JezK

Edit File: csv.rbs

# 
# ## CSV
# CSV (comma-separated variables) data is a text representation of a table:
# *   A *row* *separator* delimits table rows. A common row separator is the
#     newline character `"\n"`.
# *   A *column* *separator* delimits fields in a row. A common column separator
#     is the comma character `","`.
#
#
# This CSV String, with row separator `"\n"` and column separator `","`, has
# three rows and two columns:
#     "foo,0\nbar,1\nbaz,2\n"
#
# Despite the name CSV, a CSV representation can use different separators.
#
# For more about tables, see the Wikipedia article "[Table
# (information)](https://en.wikipedia.org/wiki/Table_(information))", especially
# its section "[Simple
# table](https://en.wikipedia.org/wiki/Table_(information)#Simple_table)"
#
# ## Class CSV
#
# Class CSV provides methods for:
# *   Parsing CSV data from a String object, a File (via its file path), or an
#     IO object.
# *   Generating CSV data to a String object.
#
#
# To make CSV available:
#     require 'csv'
#
# All examples here assume that this has been done.
#
# ## Keeping It Simple
#
# A CSV object has dozens of instance methods that offer fine-grained control of
# parsing and generating CSV data. For many needs, though, simpler approaches
# will do.
#
# This section summarizes the singleton methods in CSV that allow you to parse
# and generate without explicitly creating CSV objects. For details, follow the
# links.
#
# ### Simple Parsing
#
# Parsing methods commonly return either of:
# *   An Array of Arrays of Strings:
#     *   The outer Array is the entire "table".
#     *   Each inner Array is a row.
#     *   Each String is a field.
#
# *   A CSV::Table object.  For details, see [\CSV with
#     Headers](#class-CSV-label-CSV+with+Headers).
#
#
# #### Parsing a String
#
# The input to be parsed can be a string:
#     string = "foo,0\nbar,1\nbaz,2\n"
#
# Method CSV.parse returns the entire CSV data:
#     CSV.parse(string) # => [["foo", "0"], ["bar", "1"], ["baz", "2"]]
#
# Method CSV.parse_line returns only the first row:
#     CSV.parse_line(string) # => ["foo", "0"]
#
# CSV extends class String with instance method String#parse_csv, which also
# returns only the first row:
#     string.parse_csv # => ["foo", "0"]
#
# #### Parsing Via a File Path
#
# The input to be parsed can be in a file:
#     string = "foo,0\nbar,1\nbaz,2\n"
#     path = 't.csv'
#     File.write(path, string)
#
# Method CSV.read returns the entire CSV data:
#     CSV.read(path) # => [["foo", "0"], ["bar", "1"], ["baz", "2"]]
#
# Method CSV.foreach iterates, passing each row to the given block:
#     CSV.foreach(path) do |row|
#       p row
#     end
#
# Output:
#     ["foo", "0"]
#     ["bar", "1"]
#     ["baz", "2"]
#
# Method CSV.table returns the entire CSV data as a CSV::Table object:
#     CSV.table(path) # => #<CSV::Table mode:col_or_row row_count:3>
#
# #### Parsing from an Open IO Stream
#
# The input to be parsed can be in an open IO stream:
#
# Method CSV.read returns the entire CSV data:
#     File.open(path) do |file|
#       CSV.read(file)
#     end # => [["foo", "0"], ["bar", "1"], ["baz", "2"]]
#
# As does method CSV.parse:
#     File.open(path) do |file|
#       CSV.parse(file)
#     end # => [["foo", "0"], ["bar", "1"], ["baz", "2"]]
#
# Method CSV.parse_line returns only the first row:
#     File.open(path) do |file|
#      CSV.parse_line(file)
#     end # => ["foo", "0"]
#
# Method CSV.foreach iterates, passing each row to the given block:
#     File.open(path) do |file|
#       CSV.foreach(file) do |row|
#         p row
#       end
#     end
#
# Output:
#     ["foo", "0"]
#     ["bar", "1"]
#     ["baz", "2"]
#
# Method CSV.table returns the entire CSV data as a CSV::Table object:
#     File.open(path) do |file|
#       CSV.table(file)
#     end # => #<CSV::Table mode:col_or_row row_count:3>
#
# ### Simple Generating
#
# Method CSV.generate returns a String; this example uses method CSV#<< to
# append