123456789101112131415161718192021222324252627282930313233343536373839404142434445
// Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.
import { MAP_FORMAT_TO_EXTRACTOR_RX } from "./_formats.ts";
type Format = "yaml" | "toml" | "json" | "unknown";
/** * Tests if a string has valid front matter. Supports YAML, TOML and JSON. * * @param str String to test. * @param formats A list of formats to test for. Defaults to all supported formats. * * ```ts * import { test } from "https://deno.land/std@$STD_VERSION/front_matter/mod.ts"; * import { assert } from "https://deno.land/std@$STD_VERSION/assert/assert.ts"; * * assert(test("---\ntitle: Three dashes marks the spot\n---\n")); * assert(test("---toml\ntitle = 'Three dashes followed by format marks the spot'\n---\n")); * assert(test("---json\n{\"title\": \"Three dashes followed by format marks the spot\"}\n---\n")); * * assert(!test("---json\n{\"title\": \"Three dashes followed by format marks the spot\"}\n---\n", ["yaml"])); * ``` */export function test(  str: string,  formats?: ("yaml" | "toml" | "json" | "unknown")[],): boolean {  if (!formats) {    formats = Object.keys(MAP_FORMAT_TO_EXTRACTOR_RX) as Format[];  }
  for (const format of formats) {    if (format === "unknown") {      throw new TypeError("Unable to test for unknown front matter format");    }
    const match = MAP_FORMAT_TO_EXTRACTOR_RX[format].exec(str);    if (match?.index === 0) {      return true;    }  }
  return false;}