import type { TitleCaseRules } from "@d3plus/locales";
/**
    Capitalizes each significant word of a phrase, normalizing case in both
    directions: the locale's minor words (articles, short conjunctions/
    prepositions) are forced lowercase in the middle and known acronyms are
    forced uppercase — so "SOUTH BY SOUTHWEST" becomes "South by Southwest" and
    "jack smith, ceo" becomes "Jack Smith, CEO". The first and last words are
    always capitalized. The locale supplies the minor-word and acronym lists
    (e.g. "le"/"de"/"par" for French); pass an explicit rules object for full
    control, including `{style: "sentence"}` to capitalize only the first word.
    @param str The string to capitalize.
    @param locale A locale code (e.g. "en-US", "fr-FR") or an explicit rules object. Defaults to "en-US".
*/
export default function (str: string | undefined, locale?: string | TitleCaseRules): string;