the rows that are to be generated:
#     output_string = CSV.generate do |csv|
#       csv << ['foo', 0]
#       csv << ['bar', 1]
#       csv << ['baz', 2]
#     end
#     output_string # => "foo,0\nbar,1\nbaz,2\n"
#
# Method CSV.generate_line returns a String containing the single row
# constructed from an Array:
#     CSV.generate_line(['foo', '0']) # => "foo,0\n"
#
# CSV extends class Array with instance method `Array#to_csv`, which forms an
# Array into a String:
#     ['foo', '0'].to_csv # => "foo,0\n"
#
# ### "Filtering" CSV
#
# Method CSV.filter provides a Unix-style filter for CSV data. The input data is
# processed to form the output data:
#     in_string = "foo,0\nbar,1\nbaz,2\n"
#     out_string = ''
#     CSV.filter(in_string, out_string) do |row|
#       row[0] = row[0].upcase
#       row[1] *= 4
#     end
#     out_string # => "FOO,0000\nBAR,1111\nBAZ,2222\n"
#
# ## CSV Objects
#
# There are three ways to create a CSV object:
# *   Method CSV.new returns a new CSV object.
# *   Method CSV.instance returns a new or cached CSV object.
# *   Method CSV() also returns a new or cached CSV object.
#
#
# ### Instance Methods
#
# CSV has three groups of instance methods:
# *   Its own internally defined instance methods.
# *   Methods included by module Enumerable.
# *   Methods delegated to class IO. See below.
#
#
# #### Delegated Methods
#
# For convenience, a CSV object will delegate to many methods in class IO. (A
# few have wrapper "guard code" in CSV.) You may call:
# *   IO#binmode
# *   #binmode?
# *   IO#close
# *   IO#close_read
# *   IO#close_write
# *   IO#closed?
# *   #eof
# *   #eof?
# *   IO#external_encoding
# *   IO#fcntl
# *   IO#fileno
# *   #flock
# *   IO#flush
# *   IO#fsync
# *   IO#internal_encoding
# *   #ioctl
# *   IO#isatty
# *   #path
# *   IO#pid
# *   IO#pos
# *   IO#pos=
# *   IO#reopen
# *   #rewind
# *   IO#seek
# *   #stat
# *   IO#string
# *   IO#sync
# *   IO#sync=
# *   IO#tell
# *   #to_i
# *   #to_io
# *   IO#truncate
# *   IO#tty?
#
#
# ### Options
#
# The default values for options are:
#     DEFAULT_OPTIONS = {
#       # For both parsing and generating.
#       col_sep:            ",",
#       row_sep:            :auto,
#       quote_char:         '"',
#       # For parsing.
#       field_size_limit:   nil,
#       converters:         nil,
#       unconverted_fields: nil,
#       headers:            false,
#       return_headers:     false,
#       header_converters:  nil,
#       skip_blanks:        false,
#       skip_lines:         nil,
#       liberal_parsing:    false,
#       nil_value:          nil,
#       empty_value:        "",
#       strip:              false,
#       # For generating.
#       write_headers:      nil,
#       quote_empty:        true,
#       force_quotes:       false,
#       write_converters:   nil,
#       write_nil_value:    nil,
#       write_empty_value:  "",
#     }
#
# #### Options for Parsing
#
# Options for parsing, described in detail below, include:
# *   `row_sep`: Specifies the row separator; used to delimit rows.
# *   `col_sep`: Specifies the column separator; used to delimit fields.
# *   `quote_char`: Specifies the quote character; used to quote fields.
# *   `field_size_limit`: Specifies the maximum field size allowed.
# *   `converters`: Specifies the field converters to be used.
# *   `unconverted_fields`: Specifies whether unconverted fields are to be
#     available.
# *   `headers`: Specifies whether data contains headers, or specifies the
#     headers themselves.
# *   `return_headers`: Specifies whether headers are to be returned.
# *   `header_converters`: Specifies the header converters to be used.
# *   `skip_blanks`: Specifies whether blanks lines are to be ignored.
# *   `skip_lines`: Specifies how comments lines are to be recognized.
# *   `strip`: Specifies whether leading and trailing whitespace are to be
#     stripped from fields. This must be compatible with `col_sep`; if it is
#     not, then an `ArgumentError` exception will be raised.
