# <!-- rdoc-file=ext/strscan/strscan.c -->
# StringScanner provides for lexical scanning operations on a String.  Here is
# an example of its usage:
#
#     require 'strscan'
#
#     s = StringScanner.new('This is an example string')
#     s.eos?               # -> false
#
#     p s.scan(/\w+/)      # -> "This"
#     p s.scan(/\w+/)      # -> nil
#     p s.scan(/\s+/)      # -> " "
#     p s.scan(/\s+/)      # -> nil
#     p s.scan(/\w+/)      # -> "is"
#     s.eos?               # -> false
#
#     p s.scan(/\s+/)      # -> " "
#     p s.scan(/\w+/)      # -> "an"
#     p s.scan(/\s+/)      # -> " "
#     p s.scan(/\w+/)      # -> "example"
#     p s.scan(/\s+/)      # -> " "
#     p s.scan(/\w+/)      # -> "string"
#     s.eos?               # -> true
#
#     p s.scan(/\s+/)      # -> nil
#     p s.scan(/\w+/)      # -> nil
#
# Scanning a string means remembering the position of a *scan pointer*, which is
# just an index.  The point of scanning is to move forward a bit at a time, so
# matches are sought after the scan pointer; usually immediately after it.
#
# Given the string "test string", here are the pertinent scan pointer positions:
#
#       t e s t   s t r i n g
#     0 1 2 ...             1
#                           0
#
# When you #scan for a pattern (a regular expression), the match must occur at
# the character after the scan pointer.  If you use #scan_until, then the match
# can occur anywhere after the scan pointer.  In both cases, the scan pointer
# moves *just beyond* the last character of the match, ready to scan again from
# the next character onwards.  This is demonstrated by the example above.
#
# ## Method Categories
#
# There are other methods besides the plain scanners.  You can look ahead in the
# string without actually scanning.  You can access the most recent match. You
# can modify the string being scanned, reset or terminate the scanner, find out
# or change the position of the scan pointer, skip ahead, and so on.
#
# ### Advancing the Scan Pointer
#
# *   #getch
# *   #get_byte
# *   #scan
# *   #scan_until
# *   #skip
# *   #skip_until
#
#
# ### Looking Ahead
#
# *   #check
# *   #check_until
# *   #exist?
# *   #match?
# *   #peek
#
#
# ### Finding Where we Are
#
# *   #beginning_of_line? (`#bol?`)
# *   #eos?
# *   #rest?
# *   #rest_size
# *   #pos
#
#
# ### Setting Where we Are
#
# *   #reset
# *   #terminate
# *   #pos=
#
#
# ### Match Data
#
# *   #matched
# *   #matched?
# *   #matched_size
# *   `#[]`
# *   #pre_match
# *   #post_match
#
#
# ### Miscellaneous
#
# *   `<<`
# *   #concat
# *   #string
# *   #string=
# *   #unscan
#
#
# There are aliases to several of the methods.
#
class StringScanner
  # <!--
  #   rdoc-file=ext/strscan/strscan.c
  #   - StringScanner.must_C_version
  # -->
  # This method is defined for backward compatibility.
  #
  def self.must_C_version: () -> self

  # <!-- rdoc-file=ext/strscan/strscan.c -->
  # Appends `str` to the string being scanned. This method does not affect scan
  # pointer.
  #
  #     s = StringScanner.new("Fri Dec 12 1975 14:39")
  #     s.scan(/Fri /)
  #     s << " +1000 GMT"
  #     s.string            # -> "Fri Dec 12 1975 14:39 +1000 GMT"
  #     s.scan(/Dec/)       # -> "Dec"
  #
  def <<: (String) -> self

  # <!--
  #   rdoc-file=ext/strscan/strscan.c
  #   - [](n)
  # -->
  # Returns the n-th subgroup in the most recent match.
  #
  #     s = StringScanner.new("Fri Dec 12 1975 14:39")
  #     s.scan(/(\w+) (\w+) (\d+) /)       # -> "Fri Dec 12 "
  #     s[0]                               # -> "Fri Dec 12 "
  #     s[1]                               # -> "Fri"
  #     s[2]                               # -> "Dec"
  #     s[3]                               # -> "12"
  #     s.post_match                       # -> "1975 14:39"
  #     s.pre_match                        # -> ""
  #
  #     s.reset
  #     s.scan(/(?<wday>\w+) (?<month>\w+) (?<day>\d+) /)       # -> "Fri Dec 12 "
  #     s[0]                               # -> "Fri Dec 12 "
  #     s[1]                               # -> "Fri"
  #     s[2]                               # -> "Dec"
  #     s[3]                               # -> "12"
  #     s[:wday]                           # -> "Fri"
  #     s[:month]                          # -> "Dec"
  #     s[:day]                            # -> "12"
  #     s.post_match                       # -> "1975 14:39"
  #     s.pre_match                        # -> ""
  #
  def []: (Integer) -> String?

