(function (Prism) {
  Prism.languages.scheme = {
    // this supports "normal" single-line comments:
    //   ; comment
    // and (potentially nested) multiline comments:
    //   #| comment #| nested |# still comment |#
    // (only 1 level of nesting is supported)
    comment:
      /;.*|#;\s*(?:\((?:[^()]|\([^()]*\))*\)|\[(?:[^\[\]]|\[[^\[\]]*\])*\])|#\|(?:[^#|]|#(?!\|)|\|(?!#)|#\|(?:[^#|]|#(?!\|)|\|(?!#))*\|#)*\|#/,
    string: {
      pattern: /"(?:[^"\\]|\\.)*"/,
      greedy: true,
    },
    symbol: {
      pattern: /'[^()\[\]#'\s]+/,
      greedy: true,
    },
    char: {
      pattern:
        /#\\(?:[ux][a-fA-F\d]+\b|[-a-zA-Z]+\b|[\uD800-\uDBFF][\uDC00-\uDFFF]|\S)/,
      greedy: true,
    },
    'lambda-parameter': [
      // https://www.cs.cmu.edu/Groups/AI/html/r4rs/r4rs_6.html#SEC30
      {
        pattern:
          /((?:^|[^'`#])[(\[]lambda\s+)(?:[^|()\[\]'\s]+|\|(?:[^\\|]|\\.)*\|)/,
        lookbehind: true,
      },
      {
        pattern: /((?:^|[^'`#])[(\[]lambda\s+[(\[])[^()\[\]']+/,
        lookbehind: true,
      },
    ],
    keyword: {
      pattern:
        /((?:^|[^'`#])[(\[])(?:begin|case(?:-lambda)?|cond(?:-expand)?|define(?:-library|-macro|-record-type|-syntax|-values)?|defmacro|delay(?:-force)?|do|else|except|export|guard|if|import|include(?:-ci|-library-declarations)?|lambda|let(?:rec)?(?:-syntax|-values|\*)?|let\*-values|only|parameterize|prefix|(?:quasi-?)?quote|rename|set!|syntax-(?:case|rules)|unless|unquote(?:-splicing)?|when)(?=[()\[\]\s]|$)/,
      lookbehind: true,
    },
    builtin: {
      // all functions of the base library of R7RS plus some of built-ins of R5Rs
      pattern:
        /((?:^|[^'`#])[(\[])(?:abs|and|append|apply|assoc|ass[qv]|binary-port\?|boolean=?\?|bytevector(?:-append|-copy|-copy!|-length|-u8-ref|-u8-set!|\?)?|caar|cadr|call-with-(?:current-continuation|port|values)|call\/cc|car|cdar|cddr|cdr|ceiling|char(?:->integer|-ready\?|\?|<\?|<=\?|=\?|>\?|>=\?)|close-(?:input-port|output-port|port)|complex\?|cons|current-(?:error|input|output)-port|denominator|dynamic-wind|eof-object\??|eq\?|equal\?|eqv\?|error|error-object(?:-irritants|-message|\?)|eval|even\?|exact(?:-integer-sqrt|-integer\?|\?)?|expt|features|file-error\?|floor(?:-quotient|-remainder|\/)?|flush-output-port|for-each|gcd|get-output-(?:bytevector|string)|inexact\??|input-port(?:-open\?|\?)|integer(?:->char|\?)|lcm|length|list(?:->string|->vector|-copy|-ref|-set!|-tail|\?)?|make-(?:bytevector|list|parameter|string|vector)|map|max|member|memq|memv|min|modulo|negative\?|newline|not|null\?|number(?:->string|\?)|numerator|odd\?|open-(?:input|output)-(?:bytevector|string)|or|output-port(?:-open\?|\?)|pair\?|peek-char|peek-u8|port\?|positive\?|procedure\?|quotient|raise|raise-continuable|rational\?|rationalize|read-(?:bytevector|bytevector!|char|error\?|line|string|u8)|real\?|remainder|reverse|round|set-c[ad]r!|square|string(?:->list|->number|->symbol|->utf8|->vector|-append|-copy|-copy!|-fill!|-for-each|-length|-map|-ref|-set!|\?|<\?|<=\?|=\?|>\?|>=\?)?|substring|symbol(?:->string|\?|=\?)|syntax-error|textual-port\?|truncate(?:-quotient|-remainder|\/)?|u8-ready\?|utf8->string|values|vector(?:->list|->string|-append|-copy|-copy!|-fill!|-for-each|-length|-map|-ref|-set!|\?)?|with-exception-handler|write-(?:bytevector|char|string|u8)|zero\?)(?=[()\[\]\s]|$)/,
      lookbehind: true,
    },
    operator: {
      pattern: /((?:^|[^'`#])[(\[])(?:[-+*%/]|[<>]=?|=>?)(?=[()\[\]\s]|$)/,
      lookbehind: true,
    },
    number: {
      // The number pattern from [the R7RS spec](https://small.r7rs.org/attachment/r7rs.pdf).
      //
      // <number>      := <num 2>|<num 8>|<num 10>|<num 16>
      // <num R>       := <prefix R><complex R>
      // <complex R>   := <real R>(?:@<real R>|<imaginary R>)?|<imaginary R>
      // <imaginary R> := [+-](?:<ureal R>|(?:inf|nan)\.0)?i
      // <real R>      := [+-]?<ureal R>|[+-](?:inf|nan)\.0
      // <ureal R>     := <uint R>(?:\/<uint R>)?
      //                | <decimal R>
      //
      // <decimal 10>  := (?:\d+(?:\.\d*)?|\.\d+)(?:e[+-]?\d+)?
      // <uint R>      := <digit R>+
      // <prefix R>    := <radix R>(?:#[ei])?|(?:#[ei])?<radix R>
      // <radix 2>     := #b
      // <radix 8>     := #o
      // <radix 10>    := (?:#d)?
      // <radix 16>    := #x
      // <digit 2>     := [01]
      // <digit 8>     := [0-7]
      // <digit 10>    := \d
      // <digit 16>    := [0-9a-f]
      //
      // The problem with this grammar is that the resulting regex is way to complex, so we simplify by grouping all
      // non-decimal bases together. This results in a decimal (dec) and combined binary, octal, and hexadecimal (box)
      // pattern:
      pattern: RegExp(
        SortedBNF({
          '<ureal dec>':
            /\d+(?:\/\d+)|(?:\d+(?:\.\d*)?|\.\d+)(?:[esfdl][+-]?\d+)?/.source,
          '<real dec>': /[+-]?<ureal dec>|[+-](?:inf|nan)\.0/.source,
          '<imaginary dec>': /[+-](?:<ureal dec>|(?:inf|nan)\.0)?i/.source,
          '<complex dec>':
            /<real dec>(?:@<real dec>|<imaginary dec>)?|<imaginary dec>/.source,
          '<num dec>': /(?:#d(?:#[ei])?|#[ei](?:#d)?)?<complex dec>/.source,

