411 lines
		
	
	
		
			14 KiB
		
	
	
	
		
			JavaScript
		
	
	
	
	
	
			
		
		
	
	
			411 lines
		
	
	
		
			14 KiB
		
	
	
	
		
			JavaScript
		
	
	
	
	
	
/*
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`util/bio_metadata`
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===================
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>   For more information on the contents of this file, please contact:
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>
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>   - kibigo! [@kibi@glitch.social]
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This file provides two functions for dealing with bio metadata. The
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functions are:
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 -  __`processBio(content)` :__
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    Processes `content` to extract any frontmatter. The returned
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    object has two properties: `text`, which contains the text of
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    `content` sans-frontmatter, and `metadata`, which is an array
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    of key-value pairs (in two-element array format). If no
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    frontmatter was provided in `content`, then `metadata` will be
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    an empty array.
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 -  __`createBio(note, data)` :__
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    Reverses the process in `processBio()`; takes a `note` and an
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    array of two-element arrays (which should give keys and values)
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    and outputs a string containing a well-formed bio with
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    frontmatter.
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*/
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//  * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
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/*********************************************************************\
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                                       To my lovely code maintainers,
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  The syntax recognized by the Mastodon frontend for its bio metadata
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  feature is a subset of that provided by the YAML 1.2 specification.
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  In particular, Mastodon recognizes metadata which is provided as an
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  implicit YAML map, where each key-value pair takes up only a single
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  line (no multi-line values are permitted). To simplify the level of
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  processing required, Mastodon metadata frontmatter has been limited
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  to only allow those characters in the `c-printable` set, as defined
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  by the YAML 1.2 specification, instead of permitting those from the
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  `nb-json` characters inside double-quoted strings like YAML proper.
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    ¶ It is important to note that Mastodon only borrows the *syntax*
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  of YAML, not its semantics. This is to say, Mastodon won't make any
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  attempt to interpret the data it receives. `true` will not become a
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  boolean; `56` will not be interpreted as a number. Rather, each key
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  and every value will be read as a string, and as a string they will
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  remain. The order of the pairs is unchanged, and any duplicate keys
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  are preserved. However, YAML escape sequences will be replaced with
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  the proper interpretations according to the YAML 1.2 specification.
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    ¶ The implementation provided below interprets `<br>` as `\n` and
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  allows for an open <p> tag at the beginning of the bio. It replaces
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  the escaped character entities `'` and `"` with single or
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  double quotes, respectively, prior to processing. However, no other
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  escaped characters are replaced, not even those which might have an
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  impact on the syntax otherwise. These minor allowances are provided
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  because the Mastodon backend will insert these things automatically
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  into a bio before sending it through the API, so it is important we
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  account for them. Aside from this, the YAML frontmatter must be the
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  very first thing in the bio, leading with three consecutive hyphen-
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  minues (`---`), and ending with the same or, alternatively, instead
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  with three periods (`...`). No limits have been set with respect to
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  the number of characters permitted in the frontmatter, although one
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  should note that only limited space is provided for them in the UI.
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    ¶ The regular expression used to check the existence of, and then
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  process, the YAML frontmatter has been split into a number of small
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  components in the code below, in the vain hope that it will be much
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  easier to read and to maintain. I leave it to the future readers of
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  this code to determine the extent of my successes in this endeavor.
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                                       Sending love + warmth eternal,
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                                       - kibigo [@kibi@glitch.social]
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\*********************************************************************/
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/*  CONVENIENCE FUNCTIONS  */
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const unirex = str => new RegExp(str, 'u');
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const rexstr = exp => '(?:' + exp.source + ')';
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/*  CHARACTER CLASSES  */
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const DOCUMENT_START    = /^/;
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const DOCUMENT_END      = /$/;
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const ALLOWED_CHAR      =  //  `c-printable` in the YAML 1.2 spec.
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  /[\t\n\r\x20-\x7e\x85\xa0-\ud7ff\ue000-\ufffd\u{10000}-\u{10FFFF}]/u;
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const WHITE_SPACE       = /[ \t]/;