# *   `liberal_parsing`: Specifies whether CSV should attempt to parse
#     non-compliant data.
# *   `nil_value`: Specifies the object that is to be substituted for each null
#     (no-text) field.
# *   `empty_value`: Specifies the object that is to be substituted for each
#     empty field.
#
#
# ###### Option `row_sep`
#
# Specifies the row separator, a String or the Symbol `:auto` (see below), to be
# used for both parsing and generating.
#
# Default value:
#     CSV::DEFAULT_OPTIONS.fetch(:row_sep) # => :auto
#
# ---
#
# When `row_sep` is a String, that String becomes the row separator. The String
# will be transcoded into the data's Encoding before use.
#
# Using `"\n"`:
#     row_sep = "\n"
#     str = CSV.generate(row_sep: row_sep) do |csv|
#       csv << [:foo, 0]
#       csv << [:bar, 1]
#       csv << [:baz, 2]
#     end
#     str # => "foo,0\nbar,1\nbaz,2\n"
#     ary = CSV.parse(str)
#     ary # => [["foo", "0"], ["bar", "1"], ["baz", "2"]]
#
# Using `|` (pipe):
#     row_sep = '|'
#     str = CSV.generate(row_sep: row_sep) do |csv|
#       csv << [:foo, 0]
#       csv << [:bar, 1]
#       csv << [:baz, 2]
#     end
#     str # => "foo,0|bar,1|baz,2|"
#     ary = CSV.parse(str, row_sep: row_sep)
#     ary # => [["foo", "0"], ["bar", "1"], ["baz", "2"]]
#
# Using `--` (two hyphens):
#     row_sep = '--'
#     str = CSV.generate(row_sep: row_sep) do |csv|
#       csv << [:foo, 0]
#       csv << [:bar, 1]
#       csv << [:baz, 2]
#     end
#     str # => "foo,0--bar,1--baz,2--"
#     ary = CSV.parse(str, row_sep: row_sep)
#     ary # => [["foo", "0"], ["bar", "1"], ["baz", "2"]]
#
# Using `''` (empty string):
#     row_sep = ''
#     str = CSV.generate(row_sep: row_sep) do |csv|
#       csv << [:foo, 0]
#       csv << [:bar, 1]
#       csv << [:baz, 2]
#     end
#     str # => "foo,0bar,1baz,2"
#     ary = CSV.parse(str, row_sep: row_sep)
#     ary # => [["foo", "0bar", "1baz", "2"]]
#
# ---
#
# When `row_sep` is the Symbol `:auto` (the default), generating uses `"\n"` as
# the row separator:
#     str = CSV.generate do |csv|
#       csv << [:foo, 0]
#       csv << [:bar, 1]
#       csv << [:baz, 2]
#     end
#     str # => "foo,0\nbar,1\nbaz,2\n"
#
# Parsing, on the other hand, invokes auto-discovery of the row separator.
#
# Auto-discovery reads ahead in the data looking for the next `\r\n`, `\n`, or
# `\r` sequence. The sequence will be selected even if it occurs in a quoted
# field, assuming that you would have the same line endings there.
#
# Example:
#     str = CSV.generate do |csv|
#       csv << [:foo, 0]
#       csv << [:bar, 1]
#       csv << [:baz, 2]
#     end
#     str # => "foo,0\nbar,1\nbaz,2\n"
#     ary = CSV.parse(str)
#     ary # => [["foo", "0"], ["bar", "1"], ["baz", "2"]]
#
# The default `$INPUT_RECORD_SEPARATOR` (`$/`) is used if any of the following
# is true:
# *   None of those sequences is found.
# *   Data is `ARGF`, `STDIN`, `STDOUT`, or `STDERR`.
# *   The stream is only available for output.
#
#
# Obviously, discovery takes a little time. Set manually if speed is important.
# Also note that IO objects should be opened in binary mode on Windows if this
# feature will be used as the line-ending translation can cause problems with
# resetting the document position to where it was before the read ahead.
#
# ---
#
# Raises an exception if the given value is not String-convertible:
#     row_sep = BasicObject.new
#     # Raises NoMethodError (undefined method `to_s' for #<BasicObject:>)
#     CSV.generate(ary, row_sep: row_sep)
#     # Raises NoMethodError (undefined method `to_s' for #<BasicObject:>)
#     CSV.parse(str, row_sep: row_sep)
#
# ###### Option `col_sep`
#
# Specifies the String field separator to be used for both parsing and
# generating. The String will be transcoded into the data's Encoding before use.
