hljs-scala3.js

function highlightDotty(hljs) {

  // identifiers
  const capitalizedId = /\b[A-Z][$\w]*\b/
  const alphaId = /[a-zA-Z$_][$\w]*/
  const op1 = /[^\s\w\d,;"'()[\]{}=:]/
  const op2 = /[^\s\w\d,;"'()[\]{}]/
  const compound = `[a-zA-Z$][a-zA-Z0-9$]*_${op2.source}` // e.g. value_=
  const id = new RegExp(`(${compound}|${alphaId.source}|${op2.source}{2,}|${op1.source}+|\`.+?\`)`)

  // numbers
  const hexDigit = '[a-fA-F0-9]'
  const hexNumber = `0[xX](${hexDigit})+(_(${hexDigit})+)*[lL]?`
  const wholePart = `(\\d+)(_\\d+)*`
  const decPoint = `\\.\\d+`
  const floatingSuffix = `([eE][-+]?\\d+)?[fFdD]?`
  const intOrFloat = `${decPoint}${floatingSuffix}|\\b${wholePart}([lLfFdD]|(${decPoint})?${floatingSuffix})`
  const number = new RegExp(`(-?)((\\b(${hexNumber})|${intOrFloat}))`)

  // Regular Keywords
  // The "soft" keywords (e.g. 'using') are added later where necessary
  const alwaysKeywords = {
    $pattern: /(\w+|\?=>|\?{1,3}|=>>|=>|<:|>:|_|#|<-|\.nn)/,
    keyword:
      'abstract case catch class def do else enum export extends final finally for given ' +
      'if implicit import lazy match new object package private protected override return ' +
      'sealed then throw trait true try type val var while with yield =>> => ?=> <: >: _ ? <- #',
    literal: 'true false null this super',
    built_in: '??? asInstanceOf isInstanceOf assert implicitly locally summon valueOf .nn'
  }
  const modifiers = 'abstract|final|implicit|override|private|protected|sealed'

  // End of class, enum, etc. header
  const templateDeclEnd = /(\/[/*]|{|:(?= *\n)|\n(?! *(extends|with|derives)))/

  // all the keywords + soft keywords, separated by spaces
  function withSoftKeywords(kwd) {
    return {
      $pattern: alwaysKeywords.$pattern,
      keyword: kwd + ' ' + alwaysKeywords.keyword,
      literal: alwaysKeywords.literal,
      built_in: alwaysKeywords.built_in
    }
  }

  // title inside of a complex token made of several parts, but colored as a type (e.g. class)
  const TP_TITLE = {
    className: 'type',
    begin: id,
    returnEnd: true,
    keywords: alwaysKeywords.keyword,
    literal: alwaysKeywords.literal,
    built_in: alwaysKeywords.built_in
  }

  // title inside of a complex token made of several parts (e.g. class)
  const TITLE = {
    className: 'title',
    begin: id,
    returnEnd: true,
    keywords: alwaysKeywords.keyword,
    literal: alwaysKeywords.literal,
    built_in: alwaysKeywords.built_in
  }

  // title that goes to the end of a simple token (e.g. val)
  const TITLE2 = {
    className: 'title',
    begin: id,
    excludeEnd: true,
    endsWithParent: true
  }

  const TYPED = {
    begin: /: (?=[a-zA-Z()?])/,
    end: /\/\/|\/\*|\n/,
    endsWithParent: true,
    returnEnd: true,
    contains: [
      {
        // works better than the usual way of defining keyword,
        // in this specific situation
        className: 'keyword',
        begin: /\?\=>|=>>|[=:][><]|\?/,
      },
      {
        className: 'type',
        begin: alphaId
      }
    ]
  }

  const PROBABLY_TYPE = {
    className: 'type',
    begin: capitalizedId,
    relevance: 0
  }

  const NUMBER = {
    className: 'number',
    begin: number,
    relevance: 0,
  }

  const CHAR = {
    className: 'string',
    begin: /\'([^'\\]|\\[\s\S])\'/,
    relevance: 0,
  }

  // type parameters within [square brackets]
  const TPARAMS = {
    begin: /\[/, end: /\]/,
    keywords: {
      $pattern: /<:|>:|[+-?_:]/,
      keyword: '<: >: : + - ? _'
    },
    contains: [
      hljs.C_BLOCK_COMMENT_MODE,
      {
        className: 'type',
        begin: alphaId
      },
    ],
    relevance: 3
  }

  // Class or method parameters declaration
  const PARAMS = {
    className: 'params',
    begin: /\(/, end: /\)/,
    excludeBegin: true,
    excludeEnd: true,
    keywords: withSoftKeywords('inline using'),
    contains: [
      hljs.C_BLOCK_COMMENT_MODE,
      hljs.QUOTE_STRING_MODE,
      PROBABLY_TYPE
    ]
  }

