/**
 * The callback functions that can be provided to {@link #parseHtml}.
 */
export interface ParseHtmlCallbacks {
    onOpenTag: (tagName: string, offset: number) => void;
    onCloseTag: (tagName: string, offset: number) => void;
    onText: (text: string, offset: number) => void;
    onComment: (offset: number) => void;
    onDoctype: (offset: number) => void;
}
/**
 * Parses an HTML string, calling the callbacks to notify of tags and text.
 *
 * ## History
 *
 * This file previously used a regular expression to find html tags in the input
 * text. Unfortunately, we ran into a bunch of catastrophic backtracking issues
 * with certain input text, causing Autolinker to either hang or just take a
 * really long time to parse the string.
 *
 * The current code is intended to be a O(n) algorithm that walks through
 * the string in one pass, and tries to be as cheap as possible. We don't need
 * to implement the full HTML spec, but rather simply determine where the string
 * looks like an HTML tag, and where it looks like text (so that we can autolink
 * that).
 *
 * This state machine parser is intended just to be a simple but performant
 * parser of HTML for the subset of requirements we have. We simply need to:
 *
 * 1. Determine where HTML tags are
 * 2. Determine the tag name (Autolinker specifically only cares about <a>,
 *    <script>, and <style> tags, so as not to link any text within them)
 *
 * We don't need to:
 *
 * 1. Create a parse tree
 * 2. Auto-close tags with invalid markup
 * 3. etc.
 *
 * The other intention behind this is that we didn't want to add external
 * dependencies on the Autolinker utility which would increase its size. For
 * instance, adding htmlparser2 adds 125kb to the minified output file,
 * increasing its final size from 47kb to 172kb (at the time of writing). It
 * also doesn't work exactly correctly, treating the string "<3 blah blah blah"
 * as an HTML tag.
 *
 * Reference for HTML spec:
 *
 *     https://www.w3.org/TR/html51/syntax.html#sec-tokenization
 *
 * @param {String} html The HTML to parse
 * @param {Object} callbacks
 * @param {Function} callbacks.onOpenTag Callback function to call when an open
 *   tag is parsed. Called with the tagName as its argument.
 * @param {Function} callbacks.onCloseTag Callback function to call when a close
 *   tag is parsed. Called with the tagName as its argument. If a self-closing
 *   tag is found, `onCloseTag` is called immediately after `onOpenTag`.
 * @param {Function} callbacks.onText Callback function to call when text (i.e
 *   not an HTML tag) is parsed. Called with the text (string) as its first
 *   argument, and offset (number) into the string as its second.
 */
export declare function parseHtml(html: string, callbacks: ParseHtmlCallbacks): void;
/**
 * The subset of the parser states defined in https://www.w3.org/TR/html51/syntax.html
 * which are useful for Autolinker.
 */
export declare const enum State {
    Data = 0,
    TagOpen = 1,
    EndTagOpen = 2,
    TagName = 3,
    BeforeAttributeName = 4,
    AttributeName = 5,
    AfterAttributeName = 6,
    BeforeAttributeValue = 7,
    AttributeValueDoubleQuoted = 8,
    AttributeValueSingleQuoted = 9,
    AttributeValueUnquoted = 10,
    AfterAttributeValueQuoted = 11,
    SelfClosingStartTag = 12,
    MarkupDeclarationOpenState = 13,// When the sequence '<!' is read for an HTML comment or doctype
    CommentStart = 14,
    CommentStartDash = 15,
    Comment = 16,
    CommentEndDash = 17,
    CommentEnd = 18,
    CommentEndBang = 19,
    Doctype = 20
}