+  return sample(flatFutureFrom(stream));
+}
+
+export const flatFutureOrderedFrom = <A>(
+  stream: Stream<Future<A>>
+): Behavior<Stream<A>> => fromFunction(() => new FlatFutureOrdered(stream));
+
+export function flatFutureOrdered<A>(
+  stream: Stream<Future<A>>
+): Now<Stream<A>> {
+  return sample(flatFutureOrderedFrom(stream));
+}
+
+export const flatFutureLatestFrom = <A>(
+  stream: Stream<Future<A>>
+): Behavior<Stream<A>> => fromFunction(() => new FlatFutureLatest(stream));
+
+export function flatFutureLatest<A>(stream: Stream<Future<A>>): Now<Stream<A>> {
+  return sample(flatFutureLatestFrom(stream));
+}

src/now.ts

@@ -1,10 +1,9 @@
 import { IO, runIO } from "@funkia/io";
 import { placeholder } from "./placeholder";
-import { Time, SListener } from "./common";
-import { Future, fromPromise, mapCbFuture } from "./future";
-import { Node } from "./datastructures";
+import { Time } from "./common";
+import { Future, fromPromise, mapCbFuture, sinkFuture } from "./future";
 import { Behavior } from "./behavior";
-import { ActiveStream, Stream, mapCbStream, isStream } from "./stream";
+import { Stream, mapCbStream, isStream } from "./stream";
 import { tick } from "./clock";
 
 export type MapNowTuple<A> = { [K in keyof A]: Now<A[K]> };
@@ -104,11 +103,11 @@ export function sample<A>(b: Behavior<A>): Now<A> {
 }
 
 export class PerformNow<A> extends Now<A> {
-  constructor(private cb: () => A) {
+  constructor(private _run: () => A) {
     super();
   }
   run(): A {
-    return this.cb();
+    return this._run();
   }
 }
 
@@ -124,9 +123,9 @@ export function performIO<A>(comp: IO<A>): Now<Future<A>> {
   return perform(() => fromPromise(runIO(comp)));
 }
 
-export function performStream<A>(s: Stream<IO<A>>): Now<Stream<A>> {
+export function performStream<A>(s: Stream<IO<A>>): Now<Stream<Future<A>>> {
   return perform(() =>
-    mapCbStream<IO<A>, A>((io, cb) => runIO(io).then(cb), s)
+    mapCbStream<IO<A>, Future<A>>((io, cb) => cb(fromPromise(runIO(io))), s)
   );
 }
 
@@ -157,91 +156,6 @@ export function performMap<A, B>(
   );
 }
 
-class PerformIOLatestStream<A> extends ActiveStream<A>
-  implements SListener<IO<A>> {
-  private node: Node<this> = new Node(this);
-  constructor(s: Stream<IO<A>>) {
-    super();
-    s.addListener(this.node, tick());
-  }
-  next: number = 0;
-  newest: number = 0;
-  running: number = 0;
-  pushS(_t: number, io: IO<A>): void {
-    const time = ++this.next;
-    this.running++;
-    runIO(io).then((a: A) => {
-      this.running--;
-      if (time > this.newest) {
-        const t = tick();
-        if (this.running === 0) {
-          this.next = 0;
-          this.newest = 0;
-        } else {
-          this.newest = time;
-        }
-        this.pushSToChildren(t, a);
-      }
-    });
-  }
-}
-
-export class PerformStreamLatestNow<A> extends Now<Stream<A>> {
-  constructor(private s: Stream<IO<A>>) {
-    super();
-  }
-  run(): Stream<A> {
-    return new PerformIOLatestStream(this.s);
-  }
-}
-
-export function performStreamLatest<A>(s: Stream<IO<A>>): Now<Stream<A>> {
-  return perform(() => new PerformIOLatestStream(s));
-}
-
-class PerformIOStreamOrdered<A> extends ActiveStream<A> {
-  private node: Node<this> = new Node(this);
-  constructor(s: Stream<IO<A>>) {
-    super();
-    s.addListener(this.node, tick());
-  }
-  nextId: number = 0;
-  next: number = 0;
-  buffer: { value: A }[] = []; // Object-wrapper to support a result as undefined
-  pushS(_t: number, io: IO<A>): void {
-    const id = this.nextId++;
-    runIO(io).then((a: A) => {
-      if (id === this.next) {
-        this.buffer[0] = { value: a };
-        this.pushFromBuffer();
-      } else {
-        this.buffer[id - this.next] = { value: a };
-      }
-    });
-  }
-  pushFromBuffer(): void {
-    while (this.buffer[0] !== undefined) {
-      const t = tick();
-      const { value } = this.buffer.shift();
-      this.pushSToChildren(t, value);
-      this.next++;
-    }
-  }
-}
-
-export class PerformStreamOrderedNow<A> extends Now<Stream<A>> {
-  constructor(private s: Stream<IO<A>>) {
-    super();
-  }
-  run(): Stream<A> {
-    return new PerformIOStreamOrdered(this.s);
-  }
-}
-
-export function performStreamOrdered<A>(s: Stream<IO<A>>): Now<Stream<A>> {
-  return new PerformStreamOrderedNow(s);
-}
-
 export function plan<A>(future: Future<Now<A>>): Now<Future<A>> {
   return performMap<Now<A>, A>(runNow, future);
 }

src/stream.ts

@@ -10,7 +10,8 @@ import {
   accum
 } from "./behavior";
 import { tick } from "./clock";
-import { Now, sample } from "./now";
+import { Now, sample, perform } from "./now";
+import { Future } from ".";
 
