(function (Prism) {
  // https://mc-stan.org/docs/2_28/reference-manual/bnf-grammars.html

  var higherOrderFunctions =
    /\b(?:algebra_solver|algebra_solver_newton|integrate_1d|integrate_ode|integrate_ode_bdf|integrate_ode_rk45|map_rect|ode_(?:adams|bdf|ckrk|rk45)(?:_tol)?|ode_adjoint_tol_ctl|reduce_sum|reduce_sum_static)\b/;

  Prism.languages.stan = {
    comment: /\/\/.*|\/\*[\s\S]*?\*\/|#(?!include).*/,
    string: {
      // String literals can contain spaces and any printable ASCII characters except for " and \
      // https://mc-stan.org/docs/2_24/reference-manual/print-statements-section.html#string-literals
      pattern: /"[\x20\x21\x23-\x5B\x5D-\x7E]*"/,
      greedy: true,
    },
    directive: {
      pattern: /^([ \t]*)#include\b.*/m,
      lookbehind: true,
      alias: 'property',
    },

    'function-arg': {
      pattern: RegExp(
        '(' +
          higherOrderFunctions.source +
          /\s*\(\s*/.source +
          ')' +
          /[a-zA-Z]\w*/.source
      ),
      lookbehind: true,
      alias: 'function',
    },
    constraint: {
      pattern: /(\b(?:int|matrix|real|row_vector|vector)\s*)<[^<>]*>/,
      lookbehind: true,
      inside: {
        expression: {
          pattern: /(=\s*)\S(?:\S|\s+(?!\s))*?(?=\s*(?:>$|,\s*\w+\s*=))/,
          lookbehind: true,
          inside: null, // see below
        },
        property: /\b[a-z]\w*(?=\s*=)/i,
        operator: /=/,
        punctuation: /^<|>$|,/,
      },
    },
    keyword: [
      {
        pattern:
          /\bdata(?=\s*\{)|\b(?:functions|generated|model|parameters|quantities|transformed)\b/,
        alias: 'program-block',
      },
      /\b(?:array|break|cholesky_factor_corr|cholesky_factor_cov|complex|continue|corr_matrix|cov_matrix|data|else|for|if|in|increment_log_prob|int|matrix|ordered|positive_ordered|print|real|reject|return|row_vector|simplex|target|unit_vector|vector|void|while)\b/,
      // these are functions that are known to take another function as their first argument.
      higherOrderFunctions,
    ],
    function: /\b[a-z]\w*(?=\s*\()/i,
    number:
      /(?:\b\d+(?:_\d+)*(?:\.(?:\d+(?:_\d+)*)?)?|\B\.\d+(?:_\d+)*)(?:E[+-]?\d+(?:_\d+)*)?i?(?!\w)/i,
    boolean: /\b(?:false|true)\b/,

    operator: /<-|\.[*/]=?|\|\|?|&&|[!=<>+\-*/]=?|['^%~?:]/,
    punctuation: /[()\[\]{},;]/,
  };

  Prism.languages.stan.constraint.inside.expression.inside =
    Prism.languages.stan;
})(Prism);