#
# Default value:
#     CSV::DEFAULT_OPTIONS.fetch(:col_sep) # => "," (comma)
#
# Using the default (comma):
#     str = CSV.generate do |csv|
#       csv << [:foo, 0]
#       csv << [:bar, 1]
#       csv << [:baz, 2]
#     end
#     str # => "foo,0\nbar,1\nbaz,2\n"
#     ary = CSV.parse(str)
#     ary # => [["foo", "0"], ["bar", "1"], ["baz", "2"]]
#
# Using `:` (colon):
#     col_sep = ':'
#     str = CSV.generate(col_sep: col_sep) do |csv|
#       csv << [:foo, 0]
#       csv << [:bar, 1]
#       csv << [:baz, 2]
#     end
#     str # => "foo:0\nbar:1\nbaz:2\n"
#     ary = CSV.parse(str, col_sep: col_sep)
#     ary # => [["foo", "0"], ["bar", "1"], ["baz", "2"]]
#
# Using `::` (two colons):
#     col_sep = '::'
#     str = CSV.generate(col_sep: col_sep) do |csv|
#       csv << [:foo, 0]
#       csv << [:bar, 1]
#       csv << [:baz, 2]
#     end
#     str # => "foo::0\nbar::1\nbaz::2\n"
#     ary = CSV.parse(str, col_sep: col_sep)
#     ary # => [["foo", "0"], ["bar", "1"], ["baz", "2"]]
#
# Using `''` (empty string):
#     col_sep = ''
#     str = CSV.generate(col_sep: col_sep) do |csv|
#       csv << [:foo, 0]
#       csv << [:bar, 1]
#       csv << [:baz, 2]
#     end
#     str # => "foo0\nbar1\nbaz2\n"
#
# ---
#
# Raises an exception if parsing with the empty String:
#     col_sep = ''
#     # Raises ArgumentError (:col_sep must be 1 or more characters: "")
#     CSV.parse("foo0\nbar1\nbaz2\n", col_sep: col_sep)
#
# Raises an exception if the given value is not String-convertible:
#     col_sep = BasicObject.new
#     # Raises NoMethodError (undefined method `to_s' for #<BasicObject:>)
#     CSV.generate(line, col_sep: col_sep)
#     # Raises NoMethodError (undefined method `to_s' for #<BasicObject:>)
#     CSV.parse(str, col_sep: col_sep)
#
# ###### Option `quote_char`
#
# Specifies the character (String of length 1) used used to quote fields in both
# parsing and generating. This String will be transcoded into the data's
# Encoding before use.
#
# Default value:
#     CSV::DEFAULT_OPTIONS.fetch(:quote_char) # => "\"" (double quote)
#
# This is useful for an application that incorrectly uses `'` (single-quote) to
# quote fields, instead of the correct `"` (double-quote).
#
# Using the default (double quote):
#     str = CSV.generate do |csv|
#       csv << ['foo', 0]
#       csv << ["'bar'", 1]
#       csv << ['"baz"', 2]
#     end
#     str # => "foo,0\n'bar',1\n\"\"\"baz\"\"\",2\n"
#     ary = CSV.parse(str)
#     ary # => [["foo", "0"], ["'bar'", "1"], ["\"baz\"", "2"]]
#
# Using `'` (single-quote):
#     quote_char = "'"
#     str = CSV.generate(quote_char: quote_char) do |csv|
#       csv << ['foo', 0]
#       csv << ["'bar'", 1]
#       csv << ['"baz"', 2]
#     end
#     str # => "foo,0\n'''bar''',1\n\"baz\",2\n"
#     ary = CSV.parse(str, quote_char: quote_char)
#     ary # => [["foo", "0"], ["'bar'", "1"], ["\"baz\"", "2"]]
#
# ---
#
# Raises an exception if the String length is greater than 1:
#     # Raises ArgumentError (:quote_char has to be nil or a single character String)
#     CSV.new('', quote_char: 'xx')
#
# Raises an exception if the value is not a String:
#     # Raises ArgumentError (:quote_char has to be nil or a single character String)
#     CSV.new('', quote_char: :foo)
#
# ###### Option `field_size_limit`
#
# Specifies the Integer field size limit.
#
# Default value:
#     CSV::DEFAULT_OPTIONS.fetch(:field_size_limit) # => nil
#
# This is a maximum size CSV will read ahead looking for the closing quote for a
# field. (In truth, it reads to the first line ending beyond this size.) If a
# quote cannot be found within the limit CSV will raise a MalformedCSVError,
# assuming the data is faulty. You can use this limit to prevent what are
# effectively DoS attacks on the parser. However, this limit can cause a
# legitimate parse to fail; therefore the default value is `nil` (no limit).