 /**
  * A stream is a list of occurrences over time. Each occurrence
@@ -477,3 +478,70 @@ export function mapCbStream<A, B>(
 ): Stream<B> {
   return new PerformCbStream(cb, stream);
 }
+
+export class FlatFuture<A> extends Stream<A> {
+  constructor(stream: Stream<Future<A>>) {
+    super();
+    this.parents = cons(stream);
+  }
+  pushS(_t: number, fut: Future<A>): void {
+    fut.subscribe((a) => this.pushSToChildren(tick(), a));
+  }
+}
+
+export class FlatFutureOrdered<A> extends Stream<A> {
+  constructor(stream: Stream<Future<A>>) {
+    super();
+    this.parents = cons(stream);
+  }
+  nextId: number = 0;
+  next: number = 0;
+  buffer: { value: A }[] = []; // Object-wrapper to support a result as undefined
+  pushS(_t: number, fut: Future<A>): void {
+    const id = this.nextId++;
+    fut.subscribe((a: A) => {
+      if (id === this.next) {
+        this.buffer[0] = { value: a };
+        this.pushFromBuffer();
+      } else {
+        this.buffer[id - this.next] = { value: a };
+      }
+    });
+  }
+  pushFromBuffer(): void {
+    while (this.buffer[0] !== undefined) {
+      const t = tick();
+      const { value } = this.buffer.shift();
+      this.pushSToChildren(t, value);
+      this.next++;
+    }
+  }
+}
+
+export class FlatFutureLatest<A> extends Stream<A>
+  implements SListener<Future<A>> {
+  constructor(stream: Stream<Future<A>>) {
+    super();
+    this.parents = cons(stream);
+  }
+  next: number = 0;
+  newest: number = 0;
+  running: number = 0;
+  pushS(_t: number, fut: Future<A>): void {
+    const time = ++this.next;
+    this.running++;
+    fut.subscribe((a: A) => {
+      this.running--;
+      if (time > this.newest) {
+        const t = tick();
+        if (this.running === 0) {
+          this.next = 0;
+          this.newest = 0;
+        } else {
+          this.newest = time;
+        }
+        this.pushSToChildren(t, a);
+      }
+    });
+  }
+}

src/testing.ts

@@ -8,7 +8,10 @@ import {
   ScanStream,
   CombineStream,
   SnapshotStream,
-  isStream
+  isStream,
+  FlatFuture,
+  FlatFutureOrdered,
+  FlatFutureLatest
 } from "./stream";
 import {
   Behavior,
@@ -35,8 +38,6 @@ import {
   FlatMapNow,
   PerformNow,
   PerformMapNow,
-  PerformStreamLatestNow,
-  PerformStreamOrderedNow,
   Now,
   MapNow,
   InstantNow
@@ -218,6 +219,40 @@ DelayStream.prototype.model = function<A>(this: DelayStream<A>) {
   return s.map(({ time, value }) => ({ time: time + this.ms, value }));
 };
 
+const flatFuture = <A>(o: Occurrence<Future<A>>) => {
+  const { time, value } = o.value.model();
+  return time === "infinity" ? [] : [{ time: Math.max(o.time, time), value }];
+};
+
+FlatFuture.prototype.model = function<A>(this: FlatFuture<A>) {
+  return (this.parents.value as Stream<Future<A>>)
+    .model()
+    .flatMap(flatFuture)
+    .sort((o, p) => o.time - p.time); // FIXME: Should use stable sort here
+};
+
+FlatFutureOrdered.prototype.model = function<A>(this: FlatFutureOrdered<A>) {
+  return (this.parents.value as Stream<Future<A>>)
+    .model()
+    .flatMap(flatFuture)
+    .reduce((acc, o) => {
+      const last = acc.length === 0 ? -Infinity : acc[acc.length - 1].time;
+      return acc.concat([{ time: Math.max(last, o.time), value: o.value }]);
+    }, []);
+};
+
+FlatFutureLatest.prototype.model = function<A>(this: FlatFutureLatest<A>) {
+  return (this.parents.value as Stream<Future<A>>)
+    .model()
+    .flatMap(flatFuture)
+    .reduceRight<Occurrence<A>[]>((acc, o) => {
+      const last = acc.length === 0 ? Infinity : acc[0].time;
+      return last < o.time
+        ? acc
+        : [{ time: o.time, value: o.value }].concat(acc);
+    }, []);
+};
+
 class TestStream<A> extends Stream<A> {
   constructor(private streamModel: StreamModel<A>) {
     super();
@@ -400,22 +435,6 @@ PerformMapNow.prototype.model = function<A, B>(
   return { value, mocks };
 };
 
-PerformStreamLatestNow.prototype.model = function<A>(
-  this: PerformStreamLatestNow<A>,
-  [value, ...mocks]: any[],
-  _t: Time
-): NowModel<A> {
-  return { value, mocks };
-};
-
-PerformStreamOrderedNow.prototype.model = function<A>(
-  this: PerformStreamOrderedNow<A>,
-  [value, ...mocks]: any[],
-  _t: Time
-): NowModel<A> {
-  return { value, mocks };
-};
-
 /**
  * Test run a now computation without executing its side-effects.
  * @param now The now computation to test.