feat(transducers): add keyPermutations, tests, update readme

thi-ng · Jun 12, 2020 · 5110d50 · 5110d50
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diff --git a/packages/transducers/README.md b/packages/transducers/README.md
@@ -165,7 +165,7 @@ yarn add @thi.ng/transducers
 <script src="https://unpkg.com/@thi.ng/transducers/lib/index.umd.js" crossorigin></script>
 ```
 
-Package sizes (gzipped, pre-treeshake): ESM: 8.00 KB / CJS: 8.54 KB / UMD: 7.72 KB
+Package sizes (gzipped, pre-treeshake): ESM: 8.05 KB / CJS: 8.58 KB / UMD: 7.77 KB
 
 ## Dependencies
 
@@ -893,6 +893,7 @@ tx.transduce(tx.map((x) => x*10), tx.push(), tx.range(4))
 - [dup](https://github.com/thi-ng/umbrella/tree/develop/packages/transducers/src/iter/dup.ts)
 - [extendSides](https://github.com/thi-ng/umbrella/tree/develop/packages/transducers/src/iter/extend-sides.ts)
 - [iterate](https://github.com/thi-ng/umbrella/tree/develop/packages/transducers/src/iter/iterate.ts)
+- [keyPermutations](https://github.com/thi-ng/umbrella/tree/develop/packages/transducers/src/iter/key-permutations.ts)
 - [keys](https://github.com/thi-ng/umbrella/tree/develop/packages/transducers/src/iter/keys.ts)
 - [line](https://github.com/thi-ng/umbrella/tree/develop/packages/transducers/src/iter/line.ts)
 - [normRange](https://github.com/thi-ng/umbrella/tree/develop/packages/transducers/src/iter/norm-range.ts)

diff --git a/packages/transducers/src/index.ts b/packages/transducers/src/index.ts
@@ -116,6 +116,7 @@ export * from "./iter/cycle";
 export * from "./iter/dup";
 export * from "./iter/extend-sides";
 export * from "./iter/iterate";
+export * from "./iter/key-permutations";
 export * from "./iter/keys";
 export * from "./iter/line";
 export * from "./iter/norm-range";

diff --git a/packages/transducers/src/iter/key-permutations.ts b/packages/transducers/src/iter/key-permutations.ts
@@ -0,0 +1,46 @@
+import type { IObjectOf, Pair } from "@thi.ng/api";
+import { assocObj } from "../rfn/assoc-obj";
+import { map } from "../xform/map";
+import { mapcat } from "../xform/mapcat";
+import { partition } from "../xform/partition";
+import { pairs } from "./pairs";
+import { permutations } from "./permutations";
+
+/**
+ * Similar to {@link permutations}, however takes an object with each
+ * key specifying an array of its possible values. Yields an iterable of
+ * objects of all value permutations.
+ *
+ * @remarks
+ * The resulting object type will be derived from the value types in the
+ * given `spec` object.
+ *
+ * The order of resulting permutations is not guaranteed and depending
+ * on the VM's iteration behavior of `Object.keys()`.
+ *
+ * @example
+ * ```ts
+ * [...keyPermutations({ a: [1, 2], b: [true, false], c: ["X", "Y"] })]
+ * // [
+ * //   { a: 1, b: true, c: 'X' },
+ * //   { a: 1, b: true, c: 'Y' },
+ * //   { a: 1, b: false, c: 'X' },
+ * //   { a: 1, b: false, c: 'Y' },
+ * //   { a: 2, b: true, c: 'X' },
+ * //   { a: 2, b: true, c: 'Y' },
+ * //   { a: 2, b: false, c: 'X' },
+ * //   { a: 2, b: false, c: 'Y' }
+ * // ]
+ * ```
+ *
+ * @param spec - permutation spec object
+ */
+export const keyPermutations = <T extends IObjectOf<any[]>>(
+    spec: T
+): IterableIterator<{ [k in keyof T]: T[k][0] }> =>
+    <any>(
+        map(
+            (x) => assocObj(<Iterable<Pair<string, any>>>partition(2, x)),
+            permutations(...mapcat(([k, v]) => [[k], v], pairs(spec)))
+        )
+    );
diff --git a/packages/transducers/test/keyperms.ts b/packages/transducers/test/keyperms.ts
@@ -0,0 +1,27 @@
+import { keyPermutations } from "../src";
+
+import * as assert from "assert";
+
+describe("keyPermutations", () => {
+    it("basic", () => {
+        assert.deepEqual(
+            new Set([
+                ...keyPermutations({
+                    a: [1, 2],
+                    b: [true, false],
+                    c: ["X", "Y"],
+                }),
+            ]),
+            new Set([
+                { a: 1, b: true, c: "X" },
+                { a: 1, b: true, c: "Y" },
+                { a: 1, b: false, c: "X" },
+                { a: 1, b: false, c: "Y" },
+                { a: 2, b: true, c: "X" },
+                { a: 2, b: true, c: "Y" },
+                { a: 2, b: false, c: "X" },
+                { a: 2, b: false, c: "Y" },
+            ])
+        );
+    });
+});
diff --git a/packages/transducers/tpl.readme.md b/packages/transducers/tpl.readme.md
@@ -769,6 +769,7 @@ tx.transduce(tx.map((x) => x*10), tx.push(), tx.range(4))
 - [dup](https://github.com/thi-ng/umbrella/tree/develop/packages/transducers/src/iter/dup.ts)
 - [extendSides](https://github.com/thi-ng/umbrella/tree/develop/packages/transducers/src/iter/extend-sides.ts)
 - [iterate](https://github.com/thi-ng/umbrella/tree/develop/packages/transducers/src/iter/iterate.ts)
+- [keyPermutations](https://github.com/thi-ng/umbrella/tree/develop/packages/transducers/src/iter/key-permutations.ts)
 - [keys](https://github.com/thi-ng/umbrella/tree/develop/packages/transducers/src/iter/keys.ts)
 - [line](https://github.com/thi-ng/umbrella/tree/develop/packages/transducers/src/iter/line.ts)
 - [normRange](https://github.com/thi-ng/umbrella/tree/develop/packages/transducers/src/iter/norm-range.ts)