source: node_modules/highlight.js/lib/languages/less.js@ d24f17c

const MODES = (hljs) => {
  return {
    IMPORTANT: {
      className: 'meta',
      begin: '!important'
    },
    HEXCOLOR: {
      className: 'number',
      begin: '#([a-fA-F0-9]{6}|[a-fA-F0-9]{3})'
    },
    ATTRIBUTE_SELECTOR_MODE: {
      className: 'selector-attr',
      begin: /\[/,
      end: /\]/,
      illegal: '$',
      contains: [
        hljs.APOS_STRING_MODE,
        hljs.QUOTE_STRING_MODE
      ]
    }
  };
};

const TAGS = [
  'a',
  'abbr',
  'address',
  'article',
  'aside',
  'audio',
  'b',
  'blockquote',
  'body',
  'button',
  'canvas',
  'caption',
  'cite',
  'code',
  'dd',
  'del',
  'details',
  'dfn',
  'div',
  'dl',
  'dt',
  'em',
  'fieldset',
  'figcaption',
  'figure',
  'footer',
  'form',
  'h1',
  'h2',
  'h3',
  'h4',
  'h5',
  'h6',
  'header',
  'hgroup',
  'html',
  'i',
  'iframe',
  'img',
  'input',
  'ins',
  'kbd',
  'label',
  'legend',
  'li',
  'main',
  'mark',
  'menu',
  'nav',
  'object',
  'ol',
  'p',
  'q',
  'quote',
  'samp',
  'section',
  'span',
  'strong',
  'summary',
  'sup',
  'table',
  'tbody',
  'td',
  'textarea',
  'tfoot',
  'th',
  'thead',
  'time',
  'tr',
  'ul',
  'var',
  'video'
];

const MEDIA_FEATURES = [
  'any-hover',
  'any-pointer',
  'aspect-ratio',
  'color',
  'color-gamut',
  'color-index',
  'device-aspect-ratio',
  'device-height',
  'device-width',
  'display-mode',
  'forced-colors',
  'grid',
  'height',
  'hover',
  'inverted-colors',
  'monochrome',
  'orientation',
  'overflow-block',
  'overflow-inline',
  'pointer',
  'prefers-color-scheme',
  'prefers-contrast',
  'prefers-reduced-motion',
  'prefers-reduced-transparency',
  'resolution',
  'scan',
  'scripting',
  'update',
  'width',
  // TODO: find a better solution?
  'min-width',
  'max-width',
  'min-height',
  'max-height'
];

// https://developer.mozilla.org/en-US/docs/Web/CSS/Pseudo-classes
const PSEUDO_CLASSES = [
  'active',
  'any-link',
  'blank',
  'checked',
  'current',
  'default',
  'defined',
  'dir', // dir()
  'disabled',
  'drop',
  'empty',
  'enabled',
  'first',
  'first-child',
  'first-of-type',
  'fullscreen',
  'future',
  'focus',
  'focus-visible',
  'focus-within',
  'has', // has()
  'host', // host or host()
  'host-context', // host-context()
  'hover',
  'indeterminate',
  'in-range',
  'invalid',
  'is', // is()
  'lang', // lang()
  'last-child',
  'last-of-type',
  'left',
  'link',
  'local-link',
  'not', // not()
  'nth-child', // nth-child()
  'nth-col', // nth-col()
  'nth-last-child', // nth-last-child()
  'nth-last-col', // nth-last-col()
  'nth-last-of-type', //nth-last-of-type()
  'nth-of-type', //nth-of-type()
  'only-child',
  'only-of-type',
  'optional',
  'out-of-range',
  'past',
  'placeholder-shown',
  'read-only',
  'read-write',
  'required',
  'right',
  'root',
  'scope',
  'target',
  'target-within',
  'user-invalid',
  'valid',
  'visited',
  'where' // where()
];

