fix(crush): support dot in property name

src/object/crush.ts

@@ -1,4 +1,4 @@
-import { get, keys, objectify } from 'radashi'
+import { type Intersect, isArray, isObject, type Simplify } from 'radashi'
 
 /**
  * Flattens a deep object to a single dimension, converting the keys
@@ -11,13 +11,54 @@ import { get, keys, objectify } from 'radashi'
  * // { name: 'ra', 'children.0.name': 'hathor' }
  * ```
  */
-export function crush<TValue extends object>(value: TValue): object {
+export function crush<T extends object>(value: T): Crush<T> {
   if (!value) {
-    return {}
+    return {} as Crush<T>
   }
-  return objectify(
-    keys(value),
-    k => k,
-    k => get(value, k),
-  )
+  return (function crushReducer(
+    crushed: Crush<T>,
+    value: unknown,
+    path: string,
+  ) {
+    if (isObject(value) || isArray(value)) {
+      for (const [prop, propValue] of Object.entries(value)) {
+        crushReducer(crushed, propValue, path ? `${path}.${prop}` : prop)
+      }
+    } else {
+      crushed[path as keyof Crush<T>] = value as Crush<T>[keyof Crush<T>]
+    }
+    return crushed
+  })({} as Crush<T>, value, '')
 }
+
+/**
+ * The return type of the `crush` function.
+ *
+ * This type is limited by TypeScript's development. There's no
+ * reliable way to detect if an object will pass `isObject` or not, so
+ * we cannot infer the property types of nested objects that have been
+ * crushed.
+ *
+ * @see https://radashi-org.github.io/reference/object/crush
+ */
+export type Crush<T> = T extends readonly (infer U)[]
+  ? Record<string, U extends object ? unknown : U>
+  : Simplify<
+      Intersect<
+        keyof T extends infer Prop
+          ? Prop extends keyof T
+            ? T[Prop] extends infer Value
+              ?
+                  | ([Extract<Value, object>] extends [never]
+                      ? never
+                      : Record<string, unknown>)
+                  | ([Exclude<Value, object>] extends [never]
+                      ? never
+                      : [Extract<Value, object>] extends [never]
+                        ? { [P in Prop]: Value }
+                        : Record<string, unknown>)
+              : never
+            : never
+          : never
+      >
+    >

src/types.ts

@@ -108,3 +108,19 @@ export type ComparableProperty<T> = CompatibleProperty<T, Comparable>
  * value, and 0 to keep the order of the values.
  */
 export type Comparator<T> = (left: T, right: T) => number
+
+/** Convert a union to an intersection */
+export type Intersect<U> = (U extends any ? (k: U) => void : never) extends (
+  k: infer I,
+) => void
+  ? I
+  : never
+
+/**
+ * Useful to flatten the type output to improve type hints shown in
+ * editors. And also to transform an interface into a type to aide
+ * with assignability.
+ *
+ * @see https://github.com/microsoft/TypeScript/issues/15300
+ */
+export type Simplify<T> = {} & { [P in keyof T]: T[P] }

tests/object/crush.test-d.ts

@@ -0,0 +1,53 @@
+import * as _ from 'radashi'
+
+describe('crush', () => {
+  test('direct properties are preserved in the result type', () => {
+    const obj = _.crush({ a: 1, b: '2', c: true })
+    expectTypeOf(obj).toEqualTypeOf<{ a: number; b: string; c: boolean }>()
+  })
+  test('nested objects add Record to result type', () => {
+    const obj = _.crush({ a: { b: 1 } })
+    expectTypeOf(obj).toEqualTypeOf<Record<string, unknown>>()
+
+    const obj2 = _.crush({ a: 1, b: { c: 2 } })
+    expectTypeOf(obj2).toEqualTypeOf<{ a: number; [key: string]: unknown }>()
+    expectTypeOf(obj2.a).toEqualTypeOf<number>()
+    expectTypeOf(obj2['b.c']).toEqualTypeOf<unknown>()
+  })
+  test('optional property', () => {
+    const obj = _.crush({} as { a?: number })
+    // FIXME: Try to preserve optionality.
+    expectTypeOf(obj).toEqualTypeOf<{ a: number | undefined }>()
+  })
+  test('crushed Record type', () => {
+    const obj = _.crush({} as Record<number, number>)
+    expectTypeOf(obj).toEqualTypeOf<Record<number, number>>()
+
+    const obj2 = _.crush({} as Record<string, string>)
+    expectTypeOf(obj2).toEqualTypeOf<Record<string, string>>()
+
+    const obj3 = _.crush({} as Record<number, number | object>)
+    expectTypeOf(obj3).toEqualTypeOf<Record<string, unknown>>()
+
+    const obj4 = _.crush({} as Record<string, string | unknown[]>)
+    expectTypeOf(obj4).toEqualTypeOf<Record<string, unknown>>()
+  })
+  test('crushed array', () => {
+    // We cannot assume the keys from "number[]" input value, but we
+    // *can* assume the value type. Note that the value type doesn't
+    // contain "undefined" (which matches array behavior).
+    const obj = _.crush([1, 2, 3])
+    expectTypeOf(obj).toEqualTypeOf<Record<string, number>>()
+
+    const obj2 = _.crush([1, { b: 2 }])
+    expectTypeOf(obj2).toEqualTypeOf<Record<string, unknown>>()
+    expectTypeOf(obj2[0]).toEqualTypeOf<unknown>()
+  })
+  test('union type with object and primitive', () => {
+    // Since "a" may be an object, we cannot assume the result will
+    // have an "a" property. Therefore, the keys and values of the
+    // result are unknown.
+    const obj = _.crush({ a: {} as number | object })
+    expectTypeOf(obj).toEqualTypeOf<Record<string, unknown>>()
+  })
+})

tests/object/crush.test.ts

@@ -33,4 +33,67 @@ describe('crush', () => {
       timestamp: now,
     })
   })
+  test('handles arrays', () => {
+    const obj = ['value', 123.4, true]
+    expect(_.crush(obj)).toEqual({
+      '0': 'value',
+      '1': 123.4,
+      '2': true,
+    })
+  })
+  describe('property names containing period', () => {
+    test('inside the root object', () => {
+      const obj = {
+        'a.b': { c: 'value' },
+      }
+      expect(_.crush(obj)).toEqual({
+        'a.b.c': 'value',
+      })
+    })
+    test('inside a nested object', () => {
+      const obj = {
+        a: { 'b.c': 'value' },
+      }
+      expect(_.crush(obj)).toEqual({
+        'a.b.c': 'value',
+      })
+    })
+    test('inside both root and nested object', () => {
+      const obj = {
+        'a.b': { 'c.d': 123.4 },
+      }
+      expect(_.crush(obj)).toEqual({
+        'a.b.c.d': 123.4,
+      })
+    })
+    test('crush array containing object with nested property', () => {
+      const arr = [{ 'c.d': { 'e.f': 'g' } }]
+      const obj = {
+        'a.b': arr,
+      }
+      expect(_.crush(obj)).toEqual({
+        'a.b.0.c.d.e.f': 'g',
+      })
+    })
+    test('do not crush Date objects', () => {
+      const date = new Date()
+      const obj = {
+        'a.b': date,
+      }
+      expect(_.crush(obj)).toEqual({
+        'a.b': date,
+      })
+    })
+    test('do not crush Map objects', () => {
+      const map = new Map()
+      map.set('a', 'b')
+      map.set('c', 'd')
+      const obj = {
+        'a.b': map,
+      }
+      expect(_.crush(obj)).toEqual({
+        'a.b': map,
+      })
+    })
+  })
 })