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

// https://www.freedesktop.org/software/systemd/man/systemd.syntax.html

(function (Prism) {

        var comment = {
                pattern: /^[;#].*/m,
                greedy: true
        };

        var quotesSource = /"(?:[^\r\n"\\]|\\(?:[^\r]|\r\n?))*"(?!\S)/.source;

        Prism.languages.systemd = {
                'comment': comment,

                'section': {
                        pattern: /^\[[^\n\r\[\]]*\](?=[ \t]*$)/m,
                        greedy: true,
                        inside: {
                                'punctuation': /^\[|\]$/,
                                'section-name': {
                                        pattern: /[\s\S]+/,
                                        alias: 'selector'
                                },
                        }
                },

                'key': {
                        pattern: /^[^\s=]+(?=[ \t]*=)/m,
                        greedy: true,
                        alias: 'attr-name'
                },
                'value': {
                        // This pattern is quite complex because of two properties:
                        //  1) Quotes (strings) must be preceded by a space. Since we can't use lookbehinds, we have to "resolve"
                        //     the lookbehind. You will see this in the main loop where spaces are handled separately.
                        //  2) Line continuations.
                        //     After line continuations, empty lines and comments are ignored so we have to consume them.
                        pattern: RegExp(
                                /(=[ \t]*(?!\s))/.source +
                                // the value either starts with quotes or not
                                '(?:' + quotesSource + '|(?=[^"\r\n]))' +
                                // main loop
                                '(?:' + (
                                        /[^\s\\]/.source +
                                        // handle spaces separately because of quotes
                                        '|' + '[ \t]+(?:(?![ \t"])|' + quotesSource + ')' +
                                        // line continuation
                                        '|' + /\\[\r\n]+(?:[#;].*[\r\n]+)*(?![#;])/.source
                                ) +
                                ')*'
                        ),
                        lookbehind: true,
                        greedy: true,
                        alias: 'attr-value',
                        inside: {
                                'comment': comment,
                                'quoted': {
                                        pattern: RegExp(/(^|\s)/.source + quotesSource),
                                        lookbehind: true,
                                        greedy: true,
                                },
                                'punctuation': /\\$/m,

                                'boolean': {
                                        pattern: /^(?:false|no|off|on|true|yes)$/,
                                        greedy: true
                                }
                        }
                },

                'punctuation': /=/
        };

}(Prism));