// https://developer.mozilla.org/en-US/docs/Web/CSS/Pseudo-elements
const PSEUDO_ELEMENTS = [
  'after',
  'backdrop',
  'before',
  'cue',
  'cue-region',
  'first-letter',
  'first-line',
  'grammar-error',
  'marker',
  'part',
  'placeholder',
  'selection',
  'slotted',
  'spelling-error'
];

const ATTRIBUTES = [
  'align-content',
  'align-items',
  'align-self',
  'animation',
  'animation-delay',
  'animation-direction',
  'animation-duration',
  'animation-fill-mode',
  'animation-iteration-count',
  'animation-name',
  'animation-play-state',
  'animation-timing-function',
  'auto',
  'backface-visibility',
  'background',
  'background-attachment',
  'background-clip',
  'background-color',
  'background-image',
  'background-origin',
  'background-position',
  'background-repeat',
  'background-size',
  'border',
  'border-bottom',
  'border-bottom-color',
  'border-bottom-left-radius',
  'border-bottom-right-radius',
  'border-bottom-style',
  'border-bottom-width',
  'border-collapse',
  'border-color',
  'border-image',
  'border-image-outset',
  'border-image-repeat',
  'border-image-slice',
  'border-image-source',
  'border-image-width',
  'border-left',
  'border-left-color',
  'border-left-style',
  'border-left-width',
  'border-radius',
  'border-right',
  'border-right-color',
  'border-right-style',
  'border-right-width',
  'border-spacing',
  'border-style',
  'border-top',
  'border-top-color',
  'border-top-left-radius',
  'border-top-right-radius',
  'border-top-style',
  'border-top-width',
  'border-width',
  'bottom',
  'box-decoration-break',
  'box-shadow',
  'box-sizing',
  'break-after',
  'break-before',
  'break-inside',
  'caption-side',
  'clear',
  'clip',
  'clip-path',
  'color',
  'column-count',
  'column-fill',
  'column-gap',
  'column-rule',
  'column-rule-color',
  'column-rule-style',
  'column-rule-width',
  'column-span',
  'column-width',
  'columns',
  'content',
  'counter-increment',
  'counter-reset',
  'cursor',
  'direction',
  'display',
  'empty-cells',
  'filter',
  'flex',
  'flex-basis',
  'flex-direction',
  'flex-flow',
  'flex-grow',
  'flex-shrink',
  'flex-wrap',
  'float',
  'font',
  'font-display',
  'font-family',
  'font-feature-settings',
  'font-kerning',
  'font-language-override',
  'font-size',
  'font-size-adjust',
  'font-smoothing',
  'font-stretch',
  'font-style',
  'font-variant',
  'font-variant-ligatures',
  'font-variation-settings',
  'font-weight',
  'height',
  'hyphens',
  'icon',
  'image-orientation',
  'image-rendering',
  'image-resolution',
  'ime-mode',
  'inherit',
  'initial',
  'justify-content',
  'left',
  'letter-spacing',
  'line-height',
  'list-style',
  'list-style-image',
  'list-style-position',
  'list-style-type',
  'margin',
  'margin-bottom',
  'margin-left',
  'margin-right',
  'margin-top',
  'marks',
  'mask',
  'max-height',
  'max-width',
  'min-height',
  'min-width',
  'nav-down',
  'nav-index',
  'nav-left',
  'nav-right',
  'nav-up',
  'none',
  'normal',
  'object-fit',
  'object-position',
  'opacity',
  'order',
  'orphans',
  'outline',
  'outline-color',
  'outline-offset',
  'outline-style',
  'outline-width',
  'overflow',
  'overflow-wrap',
  'overflow-x',
  'overflow-y',
  'padding',
  'padding-bottom',
  'padding-left',
  'padding-right',
  'padding-top',
  'page-break-after',
  'page-break-before',
  'page-break-inside',
  'perspective',
  'perspective-origin',
  'pointer-events',
  'position',
  'quotes',
  'resize',
  'right',
  'src', // @font-face
  'tab-size',
  'table-layout',
  'text-align',
  'text-align-last',
  'text-decoration',
  'text-decoration-color',
  'text-decoration-line',
  'text-decoration-style',
  'text-indent',
  'text-overflow',
  'text-rendering',
  'text-shadow',
  'text-transform',
  'text-underline-position',
  'top',
  'transform',
  'transform-origin',
  'transform-style',
  'transition',
  'transition-delay',
  'transition-duration',
  'transition-property',
  'transition-timing-function',
  'unicode-bidi',
  'vertical-align',
  'visibility',
  'white-space',
  'widows',
  'width',
  'word-break',
  'word-spacing',
  'word-wrap',
  'z-index'
  // reverse makes sure longer attributes `font-weight` are matched fully
  // instead of getting false positives on say `font`
].reverse();

