refactor: move options stuff to its own file

src/deepmerge.ts

@@ -1,4 +1,4 @@
-import isPlainObj from 'is-plain-obj'
+import { getFullOptions } from './options'
 import {
 	cloneUnlessOtherwiseSpecified,
 	getKeys,
@@ -7,16 +7,6 @@ import {
 	propertyIsUnsafe
 } from './utils'
 
-function defaultIsMergeable(value) {
-	return Array.isArray(value) || isPlainObj(value)
-}
-
-function defaultArrayMerge(target, source, options) {
-	return target.concat(source).map((element) =>
-		cloneUnlessOtherwiseSpecified(element, options)
-	)
-}
-
 function mergeObject(target, source, options) {
 	const destination = {}
 	if (options.isMergeable(target)) {
@@ -52,24 +42,6 @@ export function deepmergeImpl(target, source, options) {
 	}
 }
 
-function getFullOptions(options) {
-	const overrides =
-		options === undefined
-			? undefined
-			: (Object.fromEntries(
-					// Filter out keys explicitly set to undefined.
-					Object.entries(options).filter(([key, value]) => value !== undefined)
-				))
-
-	return {
-		arrayMerge: defaultArrayMerge,
-		isMergeable: defaultIsMergeable,
-		clone: true,
-	  ...overrides,
-		cloneUnlessOtherwiseSpecified
-	};
-}
-
 export default function deepmerge(target, source, options) {
 	return deepmergeImpl(target, source, getFullOptions(options))
 }

src/options.ts

@@ -0,0 +1,31 @@
+import isPlainObj from "is-plain-obj"
+
+import { cloneUnlessOtherwiseSpecified } from "./utils"
+
+function defaultIsMergeable(value) {
+	return Array.isArray(value) || isPlainObj(value)
+}
+
+function defaultArrayMerge(target, source, options) {
+	return [...target, ...source].map((element) =>
+		cloneUnlessOtherwiseSpecified(element, options)
+	)
+}
+
+export function getFullOptions(options) {
+	const overrides =
+		options === undefined
+			? undefined
+			: (Object.fromEntries(
+					// Filter out keys explicitly set to undefined.
+					Object.entries(options).filter(([key, value]) => value !== undefined)
+				))
+
+	return {
+		arrayMerge: defaultArrayMerge,
+		isMergeable: defaultIsMergeable,
+		clone: true,
+	  ...overrides,
+		cloneUnlessOtherwiseSpecified
+	};
+}