Merge pull request #54 from vankeisb/feature/piping-updates

introduce updatePiped

Author: vankeisb

core/src/TeaCup/UpdatePiped.test.ts

@@ -0,0 +1,57 @@
+/*
+ * MIT License
+ *
+ * Copyright (c) 2019 Rémi Van Keisbelck
+ *
+ * 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.
+ *
+ */
+
+import { Cmd } from './Cmd';
+import { genericUpdatePiped, updatePiped } from './UpdatePiped';
+
+describe('UpdatePiped', () => {
+  type MyModel = number;
+  type MyCmd = readonly string[];
+
+  test('generic', () => {
+    const model0: MyModel = 6;
+    const [model, cmd] = genericUpdatePiped(
+      (cmd1: MyCmd, cmd2: MyCmd) => new Array().concat(...cmd1, ...cmd2),
+      [],
+      model0,
+      (model) => [model + 1, ['add 1']],
+      (model) => [model * 6, ['multiply by 6']],
+    );
+    expect(model).toBe(42);
+    expect(cmd).toEqual(['add 1', 'multiply by 6']);
+  });
+
+  test('example with none handling', () => {
+    type MyMsg = string;
+    const model0: MyModel = 6;
+    const [model, cmd] = updatePiped(
+      model0,
+      (model) => [model + 1, Cmd.none()],
+      (model) => [model * 6, Cmd.none()],
+    );
+    expect(model).toBe(42);
+    expect(cmd).toEqual(Cmd.none());
+  });
+});

core/src/TeaCup/UpdatePiped.ts

@@ -0,0 +1,71 @@
+/*
+ * MIT License
+ *
+ * Copyright (c) 2019 Rémi Van Keisbelck
+ *
+ * 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.
+ *
+ */
+
+import { Cmd } from './Cmd';
+
+export type UpdateFunction<Model, Msg> = GenericUpdateFunction<Model, Cmd<Msg>>;
+
+/**
+ * Piped updates.
+ * Useful for chaining building blocks making up the update loop.
+ */
+export function updatePiped<Model, Msg>(
+  model: Model,
+  ...updates: readonly UpdateFunction<Model, Msg>[]
+): [Model, Cmd<Msg>] {
+  const none: Cmd<Msg> = Cmd.none();
+  const combine = (cmd1: Cmd<Msg>, cmd2: Cmd<Msg>) => {
+    const none1 = isNone(cmd1);
+    const none2 = isNone(cmd2);
+    return none1 && none2 ? cmd1 : none1 ? cmd2 : none2 ? cmd1 : Cmd.batch([cmd1, cmd2]);
+  };
+  return genericUpdatePiped(combine, none, model, ...updates);
+}
+
+function isNone<Msg>(cmd: Cmd<Msg>): boolean {
+  return cmd.constructor.name === 'CmdNone';
+}
+
+export type GenericUpdateFunction<Model, Cmd> = (model: Model) => [Model, Cmd];
+
+/**
+ * Generic implementation of chained updates.
+ * See updatePiped().
+ */
+export function genericUpdatePiped<Model, Cmd>(
+  combine: (cmd1: Cmd, cmd2: Cmd) => Cmd,
+  none: Cmd,
+  model: Model,
+  ...updates: readonly GenericUpdateFunction<Model, Cmd>[]
+): [Model, Cmd] {
+  return updates.reduce<[Model, Cmd]>(
+    (acc: [Model, Cmd], update: GenericUpdateFunction<Model, Cmd>) => {
+      const [model0, cmd0] = acc;
+      const [model1, cmd1] = update(model0);
+      return [model1, combine(cmd0, cmd1)];
+    },
+    [model, none],
+  );
+}