# frozen_string_literal: true require 'singleton' # See also `app/javascript/features/account/util/bio_metadata.js`. class FrontmatterHandler include Singleton # CONVENIENCE FUNCTIONS # def self.unirex(str) Regexp.new str, Regexp::MULTILINE end def self.rexstr(exp) '(?:' + exp.source + ')' end # CHARACTER CLASSES # DOCUMENT_START = /^/ DOCUMENT_END = /$/ ALLOWED_CHAR = # c-printable` in the YAML 1.2 spec. /[\t\n\r\u{20}-\u{7e}\u{85}\u{a0}-\u{d7ff}\u{e000}-\u{fffd}\u{10000}-\u{10ffff}]/u WHITE_SPACE = /[ \t]/ INDENTATION = / */ LINE_BREAK = /\r?\n|\r|<br\s*\/?>/ ESCAPE_CHAR = /[0abt\tnvfre "\/\\N_LP]/ HEXADECIMAL_CHARS = /[0-9a-fA-F]/ INDICATOR = /[-?:,\[\]{}&#*!|>'"%@`]/ FLOW_CHAR = /[,\[\]{}]/ # NEGATED CHARACTER CLASSES # NOT_WHITE_SPACE = unirex '(?!' + rexstr(WHITE_SPACE) + ').' NOT_LINE_BREAK = unirex '(?!' + rexstr(LINE_BREAK) + ').' NOT_INDICATOR = unirex '(?!' + rexstr(INDICATOR) + ').' NOT_FLOW_CHAR = unirex '(?!' + rexstr(FLOW_CHAR) + ').' NOT_ALLOWED_CHAR = unirex '(?!' + rexstr(ALLOWED_CHAR) + ').' # BASIC CONSTRUCTS # ANY_WHITE_SPACE = unirex rexstr(WHITE_SPACE) + '*' ANY_ALLOWED_CHARS = unirex rexstr(ALLOWED_CHAR) + '*' NEW_LINE = unirex( rexstr(ANY_WHITE_SPACE) + rexstr(LINE_BREAK) ) SOME_NEW_LINES = unirex( '(?:' + rexstr(ANY_WHITE_SPACE) + rexstr(LINE_BREAK) + ')+' ) POSSIBLE_STARTS = unirex( rexstr(DOCUMENT_START) + rexstr(/<p[^<>]*>/) + '?' ) POSSIBLE_ENDS = unirex( rexstr(SOME_NEW_LINES) + '|' + rexstr(DOCUMENT_END) + '|' + rexstr(/<\/p>/) ) CHARACTER_ESCAPE = unirex( rexstr(/\\/) + '(?:' + rexstr(ESCAPE_CHAR) + '|' + rexstr(/x/) + rexstr(HEXADECIMAL_CHARS) + '{2}' + '|' + rexstr(/u/) + rexstr(HEXADECIMAL_CHARS) + '{4}' + '|' + rexstr(/U/) + rexstr(HEXADECIMAL_CHARS) + '{8}' + ')' ) ESCAPED_CHAR = unirex( rexstr(/(?!["\\])/) + rexstr(NOT_LINE_BREAK) + '|' + rexstr(CHARACTER_ESCAPE) ) ANY_ESCAPED_CHARS = unirex( rexstr(ESCAPED_CHAR) + '*' ) ESCAPED_APOS = unirex( '(?=' + rexstr(NOT_LINE_BREAK) + ')' + rexstr(/[^']|''/) ) ANY_ESCAPED_APOS = unirex( rexstr(ESCAPED_APOS) + '*' ) FIRST_KEY_CHAR = unirex( '(?=' + rexstr(NOT_LINE_BREAK) + ')' + '(?=' + rexstr(NOT_WHITE_SPACE) + ')' + rexstr(NOT_INDICATOR) + '|' + rexstr(/[?:-]/) + '(?=' + rexstr(NOT_LINE_BREAK) + ')' + '(?=' + rexstr(NOT_WHITE_SPACE) + ')' + '(?=' + rexstr(NOT_FLOW_CHAR) + ')' ) FIRST_VALUE_CHAR = unirex( '(?=' + rexstr(NOT_LINE_BREAK) + ')' + '(?=' + rexstr(NOT_WHITE_SPACE) + ')' + rexstr(NOT_INDICATOR) + '|' + rexstr(/[?:-]/) + '(?=' + rexstr(NOT_LINE_BREAK) + ')' + '(?=' + rexstr(NOT_WHITE_SPACE) + ')' # Flow indicators are allowed in values. ) LATER_KEY_CHAR = unirex( rexstr(WHITE_SPACE) + '|' + '(?