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const INDENTATION       = / */;  //  Indentation must be only spaces.
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const LINE_BREAK        = /\r?\n|\r|<br\s*\/?>/;
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const ESCAPE_CHAR       = /[0abt\tnvfre "\/\\N_LP]/;
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const HEXADECIMAL_CHARS = /[0-9a-fA-F]/;
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const INDICATOR         = /[-?:,[\]{}&#*!|>'"%@`]/;
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const FLOW_CHAR         = /[,[\]{}]/;
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/*  NEGATED CHARACTER CLASSES  */
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const NOT_WHITE_SPACE   = unirex('(?!' + rexstr(WHITE_SPACE) + ')[^]');
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const NOT_LINE_BREAK    = unirex('(?!' + rexstr(LINE_BREAK) + ')[^]');
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const NOT_INDICATOR     = unirex('(?!' + rexstr(INDICATOR) + ')[^]');
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const NOT_FLOW_CHAR     = unirex('(?!' + rexstr(FLOW_CHAR) + ')[^]');
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const NOT_ALLOWED_CHAR  = unirex(
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  '(?!' + rexstr(ALLOWED_CHAR) + ')[^]'
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);
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/*  BASIC CONSTRUCTS  */
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const ANY_WHITE_SPACE   = unirex(rexstr(WHITE_SPACE) + '*');
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const ANY_ALLOWED_CHARS = unirex(rexstr(ALLOWED_CHAR) + '*');
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const NEW_LINE          = unirex(
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  rexstr(ANY_WHITE_SPACE) + rexstr(LINE_BREAK)
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);
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const SOME_NEW_LINES    = unirex(
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  '(?:' + rexstr(ANY_WHITE_SPACE) + rexstr(LINE_BREAK) + ')+'
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);
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const POSSIBLE_STARTS   = unirex(
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  rexstr(DOCUMENT_START) + rexstr(/<p[^<>]*>/) + '?'
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);
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const POSSIBLE_ENDS     = unirex(
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  rexstr(SOME_NEW_LINES) + '|' +
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  rexstr(DOCUMENT_END) + '|' +
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  rexstr(/<\/p>/)
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);
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const CHARACTER_ESCAPE  = unirex(
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  rexstr(/\\/) +
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  '(?:' +
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    rexstr(ESCAPE_CHAR) + '|' +
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    rexstr(/x/) + rexstr(HEXADECIMAL_CHARS) + '{2}' + '|' +
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    rexstr(/u/) + rexstr(HEXADECIMAL_CHARS) + '{4}' + '|' +
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    rexstr(/U/) + rexstr(HEXADECIMAL_CHARS) + '{8}' +
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  ')'
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);
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const ESCAPED_CHAR      = unirex(
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  rexstr(/(?!["\\])/) + rexstr(NOT_LINE_BREAK) + '|' +
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  rexstr(CHARACTER_ESCAPE)
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);
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const ANY_ESCAPED_CHARS = unirex(
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  rexstr(ESCAPED_CHAR) + '*'
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);
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const ESCAPED_APOS      = unirex(
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  '(?=' + rexstr(NOT_LINE_BREAK) + ')' + rexstr(/[^']|''/)
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);
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const ANY_ESCAPED_APOS  = unirex(
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  rexstr(ESCAPED_APOS) + '*'
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);
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const FIRST_KEY_CHAR    = unirex(
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  '(?=' + rexstr(NOT_LINE_BREAK) + ')' +
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  '(?=' + rexstr(NOT_WHITE_SPACE) + ')' +
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  rexstr(NOT_INDICATOR) + '|' +
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  rexstr(/[?:-]/) +
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  '(?=' + rexstr(NOT_LINE_BREAK) + ')' +
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  '(?=' + rexstr(NOT_WHITE_SPACE) + ')' +
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  '(?=' + rexstr(NOT_FLOW_CHAR) + ')'
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);
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const FIRST_VALUE_CHAR  = unirex(
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  '(?=' + rexstr(NOT_LINE_BREAK) + ')' +
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  '(?=' + rexstr(NOT_WHITE_SPACE) + ')' +
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  rexstr(NOT_INDICATOR) + '|' +
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  rexstr(/[?:-]/) +
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  '(?=' + rexstr(NOT_LINE_BREAK) + ')' +
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  '(?=' + rexstr(NOT_WHITE_SPACE) + ')'
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  //  Flow indicators are allowed in values.
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);
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const LATER_KEY_CHAR    = unirex(
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  rexstr(WHITE_SPACE) + '|' +
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  '(?=' + rexstr(NOT_LINE_BREAK) + ')' +
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  '(?=' + rexstr(NOT_WHITE_SPACE) + ')' +
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  '(?=' + rexstr(NOT_FLOW_CHAR) + ')' +
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  rexstr(/[^:#]#?/) + '|' +
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  rexstr(/:/) + '(?=' + rexstr(NOT_WHITE_SPACE) + ')'
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);
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const LATER_VALUE_CHAR  = unirex(
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  rexstr(WHITE_SPACE) + '|' +
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  '(?=' + rexstr(NOT_LINE_BREAK) + ')' +
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  '(?=' + rexstr(NOT_WHITE_SPACE) + ')' +
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  //  Flow indicators are allowed in values.
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  rexstr(/[^:#]#?/) + '|' +
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  rexstr(/:/) + '(?=' + rexstr(NOT_WHITE_SPACE) + ')'
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);
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/*  YAML CONSTRUCTS  */
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const YAML_START        = unirex(
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  rexstr(ANY_WHITE_SPACE) + rexstr(/---/)
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);
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const YAML_END          = unirex(
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  rexstr(ANY_WHITE_SPACE) + rexstr(/(?:---|\.\.\.)/)
