swift.js

/*
Language: Swift
Description: Swift is a general-purpose programming language built using a modern approach to safety, performance, and software design patterns.
Author: Steven Van Impe <steven.vanimpe@icloud.com>
Contributors: Chris Eidhof <chris@eidhof.nl>, Nate Cook <natecook@gmail.com>, Alexander Lichter <manniL@gmx.net>, Richard Gibson <gibson042@github>
Website: https://swift.org
Category: common, system
*/

import * as Swift from './lib/kws_swift.js';
import {
  concat,
  either,
  lookahead
} from '../lib/regex.js';

/** @type LanguageFn */
export default function(hljs) {
  const WHITESPACE = {
    match: /\s+/,
    relevance: 0
  };
  // https://docs.swift.org/swift-book/ReferenceManual/LexicalStructure.html#ID411
  const BLOCK_COMMENT = hljs.COMMENT(
    '/\\*',
    '\\*/',
    { contains: [ 'self' ] }
  );
  const COMMENTS = [
    hljs.C_LINE_COMMENT_MODE,
    BLOCK_COMMENT
  ];

  // https://docs.swift.org/swift-book/ReferenceManual/LexicalStructure.html#ID413
  // https://docs.swift.org/swift-book/ReferenceManual/zzSummaryOfTheGrammar.html
  const DOT_KEYWORD = {
    match: [
      /\./,
      either(...Swift.dotKeywords, ...Swift.optionalDotKeywords)
    ],
    className: { 2: "keyword" }
  };
  const KEYWORD_GUARD = {
    // Consume .keyword to prevent highlighting properties and methods as keywords.
    match: concat(/\./, either(...Swift.keywords)),
    relevance: 0
  };
  const PLAIN_KEYWORDS = Swift.keywords
    .filter(kw => typeof kw === 'string')
    .concat([ "_|0" ]); // seems common, so 0 relevance
  const REGEX_KEYWORDS = Swift.keywords
    .filter(kw => typeof kw !== 'string') // find regex
    .concat(Swift.keywordTypes)
    .map(Swift.keywordWrapper);
  const KEYWORD = { variants: [
    {
      className: 'keyword',
      match: either(...REGEX_KEYWORDS, ...Swift.optionalDotKeywords)
    }
  ] };
  // find all the regular keywords
  const KEYWORDS = {
    $pattern: either(
      /\b\w+/, // regular keywords
      /#\w+/ // number keywords
    ),
    keyword: PLAIN_KEYWORDS
      .concat(Swift.numberSignKeywords),
    literal: Swift.literals
  };
  const KEYWORD_MODES = [
    DOT_KEYWORD,
    KEYWORD_GUARD,
    KEYWORD
  ];

  // https://github.com/apple/swift/tree/main/stdlib/public/core
  const BUILT_IN_GUARD = {
    // Consume .built_in to prevent highlighting properties and methods.
    match: concat(/\./, either(...Swift.builtIns)),
    relevance: 0
  };
  const BUILT_IN = {
    className: 'built_in',
    match: concat(/\b/, either(...Swift.builtIns), /(?=\()/)
  };
  const BUILT_INS = [
    BUILT_IN_GUARD,
    BUILT_IN
  ];

  // https://docs.swift.org/swift-book/ReferenceManual/LexicalStructure.html#ID418
  const OPERATOR_GUARD = {
    // Prevent -> from being highlighting as an operator.
    match: /->/,
    relevance: 0
  };
  const OPERATOR = {
    className: 'operator',
    relevance: 0,
    variants: [
      { match: Swift.operator },
      {
        // dot-operator: only operators that start with a dot are allowed to use dots as
        // characters (..., ...<, .*, etc). So there rule here is: a dot followed by one or more
        // characters that may also include dots.
        match: `\\.(\\.|${Swift.operatorCharacter})+` }
    ]
  };
  const OPERATORS = [
    OPERATOR_GUARD,
    OPERATOR
  ];

  // https://docs.swift.org/swift-book/ReferenceManual/LexicalStructure.html#grammar_numeric-literal
  // TODO: Update for leading `-` after lookbehind is supported everywhere
  const decimalDigits = '([0-9]_*)+';
  const hexDigits = '([0-9a-fA-F]_*)+';
  const NUMBER = {
    className: 'number',
    relevance: 0,
    variants: [
      // decimal floating-point-literal (subsumes decimal-literal)
      { match: `\\b(${decimalDigits})(\\.(${decimalDigits}))?` + `([eE][+-]?(${decimalDigits}))?\\b` },
      // hexadecimal floating-point-literal (subsumes hexadecimal-literal)
      { match: `\\b0x(${hexDigits})(\\.(${hexDigits}))?` + `([pP][+-]?(${decimalDigits}))?\\b` },
      // octal-literal
      { match: /\b0o([0-7]_*)+\b/ },
      // binary-literal
      { match: /\b0b([01]_*)+\b/ }
    ]
  };

