From 344475942251da5d3ff4d983dd95caa7696a62cd Mon Sep 17 00:00:00 2001
From: Eloy Toro <eloy.toro@datadoghq.com>
Date: Tue, 28 Mar 2023 10:43:39 +0300
Subject: [PATCH 1/2] Objects TerminalPaths

---
 src/internals/objects/Objects.ts      |  41 +++++++++
 src/internals/objects/impl/objects.ts |  41 +++++++++
 test/objects.test.ts                  | 115 ++++++++++++++++++++++++++
 3 files changed, 197 insertions(+)

diff --git a/src/internals/objects/Objects.ts b/src/internals/objects/Objects.ts
index c3979b8..6d1fed6 100644
--- a/src/internals/objects/Objects.ts
+++ b/src/internals/objects/Objects.ts
@@ -646,4 +646,45 @@ export namespace Objects {
   export interface AllPaths extends Fn {
     return: Impl.AllPaths<this["arg0"]>;
   }
+
+  /**
+   * Create a union of all terminal paths the object has
+   * @description This function is used to create a union from an object with keys
+   * @param obj - The object from which the union will be generated
+   * @returns An union with all the possible terminal paths
+   *
+   * @example
+   * ```ts
+   * type T0 = Call<O.TerminalPaths, { a: { b: number } }>; // 'a.b'
+   * ```
+   */
+  export interface TerminalPaths extends Fn {
+    return: Impl.TerminalPaths<this["arg0"]>;
+  }
+
+  /**
+   * Turn an object into a union of entries of its terminal paths
+   * @param obj - The object to transform to entries
+   * @returns a union of `[key, value]` entry tuples.
+   * @example
+   * ```ts
+   * type T0 = Call<Objects.DeepEntries, { a: [true]; b: { c: number } }>; // ["a[0]", true] | ["b.c", number]
+   * ```
+   */
+  export interface DeepEntries extends Fn {
+    return: Impl.DeepEntries<this["arg0"]>;
+  }
+
+  /**
+   * Create an object from a union of deep `[key, value]` entries.
+   * @param entries - union of entries to convert to an object
+   * @returns an object
+   * @example
+   * ```ts
+   * type T0 = Call<Objects.FromDeepEntries, ["a[0]", true] | ["b.c", number]>; // { a: [true]; b: { c: number } }
+   * ```
+   */
+  export interface FromDeepEntries extends Fn {
+    return: Impl.FromDeepEntries<this["arg0"]>;
+  }
 }
diff --git a/src/internals/objects/impl/objects.ts b/src/internals/objects/impl/objects.ts
index 3a2125f..ffbb754 100644
--- a/src/internals/objects/impl/objects.ts
+++ b/src/internals/objects/impl/objects.ts
@@ -5,6 +5,7 @@ import {
   IsTuple,
   Prettify,
   Primitive,
+  RecursivePrettify,
   UnionToIntersection,
 } from "../../helpers";
 