#
# For the examples in this section:
#     str = <<~EOT
#       "a","b"
#       "
#       2345
#       ",""
#     EOT
#     str # => "\"a\",\"b\"\n\"\n2345\n\",\"\"\n"
#
# Using the default `nil`:
#     ary = CSV.parse(str)
#     ary # => [["a", "b"], ["\n2345\n", ""]]
#
# Using `50`:
#     field_size_limit = 50
#     ary = CSV.parse(str, field_size_limit: field_size_limit)
#     ary # => [["a", "b"], ["\n2345\n", ""]]
#
# ---
#
# Raises an exception if a field is too long:
#     big_str = "123456789\n" * 1024
#     # Raises CSV::MalformedCSVError (Field size exceeded in line 1.)
#     CSV.parse('valid,fields,"' + big_str + '"', field_size_limit: 2048)
#
# ###### Option `converters`
#
# Specifies converters to be used in parsing fields. See [Field
# Converters](#class-CSV-label-Field+Converters)
#
# Default value:
#     CSV::DEFAULT_OPTIONS.fetch(:converters) # => nil
#
# The value may be a field converter name (see [Stored
# Converters](#class-CSV-label-Stored+Converters)):
#     str = '1,2,3'
#     # Without a converter
#     array = CSV.parse_line(str)
#     array # => ["1", "2", "3"]
#     # With built-in converter :integer
#     array = CSV.parse_line(str, converters: :integer)
#     array # => [1, 2, 3]
#
# The value may be a converter list (see [Converter
# Lists](#class-CSV-label-Converter+Lists)):
#     str = '1,3.14159'
#     # Without converters
#     array = CSV.parse_line(str)
#     array # => ["1", "3.14159"]
#     # With built-in converters
#     array = CSV.parse_line(str, converters: [:integer, :float])
#     array # => [1, 3.14159]
#
# The value may be a Proc custom converter: (see [Custom Field
# Converters](#class-CSV-label-Custom+Field+Converters)):
#     str = ' foo  ,  bar  ,  baz  '
#     # Without a converter
#     array = CSV.parse_line(str)
#     array # => [" foo  ", "  bar  ", "  baz  "]
#     # With a custom converter
#     array = CSV.parse_line(str, converters: proc {|field| field.strip })
#     array # => ["foo", "bar", "baz"]
#
# See also [Custom Field Converters](#class-CSV-label-Custom+Field+Converters)
#
# ---
#
# Raises an exception if the converter is not a converter name or a Proc:
#     str = 'foo,0'
#     # Raises NoMethodError (undefined method `arity' for nil:NilClass)
#     CSV.parse(str, converters: :foo)
#
# ###### Option `unconverted_fields`
#
# Specifies the boolean that determines whether unconverted field values are to
# be available.
#
# Default value:
#     CSV::DEFAULT_OPTIONS.fetch(:unconverted_fields) # => nil
#
# The unconverted field values are those found in the source data, prior to any
# conversions performed via option `converters`.
#
# When option `unconverted_fields` is `true`, each returned row (Array or
# CSV::Row) has an added method, `unconverted_fields`, that returns the
# unconverted field values:
#     str = <<-EOT
#     foo,0
#     bar,1
#     baz,2
#     EOT
#     # Without unconverted_fields
#     csv = CSV.parse(str, converters: :integer)
#     csv # => [["foo", 0], ["bar", 1], ["baz", 2]]
#     csv.first.respond_to?(:unconverted_fields) # => false
#     # With unconverted_fields
#     csv = CSV.parse(str, converters: :integer, unconverted_fields: true)
#     csv # => [["foo", 0], ["bar", 1], ["baz", 2]]
#     csv.first.respond_to?(:unconverted_fields) # => true
#     csv.first.unconverted_fields # => ["foo", "0"]
#
# ###### Option `headers`
#
# Specifies a boolean, Symbol, Array, or String to be used to define column
# headers.
#
# Default value:
#     CSV::DEFAULT_OPTIONS.fetch(:headers) # => false
#
# ---
#
# Without `headers`:
#     str = <<-EOT
#     Name,Count
#     foo,0
#     bar,1
#     bax,2
#     EOT
#     csv = CSV.new(str)
#     csv # => #<CSV io_type:StringIO encoding:UTF-8 lineno:0 col_sep:"," row_sep:"\n" quote_char:"\"">
#     csv.headers # => nil
#     csv.shift # => ["Name", "Count"]
#
# ---
#
# If set to `true` or the Symbol `:first_row`, the first row of the data is
# treated as a row of headers:
#     str = <<-EOT
#     Name,Count
#     foo,0
#     bar,1
#     bax,2
#     EOT
#     csv = CSV.new(str, headers: true)
#     csv # => #<CSV io_type:StringIO encoding:UTF-8 lineno:2 col_sep:"," row_sep:"\n" quote_char:"\"" headers:["Name", "Count"]>
