✨ Add String trimLeft, trimRight and trim functions

deps.ts

@@ -1,2 +1,3 @@
 // Copyright 2021-present the Core-fn authors. All rights reserved. MIT license.
 export { curry } from "https://deno.land/x/curry@v1.0.0/mod.ts";
+export type { Space } from "https://deno.land/x/fonction@v1.8.1/mod.ts";

string/mod.ts

@@ -2,3 +2,6 @@
 export { replace } from "./replace.ts";
 export { startsWith } from "./starts_with.ts";
 export { endsWith } from "./ends_with.ts";
+export { trim } from "./trim.ts";
+export { trimLeft } from "./trim_left.ts";
+export { trimRight } from "./trim_right.ts";

string/trim.ts

@@ -0,0 +1,46 @@
+// Copyright 2021-present the Core-fn authors. All rights reserved. MIT license.
+import { TrimLeft } from "./trim_left.ts";
+import { TrimRight } from "./trim_right.ts";
+
+/**
+ * Infer the trimmed string.
+ *
+ * @typeParam T - Any string
+ * @returns Trimmed string
+ *
+ * @remarks
+ * The definition of space
+ * - `''`
+ * - `\n`
+ * - `\t`
+ *
+ * @example
+ * ```ts
+ * Trim<'\t\n hello \t\n'> // 'hello'
+ * ```
+ *
+ * @category `String`
+ *
+ * @beta
+ */
+type Trim<T extends string> = TrimLeft<TrimRight<T>>;
+
+/**
+ * Removes whitespace from both ends of the string.
+ *
+ * @param val - `string` to trim
+ * @returns The result of `val.trim()`
+ *
+ * @example
+ * ```ts
+ * trim('   hello   ') // 'hello'
+ * ```
+ *
+ * @category `String`
+ *
+ * @beta
+ */
+const trim = <T extends string>(val: T): Trim<T> => val.trim() as Trim<T>;
+
+export { trim };
+export type { Trim };

string/trim_left.ts

@@ -0,0 +1,53 @@
+// Copyright 2021-present the Core-fn authors. All rights reserved. MIT license.
+import { Space } from "../deps.ts";
+
+/**
+ * Infer the string with the left ends of trimmed.
+ *
+ * @returns String left ends of trimmed
+ *
+ * @remarks
+ * The definition of space
+ * - `''`
+ * - `\n`
+ * - `\t`
+ *
+ * @example
+ * ```ts
+ * TrimLeft<' \n\thello'> // 'hello'
+ * ```
+ *
+ * @category `String`
+ *
+ * @beta
+ */
+type TrimLeft<T extends string> = T extends `${Space}${infer R}` ? TrimLeft<R>
+  : T;
+
+/**
+ * Removes space from left ends of the string.
+ *
+ * @param val - input string
+ * @returns The result of `val.trimLeft()`
+ *
+ * @remarks
+ * The definition of space
+ * - `''`
+ * - `\n`
+ * - `\t`
+ *
+ * @example
+ * ```ts
+ * trimLeft('   hello') // 'hello'
+ * trimLeft(' \n\thello') // 'hello'
+ * ```
+ *
+ * @category `String`
+ *
+ * @beta
+ */
+const trimLeft = <T extends string>(val: T): TrimLeft<T> =>
+  val.trimLeft() as TrimLeft<T>;
+
+export { trimLeft };
+export type { TrimLeft };

string/trim_left_test.ts

@@ -0,0 +1,30 @@
+// Copyright 2021-present the Core-fn authors. All rights reserved. MIT license.
+import { assertEquals, assertEqualsType } from "../dev_deps.ts";
+import { TrimLeft, trimLeft } from "./trim_left.ts";
+
+Deno.test("trimLeft", () => {
+  const table: [string, string][] = [
+    ["", ""],
+    ["         ", ""],
+    ["\n\n", ""],
+    ["\t\t\t\t", ""],
+    ["hello", "hello"],
+    [" hello", "hello"],
+    ["hello ", "hello "],
+    [" hello ", "hello "],
+    ["   hello   ", "hello   "],
+    ["   hello  world  ", "hello  world  "],
+    ["   hello  world\n\n", "hello  world\n\n"],
+  ];
+  table.forEach(([val, expected]) => {
+    assertEquals(trimLeft(val), expected, `trimLeft(${val}) -> ${expected}`);
+  });
+
+  assertEqualsType<"", TrimLeft<"">>();
+  assertEqualsType<"hello", TrimLeft<"hello">>();
+  assertEqualsType<"", TrimLeft<"\n">>();
+  assertEqualsType<"", TrimLeft<"\t">>();
+  assertEqualsType<"", TrimLeft<"\t\n ">>();
+  assertEqualsType<"hello ", TrimLeft<"hello ">>();
+  assertEqualsType<"hello\n\t ", TrimLeft<"\n\t hello\n\t ">>();
+});