@@ -168,3 +169,43 @@ export type AllPaths<T, ParentPath extends string = never> = T extends Primitive
         | AllPaths<T[key], JoinPath<ParentPath, key, ".">>
     : never
   : ParentPath;
+
+export type TerminalPaths<
+  T,
+  ParentPath extends string = never
+> = T extends Primitive
+  ? ParentPath
+  : unknown extends T
+  ? JoinPath<ParentPath, string, ".">
+  : T extends readonly any[]
+  ? Keys<T> extends infer key extends string | number
+    ? TerminalPaths<T[number], JoinPath<ParentPath, `[${key}]`>>
+    : never
+  : keyof T extends infer key extends keyof T & string
+  ? key extends any
+    ? TerminalPaths<T[key], JoinPath<ParentPath, key, ".">>
+    : never
+  : ParentPath;
+
+export type DeepEntries<T> = TerminalPaths<T> extends infer keys extends string | number
+  ? {
+      [K in keys]: [K, GetFromPath<T, K>];
+    }[keys]
+  : never;
+
+type BuildDeepObject<pathList, Value> = pathList extends [
+  infer First extends PropertyKey,
+  ...infer Rest
+]
+  ? number extends First
+    ? BuildDeepObject<Rest, Value>[]
+    : { [key in First]: BuildDeepObject<Rest, Value> }
+  : Value;
+
+export type FromDeepEntries<entries extends [PropertyKey, any]> = RecursivePrettify<
+  UnionToIntersection<
+    entries extends [infer K, infer V]
+      ? BuildDeepObject<ParsePath<K>, V>
+      : never
+  >
+>;
diff --git a/test/objects.test.ts b/test/objects.test.ts
index e903702..cfcf6ba 100644
--- a/test/objects.test.ts
+++ b/test/objects.test.ts
@@ -841,4 +841,119 @@ describe("Objects", () => {
       >
     >;
   });
+
+  describe("TerminalPaths", () => {
+    type res1 = Call<
+      // ^?
+      Objects.TerminalPaths,
+      {
+        shallow: string;
+        object: {
+          nested: boolean;
+        };
+        constant: true;
+        tuple: [0, 1];
+        union:
+          | { flag: true; ordinal: number }
+          | { flag: false; cardinal: string };
+        array: { inner: number }[];
+        conditional?: number;
+      }
+    >;
+    type test1 = Expect<
+      Equal<
+        res1,
+        | "object.nested"
+        | "shallow"
+        | "constant"
+        | "tuple[0]"
+        | "tuple[1]"
+        | "union.flag"
+        | "union.ordinal"
+        | "union.cardinal"
+        | `array[${number}].inner`
+        | "conditional"
+      >
+    >;
+
+    type res2 = Call<Objects.TerminalPaths, unknown>;
+    //   ^?
+    type test2 = Expect<Equal<res2, string>>;
+
+    type res3 = Call<Objects.TerminalPaths, any>;
+    //   ^?
+    type test3 = Expect<Equal<res3, string>>;
+
+    type res4 = Call<Objects.TerminalPaths, { f: any }>;
+    //   ^?
+    type test4 = Expect<Equal<res4, "f" | `f.${string}`>>;
+
+    type res5 = Call<Objects.TerminalPaths, [0, 1]>;
+    //   ^?
+    type test5 = Expect<Equal<res5, "[0]" | "[1]">>;
+
+    type res6 = Call<Objects.TerminalPaths, boolean[]>;
+    //   ^?
+    type test6 = Expect<Equal<res6, `[${number}]`>>;
+
+    const readonlyObj = { a: 1, b: 2, c: [{ d: 3 }, { e: 4 }] } as const;
+    type res7 = Call<Objects.TerminalPaths, typeof readonlyObj>;
+    //   ^?
+    type test7 = Expect<
+      Equal<res7, "a" | "b" | "c[0].d" | "c[1].d" | "c[0].e" | "c[1].e">
+    >;
+  });
+
+  it("DeepEntries", () => {
+    type res1 = Call<
+      //   ^?
+      Objects.DeepEntries,
+      { a: string; b: { c: number; d: [{ f: boolean }] } }
+    >;
+
+    type test1 = Expect<
+      Equal<res1, ["a", string] | ["b.c", number] | ["b.d[0].f", boolean]>
+    >;
+  });
+
+  describe("FromDeepEntries", () => {
+    type res1 = Call<
+      Objects.FromDeepEntries,
+      ["a", string] | ["b.c", number] | ["b.d[0].f", boolean]
+    >;
+
+    type test1 = Expect<
+      Equal<
+        res1,
+        {
+          a: string;
+          b: {
+            c: number;
+            d: {
+              0: {
+                f: boolean;
+              };
+            };
+          };
+        }
+      >
+    >;
+  });
+
+  it("DeepEntries >> FromDeepEntries identity", () => {
+    type expected1 = {
+      a: string;
+      b: {
+        c: number;
+        d: {
+          0: {
+            f: boolean;
+          };
+        };
+      };
+    };
+    type res1 = Pipe<expected1, [Objects.DeepEntries, Objects.FromDeepEntries]>;
+
+    type test1 = Expect<Equal<res1, expected1>>;
+  });
 });

From f31599b68397506eb035f7fd6e42b9e16e0e57b2 Mon Sep 17 00:00:00 2001
From: Eloy Toro <eloy.toro@datadoghq.com>
Date: Wed, 5 Apr 2023 16:42:58 +0200
Subject: [PATCH 2/2] update README.md

---
 README.md | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/README.md b/README.md
index 07abe08..ff5abc4 100644
--- a/README.md
+++ b/README.md
@@ -182,10 +182,13 @@ type res5 = Pipe<
   - [x] Keys
   - [x] Values
   - [x] AllPaths
+  - [x] TerminalPaths
   - [x] Create
   - [x] Get
   - [x] FromEntries
   - [x] Entries
+  - [x] FromDeepEntries
+  - [x] DeepEntries
   - [x] MapValues
   - [x] MapKeys
   - [x] Assign