          '<ureal box>': /[0-9a-f]+(?:\/[0-9a-f]+)?/.source,
          '<real box>': /[+-]?<ureal box>|[+-](?:inf|nan)\.0/.source,
          '<imaginary box>': /[+-](?:<ureal box>|(?:inf|nan)\.0)?i/.source,
          '<complex box>':
            /<real box>(?:@<real box>|<imaginary box>)?|<imaginary box>/.source,
          '<num box>': /#[box](?:#[ei])?|(?:#[ei])?#[box]<complex box>/.source,

          '<number>': /(^|[()\[\]\s])(?:<num dec>|<num box>)(?=[()\[\]\s]|$)/
            .source,
        }),
        'i'
      ),
      lookbehind: true,
    },
    boolean: {
      pattern: /(^|[()\[\]\s])#(?:[ft]|false|true)(?=[()\[\]\s]|$)/,
      lookbehind: true,
    },
    function: {
      pattern:
        /((?:^|[^'`#])[(\[])(?:[^|()\[\]'\s]+|\|(?:[^\\|]|\\.)*\|)(?=[()\[\]\s]|$)/,
      lookbehind: true,
    },
    identifier: {
      pattern: /(^|[()\[\]\s])\|(?:[^\\|]|\\.)*\|(?=[()\[\]\s]|$)/,
      lookbehind: true,
      greedy: true,
    },
    punctuation: /[()\[\]']/,
  };

  /**
   * Given a topologically sorted BNF grammar, this will return the RegExp source of last rule of the grammar.
   *
   * @param {Record<string, string>} grammar
   * @returns {string}
   */
  function SortedBNF(grammar) {
    for (var key in grammar) {
      grammar[key] = grammar[key].replace(/<[\w\s]+>/g, function (key) {
        return '(?:' + grammar[key].trim() + ')';
      });
    }
    // return the last item
    return grammar[key];
  }
})(Prism);