module.exports = function(hljs) {
    return {
        keywords: {
            typename: 'byte short char int long boolean float double void',
            literal : 'true false null',
            keyword:
            // groovy specific keywords
            'def as in assert trait ' +
            // common keywords with Java
            'super this abstract static volatile transient public private protected synchronized final ' +
            'class interface enum if else for while switch case break default continue ' +
            'throw throws try catch finally implements extends new import package return instanceof'
        },

        contains: [
            hljs.COMMENT(
                '/\\*\\*',
                '\\*/',
                {
                    relevance : 0,
                    contains : [{
                        className : 'doctag',
                        begin : '@[A-Za-z]+'
                    }]
                }
            ),
            hljs.C_LINE_COMMENT_MODE,
            hljs.C_BLOCK_COMMENT_MODE,
            {
                className: 'string',
                begin: '"""', end: '"""'
            },
            {
                className: 'string',
                begin: "'''", end: "'''"
            },
            {
                className: 'string',
                begin: "\\$/", end: "/\\$",
                relevance: 10
            },
            hljs.APOS_STRING_MODE,
            {
                className: 'regexp',
                begin: /~?\/[^\/\n]+\//,
                contains: [
                    hljs.BACKSLASH_ESCAPE
                ]
            },
            hljs.QUOTE_STRING_MODE,
            {
                className: 'shebang',
                begin: "^#!/usr/bin/env", end: '$',
                illegal: '\n'
            },
            hljs.BINARY_NUMBER_MODE,
            {
                className: 'class',
                beginKeywords: 'class interface trait enum', end: '{',
                illegal: ':',
                contains: [
                    {beginKeywords: 'extends implements'},
                    hljs.UNDERSCORE_TITLE_MODE,
                ]
            },
            hljs.C_NUMBER_MODE,
            {
                className: 'annotation', begin: '@[A-Za-z]+'
            },
            {
                // highlight map keys and named parameters as strings
                className: 'string', begin: /[^\?]{0}[A-Za-z0-9_$]+ *:/
            },
            {
                // catch middle element of the ternary operator
                // to avoid highlight it as a label, named parameter, or map key
                begin: /\?/, end: /\:/
            },
            {
                // highlight labeled statements
                className: 'label', begin: '^\\s*[A-Za-z0-9_$]+:',
                relevance: 0
            },
        ],
        illegal: /#/
    }
};