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);
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const YAML_LOOKAHEAD    = unirex(
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  '(?=' +
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    rexstr(YAML_START) +
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    rexstr(ANY_ALLOWED_CHARS) + rexstr(NEW_LINE) +
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    rexstr(YAML_END) + rexstr(POSSIBLE_ENDS) +
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  ')'
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);
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const YAML_DOUBLE_QUOTE = unirex(
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  rexstr(/"/) + rexstr(ANY_ESCAPED_CHARS) + rexstr(/"/)
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);
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const YAML_SINGLE_QUOTE = unirex(
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  rexstr(/'/) + rexstr(ANY_ESCAPED_APOS) + rexstr(/'/)
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);
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const YAML_SIMPLE_KEY   = unirex(
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  rexstr(FIRST_KEY_CHAR) + rexstr(LATER_KEY_CHAR) + '*'
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);
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const YAML_SIMPLE_VALUE = unirex(
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  rexstr(FIRST_VALUE_CHAR) + rexstr(LATER_VALUE_CHAR) + '*'
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);
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const YAML_KEY          = unirex(
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  rexstr(YAML_DOUBLE_QUOTE) + '|' +
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  rexstr(YAML_SINGLE_QUOTE) + '|' +
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  rexstr(YAML_SIMPLE_KEY)
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);
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const YAML_VALUE        = unirex(
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  rexstr(YAML_DOUBLE_QUOTE) + '|' +
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  rexstr(YAML_SINGLE_QUOTE) + '|' +
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  rexstr(YAML_SIMPLE_VALUE)
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);
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const YAML_SEPARATOR    = unirex(
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  rexstr(ANY_WHITE_SPACE) +
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  ':' + rexstr(WHITE_SPACE) +
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  rexstr(ANY_WHITE_SPACE)
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);
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const YAML_LINE         = unirex(
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  '(' + rexstr(YAML_KEY) + ')' +
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  rexstr(YAML_SEPARATOR) +
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  '(' + rexstr(YAML_VALUE) + ')'
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);
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/*  FRONTMATTER REGEX  */
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const YAML_FRONTMATTER  = unirex(
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  rexstr(POSSIBLE_STARTS) +
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  rexstr(YAML_LOOKAHEAD) +
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  rexstr(YAML_START) + rexstr(SOME_NEW_LINES) +
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  '(?:' +
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    '(' + rexstr(INDENTATION) + ')' +
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    rexstr(YAML_LINE) + rexstr(SOME_NEW_LINES) +
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    '(?:' +
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      '\\1' + rexstr(YAML_LINE) + rexstr(SOME_NEW_LINES) +
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    '){0,4}' +
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  ')?' +
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  rexstr(YAML_END) + rexstr(POSSIBLE_ENDS)
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);
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/*  SEARCHES  */
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const FIND_YAML_LINES   = unirex(
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  rexstr(NEW_LINE) + rexstr(INDENTATION) + rexstr(YAML_LINE)
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);
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/*  STRING PROCESSING  */
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function processString(str) {
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  switch (str.charAt(0)) {
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  case '"':
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    return str
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      .substring(1, str.length - 1)
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      .replace(/\\0/g, '\x00')
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      .replace(/\\a/g, '\x07')
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      .replace(/\\b/g, '\x08')
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      .replace(/\\t/g, '\x09')
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      .replace(/\\\x09/g, '\x09')
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      .replace(/\\n/g, '\x0a')
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      .replace(/\\v/g, '\x0b')
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      .replace(/\\f/g, '\x0c')
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      .replace(/\\r/g, '\x0d')
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      .replace(/\\e/g, '\x1b')
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      .replace(/\\ /g, '\x20')
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      .replace(/\\"/g, '\x22')
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      .replace(/\\\//g, '\x2f')
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      .replace(/\\\\/g, '\x5c')
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      .replace(/\\N/g, '\x85')
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      .replace(/\\_/g, '\xa0')
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      .replace(/\\L/g, '\u2028')
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      .replace(/\\P/g, '\u2029')
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      .replace(
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        new RegExp(
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          unirex(
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            rexstr(/\\x/) + '(' + rexstr(HEXADECIMAL_CHARS) + '{2})'
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          ), 'gu'
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        ), (_, n) => String.fromCodePoint('0x' + n)
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      )
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      .replace(
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        new RegExp(
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          unirex(
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            rexstr(/\\u/) + '(' + rexstr(HEXADECIMAL_CHARS) + '{4})'
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          ), 'gu'
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        ), (_, n) => String.fromCodePoint('0x' + n)
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      )
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      .replace(
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        new RegExp(
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          unirex(
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            rexstr(/\\U/) + '(' + rexstr(HEXADECIMAL_CHARS) + '{8})'