  # <!--
  #   rdoc-file=ext/strscan/strscan.c
  #   - beginning_of_line?()
  # -->
  # Returns `true` if and only if the scan pointer is at the beginning of the
  # line.
  #
  #     s = StringScanner.new("test\ntest\n")
  #     s.bol?           # => true
  #     s.scan(/te/)
  #     s.bol?           # => false
  #     s.scan(/st\n/)
  #     s.bol?           # => true
  #     s.terminate
  #     s.bol?           # => true
  #
  def beginning_of_line?: () -> bool

  alias bol? beginning_of_line?

  # <!--
  #   rdoc-file=ext/strscan/strscan.c
  #   - captures
  # -->
  # Returns the subgroups in the most recent match (not including the full match).
  # If nothing was priorly matched, it returns nil.
  #
  #     s = StringScanner.new("Fri Dec 12 1975 14:39")
  #     s.scan(/(\w+) (\w+) (\d+) (1980)?/)       # -> "Fri Dec 12 "
  #     s.captures                                # -> ["Fri", "Dec", "12", nil]
  #     s.scan(/(\w+) (\w+) (\d+) (1980)?/)       # -> nil
  #     s.captures                                # -> nil
  #
  def captures: () -> Array[String]?

  # <!--
  #   rdoc-file=ext/strscan/strscan.c
  #   - charpos()
  # -->
  # Returns the character position of the scan pointer.  In the 'reset' position,
  # this value is zero.  In the 'terminated' position (i.e. the string is
  # exhausted), this value is the size of the string.
  #
  # In short, it's a 0-based index into the string.
  #
  #     s = StringScanner.new("abc\u00e4def\u00f6ghi")
  #     s.charpos                # -> 0
  #     s.scan_until(/\u00e4/)   # -> "abc\u00E4"
  #     s.pos                    # -> 5
  #     s.charpos                # -> 4
  #
  def charpos: () -> Integer

  # <!--
  #   rdoc-file=ext/strscan/strscan.c
  #   - check(pattern)
  # -->
  # This returns the value that #scan would return, without advancing the scan
  # pointer.  The match register is affected, though.
  #
  #     s = StringScanner.new("Fri Dec 12 1975 14:39")
  #     s.check /Fri/               # -> "Fri"
  #     s.pos                       # -> 0
  #     s.matched                   # -> "Fri"
  #     s.check /12/                # -> nil
  #     s.matched                   # -> nil
  #
  # Mnemonic: it "checks" to see whether a #scan will return a value.
  #
  def check: (Regexp) -> String?

  # <!--
  #   rdoc-file=ext/strscan/strscan.c
  #   - check_until(pattern)
  # -->
  # This returns the value that #scan_until would return, without advancing the
  # scan pointer.  The match register is affected, though.
  #
  #     s = StringScanner.new("Fri Dec 12 1975 14:39")
  #     s.check_until /12/          # -> "Fri Dec 12"
  #     s.pos                       # -> 0
  #     s.matched                   # -> 12
  #
  # Mnemonic: it "checks" to see whether a #scan_until will return a value.
  #
  def check_until: (Regexp) -> String

  # <!--
  #   rdoc-file=ext/strscan/strscan.c
  #   - clear()
  # -->
  # Equivalent to #terminate. This method is obsolete; use #terminate instead.
  #
  def clear: () -> void

  # <!--
  #   rdoc-file=ext/strscan/strscan.c
  #   - concat(str)
  #   - <<(str)
  # -->
  # Appends `str` to the string being scanned. This method does not affect scan
  # pointer.
  #
  #     s = StringScanner.new("Fri Dec 12 1975 14:39")
  #     s.scan(/Fri /)
  #     s << " +1000 GMT"
  #     s.string            # -> "Fri Dec 12 1975 14:39 +1000 GMT"
  #     s.scan(/Dec/)       # -> "Dec"
  #
  alias concat <<