  // https://docs.swift.org/swift-book/ReferenceManual/LexicalStructure.html#grammar_string-literal
  const ESCAPED_CHARACTER = (rawDelimiter = "") => ({
    className: 'subst',
    variants: [
      { match: concat(/\\/, rawDelimiter, /[0\\tnr"']/) },
      { match: concat(/\\/, rawDelimiter, /u\{[0-9a-fA-F]{1,8}\}/) }
    ]
  });
  const ESCAPED_NEWLINE = (rawDelimiter = "") => ({
    className: 'subst',
    match: concat(/\\/, rawDelimiter, /[\t ]*(?:[\r\n]|\r\n)/)
  });
  const INTERPOLATION = (rawDelimiter = "") => ({
    className: 'subst',
    label: "interpol",
    begin: concat(/\\/, rawDelimiter, /\(/),
    end: /\)/
  });
  const MULTILINE_STRING = (rawDelimiter = "") => ({
    begin: concat(rawDelimiter, /"""/),
    end: concat(/"""/, rawDelimiter),
    contains: [
      ESCAPED_CHARACTER(rawDelimiter),
      ESCAPED_NEWLINE(rawDelimiter),
      INTERPOLATION(rawDelimiter)
    ]
  });
  const SINGLE_LINE_STRING = (rawDelimiter = "") => ({
    begin: concat(rawDelimiter, /"/),
    end: concat(/"/, rawDelimiter),
    contains: [
      ESCAPED_CHARACTER(rawDelimiter),
      INTERPOLATION(rawDelimiter)
    ]
  });
  const STRING = {
    className: 'string',
    variants: [
      MULTILINE_STRING(),
      MULTILINE_STRING("#"),
      MULTILINE_STRING("##"),
      MULTILINE_STRING("###"),
      SINGLE_LINE_STRING(),
      SINGLE_LINE_STRING("#"),
      SINGLE_LINE_STRING("##"),
      SINGLE_LINE_STRING("###")
    ]
  };

  const REGEXP_CONTENTS = [
    hljs.BACKSLASH_ESCAPE,
    {
      begin: /\[/,
      end: /\]/,
      relevance: 0,
      contains: [ hljs.BACKSLASH_ESCAPE ]
    }
  ];

  const BARE_REGEXP_LITERAL = {
    begin: /\/[^\s](?=[^/\n]*\/)/,
    end: /\//,
    contains: REGEXP_CONTENTS
  };

  const EXTENDED_REGEXP_LITERAL = (rawDelimiter) => {
    const begin = concat(rawDelimiter, /\//);
    const end = concat(/\//, rawDelimiter);
    return {
      begin,
      end,
      contains: [
        ...REGEXP_CONTENTS,
        {
          scope: "comment",
          begin: `#(?!.*${end})`,
          end: /$/,
        },
      ],
    };
  };

  // https://docs.swift.org/swift-book/documentation/the-swift-programming-language/lexicalstructure/#Regular-Expression-Literals
  const REGEXP = {
    scope: "regexp",
    variants: [
      EXTENDED_REGEXP_LITERAL('###'),
      EXTENDED_REGEXP_LITERAL('##'),
      EXTENDED_REGEXP_LITERAL('#'),
      BARE_REGEXP_LITERAL
    ]
  };

  // https://docs.swift.org/swift-book/ReferenceManual/LexicalStructure.html#ID412
  const QUOTED_IDENTIFIER = { match: concat(/`/, Swift.identifier, /`/) };
  const IMPLICIT_PARAMETER = {
    className: 'variable',
    match: /\$\d+/
  };
  const PROPERTY_WRAPPER_PROJECTION = {
    className: 'variable',
    match: `\\$${Swift.identifierCharacter}+`
  };
  const IDENTIFIERS = [
    QUOTED_IDENTIFIER,
    IMPLICIT_PARAMETER,
    PROPERTY_WRAPPER_PROJECTION
  ];

