feat(defmulti): add .dependencies(), add tests

thi-ng · Nov 2, 2020 · d15a159 · d15a159
1 parent a339ee0
commit d15a159
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diff --git a/packages/defmulti/src/api.ts b/packages/defmulti/src/api.ts
@@ -9,6 +9,7 @@ import type {
     Fn8,
     FnAny,
     IObjectOf,
+    Pair,
 } from "@thi.ng/api";
 
 export type DispatchFn = FnAny<PropertyKey>;
@@ -230,6 +231,15 @@ export interface MultiFnBase<I> {
      * @param id - implementation ID
      */
     ancestors(id: PropertyKey): Set<PropertyKey>;
+    /**
+     * Returns iterator of all known dispatch values and their dependencies in
+     * the hierarchy of dispatch values. Each dependency is encoded as `[value,
+     * parent-value?]`. If `parent-value` is undefined, the dispatch value has
+     * no parent.
+     */
+    dependencies(): IterableIterator<
+        Pair<PropertyKey, PropertyKey | undefined>
+    >;
 }
 
 export interface MultiFn<T>

diff --git a/packages/defmulti/src/defmulti.ts b/packages/defmulti/src/defmulti.ts
@@ -151,6 +151,14 @@ export function defmulti<T>(f: any, ancestors?: AncestorDefs) {
     fn.parents = (id: PropertyKey) => rels[<any>id];
     fn.ancestors = (id: PropertyKey) =>
         new Set<PropertyKey>(findAncestors([], rels, id));
+    fn.dependencies = function* () {
+        for (let a in rels) {
+            for (let b of rels[a]) yield [a, b];
+        }
+        for (let id in impls) {
+            !rels[id] && (yield [id, undefined]);
+        }
+    };
     return fn;
 }
 

diff --git a/packages/defmulti/test/index.ts b/packages/defmulti/test/index.ts
@@ -129,4 +129,25 @@ describe("defmulti", () => {
         assert.strictEqual(foo({ id: "a", val: "alice" }), "foo: alice");
         assert.strictEqual(bar({ id: "a", val: "alice" }), "bar: ALICE");
     });
+
+    it("dependencies", () => {
+        const a = defmulti((x) => x);
+        assert.deepStrictEqual([...a.dependencies()], []);
+        a.add("a", () => { });
+        assert.deepStrictEqual([...a.dependencies()], [["a",undefined]]);
+        a.add("d",()=>{});
+        a.isa("b", "a");
+        a.isa("c", "b");
+        a.isa("e", "b");
+        assert.deepStrictEqual(
+            new Set([...a.dependencies()]),
+            new Set([
+                ["b", "a"],
+                ["c", "b"],
+                ["e", "b"],
+                ["a", undefined],
+                ["d", undefined]
+            ])
+        );
+    });
 });