// some grammars use them all as a single group
const PSEUDO_SELECTORS = PSEUDO_CLASSES.concat(PSEUDO_ELEMENTS);

/*
Language: Less
Description: It's CSS, with just a little more.
Author:   Max Mikhailov <seven.phases.max@gmail.com>
Website: http://lesscss.org
Category: common, css
*/

/** @type LanguageFn */
function less(hljs) {
  const modes = MODES(hljs);
  const PSEUDO_SELECTORS$1 = PSEUDO_SELECTORS;

  const AT_MODIFIERS = "and or not only";
  const IDENT_RE = '[\\w-]+'; // yes, Less identifiers may begin with a digit
  const INTERP_IDENT_RE = '(' + IDENT_RE + '|@\\{' + IDENT_RE + '\\})';

  /* Generic Modes */

  const RULES = []; const VALUE_MODES = []; // forward def. for recursive modes

  const STRING_MODE = function(c) {
    return {
    // Less strings are not multiline (also include '~' for more consistent coloring of "escaped" strings)
      className: 'string',
      begin: '~?' + c + '.*?' + c
    };
  };

  const IDENT_MODE = function(name, begin, relevance) {
    return {
      className: name,
      begin: begin,
      relevance: relevance
    };
  };

  const AT_KEYWORDS = {
    $pattern: /[a-z-]+/,
    keyword: AT_MODIFIERS,
    attribute: MEDIA_FEATURES.join(" ")
  };

  const PARENS_MODE = {
    // used only to properly balance nested parens inside mixin call, def. arg list
    begin: '\\(',
    end: '\\)',
    contains: VALUE_MODES,
    keywords: AT_KEYWORDS,
    relevance: 0
  };

  // generic Less highlighter (used almost everywhere except selectors):
  VALUE_MODES.push(
    hljs.C_LINE_COMMENT_MODE,
    hljs.C_BLOCK_COMMENT_MODE,
    STRING_MODE("'"),
    STRING_MODE('"'),
    hljs.CSS_NUMBER_MODE, // fixme: it does not include dot for numbers like .5em :(
    {
      begin: '(url|data-uri)\\(',
      starts: {
        className: 'string',
        end: '[\\)\\n]',
        excludeEnd: true
      }
    },
    modes.HEXCOLOR,
    PARENS_MODE,
    IDENT_MODE('variable', '@@?' + IDENT_RE, 10),
    IDENT_MODE('variable', '@\\{' + IDENT_RE + '\\}'),
    IDENT_MODE('built_in', '~?`[^`]*?`'), // inline javascript (or whatever host language) *multiline* string
    { // @media features (it’s here to not duplicate things in AT_RULE_MODE with extra PARENS_MODE overriding):
      className: 'attribute',
      begin: IDENT_RE + '\\s*:',
      end: ':',
      returnBegin: true,
      excludeEnd: true
    },
    modes.IMPORTANT
  );

  const VALUE_WITH_RULESETS = VALUE_MODES.concat({
    begin: /\{/,
    end: /\}/,
    contains: RULES
  });

  const MIXIN_GUARD_MODE = {
    beginKeywords: 'when',
    endsWithParent: true,
    contains: [
      {
        beginKeywords: 'and not'
      }
    ].concat(VALUE_MODES) // using this form to override VALUE’s 'function' match
  };