  // https://docs.swift.org/swift-book/ReferenceManual/Attributes.html
  const AVAILABLE_ATTRIBUTE = {
    match: /(@|#(un)?)available/,
    scope: 'keyword',
    starts: { contains: [
      {
        begin: /\(/,
        end: /\)/,
        keywords: Swift.availabilityKeywords,
        contains: [
          ...OPERATORS,
          NUMBER,
          STRING
        ]
      }
    ] }
  };

  const KEYWORD_ATTRIBUTE = {
    scope: 'keyword',
    match: concat(/@/, either(...Swift.keywordAttributes), lookahead(either(/\(/, /\s+/))),
  };

  const USER_DEFINED_ATTRIBUTE = {
    scope: 'meta',
    match: concat(/@/, Swift.identifier)
  };

  const ATTRIBUTES = [
    AVAILABLE_ATTRIBUTE,
    KEYWORD_ATTRIBUTE,
    USER_DEFINED_ATTRIBUTE
  ];

  // https://docs.swift.org/swift-book/ReferenceManual/Types.html
  const TYPE = {
    match: lookahead(/\b[A-Z]/),
    relevance: 0,
    contains: [
      { // Common Apple frameworks, for relevance boost
        className: 'type',
        match: concat(/(AV|CA|CF|CG|CI|CL|CM|CN|CT|MK|MP|MTK|MTL|NS|SCN|SK|UI|WK|XC)/, Swift.identifierCharacter, '+')
      },
      { // Type identifier
        className: 'type',
        match: Swift.typeIdentifier,
        relevance: 0
      },
      { // Optional type
        match: /[?!]+/,
        relevance: 0
      },
      { // Variadic parameter
        match: /\.\.\./,
        relevance: 0
      },
      { // Protocol composition
        match: concat(/\s+&\s+/, lookahead(Swift.typeIdentifier)),
        relevance: 0
      }
    ]
  };
  const GENERIC_ARGUMENTS = {
    begin: /</,
    end: />/,
    keywords: KEYWORDS,
    contains: [
      ...COMMENTS,
      ...KEYWORD_MODES,
      ...ATTRIBUTES,
      OPERATOR_GUARD,
      TYPE
    ]
  };
  TYPE.contains.push(GENERIC_ARGUMENTS);

  // https://docs.swift.org/swift-book/ReferenceManual/Expressions.html#ID552
  // Prevents element names from being highlighted as keywords.
  const TUPLE_ELEMENT_NAME = {
    match: concat(Swift.identifier, /\s*:/),
    keywords: "_|0",
    relevance: 0
  };
  // Matches tuples as well as the parameter list of a function type.
  const TUPLE = {
    begin: /\(/,
    end: /\)/,
    relevance: 0,
    keywords: KEYWORDS,
    contains: [
      'self',
      TUPLE_ELEMENT_NAME,
      ...COMMENTS,
      REGEXP,
      ...KEYWORD_MODES,
      ...BUILT_INS,
      ...OPERATORS,
      NUMBER,
      STRING,
      ...IDENTIFIERS,
      ...ATTRIBUTES,
      TYPE
    ]
  };

  const GENERIC_PARAMETERS = {
    begin: /</,
    end: />/,
    keywords: 'repeat each',
    contains: [
      ...COMMENTS,
      TYPE
    ]
  };
  const FUNCTION_PARAMETER_NAME = {
    begin: either(
      lookahead(concat(Swift.identifier, /\s*:/)),
      lookahead(concat(Swift.identifier, /\s+/, Swift.identifier, /\s*:/))
    ),
    end: /:/,
    relevance: 0,
    contains: [
      {
        className: 'keyword',
        match: /\b_\b/
      },
      {
        className: 'params',
        match: Swift.identifier
      }
    ]
  };
  const FUNCTION_PARAMETERS = {
    begin: /\(/,
    end: /\)/,
    keywords: KEYWORDS,
    contains: [
      FUNCTION_PARAMETER_NAME,
      ...COMMENTS,
      ...KEYWORD_MODES,
      ...OPERATORS,
      NUMBER,
      STRING,
      ...ATTRIBUTES,
      TYPE,
      TUPLE
    ],
    endsParent: true,
    illegal: /["']/
  };
  // https://docs.swift.org/swift-book/ReferenceManual/Declarations.html#ID362
  // https://docs.swift.org/swift-book/documentation/the-swift-programming-language/declarations/#Macro-Declaration
  const FUNCTION_OR_MACRO = {
    match: [
      /(func|macro)/,
      /\s+/,
      either(QUOTED_IDENTIFIER.match, Swift.identifier, Swift.operator)
    ],
    className: {
      1: "keyword",
      3: "title.function"
    },
    contains: [
      GENERIC_PARAMETERS,
      FUNCTION_PARAMETERS,
      WHITESPACE
    ],
    illegal: [
      /\[/,
      /%/
    ]
  };

