refactor: replace with regex (#42)

README.md

@@ -83,6 +83,7 @@ npm install string-ts
 ```
 
 ## 👌 Supported TypeScript Versions
+
 `string-ts` currently only works on TypeScript v5+.
 
 It also only work with common ASCII characters characters. We don't plan to support international characters or emojis.
@@ -284,29 +285,33 @@ const result = repeat(str, 3)
 
 This function is a strongly-typed counterpart of `String.prototype.replace`.
 
-_Warning: this is a partial implementation as we don't support Regex._
+_Warning: this is a partial implementation, as we don't fully support Regex. Using a RegExp lookup will result in a loose typing._
 
 ```ts
 import { replace } from 'string-ts'
 
 const str = 'hello-world-'
 const result = replace(str, '-', ' ')
 //    ^ 'hello world-'
+const looselyTypedResult = replace(str, /-/, ' ')
+//    ^ string
 ```
 
 ### replaceAll
 
 This function is a strongly-typed counterpart of `String.prototype.replaceAll`.
 It also has a polyfill for runtimes older than ES2021.
 
-_Warning: this is a partial implementation as we don't support Regex._
+_Warning: this is a partial implementation, as we don't fully support Regex. Using a RegExp lookup will result in a loose typing._
 
 ```ts
 import { replaceAll } from 'string-ts'
 
 const str = 'hello-world-'
 const result = replaceAll(str, '-', ' ')
 //    ^ 'hello world '
+const looselyTypedResult = replaceAll(str, /-/g, ' ')
+//    ^ string
 ```
 
 ### slice

src/primitives.test.ts

@@ -279,6 +279,12 @@ describe('primitives', () => {
       expect(result).toEqual('somenice string')
       type test = Expect<Equal<typeof result, 'somenice string'>>
     })
+    test('should replace chars but not at type level when using RegExp', () => {
+      const data = 'some nice string'
+      const result = subject.replace(data, /nice /)
+      expect(result).toEqual('some string')
+      type test = Expect<Equal<typeof result, string>>
+    })
   })
 
   describe('replaceAll', () => {
@@ -295,6 +301,14 @@ describe('primitives', () => {
       expect(result).toEqual('some@nice@string')
       type test = Expect<Equal<typeof result, 'some@nice@string'>>
     })
+
+    test('should replace chars but not at type level when using RegExp', () => {
+      const data = 'some nice string'
+      const result = subject.replaceAll(data, / /g, '-')
+      expect(result).toEqual('some-nice-string')
+      // Note: `string` instead of `some-nice-string`
+      type test = Expect<Equal<typeof result, string>>
+    })
   })
 
   describe('replaceAll polyfill', () => {

src/primitives.ts

@@ -212,12 +212,13 @@ function repeat<T extends string, N extends number = 0>(
  */
 type Replace<
   sentence extends string,
-  lookup extends string,
+  lookup extends string | RegExp,
   replacement extends string = '',
-> = sentence extends `${infer rest}${lookup}${infer rest2}`
-  ? `${rest}${replacement}${rest2}`
-  : sentence
-
+> = lookup extends string
+  ? sentence extends `${infer rest}${lookup}${infer rest2}`
+    ? `${rest}${replacement}${rest2}`
+    : sentence
+  : string
 /**
  * A strongly-typed version of `String.prototype.replace`.
  * @param sentence the sentence to replace.
@@ -226,11 +227,11 @@ type Replace<
  * @returns the replaced string in both type level and runtime.
  * @example replace('hello world', 'l', '1') // 'he1lo world'
  */
-function replace<T extends string, S extends string, R extends string = ''>(
-  sentence: T,
-  lookup: S,
-  replacement: R = '' as R,
-) {
+function replace<
+  T extends string,
+  S extends string | RegExp,
+  R extends string = '',
+>(sentence: T, lookup: S, replacement: R = '' as R) {
   return sentence.replace(lookup, replacement) as Replace<T, S, R>
 }
 
@@ -242,11 +243,13 @@ function replace<T extends string, S extends string, R extends string = ''>(
  */
 type ReplaceAll<
   sentence extends string,
-  lookup extends string,
+  lookup extends string | RegExp,
   replacement extends string = '',
-> = sentence extends `${infer rest}${lookup}${infer rest2}`
-  ? `${rest}${replacement}${ReplaceAll<rest2, lookup, replacement>}`
-  : sentence
+> = lookup extends string
+  ? sentence extends `${infer rest}${lookup}${infer rest2}`
+    ? `${rest}${replacement}${ReplaceAll<rest2, lookup, replacement>}`
+    : sentence
+  : string
 
 /**
  * A strongly-typed version of `String.prototype.replaceAll`.
@@ -256,11 +259,11 @@ type ReplaceAll<
  * @returns the replaced string in both type level and runtime.
  * @example replaceAll('hello world', 'l', '1') // 'he11o wor1d'
  */
-function replaceAll<T extends string, S extends string, R extends string = ''>(
-  sentence: T,
-  lookup: S,
-  replacement: R = '' as R,
-) {
+function replaceAll<
+  T extends string,
+  S extends string | RegExp,
+  R extends string = '',
+>(sentence: T, lookup: S, replacement: R = '' as R) {
   // Only supported in ES2021+
   if (typeof sentence.replaceAll === 'function') {
     return sentence.replaceAll(lookup, replacement) as ReplaceAll<T, S, R>