// https://www.graphviz.org/doc/info/lang.html

(function (Prism) {

	var ID = '(?:' + [
		// an identifier
		/[a-zA-Z_\x80-\uFFFF][\w\x80-\uFFFF]*/.source,
		// a number
		/-?(?:\.\d+|\d+(?:\.\d*)?)/.source,
		// a double-quoted string
		/"[^"\\]*(?:\\[\s\S][^"\\]*)*"/.source,
		// HTML-like string
		/<(?:[^<>]|(?!<!--)<(?:[^<>"']|"[^"]*"|'[^']*')+>|<!--(?:[^-]|-(?!->))*-->)*>/.source
	].join('|') + ')';

	var IDInside = {
		'markup': {
			pattern: /(^<)[\s\S]+(?=>$)/,
			lookbehind: true,
			alias: ['language-markup', 'language-html', 'language-xml'],
			inside: Prism.languages.markup
		}
	};

	/**
	 * @param {string} source
	 * @param {string} flags
	 * @returns {RegExp}
	 */
	function withID(source, flags) {
		return RegExp(source.replace(/<ID>/g, function () { return ID; }), flags);
	}

	Prism.languages.dot = {
		'comment': {
			pattern: /\/\/.*|\/\*[\s\S]*?\*\/|^#.*/m,
			greedy: true
		},
		'graph-name': {
			pattern: withID(/(\b(?:digraph|graph|subgraph)[ \t\r\n]+)<ID>/.source, 'i'),
			lookbehind: true,
			greedy: true,
			alias: 'class-name',
			inside: IDInside
		},
		'attr-value': {
			pattern: withID(/(=[ \t\r\n]*)<ID>/.source),
			lookbehind: true,
			greedy: true,
			inside: IDInside
		},
		'attr-name': {
			pattern: withID(/([\[;, \t\r\n])<ID>(?=[ \t\r\n]*=)/.source),
			lookbehind: true,
			greedy: true,
			inside: IDInside
		},
		'keyword': /\b(?:digraph|edge|graph|node|strict|subgraph)\b/i,
		'compass-point': {
			pattern: /(:[ \t\r\n]*)(?:[ewc_]|[ns][ew]?)(?![\w\x80-\uFFFF])/,
			lookbehind: true,
			alias: 'builtin'
		},
		'node': {
			pattern: withID(/(^|[^-.\w\x80-\uFFFF\\])<ID>/.source),
			lookbehind: true,
			greedy: true,
			inside: IDInside
		},
		'operator': /[=:]|-[->]/,
		'punctuation': /[\[\]{};,]/
	};

	Prism.languages.gv = Prism.languages.dot;

}(Prism));