  # <!--
  #   rdoc-file=ext/strscan/strscan.c
  #   - empty?()
  # -->
  # Equivalent to #eos?. This method is obsolete, use #eos? instead.
  #
  def empty?: () -> bool

  # <!--
  #   rdoc-file=ext/strscan/strscan.c
  #   - eos?()
  # -->
  # Returns `true` if the scan pointer is at the end of the string.
  #
  #     s = StringScanner.new('test string')
  #     p s.eos?          # => false
  #     s.scan(/test/)
  #     p s.eos?          # => false
  #     s.terminate
  #     p s.eos?          # => true
  #
  def eos?: () -> bool

  # <!--
  #   rdoc-file=ext/strscan/strscan.c
  #   - exist?(pattern)
  # -->
  # Looks *ahead* to see if the `pattern` exists *anywhere* in the string, without
  # advancing the scan pointer.  This predicates whether a #scan_until will return
  # a value.
  #
  #     s = StringScanner.new('test string')
  #     s.exist? /s/            # -> 3
  #     s.scan /test/           # -> "test"
  #     s.exist? /s/            # -> 2
  #     s.exist? /e/            # -> nil
  #
  def exist?: (Regexp) -> Integer?

  # <!--
  #   rdoc-file=ext/strscan/strscan.c
  #   - scanner.fixed_anchor? -> true or false
  # -->
  # Whether `scanner` uses fixed anchor mode or not.
  #
  # If fixed anchor mode is used, `\A` always matches the beginning of the string.
  # Otherwise, `\A` always matches the current position.
  #
  def fixed_anchor?: () -> bool

  # <!--
  #   rdoc-file=ext/strscan/strscan.c
  #   - get_byte()
  # -->
  # Scans one byte and returns it. This method is not multibyte character
  # sensitive. See also: #getch.
  #
  #     s = StringScanner.new('ab')
  #     s.get_byte         # => "a"
  #     s.get_byte         # => "b"
  #     s.get_byte         # => nil
  #
  #     s = StringScanner.new("\244\242".force_encoding("euc-jp"))
  #     s.get_byte         # => "\xA4"
  #     s.get_byte         # => "\xA2"
  #     s.get_byte         # => nil
  #
  def get_byte: () -> String?

  # <!--
  #   rdoc-file=ext/strscan/strscan.c
  #   - getbyte()
  # -->
  # Equivalent to #get_byte. This method is obsolete; use #get_byte instead.
  #
  def getbyte: () -> String?

  # <!--
  #   rdoc-file=ext/strscan/strscan.c
  #   - getch()
  # -->
  # Scans one character and returns it. This method is multibyte character
  # sensitive.
  #
  #     s = StringScanner.new("ab")
  #     s.getch           # => "a"
  #     s.getch           # => "b"
  #     s.getch           # => nil
  #
  #     s = StringScanner.new("\244\242".force_encoding("euc-jp"))
  #     s.getch           # => "\x{A4A2}"   # Japanese hira-kana "A" in EUC-JP
  #     s.getch           # => nil
  #
  def getch: () -> String?

  # <!--
  #   rdoc-file=ext/strscan/strscan.c
  #   - inspect()
  # -->
  # Returns a string that represents the StringScanner object, showing:
  # *   the current position
  # *   the size of the string
  # *   the characters surrounding the scan pointer
  #
  #     s = StringScanner.new("Fri Dec 12 1975 14:39") s.inspect            # ->
  #     '#<StringScanner 0/21 @ "Fri D...">' s.scan_until /12/    # -> "Fri Dec
  #     12" s.inspect            # -> '#<StringScanner 10/21 "...ec 12" @ "
  #     1975...">'
  #
  def inspect: () -> String

  # <!--
  #   rdoc-file=ext/strscan/strscan.c
  #   - match?(pattern)
  # -->
  # Tests whether the given `pattern` is matched from the current scan pointer.
  # Returns the length of the match, or `nil`.  The scan pointer is not advanced.
  #
  #     s = StringScanner.new('test string')
  #     p s.match?(/\w+/)   # -> 4
  #     p s.match?(/\w+/)   # -> 4
  #     p s.match?("test")  # -> 4
  #     p s.match?(/\s+/)   # -> nil
  #
  def match?: (Regexp) -> Integer?