  // https://docs.swift.org/swift-book/ReferenceManual/Declarations.html#ID375
  // https://docs.swift.org/swift-book/ReferenceManual/Declarations.html#ID379
  const INIT_SUBSCRIPT = {
    match: [
      /\b(?:subscript|init[?!]?)/,
      /\s*(?=[<(])/,
    ],
    className: { 1: "keyword" },
    contains: [
      GENERIC_PARAMETERS,
      FUNCTION_PARAMETERS,
      WHITESPACE
    ],
    illegal: /\[|%/
  };
  // https://docs.swift.org/swift-book/ReferenceManual/Declarations.html#ID380
  const OPERATOR_DECLARATION = {
    match: [
      /operator/,
      /\s+/,
      Swift.operator
    ],
    className: {
      1: "keyword",
      3: "title"
    }
  };

  // https://docs.swift.org/swift-book/ReferenceManual/Declarations.html#ID550
  const PRECEDENCEGROUP = {
    begin: [
      /precedencegroup/,
      /\s+/,
      Swift.typeIdentifier
    ],
    className: {
      1: "keyword",
      3: "title"
    },
    contains: [ TYPE ],
    keywords: [
      ...Swift.precedencegroupKeywords,
      ...Swift.literals
    ],
    end: /}/
  };

  const CLASS_FUNC_DECLARATION = {
    match: [
      /class\b/,          
      /\s+/,
      /func\b/,
      /\s+/,
      /\b[A-Za-z_][A-Za-z0-9_]*\b/ 
    ],
    scope: {
      1: "keyword",
      3: "keyword",
      5: "title.function"
    }
  };

  const CLASS_VAR_DECLARATION = {
    match: [
      /class\b/,
      /\s+/,          
      /var\b/, 
    ],
    scope: {
      1: "keyword",
      3: "keyword"
    }
  };

  const TYPE_DECLARATION = {
    begin: [
      /(struct|protocol|class|extension|enum|actor)/,
      /\s+/,
      Swift.identifier,
      /\s*/,
    ],
    beginScope: {
      1: "keyword",
      3: "title.class"
    },
    keywords: KEYWORDS,
    contains: [
      GENERIC_PARAMETERS,
      ...KEYWORD_MODES,
      {
        begin: /:/,
        end: /\{/,
        keywords: KEYWORDS,
        contains: [
          {
            scope: "title.class.inherited",
            match: Swift.typeIdentifier,
          },
          ...KEYWORD_MODES,
        ],
        relevance: 0,
      },
    ]
  };

  // Add supported submodes to string interpolation.
  for (const variant of STRING.variants) {
    const interpolation = variant.contains.find(mode => mode.label === "interpol");
    // TODO: Interpolation can contain any expression, so there's room for improvement here.
    interpolation.keywords = KEYWORDS;
    const submodes = [
      ...KEYWORD_MODES,
      ...BUILT_INS,
      ...OPERATORS,
      NUMBER,
      STRING,
      ...IDENTIFIERS
    ];
    interpolation.contains = [
      ...submodes,
      {
        begin: /\(/,
        end: /\)/,
        contains: [
          'self',
          ...submodes
        ]
      }
    ];
  }

  return {
    name: 'Swift',
    keywords: KEYWORDS,
    contains: [
      ...COMMENTS,
      FUNCTION_OR_MACRO,
      INIT_SUBSCRIPT,
      CLASS_FUNC_DECLARATION,
      CLASS_VAR_DECLARATION,
      TYPE_DECLARATION,
      OPERATOR_DECLARATION,
      PRECEDENCEGROUP,
      {
        beginKeywords: 'import',
        end: /$/,
        contains: [ ...COMMENTS ],
        relevance: 0
      },
      REGEXP,
      ...KEYWORD_MODES,
      ...BUILT_INS,
      ...OPERATORS,
      NUMBER,
      STRING,
      ...IDENTIFIERS,
      ...ATTRIBUTES,
      TYPE,
      TUPLE
    ]
  };
}