  // (using T1, T2, T3)
  const CTX_PARAMS = {
    className: 'params',
    begin: /\(using (?!\w+:)/, end: /\)/,
    excludeBegin: false,
    excludeEnd: true,
    relevance: 5,
    keywords: withSoftKeywords('using'),
    contains: [
      PROBABLY_TYPE
    ]
  }

  // String interpolation
  const SUBST = {
    className: 'subst',
    variants: [
      { begin: /\$[a-zA-Z_]\w*/ },
      {
        begin: /\${/, end: /}/,
        contains: [
          NUMBER,
          hljs.QUOTE_STRING_MODE
        ]
      }
    ]
  }

  // "string" or """string""", with or without interpolation
  const STRING = {
    className: 'string',
    variants: [
      // triple-quote strings must have higher precedence otherwise `foo"""{"bar": "Baz"}"""` interpolates as [foo"", "{", message": ", Baz, "}", ""]
      {
        begin: '"""', end: '"""',
        contains: [hljs.BACKSLASH_ESCAPE],
        relevance: 10
      },
      hljs.QUOTE_STRING_MODE,
      {
        begin: alphaId.source + '"""', end: '"""',
        contains: [hljs.BACKSLASH_ESCAPE, SUBST],
        relevance: 10
      },
      {
        begin: alphaId.source + '"', end: '"',
        contains: [hljs.BACKSLASH_ESCAPE, SUBST],
        illegal: /\n/,
        relevance: 5
      }
    ]
  }

  // Class or method apply
  const APPLY = {
    begin: /\(/, end: /\)/,
    excludeBegin: true, excludeEnd: true,
    keywords: {
      $pattern: alwaysKeywords.$pattern,
      keyword: 'using ' + alwaysKeywords.keyword,
      literal: alwaysKeywords.literal,
      built_in: alwaysKeywords.built_in
    },
    contains: [
      STRING,
      NUMBER,
      CHAR,
      hljs.C_LINE_COMMENT_MODE,
      hljs.C_BLOCK_COMMENT_MODE,
      PROBABLY_TYPE,
    ]
  }

  // @annot(...) or @my.package.annot(...)
  const ANNOTATION = {
    className: 'meta',
    begin: `@${id.source}(\\.${id.source})*`,
    contains: [
      APPLY,
      hljs.C_BLOCK_COMMENT_MODE
    ]
  }

  // glob all non-whitespace characters as a "string"
  const DIRECTIVE_VALUE = {
    className: 'string',
    begin: /\S+/,
  }

  // glob all non-whitespace characters as a "type", so that we can highlight differently to values
  const DIRECTIVE_KEY = {
    className: 'type',
    begin: /\S+/,
  }

  // directives
  const USING_DIRECTIVE = hljs.COMMENT('//>', '\n', {
    contains: [
      {
        begin: /using /,
        end: /\s/,
        keywords: 'using',
        contains: [
          DIRECTIVE_KEY
        ]
      },
      DIRECTIVE_VALUE,
    ]
  })

  // Documentation
  const SCALADOC = hljs.COMMENT('/\\*\\*', '\\*/', {
    contains: [
      {
        className: 'doctag',
        begin: /@[a-zA-Z]+/
      },
      // markdown syntax elements:
      {
        className: 'code',
        variants: [
          { begin: /```.*\n/, end: /```/ },
          { begin: /`/, end: /`/ }
        ],
      },
      {
        className: 'bold',
        variants: [
          { begin: /\*\*/, end: /\*\*/ },
          { begin: /__/, end: /__/ }
        ],
      },
      {
        className: 'emphasis',
        variants: [
          { begin: /\*(?!([\*\s/])|([^\*]*\*[\*/]))/, end: /\*/ },
          { begin: /_/, end: /_/ }
        ],
      },
      {
        className: 'bullet', // list item
        begin: /- (?=\S)/, end: /\s/,
      },
      {
        begin: /\[.*?\]\(/, end: /\)/,
        contains: [
          {
            // mark as "link" only the URL
            className: 'link',
            begin: /.*?/,
            endsWithParent: true
          }
        ]
      }
    ]
  })

  // Methods
  const METHOD = {
    className: 'function',
    begin: `((${modifiers}|transparent|inline|infix) +)*def `, end: / =\s|\n/,
    excludeEnd: true,
    relevance: 5,
    keywords: withSoftKeywords('inline infix transparent'),
    contains: [
      hljs.C_LINE_COMMENT_MODE,
      hljs.C_BLOCK_COMMENT_MODE,
      TPARAMS,
      CTX_PARAMS,
      PARAMS,
      TYPED, // prevents the ":" (declared type) to become a title
      PROBABLY_TYPE,
      TITLE
    ]
  }

  // Variables & Constants
  const VAL = {
    beginKeywords: 'val var', end: /[=:;\n/]/,
    excludeEnd: true,
    contains: [
      hljs.C_LINE_COMMENT_MODE,
      hljs.C_BLOCK_COMMENT_MODE,
      TITLE2
    ]
  }

