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boilerplate/api/libraries/utilities/dedent.ts

63 lines
1.6 KiB
TypeScript

/**
* Removes excess indentation caused by using multiline template strings.
*
* Ported from `dedent-js` solution.
*
* @see https://github.com/MartinKolarik/dedent-js
*
* @param templateStrings - Template strings to dedent.
*
* @example
* {
* nested: {
* examples: [
* dedent(`
* I am 8 spaces off from the beginning of this file.
* But I will be 2 spaces based on the trimmed distance
* of the first line.
* `),
* ]
* }
* }
*/
export function dedent(templateStrings: TemplateStringsArray | string, ...values: any[]) {
const matches = [];
const strings = typeof templateStrings === "string" ? [templateStrings] : templateStrings.slice();
// Remove trailing whitespace.
strings[strings.length - 1] = strings[strings.length - 1].replace(/\r?\n([\t ]*)$/, "");
// Find all line breaks to determine the highest common indentation level.
for (let i = 0; i < strings.length; i++) {
const match = strings[i].match(/\n[\t ]+/g);
if (match) {
matches.push(...match);
}
}
// Remove the common indentation from all strings.
if (matches.length) {
const size = Math.min(...matches.map((value) => value.length - 1));
const pattern = new RegExp(`\n[\t ]{${size}}`, "g");
for (let i = 0; i < strings.length; i++) {
strings[i] = strings[i].replace(pattern, "\n");
}
}
// Remove leading whitespace.
strings[0] = strings[0].replace(/^\r?\n/, "");
// Perform interpolation.
let string = strings[0];
for (let i = 0; i < values.length; i++) {
string += values[i] + strings[i + 1];
}
return string;
}