  # <!--
  #   rdoc-file=ext/strscan/strscan.c
  #   - matched()
  # -->
  # Returns the last matched string.
  #
  #     s = StringScanner.new('test string')
  #     s.match?(/\w+/)     # -> 4
  #     s.matched           # -> "test"
  #
  def matched: () -> String?

  # <!--
  #   rdoc-file=ext/strscan/strscan.c
  #   - matched?()
  # -->
  # Returns `true` if and only if the last match was successful.
  #
  #     s = StringScanner.new('test string')
  #     s.match?(/\w+/)     # => 4
  #     s.matched?          # => true
  #     s.match?(/\d+/)     # => nil
  #     s.matched?          # => false
  #
  def matched?: () -> bool

  # <!--
  #   rdoc-file=ext/strscan/strscan.c
  #   - matched_size()
  # -->
  # Returns the size of the most recent match in bytes, or `nil` if there was no
  # recent match.  This is different than `matched.size`, which will return the
  # size in characters.
  #
  #     s = StringScanner.new('test string')
  #     s.check /\w+/           # -> "test"
  #     s.matched_size          # -> 4
  #     s.check /\d+/           # -> nil
  #     s.matched_size          # -> nil
  #
  def matched_size: () -> Integer?

  # <!--
  #   rdoc-file=ext/strscan/strscan.c
  #   - peek(len)
  # -->
  # Extracts a string corresponding to `string[pos,len]`, without advancing the
  # scan pointer.
  #
  #     s = StringScanner.new('test string')
  #     s.peek(7)          # => "test st"
  #     s.peek(7)          # => "test st"
  #
  def peek: (Integer) -> String

  # <!--
  #   rdoc-file=ext/strscan/strscan.c
  #   - peep(p1)
  # -->
  # Equivalent to #peek. This method is obsolete; use #peek instead.
  #
  def peep: (Integer) -> String

  # <!-- rdoc-file=ext/strscan/strscan.c -->
  # Returns the byte position of the scan pointer.  In the 'reset' position, this
  # value is zero.  In the 'terminated' position (i.e. the string is exhausted),
  # this value is the bytesize of the string.
  #
  # In short, it's a 0-based index into bytes of the string.
  #
  #     s = StringScanner.new('test string')
  #     s.pos               # -> 0
  #     s.scan_until /str/  # -> "test str"
  #     s.pos               # -> 8
  #     s.terminate         # -> #<StringScanner fin>
  #     s.pos               # -> 11
  #
  def pointer: () -> Integer

  # <!-- rdoc-file=ext/strscan/strscan.c -->
  # Sets the byte position of the scan pointer.
  #
  #     s = StringScanner.new('test string')
  #     s.pos = 7            # -> 7
  #     s.rest               # -> "ring"
  #
  def pointer=: (Integer) -> Integer

  # <!--
  #   rdoc-file=ext/strscan/strscan.c
  #   - pos()
  # -->
  # Returns the byte position of the scan pointer.  In the 'reset' position, this
  # value is zero.  In the 'terminated' position (i.e. the string is exhausted),
  # this value is the bytesize of the string.
  #
  # In short, it's a 0-based index into bytes of the string.
  #
  #     s = StringScanner.new('test string')
  #     s.pos               # -> 0
  #     s.scan_until /str/  # -> "test str"
  #     s.pos               # -> 8
  #     s.terminate         # -> #<StringScanner fin>
  #     s.pos               # -> 11
  #
  def pos: () -> Integer

  # <!--
  #   rdoc-file=ext/strscan/strscan.c
  #   - pos=(n)
  # -->
  # Sets the byte position of the scan pointer.
  #
  #     s = StringScanner.new('test string')
  #     s.pos = 7            # -> 7
  #     s.rest               # -> "ring"
  #
  def pos=: (Integer) -> Integer

  # <!--
  #   rdoc-file=ext/strscan/strscan.c
  #   - post_match()
  # -->
  # Returns the ***post**-match* (in the regular expression sense) of the last
  # scan.
  #
  #     s = StringScanner.new('test string')
  #     s.scan(/\w+/)           # -> "test"
  #     s.scan(/\s+/)           # -> " "
  #     s.pre_match             # -> "test"
  #     s.post_match            # -> "string"
  #
  def post_match: () -> String

