source: node_modules/prismjs/components/prism-diff.js

(function (Prism) {

        Prism.languages.diff = {
                'coord': [
                        // Match all kinds of coord lines (prefixed by "+++", "---" or "***").
                        /^(?:\*{3}|-{3}|\+{3}).*$/m,
                        // Match "@@ ... @@" coord lines in unified diff.
                        /^@@.*@@$/m,
                        // Match coord lines in normal diff (starts with a number).
                        /^\d.*$/m
                ]

                // deleted, inserted, unchanged, diff
        };

        /**
         * A map from the name of a block to its line prefix.
         *
         * @type {Object<string, string>}
         */
        var PREFIXES = {
                'deleted-sign': '-',
                'deleted-arrow': '<',
                'inserted-sign': '+',
                'inserted-arrow': '>',
                'unchanged': ' ',
                'diff': '!',
        };

        // add a token for each prefix
        Object.keys(PREFIXES).forEach(function (name) {
                var prefix = PREFIXES[name];

                var alias = [];
                if (!/^\w+$/.test(name)) { // "deleted-sign" -> "deleted"
                        alias.push(/\w+/.exec(name)[0]);
                }
                if (name === 'diff') {
                        alias.push('bold');
                }

                Prism.languages.diff[name] = {
                        pattern: RegExp('^(?:[' + prefix + '].*(?:\r\n?|\n|(?![\\s\\S])))+', 'm'),
                        alias: alias,
                        inside: {
                                'line': {
                                        pattern: /(.)(?=[\s\S]).*(?:\r\n?|\n)?/,
                                        lookbehind: true
                                },
                                'prefix': {
                                        pattern: /[\s\S]/,
                                        alias: /\w+/.exec(name)[0]
                                }
                        }
                };

        });

        // make prefixes available to Diff plugin
        Object.defineProperty(Prism.languages.diff, 'PREFIXES', {
                value: PREFIXES
        });

}(Prism));