#     csv.headers # => ["Name", "Count"]
#     csv.shift # => #<CSV::Row "Name":"bar" "Count":"1">
#
# ---
#
# If set to an Array, the Array elements are treated as headers:
#     str = <<-EOT
#     foo,0
#     bar,1
#     bax,2
#     EOT
#     csv = CSV.new(str, headers: ['Name', 'Count'])
#     csv
#     csv.headers # => ["Name", "Count"]
#     csv.shift # => #<CSV::Row "Name":"bar" "Count":"1">
#
# ---
#
# If set to a String `str`, method `CSV::parse_line(str, options)` is called
# with the current `options`, and the returned Array is treated as headers:
#     str = <<-EOT
#     foo,0
#     bar,1
#     bax,2
#     EOT
#     csv = CSV.new(str, headers: 'Name,Count')
#     csv
#     csv.headers # => ["Name", "Count"]
#     csv.shift # => #<CSV::Row "Name":"bar" "Count":"1">
#
# ###### Option `return_headers`
#
# Specifies the boolean that determines whether method #shift returns or ignores
# the header row.
#
# Default value:
#     CSV::DEFAULT_OPTIONS.fetch(:return_headers) # => false
#
# Examples:
#     str = <<-EOT
#     Name,Count
#     foo,0
#     bar,1
#     bax,2
#     EOT
#     # Without return_headers first row is str.
#     csv = CSV.new(str, headers: true)
#     csv.shift # => #<CSV::Row "Name":"foo" "Count":"0">
#     # With return_headers first row is headers.
#     csv = CSV.new(str, headers: true, return_headers: true)
#     csv.shift # => #<CSV::Row "Name":"Name" "Count":"Count">
#
# ###### Option `header_converters`
#
# Specifies converters to be used in parsing headers. See [Header
# Converters](#class-CSV-label-Header+Converters)
#
# Default value:
#     CSV::DEFAULT_OPTIONS.fetch(:header_converters) # => nil
#
# Identical in functionality to option
# [converters](#class-CSV-label-Option+converters) except that:
# *   The converters apply only to the header row.
# *   The built-in header converters are `:downcase` and `:symbol`.
#
#
# This section assumes prior execution of:
#     str = <<-EOT
#     Name,Value
#     foo,0
#     bar,1
#     baz,2
#     EOT
#     # With no header converter
#     table = CSV.parse(str, headers: true)
#     table.headers # => ["Name", "Value"]
#
# The value may be a header converter name (see [Stored
# Converters](#class-CSV-label-Stored+Converters)):
#     table = CSV.parse(str, headers: true, header_converters: :downcase)
#     table.headers # => ["name", "value"]
#
# The value may be a converter list (see [Converter
# Lists](#class-CSV-label-Converter+Lists)):
#     header_converters = [:downcase, :symbol]
#     table = CSV.parse(str, headers: true, header_converters: header_converters)
#     table.headers # => [:name, :value]
#
# The value may be a Proc custom converter (see [Custom Header
# Converters](#class-CSV-label-Custom+Header+Converters)):
#     upcase_converter = proc {|field| field.upcase }
#     table = CSV.parse(str, headers: true, header_converters: upcase_converter)
#     table.headers # => ["NAME", "VALUE"]
#
# See also [Custom Header Converters](#class-CSV-label-Custom+Header+Converters)
#
# ###### Option `skip_blanks`
#
# Specifies a boolean that determines whether blank lines in the input will be
# ignored; a line that contains a column separator is not considered to be
# blank.
#
# Default value:
#     CSV::DEFAULT_OPTIONS.fetch(:skip_blanks) # => false
#
# See also option [skiplines](#class-CSV-label-Option+skip_lines).