=' + rexstr(NOT_LINE_BREAK) + ')' + '(?=' + rexstr(NOT_WHITE_SPACE) + ')' + '(?=' + rexstr(NOT_FLOW_CHAR) + ')' + rexstr(/[^:#]#?/) + '|' + rexstr(/:/) + '(?=' + rexstr(NOT_WHITE_SPACE) + ')' ) LATER_VALUE_CHAR = unirex( rexstr(WHITE_SPACE) + '|' + '(?=' + rexstr(NOT_LINE_BREAK) + ')' + '(?=' + rexstr(NOT_WHITE_SPACE) + ')' + # Flow indicators are allowed in values. rexstr(/[^:#]#?/) + '|' + rexstr(/:/) + '(?=' + rexstr(NOT_WHITE_SPACE) + ')' ) # YAML CONSTRUCTS # YAML_START = unirex( rexstr(ANY_WHITE_SPACE) + rexstr(/---/) ) YAML_END = unirex( rexstr(ANY_WHITE_SPACE) + rexstr(/(?:---|\.\.\.)/) ) YAML_LOOKAHEAD = unirex( '(?=' + rexstr(YAML_START) + rexstr(ANY_ALLOWED_CHARS) + rexstr(NEW_LINE) + rexstr(YAML_END) + rexstr(POSSIBLE_ENDS) + ')' ) YAML_DOUBLE_QUOTE = unirex( rexstr(/"/) + rexstr(ANY_ESCAPED_CHARS) + rexstr(/"/) ) YAML_SINGLE_QUOTE = unirex( rexstr(/'/) + rexstr(ANY_ESCAPED_APOS) + rexstr(/'/) ) YAML_SIMPLE_KEY = unirex( rexstr(FIRST_KEY_CHAR) + rexstr(LATER_KEY_CHAR) + '*' ) YAML_SIMPLE_VALUE = unirex( rexstr(FIRST_VALUE_CHAR) + rexstr(LATER_VALUE_CHAR) + '*' ) YAML_KEY = unirex( rexstr(YAML_DOUBLE_QUOTE) + '|' + rexstr(YAML_SINGLE_QUOTE) + '|' + rexstr(YAML_SIMPLE_KEY) ) YAML_VALUE = unirex( rexstr(YAML_DOUBLE_QUOTE) + '|' + rexstr(YAML_SINGLE_QUOTE) + '|' + rexstr(YAML_SIMPLE_VALUE) ) YAML_SEPARATOR = unirex( rexstr(ANY_WHITE_SPACE) + ':' + rexstr(WHITE_SPACE) + rexstr(ANY_WHITE_SPACE) ) YAML_LINE = unirex( '(' + rexstr(YAML_KEY) + ')' + rexstr(YAML_SEPARATOR) + '(' + rexstr(YAML_VALUE) + ')' ) # FRONTMATTER REGEX # YAML_FRONTMATTER = unirex( rexstr(POSSIBLE_STARTS) + rexstr(YAML_LOOKAHEAD) + rexstr(YAML_START) + rexstr(SOME_NEW_LINES) + '(?:' + '(' + rexstr(INDENTATION) + ')' + rexstr(YAML_LINE) + rexstr(SOME_NEW_LINES) + '(?:' + '\\1' + rexstr(YAML_LINE) + rexstr(SOME_NEW_LINES) + '){0,4}' + ')?' + rexstr(YAML_END) + rexstr(POSSIBLE_ENDS) ) # SEARCHES # FIND_YAML_LINES = unirex( rexstr(NEW_LINE) + rexstr(INDENTATION) + rexstr(YAML_LINE) ) # STRING PROCESSING # def process_string(str) case str[0] when '"' str[1..-2] when "'" str[1..-2].gsub(/''/, "'") else str end end # BIO PROCESSING # def process_bio content result = { text: content.gsub(/"/, '"').gsub(/'/, "'"), metadata: [] } yaml = YAML_FRONTMATTER.match(result[:text]) return result unless yaml yaml = yaml[0] start = YAML_START =~ result[:text] ending = start + yaml.length - (YAML_START =~ yaml) result[:text][start..ending - 1] = '' metadata = nil index = 0 while metadata = FIND_YAML_LINES.match(yaml, index) do index = metadata.end(0) result[:metadata].push [ process_string(metadata[1]), process_string(metadata[2]) ] end return result end end