string/trim_right.ts

@@ -0,0 +1,54 @@
+// Copyright 2021-present the Core-fn authors. All rights reserved. MIT license.
+import { Space } from "../deps.ts";
+
+/**
+ * Infer the string with the right ends of trimmed.
+ *
+ * @typeParam T - Any string
+ * @returns String right ends of trimmed
+ *
+ * @remarks
+ * The definition of space
+ * - `''`
+ * - `\n`
+ * - `\t`
+ *
+ * @example
+ * ```ts
+ * TrimRight<'hello \n\t'> // 'hello'
+ * ```
+ *
+ * @category `String`
+ *
+ * @beta
+ */
+type TrimRight<T extends string> = T extends `${infer R}${Space}` ? TrimRight<R>
+  : T;
+
+/**
+ * Removes space from right ends of the string.
+ *
+ * @param val - input string
+ * @returns The result of `val.trimRight()`
+ *
+ * @remarks
+ * The definition of space
+ * - `''`
+ * - `\n`
+ * - `\t`
+ *
+ * @example
+ * ```ts
+ * trimRight('hello   ') // 'hello'
+ * trimRight('hello \n\t') // 'hello'
+ * ```
+ *
+ * @category `String`
+ *
+ * @beta
+ */
+const trimRight = <T extends string>(val: T): TrimRight<T> =>
+  val.trimRight() as TrimRight<T>;
+
+export { trimRight };
+export type { TrimRight };

string/trim_right_test.ts

@@ -0,0 +1,30 @@
+// Copyright 2021-present the Core-fn authors. All rights reserved. MIT license.
+import { assertEquals, assertEqualsType } from "../dev_deps.ts";
+import { TrimRight, trimRight } from "./trim_right.ts";
+
+Deno.test("trimRight", () => {
+  const table: [string, string][] = [
+    ["", ""],
+    ["         ", ""],
+    ["\n\n", ""],
+    ["\t\t\t\t", ""],
+    ["hello", "hello"],
+    [" hello", " hello"],
+    ["hello ", "hello"],
+    [" hello ", " hello"],
+    ["   hello   ", "   hello"],
+    ["   hello  world  ", "   hello  world"],
+    ["   hello  world\n\n", "   hello  world"],
+  ];
+  table.forEach(([val, expected]) => {
+    assertEquals(trimRight(val), expected, `trimRight(${val}) -> ${expected}`);
+  });
+
+  assertEqualsType<"", TrimRight<"">>();
+  assertEqualsType<"hello", TrimRight<"hello">>();
+  assertEqualsType<"", TrimRight<"\n">>();
+  assertEqualsType<"", TrimRight<"\t">>();
+  assertEqualsType<"", TrimRight<"\t\n ">>();
+  assertEqualsType<"hello", TrimRight<"hello ">>();
+  assertEqualsType<"\n\t hello", TrimRight<"\n\t hello\n\t ">>();
+});

string/trim_test.ts

@@ -0,0 +1,30 @@
+// Copyright 2021-present the Core-fn authors. All rights reserved. MIT license.
+import { assertEquals, assertEqualsType } from "../dev_deps.ts";
+import { Trim, trim } from "./trim.ts";
+
+Deno.test("trim", () => {
+  const table: [string, string][] = [
+    ["", ""],
+    ["         ", ""],
+    ["\n\n", ""],
+    ["\t\t\t\t", ""],
+    ["hello", "hello"],
+    [" hello", "hello"],
+    ["hello ", "hello"],
+    [" hello ", "hello"],
+    ["   hello   ", "hello"],
+    ["   hello  world  ", "hello  world"],
+    ["   hello  world\n\n", "hello  world"],
+  ];
+  table.forEach(([val, expected]) => {
+    assertEquals(trim(val), expected, `trim(${val}) -> ${expected}`);
+  });
+
+  assertEqualsType<"", Trim<"">>();
+  assertEqualsType<"hello", Trim<"hello">>();
+  assertEqualsType<"", Trim<"\n">>();
+  assertEqualsType<"", Trim<"\t">>();
+  assertEqualsType<"", Trim<"\t\n ">>();
+  assertEqualsType<"hello", Trim<"hello ">>();
+  assertEqualsType<"hello", Trim<"\n\t hello\n\t ">>();
+});