#
# For examples in this section:
#     str = <<-EOT
#     foo,0
#
#     bar,1
#     baz,2
#
#     ,
#     EOT
#
# Using the default, `false`:
#     ary = CSV.parse(str)
#     ary # => [["foo", "0"], [], ["bar", "1"], ["baz", "2"], [], [nil, nil]]
#
# Using `true`:
#     ary = CSV.parse(str, skip_blanks: true)
#     ary # => [["foo", "0"], ["bar", "1"], ["baz", "2"], [nil, nil]]
#
# Using a truthy value:
#     ary = CSV.parse(str, skip_blanks: :foo)
#     ary # => [["foo", "0"], ["bar", "1"], ["baz", "2"], [nil, nil]]
#
# ###### Option `skip_lines`
#
# Specifies an object to use in identifying comment lines in the input that are
# to be ignored:
# *   If a Regexp, ignores lines that match it.
# *   If a String, converts it to a Regexp, ignores lines that match it.
# *   If `nil`, no lines are considered to be comments.
#
#
# Default value:
#     CSV::DEFAULT_OPTIONS.fetch(:skip_lines) # => nil
#
# For examples in this section:
#     str = <<-EOT
#     # Comment
#     foo,0
#     bar,1
#     baz,2
#     # Another comment
#     EOT
#     str # => "# Comment\nfoo,0\nbar,1\nbaz,2\n# Another comment\n"
#
# Using the default, `nil`:
#     ary = CSV.parse(str)
#     ary # => [["# Comment"], ["foo", "0"], ["bar", "1"], ["baz", "2"], ["# Another comment"]]
#
# Using a Regexp:
#     ary = CSV.parse(str, skip_lines: /^#/)
#     ary # => [["foo", "0"], ["bar", "1"], ["baz", "2"]]
#
# Using a String:
#     ary = CSV.parse(str, skip_lines: '#')
#     ary # => [["foo", "0"], ["bar", "1"], ["baz", "2"]]
#
# ---
#
# Raises an exception if given an object that is not a Regexp, a String, or
# `nil`:
#     # Raises ArgumentError (:skip_lines has to respond to #match: 0)
#     CSV.parse(str, skip_lines: 0)
#
# ###### Option `strip`
#
# Specifies the boolean value that determines whether whitespace is stripped
# from each input field.
#
# Default value:
#     CSV::DEFAULT_OPTIONS.fetch(:strip) # => false
#
# With default value `false`:
#     ary = CSV.parse_line(' a , b ')
#     ary # => [" a ", " b "]
#
# With value `true`:
#     ary = CSV.parse_line(' a , b ', strip: true)
#     ary # => ["a", "b"]
#
# ###### Option `liberal_parsing`
#
# Specifies the boolean value that determines whether CSV will attempt to parse
# input not conformant with RFC 4180, such as double quotes in unquoted fields.
#
# Default value:
#     CSV::DEFAULT_OPTIONS.fetch(:liberal_parsing) # => false
#
# For examples in this section:
#     str = 'is,this "three, or four",fields'
#
# Without `liberal_parsing`:
#     # Raises CSV::MalformedCSVError (Illegal quoting in str 1.)
#     CSV.parse_line(str)
#
# With `liberal_parsing`:
#     ary = CSV.parse_line(str, liberal_parsing: true)
#     ary # => ["is", "this \"three", " or four\"", "fields"]
#
# ###### Option `nil_value`
#
# Specifies the object that is to be substituted for each null (no-text) field.
#
# Default value:
#     CSV::DEFAULT_OPTIONS.fetch(:nil_value) # => nil
#
# With the default, `nil`:
#     CSV.parse_line('a,,b,,c') # => ["a", nil, "b", nil, "c"]
#
# With a different object:
#     CSV.parse_line('a,,b,,c', nil_value: 0) # => ["a", 0, "b", 0, "c"]
#
# ###### Option `empty_value`
#
# Specifies the object that is to be substituted for each field that has an
# empty String.
#
# Default value:
#     CSV::DEFAULT_OPTIONS.fetch(:empty_value) # => "" (empty string)
#
# With the default, `""`:
#     CSV.parse_line('a,"",b,"",c') # => ["a", "", "b", "", "c"]
#
# With a different object:
#     CSV.parse_line('a,"",b,"",c', empty_value: 'x') # => ["a", "x", "b", "x", "c"]
#
# #### Options for Generating
#
# Options for generating, described in detail below, include:
# *   `row_sep`: Specifies the row separator; used to delimit rows.
# *   `col_sep`: Specifies the column separator; used to delimit fields.
# *   `quote_char`: Specifies the quote character; used to quote fields.
# *   `write_headers`: Specifies whether headers are to be written.
# *   `force_quotes`: Specifies whether each output field is to be quoted.
