text: /*
  Language: Prolog
  Description: Prolog is a general purpose logic programming language associated with artificial intelligence and computational linguistics.
  Author: Raivo Laanemets <raivo@infdot.com>
  Website: https://en.wikipedia.org/wiki/Prolog
  */
  
  export default function(hljs) {
  
    var ATOM = {
  
      begin: /[a-z][A-Za-z0-9_]*/,
      relevance: 0
    };
  
    var VAR = {
  
      className: 'symbol',
      variants: [
        {begin: /[A-Z][a-zA-Z0-9_]*/},
        {begin: /_[A-Za-z0-9_]*/},
      ],
      relevance: 0
    };
  
    var PARENTED = {
  
      begin: /\(/,
      end: /\)/,
      relevance: 0
    };
  
    var LIST = {
  
      begin: /\[/,
      end: /\]/
    };
  
    var LINE_COMMENT = {
  
      className: 'comment',
      begin: /%/, end: /$/,
      contains: [hljs.PHRASAL_WORDS_MODE]
    };
  
    var BACKTICK_STRING = {
  
      className: 'string',
      begin: /`/, end: /`/,
      contains: [hljs.BACKSLASH_ESCAPE]
    };
  
    var CHAR_CODE = {
      className: 'string', // 0'a etc.
      begin: /0'(\\'|.)/
    };
  
    var SPACE_CODE = {
      className: 'string',
      begin: /0'\\s/ // 0'\s
    };
  
    var PRED_OP = { // relevance booster
      begin: /:-/
    };
  
    var inner = [
  
      ATOM,
      VAR,
      PARENTED,
      PRED_OP,
      LIST,
      LINE_COMMENT,
      hljs.C_BLOCK_COMMENT_MODE,
      hljs.QUOTE_STRING_MODE,
      hljs.APOS_STRING_MODE,
      BACKTICK_STRING,
      CHAR_CODE,
      SPACE_CODE,
      hljs.C_NUMBER_MODE
    ];
  
    PARENTED.contains = inner;
    LIST.contains = inner;
  
    return {
      name: 'Prolog',
      contains: inner.concat([
        {begin: /\.$/} // relevance booster
      ])
    };
  }
  