  # <!--
  #   rdoc-file=ext/strscan/strscan.c
  #   - pre_match()
  # -->
  # Returns the ***pre**-match* (in the regular expression sense) of the last
  # scan.
  #
  #     s = StringScanner.new('test string')
  #     s.scan(/\w+/)           # -> "test"
  #     s.scan(/\s+/)           # -> " "
  #     s.pre_match             # -> "test"
  #     s.post_match            # -> "string"
  #
  def pre_match: () -> String

  # <!--
  #   rdoc-file=ext/strscan/strscan.c
  #   - reset()
  # -->
  # Reset the scan pointer (index 0) and clear matching data.
  #
  def reset: () -> void

  # <!--
  #   rdoc-file=ext/strscan/strscan.c
  #   - rest()
  # -->
  # Returns the "rest" of the string (i.e. everything after the scan pointer). If
  # there is no more data (eos? = true), it returns `""`.
  #
  def rest: () -> String

  # <!--
  #   rdoc-file=ext/strscan/strscan.c
  #   - rest?()
  # -->
  # Returns true if and only if there is more data in the string.  See #eos?. This
  # method is obsolete; use #eos? instead.
  #
  #     s = StringScanner.new('test string')
  #     # These two are opposites
  #     s.eos? # => false
  #     s.rest? # => true
  #
  def rest?: () -> bool

  # <!--
  #   rdoc-file=ext/strscan/strscan.c
  #   - rest_size()
  # -->
  # `s.rest_size` is equivalent to `s.rest.size`.
  #
  def rest_size: () -> Integer

  # <!--
  #   rdoc-file=ext/strscan/strscan.c
  #   - restsize()
  # -->
  # `s.restsize` is equivalent to `s.rest_size`. This method is obsolete; use
  # #rest_size instead.
  #
  def restsize: () -> Integer

  # <!--
  #   rdoc-file=ext/strscan/strscan.c
  #   - scan(pattern) => String
  # -->
  # Tries to match with `pattern` at the current position. If there's a match, the
  # scanner advances the "scan pointer" and returns the matched string. Otherwise,
  # the scanner returns `nil`.
  #
  #     s = StringScanner.new('test string')
  #     p s.scan(/\w+/)   # -> "test"
  #     p s.scan(/\w+/)   # -> nil
  #     p s.scan(/\s+/)   # -> " "
  #     p s.scan("str")   # -> "str"
  #     p s.scan(/\w+/)   # -> "ing"
  #     p s.scan(/./)     # -> nil
  #
  def scan: (Regexp) -> String?

  # <!--
  #   rdoc-file=ext/strscan/strscan.c
  #   - scan_full(pattern, advance_pointer_p, return_string_p)
  # -->
  # Tests whether the given `pattern` is matched from the current scan pointer.
  # Advances the scan pointer if `advance_pointer_p` is true. Returns the matched
  # string if `return_string_p` is true. The match register is affected.
  #
  # "full" means "#scan with full parameters".
  #
  def scan_full: (Regexp pattern, bool advance_pointer_p, bool return_string_p) -> untyped

  # <!--
  #   rdoc-file=ext/strscan/strscan.c
  #   - scan_until(pattern)
  # -->
  # Scans the string *until* the `pattern` is matched.  Returns the substring up
  # to and including the end of the match, advancing the scan pointer to that
  # location. If there is no match, `nil` is returned.
  #
  #     s = StringScanner.new("Fri Dec 12 1975 14:39")
  #     s.scan_until(/1/)        # -> "Fri Dec 1"
  #     s.pre_match              # -> "Fri Dec "
  #     s.scan_until(/XYZ/)      # -> nil
  #
  def scan_until: (Regexp) -> String?

  # <!--
  #   rdoc-file=ext/strscan/strscan.c
  #   - search_full(pattern, advance_pointer_p, return_string_p)
  # -->
  # Scans the string *until* the `pattern` is matched. Advances the scan pointer
  # if `advance_pointer_p`, otherwise not. Returns the matched string if
  # `return_string_p` is true, otherwise returns the number of bytes advanced.
  # This method does affect the match register.
  #
  def search_full: (Regexp pattern, bool advance_pointer_p, bool return_string_p) -> untyped

  # <!--
  #   rdoc-file=ext/strscan/strscan.c
  #   - size
  # -->
  # Returns the amount of subgroups in the most recent match. The full match
  # counts as a subgroup.
  #
  #     s = StringScanner.new("Fri Dec 12 1975 14:39")
  #     s.scan(/(\w+) (\w+) (\d+) /)       # -> "Fri Dec 12 "
  #     s.size                             # -> 4
  #
  def size: () -> Integer

