Add Colorize.rainbow.

Author: iclanton

build-tests/install-test-workspace/workspace/common/pnpm-lock.yaml

@@ -0,0 +1,10 @@
+{
+  "changes": [
+    {
+      "packageName": "@rushstack/terminal",
+      "comment": "Add a `Colorize.rainbow` API.",
+      "type": "minor"
+    }
+  ],
+  "packageName": "@rushstack/terminal"
+}

common/changes/@rushstack/terminal/use-supports-color_2024-02-24-17-12.json

@@ -63,6 +63,8 @@ export class Colorize {
     // (undocumented)
     static magentaBackground(text: string): string;
     // (undocumented)
+    static rainbow(text: string): string;
+    // (undocumented)
     static red(text: string): string;
     // (undocumented)
     static redBackground(text: string): string;

common/reviews/api/terminal.api.md

@@ -45,6 +45,15 @@ export enum SgrParameterAttribute {
   HiddenOff = 28
 }
 
+const RAINBOW_SEQUENCE: SgrParameterAttribute[] = [
+  SgrParameterAttribute.RedForeground,
+  SgrParameterAttribute.YellowForeground,
+  SgrParameterAttribute.GreenForeground,
+  SgrParameterAttribute.CyanForeground,
+  SgrParameterAttribute.BlueForeground,
+  SgrParameterAttribute.MagentaForeground
+];
+
 /**
  * The static functions on this class are used to produce colored text
  * for use with a terminal that supports ANSI escape codes.
@@ -256,6 +265,20 @@ export class Colorize {
     );
   }
 
+  public static rainbow(text: string): string {
+    return Colorize._applyColorSequence(text, RAINBOW_SEQUENCE);
+  }
+
+  private static _applyColorSequence(text: string, sequence: SgrParameterAttribute[]): string {
+    let result: string = '';
+    const sequenceLength: number = sequence.length;
+    for (let i: number = 0; i < text.length; i++) {
+      result += AnsiEscape.getEscapeSequenceForAnsiCode(sequence[i % sequenceLength]) + text[i];
+    }
+
+    return result + AnsiEscape.getEscapeSequenceForAnsiCode(SgrParameterAttribute.DefaultForeground);
+  }
+
   private static _wrapTextInAnsiEscapeCodes(startCode: number, endCode: number, text: string): string {
     return (
       AnsiEscape.getEscapeSequenceForAnsiCode(startCode) +

libraries/terminal/src/Colorize.ts

@@ -6,7 +6,7 @@ import { Colorize } from '../Colorize';
 
 describe(AnsiEscape.name, () => {
   it('calls removeCodes() successfully', () => {
-    const coloredInput: string = Colorize.green('Hello, world!');
+    const coloredInput: string = Colorize.rainbow('Hello, world!');
     const decoloredInput: string = AnsiEscape.removeCodes(coloredInput);
     expect(coloredInput).not.toBe(decoloredInput);
     expect(decoloredInput).toBe('Hello, world!');