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          ), 'gu'
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        ), (_, n) => String.fromCodePoint('0x' + n)
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      );
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  case '\'':
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    return str
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      .substring(1, str.length - 1)
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      .replace(/''/g, '\'');
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  default:
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    return str;
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  }
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}
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/*  BIO PROCESSING  */
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export function processBio(content) {
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  content = content.replace(/"/g, '"').replace(/'/g, '\'');
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  let result = {
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    text: content,
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    metadata: [],
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  };
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  let yaml = content.match(YAML_FRONTMATTER);
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  if (!yaml) return result;
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  else yaml = yaml[0];
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  let start = content.search(YAML_START);
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  let end = start + yaml.length - yaml.search(YAML_START);
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  result.text = content.substr(0, start) + content.substr(end);
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  let metadata = null;
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  let query = new RegExp(FIND_YAML_LINES, 'g');
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  while ((metadata = query.exec(yaml))) {
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    result.metadata.push([
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      processString(metadata[1]),
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      processString(metadata[2]),
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    ]);
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  }
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  return result;
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}
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/*  BIO CREATION  */
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export function createBio(note, data) {
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  if (!note) note = '';
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  let frontmatter = '';
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  if ((data && data.length) || note.match(/^\s*---\s+/)) {
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    if (!data) frontmatter = '---\n...\n';
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    else {
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      frontmatter += '---\n';
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      for (let i = 0; i < data.length; i++) {
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        let key = '' + data[i][0];
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        let val = '' + data[i][1];
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        //  Key processing
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        if (key === (key.match(YAML_SIMPLE_KEY) || [])[0]) /*  do nothing  */;
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        else if (key.indexOf('\'') === -1 && key === (key.match(ANY_ESCAPED_APOS) || [])[0]) key = '\'' + key + '\'';
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        else {
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          key = key
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            .replace(/\x00/g, '\\0')
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            .replace(/\x07/g, '\\a')
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            .replace(/\x08/g, '\\b')
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            .replace(/\x0a/g, '\\n')
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            .replace(/\x0b/g, '\\v')
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            .replace(/\x0c/g, '\\f')
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            .replace(/\x0d/g, '\\r')
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            .replace(/\x1b/g, '\\e')
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            .replace(/\x22/g, '\\"')
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            .replace(/\x5c/g, '\\\\');
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          let badchars = key.match(
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            new RegExp(rexstr(NOT_ALLOWED_CHAR), 'gu')
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          ) || [];
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          for (let j = 0; j < badchars.length; j++) {
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            key = key.replace(
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              badchars[i],
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              '\\u' + badchars[i].codePointAt(0).toLocaleString('en', {
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                useGrouping: false,
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                minimumIntegerDigits: 4,
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              })
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            );
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          }
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          key = '"' + key + '"';
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        }
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        //  Value processing
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        if (val === (val.match(YAML_SIMPLE_VALUE) || [])[0]) /*  do nothing  */;
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        else if (val.indexOf('\'') === -1 && val === (val.match(ANY_ESCAPED_APOS) || [])[0]) val = '\'' + val + '\'';
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						|
        else {
 | 
						|
          val = val
 | 
						|
            .replace(/\x00/g, '\\0')
 | 
						|
            .replace(/\x07/g, '\\a')
 | 
						|
            .replace(/\x08/g, '\\b')
 | 
						|
            .replace(/\x0a/g, '\\n')
 | 
						|
            .replace(/\x0b/g, '\\v')
 | 
						|
            .replace(/\x0c/g, '\\f')
 | 
						|
            .replace(/\x0d/g, '\\r')
 | 
						|
            .replace(/\x1b/g, '\\e')
 | 
						|
            .replace(/\x22/g, '\\"')
 | 
						|
            .replace(/\x5c/g, '\\\\');
 | 
						|
          let badchars = val.match(
 | 
						|
            new RegExp(rexstr(NOT_ALLOWED_CHAR), 'gu')
 | 
						|
          ) || [];
 | 
						|
          for (let j = 0; j < badchars.length; j++) {
 | 
						|
            val = val.replace(
 | 
						|
              badchars[i],
 | 
						|
              '\\u' + badchars[i].codePointAt(0).toLocaleString('en', {
 | 
						|
                useGrouping: false,
 | 
						|
                minimumIntegerDigits: 4,
 | 
						|
              })
 | 
						|
            );
 | 
						|
          }
 | 
						|
          val = '"' + val + '"';
 | 
						|
        }
 | 
						|
 | 
						|
        frontmatter += key + ': ' + val + '\n';
 | 
						|
      }
 | 
						|
      frontmatter += '...\n';
 | 
						|
    }
 | 
						|
  }
 | 
						|
  return frontmatter + note;
 | 
						|
}
 |