  /* Rule-Level Modes */

  const RULE_MODE = {
    begin: INTERP_IDENT_RE + '\\s*:',
    returnBegin: true,
    end: /[;}]/,
    relevance: 0,
    contains: [
      {
        begin: /-(webkit|moz|ms|o)-/
      },
      {
        className: 'attribute',
        begin: '\\b(' + ATTRIBUTES.join('|') + ')\\b',
        end: /(?=:)/,
        starts: {
          endsWithParent: true,
          illegal: '[<=$]',
          relevance: 0,
          contains: VALUE_MODES
        }
      }
    ]
  };

  const AT_RULE_MODE = {
    className: 'keyword',
    begin: '@(import|media|charset|font-face|(-[a-z]+-)?keyframes|supports|document|namespace|page|viewport|host)\\b',
    starts: {
      end: '[;{}]',
      keywords: AT_KEYWORDS,
      returnEnd: true,
      contains: VALUE_MODES,
      relevance: 0
    }
  };

  // variable definitions and calls
  const VAR_RULE_MODE = {
    className: 'variable',
    variants: [
      // using more strict pattern for higher relevance to increase chances of Less detection.
      // this is *the only* Less specific statement used in most of the sources, so...
      // (we’ll still often loose to the css-parser unless there's '//' comment,
      // simply because 1 variable just can't beat 99 properties :)
      {
        begin: '@' + IDENT_RE + '\\s*:',
        relevance: 15
      },
      {
        begin: '@' + IDENT_RE
      }
    ],
    starts: {
      end: '[;}]',
      returnEnd: true,
      contains: VALUE_WITH_RULESETS
    }
  };

  const SELECTOR_MODE = {
    // first parse unambiguous selectors (i.e. those not starting with tag)
    // then fall into the scary lookahead-discriminator variant.
    // this mode also handles mixin definitions and calls
    variants: [
      {
        begin: '[\\.#:&\\[>]',
        end: '[;{}]' // mixin calls end with ';'
      },
      {
        begin: INTERP_IDENT_RE,
        end: /\{/
      }
    ],
    returnBegin: true,
    returnEnd: true,
    illegal: '[<=\'$"]',
    relevance: 0,
    contains: [
      hljs.C_LINE_COMMENT_MODE,
      hljs.C_BLOCK_COMMENT_MODE,
      MIXIN_GUARD_MODE,
      IDENT_MODE('keyword', 'all\\b'),
      IDENT_MODE('variable', '@\\{' + IDENT_RE + '\\}'), // otherwise it’s identified as tag
      {
        begin: '\\b(' + TAGS.join('|') + ')\\b',
        className: 'selector-tag'
      },
      IDENT_MODE('selector-tag', INTERP_IDENT_RE + '%?', 0), // '%' for more consistent coloring of @keyframes "tags"
      IDENT_MODE('selector-id', '#' + INTERP_IDENT_RE),
      IDENT_MODE('selector-class', '\\.' + INTERP_IDENT_RE, 0),
      IDENT_MODE('selector-tag', '&', 0),
      modes.ATTRIBUTE_SELECTOR_MODE,
      {
        className: 'selector-pseudo',
        begin: ':(' + PSEUDO_CLASSES.join('|') + ')'
      },
      {
        className: 'selector-pseudo',
        begin: '::(' + PSEUDO_ELEMENTS.join('|') + ')'
      },
      {
        begin: '\\(',
        end: '\\)',
        contains: VALUE_WITH_RULESETS
      }, // argument list of parametric mixins
      {
        begin: '!important'
      } // eat !important after mixin call or it will be colored as tag
    ]
  };

  const PSEUDO_SELECTOR_MODE = {
    begin: IDENT_RE + ':(:)?' + `(${PSEUDO_SELECTORS$1.join('|')})`,
    returnBegin: true,
    contains: [ SELECTOR_MODE ]
  };

  RULES.push(
    hljs.C_LINE_COMMENT_MODE,
    hljs.C_BLOCK_COMMENT_MODE,
    AT_RULE_MODE,
    VAR_RULE_MODE,
    PSEUDO_SELECTOR_MODE,
    RULE_MODE,
    SELECTOR_MODE
  );

  return {
    name: 'Less',
    case_insensitive: true,
    illegal: '[=>\'/<($"]',
    contains: RULES
  };
}

module.exports = less;