prism-diff-highlight.js

(function () {

	if (typeof Prism === 'undefined') {
		return;
	}


	var LANGUAGE_REGEX = /^diff-([\w-]+)/i;
	var HTML_TAG = /<\/?(?!\d)[^\s>\/=$<%]+(?:\s(?:\s*[^\s>\/=]+(?:\s*=\s*(?:"[^"]*"|'[^']*'|[^\s'">=]+(?=[\s>]))|(?=[\s/>])))+)?\s*\/?>/g;
	//this will match a line plus the line break while ignoring the line breaks HTML tags may contain.
	var HTML_LINE = RegExp(/(?:__|[^\r\n<])*(?:\r\n?|\n|(?:__|[^\r\n<])(?![^\r\n]))/.source.replace(/__/g, function () { return HTML_TAG.source; }), 'gi');

	var warningLogged = false;

	Prism.hooks.add('before-sanity-check', function (env) {
		var lang = env.language;
		if (LANGUAGE_REGEX.test(lang) && !env.grammar) {
			env.grammar = Prism.languages[lang] = Prism.languages.diff;
		}
	});
	Prism.hooks.add('before-tokenize', function (env) {
		if (!warningLogged && !Prism.languages.diff && !Prism.plugins.autoloader) {
			warningLogged = true;
			console.warn("Prism's Diff Highlight plugin requires the Diff language definition (prism-diff.js)." +
				"Make sure the language definition is loaded or use Prism's Autoloader plugin.");
		}

		var lang = env.language;
		if (LANGUAGE_REGEX.test(lang) && !Prism.languages[lang]) {
			Prism.languages[lang] = Prism.languages.diff;
		}
	});

	Prism.hooks.add('wrap', function (env) {
		var diffLanguage; var diffGrammar;

		if (env.language !== 'diff') {
			var langMatch = LANGUAGE_REGEX.exec(env.language);
			if (!langMatch) {
				return; // not a language specific diff
			}

			diffLanguage = langMatch[1];
			diffGrammar = Prism.languages[diffLanguage];
		}

		var PREFIXES = Prism.languages.diff && Prism.languages.diff.PREFIXES;

		// one of the diff tokens without any nested tokens
		if (PREFIXES && env.type in PREFIXES) {
			/** @type {string} */
			var content = env.content.replace(HTML_TAG, ''); // remove all HTML tags

			/** @type {string} */
			var decoded = content.replace(/&lt;/g, '<').replace(/&amp;/g, '&');

			// remove any one-character prefix
			var code = decoded.replace(/(^|[\r\n])./g, '$1');

			// highlight, if possible
			var highlighted;
			if (diffGrammar) {
				highlighted = Prism.highlight(code, diffGrammar, diffLanguage);
			} else {
				highlighted = Prism.util.encode(code);
			}

			// get the HTML source of the prefix token
			var prefixToken = new Prism.Token('prefix', PREFIXES[env.type], [/\w+/.exec(env.type)[0]]);
			var prefix = Prism.Token.stringify(prefixToken, env.language);

			// add prefix
			var lines = []; var m;
			HTML_LINE.lastIndex = 0;
			while ((m = HTML_LINE.exec(highlighted))) {
				lines.push(prefix + m[0]);
			}
			if (/(?:^|[\r\n]).$/.test(decoded)) {
				// because both "+a\n+" and "+a\n" will map to "a\n" after the line prefixes are removed
				lines.push(prefix);
			}
			env.content = lines.join('');

			if (diffGrammar) {
				env.classes.push('language-' + diffLanguage);
			}
		}
	});

}());