src/parser/generated/regexp-tree.js
function NamedGroupRefOrChars(text, textLoc) {
  const groupName = text.slice(3, -1);

  if (namedGroups.hasOwnProperty(groupName)) {
    return Node({
      type: 'Backreference',
      kind: 'name',
      number: namedGroups[groupName],
      reference: groupName,
    }, textLoc);
  }

  // Else `\k<foo>` should be parsed as a list of `Char`s.
  // This is really a 0.01% edge case, but we should handle it.

  let startOffset = null;
  let startLine = null;
  let endLine = null;
  let startColumn = null;

  if (textLoc) {
    startOffset = textLoc.startOffset;
    startLine = textLoc.startLine;
    endLine = textLoc.endLine;
    startColumn = textLoc.startColumn;
  }

  const charRe = /^[\w$<>]/;
  let loc;

  const chars = [
    // Init to first \k, taking 2 symbols.
    Char(
      text.slice(1, 2),
      'simple',
      startOffset
        ? {
          startLine,
          endLine,
          startColumn,
          startOffset,
          endOffset: startOffset += 2,
          endColumn: startColumn += 2,
        }
        : null
    ),
  ];

  // For \k
  chars[0].escaped = true;

  // Other symbols.
  text = text.slice(2);

  while (text.length > 0) {
    let matched = null;

    // Unicode, \u003B or \u{003B}
    if ((matched = text.match(uRe)) || (matched = text.match(ucpRe))) {
      if (startOffset) {
        loc = {
          startLine,
          endLine,
          startColumn,
          startOffset,
          endOffset: (startOffset += matched[0].length),
          endColumn: (startColumn += matched[0].length),
        };
      }
      chars.push(Char(matched[0], 'unicode', loc));
      text = text.slice(matched[0].length);
    }

    // Simple char.
    else if ((matched = text.match(charRe))) {
      if (startOffset) {
        loc = {
          startLine,
          endLine,
          startColumn,
          startOffset,
          endOffset: ++startOffset,
          endColumn: ++startColumn,
        };
      }
      chars.push(Char(matched[0], 'simple', loc));
      text = text.slice(1);
    }
  }

  return chars;
}
function NamedGroupRefOrChars(text, textLoc) {
  const groupName = text.slice(3, -1);

  if (namedGroups.hasOwnProperty(groupName)) {
    return Node({
      type: 'Backreference',
      kind: 'name',
      number: namedGroups[groupName],
      reference: groupName,
    }, textLoc);
  }

  // Else `\k<foo>` should be parsed as a list of `Char`s.
  // This is really a 0.01% edge case, but we should handle it.

  let startOffset = null;
  let startLine = null;
  let endLine = null;
  let startColumn = null;

  if (textLoc) {
    startOffset = textLoc.startOffset;
    startLine = textLoc.startLine;
    endLine = textLoc.endLine;
    startColumn = textLoc.startColumn;
  }

  const charRe = /^[\w$<>]/;
  let loc;

  const chars = [
    // Init to first \k, taking 2 symbols.
    Char(
      text.slice(1, 2),
      'simple',
      startOffset
        ? {
          startLine,
          endLine,
          startColumn,
          startOffset,
          endOffset: startOffset += 2,
          endColumn: startColumn += 2,
        }
        : null
    ),
  ];

  // For \k
  chars[0].escaped = true;

  // Other symbols.
  text = text.slice(2);

  while (text.length > 0) {
    let matched = null;

    // Unicode, \u003B or \u{003B}
    if ((matched = text.match(uRe)) || (matched = text.match(ucpRe))) {
      if (startOffset) {
        loc = {
          startLine,
          endLine,
          startColumn,
          startOffset,
          endOffset: (startOffset += matched[0].length),
          endColumn: (startColumn += matched[0].length),
        };
      }
      chars.push(Char(matched[0], 'unicode', loc));
      text = text.slice(matched[0].length);
    }

    // Simple char.
    else if ((matched = text.match(charRe))) {
      if (startOffset) {
        loc = {
          startLine,
          endLine,
          startColumn,
          startOffset,
          endOffset: ++startOffset,
          endColumn: ++startColumn,
        };
      }
      chars.push(Char(matched[0], 'simple', loc));
      text = text.slice(1);
    }
  }

  return chars;
}
function NamedGroupRefOrChars ( text , textLoc ) { const groupName = text . slice ( 3 , - 1 ) ; if ( namedGroups . hasOwnProperty ( groupName ) ) { return Node ( { type : 'Backreference' , kind : 'name' , number : namedGroups [ groupName ] , reference : groupName , } , textLoc ) ; } // Else `\k<foo>` should be parsed as a list of `Char`s. // This is really a 0.01% edge case, but we should handle it. let startOffset = null ; let startLine = null ; let endLine = null ; let startColumn = null ; if ( textLoc ) { startOffset = textLoc . startOffset ; startLine = textLoc . startLine ; endLine = textLoc . endLine ; startColumn = textLoc . startColumn ; } const charRe = / ^[\w$<>] / ; let loc ; const chars = [ // Init to first \k, taking 2 symbols. Char ( text . slice ( 1 , 2 ) , 'simple' , startOffset ? { startLine , endLine , startColumn , startOffset , endOffset : startOffset += 2 , endColumn : startColumn += 2 , } : null ) , ] ; // For \k chars [ 0 ] . escaped = true ; // Other symbols. text = text . slice ( 2 ) ; while ( text . length > 0 ) { let matched = null ; // Unicode, \u003B or \u{003B} if ( ( matched = text . match ( uRe ) ) || ( matched = text . match ( ucpRe ) ) ) { if ( startOffset ) { loc = { startLine , endLine , startColumn , startOffset , endOffset : ( startOffset += matched [ 0 ] . length ) , endColumn : ( startColumn += matched [ 0 ] . length ) , } ; } chars . push ( Char ( matched [ 0 ] , 'unicode' , loc ) ) ; text = text . slice ( matched [ 0 ] . length ) ; } // Simple char. else if ( ( matched = text . match ( charRe ) ) ) { if ( startOffset ) { loc = { startLine , endLine , startColumn , startOffset , endOffset : ++ startOffset , endColumn : ++ startColumn , } ; } chars . push ( Char ( matched [ 0 ] , 'simple' , loc ) ) ; text = text . slice ( 1 ) ; } } return chars ; }
Extracts from `\k<foo>` pattern either a backreference
to a named capturing group (if it presents), or parses it
as a list of char: `\k`, `<`, `f`, etc.
Extracts from \ k<foo > pattern either a backreference to a named capturing group ( if it presents ) or parses it as a list of char : \ k < f etc .