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// Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.
import { EXTRACT_REGEXP_MAP } from "./_formats.ts";
export 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/test.ts"; * * test("---\ntitle: Three dashes marks the spot\n---\n"); // true * test("---toml\ntitle = 'Three dashes followed by format marks the spot'\n---\n"); // true * test("---json\n{\"title\": \"Three dashes followed by format marks the spot\"}\n---\n"); // true * test("---json\n{\"title\": \"Three dashes followed by format marks the spot\"}\n---\n", ["yaml"]); // false * ``` */export function test(  str: string,  formats?: Format[],): boolean {  if (!formats) {    formats = Object.keys(EXTRACT_REGEXP_MAP) as Format[];  }
  for (const format of formats) {    if (format === "unknown") {      throw new TypeError("Unable to test for unknown front matter format");    }
    const match = EXTRACT_REGEXP_MAP[format].exec(str);    if (match?.index === 0) {      return true;    }  }
  return false;}