  # <!--
  #   rdoc-file=ext/strscan/strscan.c
  #   - skip(pattern)
  # -->
  # Attempts to skip over the given `pattern` beginning with the scan pointer. If
  # it matches, the scan pointer is advanced to the end of the match, and the
  # length of the match is returned.  Otherwise, `nil` is returned.
  #
  # It's similar to #scan, but without returning the matched string.
  #
  #     s = StringScanner.new('test string')
  #     p s.skip(/\w+/)   # -> 4
  #     p s.skip(/\w+/)   # -> nil
  #     p s.skip(/\s+/)   # -> 1
  #     p s.skip("st")    # -> 2
  #     p s.skip(/\w+/)   # -> 4
  #     p s.skip(/./)     # -> nil
  #
  def skip: (Regexp) -> Integer?

  # <!--
  #   rdoc-file=ext/strscan/strscan.c
  #   - skip_until(pattern)
  # -->
  # Advances the scan pointer until `pattern` is matched and consumed.  Returns
  # the number of bytes advanced, or `nil` if no match was found.
  #
  # Look ahead to match `pattern`, and advance the scan pointer to the *end* of
  # the match.  Return the number of characters advanced, or `nil` if the match
  # was unsuccessful.
  #
  # It's similar to #scan_until, but without returning the intervening string.
  #
  #     s = StringScanner.new("Fri Dec 12 1975 14:39")
  #     s.skip_until /12/           # -> 10
  #     s                           #
  #
  def skip_until: (Regexp) -> Integer?

  # <!--
  #   rdoc-file=ext/strscan/strscan.c
  #   - string()
  # -->
  # Returns the string being scanned.
  #
  def string: () -> String

  # <!--
  #   rdoc-file=ext/strscan/strscan.c
  #   - string=(str)
  # -->
  # Changes the string being scanned to `str` and resets the scanner. Returns
  # `str`.
  #
  def string=: (String) -> String

  # <!--
  #   rdoc-file=ext/strscan/strscan.c
  #   - terminate
  #   - clear
  # -->
  # Sets the scan pointer to the end of the string and clear matching data.
  #
  def terminate: () -> void

  # <!--
  #   rdoc-file=ext/strscan/strscan.c
  #   - unscan()
  # -->
  # Sets the scan pointer to the previous position.  Only one previous position is
  # remembered, and it changes with each scanning operation.
  #
  #     s = StringScanner.new('test string')
  #     s.scan(/\w+/)        # => "test"
  #     s.unscan
  #     s.scan(/../)         # => "te"
  #     s.scan(/\d/)         # => nil
  #     s.unscan             # ScanError: unscan failed: previous match record not exist
  #
  def unscan: () -> void

  # <!--
  #   rdoc-file=ext/strscan/strscan.c
  #   - scanner.values_at( i1, i2, ... iN )   -> an_array
  # -->
  # Returns the subgroups in the most recent match at the given indices. If
  # nothing was priorly matched, it returns nil.
  #
  #     s = StringScanner.new("Fri Dec 12 1975 14:39")
  #     s.scan(/(\w+) (\w+) (\d+) /)       # -> "Fri Dec 12 "
  #     s.values_at 0, -1, 5, 2            # -> ["Fri Dec 12 ", "12", nil, "Dec"]
  #     s.scan(/(\w+) (\w+) (\d+) /)       # -> nil
  #     s.values_at 0, -1, 5, 2            # -> nil
  #
  def values_at: (*Integer) -> Array[String]?

  private

  # <!--
  #   rdoc-file=ext/strscan/strscan.c
  #   - StringScanner.new(string, fixed_anchor: false)
  #   - StringScanner.new(string, dup = false)
  # -->
  # Creates a new StringScanner object to scan over the given `string`.
  #
  # If `fixed_anchor` is `true`, `\A` always matches the beginning of the string.
  # Otherwise, `\A` always matches the current position.
  #
  # `dup` argument is obsolete and not used now.
  #
  def initialize: (String, ?bool dup, ?fixed_anchor: bool) -> untyped

  # <!--
  #   rdoc-file=ext/strscan/strscan.c
  #   - dup
  #   - clone
  # -->
  # Duplicates a StringScanner object.
  #
  def initialize_copy: (StringScanner) -> void
end

StringScanner::Id: String

StringScanner::Version: String