  // Type declarations
  const TYPEDEF = {
    className: 'typedef',
    begin: `((${modifiers}|opaque) +)*type `, end: /[=;\n]| ?[<>]:/,
    excludeEnd: true,
    keywords: withSoftKeywords('opaque'),
    contains: [
      hljs.C_LINE_COMMENT_MODE,
      hljs.C_BLOCK_COMMENT_MODE,
      PROBABLY_TYPE,
      TITLE,
    ]
  }

  // Given instances
  const GIVEN = {
    begin: `((${modifiers}|transparent|inline) +)*given `, end: / =|[=;\n]/,
    excludeEnd: true,
    keywords: withSoftKeywords('inline transparent given using with'),
    contains: [
      hljs.C_LINE_COMMENT_MODE,
      hljs.C_BLOCK_COMMENT_MODE,
      PARAMS,
      CTX_PARAMS,
      PROBABLY_TYPE,
      TITLE
    ]
  }

  // Extension methods
  const EXTENSION = {
    begin: /extension/, end: /(\n|def)/,
    returnEnd: true,
    keywords: 'extension implicit using',
    contains: [
      hljs.C_LINE_COMMENT_MODE,
      hljs.C_BLOCK_COMMENT_MODE,
      CTX_PARAMS,
      PARAMS,
      PROBABLY_TYPE
    ]
  }

  // 'end' soft keyword
  const END = {
    begin: `end(?= (if|while|for|match|try|given|extension|this|val|${id.source})\\n)`, end: /\s/,
    keywords: 'end'
  }

  // Classes, traits, enums, etc.
  const EXTENDS_PARENT = {
    begin: ' extends ', end: /( with | derives |\/[/*])/,
    endsWithParent: true,
    returnEnd: true,
    keywords: 'extends',
    contains: [APPLY, PROBABLY_TYPE]
  }
  const WITH_MIXIN = {
    begin: ' with ', end: / derives |\/[/*]/,
    endsWithParent: true,
    returnEnd: true,
    keywords: 'with',
    contains: [APPLY, PROBABLY_TYPE],
    relevance: 10
  }
  const DERIVES_TYPECLASS = {
    begin: ' derives ', end: /\n|\/[/*]/,
    endsWithParent: true,
    returnEnd: true,
    keywords: 'derives',
    contains: [PROBABLY_TYPE],
    relevance: 10
  }

  const CLASS = {
    className: 'class',
    begin: `((${modifiers}|open|case|transparent) +)*(class|trait|enum|object|package object)`, end: templateDeclEnd,
    keywords: withSoftKeywords('open transparent'),
    excludeEnd: true,
    contains: [
      hljs.C_LINE_COMMENT_MODE,
      hljs.C_BLOCK_COMMENT_MODE,
      TPARAMS,
      CTX_PARAMS,
      PARAMS,
      EXTENDS_PARENT,
      WITH_MIXIN,
      DERIVES_TYPECLASS,
      TITLE,
      PROBABLY_TYPE
    ]
  }

  // package declaration with a content
  const PACKAGE = {
    className: 'package',
    begin: /package (?=\w+ *[:{\n])/, end: /[:{\n]/,
    excludeEnd: true,
    keywords: alwaysKeywords,
    contains: [
      TITLE
    ]
  }

  // Case in enum
  const ENUM_CASE = {
    begin: /case (?!.*=>)/, end: /\n/,
    keywords: 'case',
    excludeEnd: true,
    contains: [
      hljs.C_LINE_COMMENT_MODE,
      hljs.C_BLOCK_COMMENT_MODE,
      PARAMS,
      EXTENDS_PARENT,
      WITH_MIXIN,
      DERIVES_TYPECLASS,
      TP_TITLE,
      PROBABLY_TYPE
    ]
  }

  // Case in pattern matching
  const MATCH_CASE = {
    begin: /case/, end: /=>|\n/,
    keywords: 'case',
    excludeEnd: true,
    contains: [
      hljs.C_LINE_COMMENT_MODE,
      hljs.C_BLOCK_COMMENT_MODE,
      {
        begin: /[@_]/,
        keywords: {
          $pattern: /[@_]/,
          keyword: '@ _'
        }
      },
      NUMBER,
      STRING,
      PROBABLY_TYPE
    ]
  }

  // inline someVar[andMaybeTypeParams] match
  const INLINE_MATCH = {
    begin: /inline [^\n:]+ match/,
    keywords: 'inline match'
  }

  return {
    name: 'Scala3',
    aliases: ['scala', 'dotty'],
    keywords: alwaysKeywords,
    contains: [
      NUMBER,
      CHAR,
      STRING,
      USING_DIRECTIVE,
      SCALADOC,
      hljs.C_LINE_COMMENT_MODE,
      hljs.C_BLOCK_COMMENT_MODE,
      METHOD,
      VAL,
      TYPEDEF,
      PACKAGE,
      CLASS,
      GIVEN,
      EXTENSION,
      ANNOTATION,
      ENUM_CASE,
      MATCH_CASE,
      INLINE_MATCH,
      END,
      APPLY,
      PROBABLY_TYPE
    ]
  }
}