diff --git a/strings/pad.ts b/strings/pad.ts new file mode 100644 index 0000000000..f74742cc17 --- /dev/null +++ b/strings/pad.ts @@ -0,0 +1,75 @@ +// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license. + +/** FillOption Object */ +export interface FillOption { + /** Char to fill in */ + char: string; + /** Side to fill in */ + side: "left" | "right"; + /** If strict, output string can't be greater than strLen*/ + strict?: boolean; + /** char/string used to specify the string has been truncated */ + strictChar?: string; + /** Side of truncate */ + strictSide?: "left" | "right"; +} + +/** + * Pad helper for strings. + * Input string is processed to output a string with a minimal length. + * If the parameter `strict` is set to true, the output string length + * is equal to the `strLen` parameter. + * Example: + * + * pad("deno", 6, { char: "*", side: "left" }) // output : "**deno" + * pad("deno", 6, { char: "*", side: "right"}) // output : "deno**" + * pad("denosorusrex", 6 { + * char: "*", + * side: "left", + * strict: true, + * strictSide: "right", + * strictChar: "..." + * }) // output : "den..." + * + * @param input Input string + * @param strLen Output string lenght + * @param opts Configuration object + * @param [opts.char=" "] Character used to fill in + * @param [opts.side="left"] Side to fill in + * @param [opts.strict=false] Flag to truncate the string if length > strLen + * @param [opts.strictChar=""] Character to add if string is truncated + * @param [opts.strictSide="right"] Side to truncate + */ +export function pad( + input: string, + strLen: number, + opts: FillOption = { + char: " ", + strict: false, + side: "left", + strictChar: "", + strictSide: "right" + } +): string { + let out = input; + const outL = out.length; + if (outL < strLen) { + if (opts.side === "left") { + out = out.padStart(strLen, opts.char); + } else { + out = out.padEnd(strLen, opts.char); + } + } else if (opts.strict && outL > strLen) { + let addChar = opts.strictChar ? opts.strictChar : ""; + if (opts.strictSide === "left") { + let toDrop = outL - strLen; + if (opts.strictChar) { + toDrop += opts.strictChar.length; + } + out = `${addChar}${out.slice(toDrop, outL)}`; + } else { + out = `${out.substring(0, strLen - addChar.length)}${addChar}`; + } + } + return out; +} diff --git a/strings/pad_test.ts b/strings/pad_test.ts new file mode 100644 index 0000000000..43c80b36fa --- /dev/null +++ b/strings/pad_test.ts @@ -0,0 +1,73 @@ +import { test } from "../testing/mod.ts"; +import { assertEquals } from "../testing/asserts.ts"; +import { pad } from "./pad.ts"; + +test(function padTest() { + const expected1 = "**deno"; + const expected2 = "deno"; + const expected3 = "deno**"; + const expected4 = "denosorusrex"; + const expected5 = "denosorus"; + const expected6 = "sorusrex"; + const expected7 = "den..."; + const expected8 = "...rex"; + assertEquals(pad("deno", 6, { char: "*", side: "left" }), expected1); + assertEquals(pad("deno", 4, { char: "*", side: "left" }), expected2); + assertEquals(pad("deno", 6, { char: "*", side: "right" }), expected3); + assertEquals( + pad("denosorusrex", 4, { + char: "*", + side: "right", + strict: false + }), + expected4 + ); + assertEquals( + pad("denosorusrex", 9, { + char: "*", + side: "left", + strict: true, + strictSide: "right" + }), + expected5 + ); + assertEquals( + pad("denosorusrex", 8, { + char: "*", + side: "left", + strict: true, + strictSide: "left" + }), + expected6 + ); + assertEquals( + pad("denosorusrex", 6, { + char: "*", + side: "left", + strict: true, + strictSide: "right", + strictChar: "..." + }), + expected7 + ); + assertEquals( + pad("denosorusrex", 6, { + char: "*", + side: "left", + strict: true, + strictSide: "left", + strictChar: "..." + }), + expected8 + ); + assertEquals( + pad("deno", 4, { + char: "*", + side: "left", + strict: true, + strictSide: "right", + strictChar: "..." + }), + expected2 + ); +}); diff --git a/test.ts b/test.ts index 9034631a6a..ee449a9719 100755 --- a/test.ts +++ b/test.ts @@ -28,6 +28,7 @@ import "./media_types/test.ts"; import "./multipart/formfile_test.ts"; import "./multipart/multipart_test.ts"; import "./prettier/main_test.ts"; +import "./strings/pad_test.ts"; import "./testing/test.ts"; import "./textproto/test.ts"; import "./ws/test.ts";