# *   `quote_empty`: Specifies whether each empty output field is to be quoted.
# *   `write_converters`: Specifies the field converters to be used in writing.
# *   `write_nil_value`: Specifies the object that is to be substituted for each
#     `nil`-valued field.
# *   `write_empty_value`: Specifies the object that is to be substituted for
#     each empty field.
#
#
# ###### Option `row_sep`
#
# Specifies the row separator, a String or the Symbol `:auto` (see below), to be
# used for both parsing and generating.
#
# Default value:
#     CSV::DEFAULT_OPTIONS.fetch(:row_sep) # => :auto
#
# ---
#
# When `row_sep` is a String, that String becomes the row separator. The String
# will be transcoded into the data's Encoding before use.
#
# Using `"\n"`:
#     row_sep = "\n"
#     str = CSV.generate(row_sep: row_sep) do |csv|
#       csv << [:foo, 0]
#       csv << [:bar, 1]
#       csv << [:baz, 2]
#     end
#     str # => "foo,0\nbar,1\nbaz,2\n"
#     ary = CSV.parse(str)
#     ary # => [["foo", "0"], ["bar", "1"], ["baz", "2"]]
#
# Using `|` (pipe):
#     row_sep = '|'
#     str = CSV.generate(row_sep: row_sep) do |csv|
#       csv << [:foo, 0]
#       csv << [:bar, 1]
#       csv << [:baz, 2]
#     end
#     str # => "foo,0|bar,1|baz,2|"
#     ary = CSV.parse(str, row_sep: row_sep)
#     ary # => [["foo", "0"], ["bar", "1"], ["baz", "2"]]
#
# Using `--` (two hyphens):
#     row_sep = '--'
#     str = CSV.generate(row_sep: row_sep) do |csv|
#       csv << [:foo, 0]
#       csv << [:bar, 1]
#       csv << [:baz, 2]
#     end
#     str # => "foo,0--bar,1--baz,2--"
#     ary = CSV.parse(str, row_sep: row_sep)
#     ary # => [["foo", "0"], ["bar", "1"], ["baz", "2"]]
#
# Using `''` (empty string):
#     row_sep = ''
#     str = CSV.generate(row_sep: row_sep) do |csv|
#       csv << [:foo, 0]
#       csv << [:bar, 1]
#       csv << [:baz, 2]
#     end
#     str # => "foo,0bar,1baz,2"
#     ary = CSV.parse(str, row_sep: row_sep)
#     ary # => [["foo", "0bar", "1baz", "2"]]
#
# ---
#
# When `row_sep` is the Symbol `:auto` (the default), generating uses `"\n"` as
# the row separator:
#     str = CSV.generate do |csv|
#       csv << [:foo, 0]
#       csv << [:bar, 1]
#       csv << [:baz, 2]
#     end
#     str # => "foo,0\nbar,1\nbaz,2\n"
#
# Parsing, on the other hand, invokes auto-discovery of the row separator.
#
# Auto-discovery reads ahead in the data looking for the next `\r\n`, `\n`, or
# `\r` sequence. The sequence will be selected even if it occurs in a quoted
# field, assuming that you would have the same line endings there.
#
# Example:
#     str = CSV.generate do |csv|
#       csv << [:foo, 0]
#       csv << [:bar, 1]
#       csv << [:baz, 2]
#     end
#     str # => "foo,0\nbar,1\nbaz,2\n"
#     ary = CSV.parse(str)
#     ary # => [["foo", "0"], ["bar", "1"], ["baz", "2"]]
#
# The default `$INPUT_RECORD_SEPARATOR` (`$/`) is used if any of the following
# is true:
# *   None of those sequences is found.
# *   Data is `ARGF`, `STDIN`, `STDOUT`, or `STDERR`.
# *   The stream is only available for output.
#
#
# Obviously, discovery takes a little time. Set manually if speed is important.
# Also note that IO objects should be opened in binary mode on Windows if this
# feature will be used as the line-ending translation can cause problems with
# resetting the document position to where it was before the read ahead.
#
# ---
#
# Raises an exception if the given value is not String-convertible:
#     row_sep = BasicObject.new
#     # Raises NoMethodError (undefined method `to_s' for #<BasicObject:>)
#     CSV.generate(ary, row_sep: row_sep)
#     # Raises NoMethodError (undefined method `to_s' for #<BasicObject:>)
#     CSV.parse(str, row_sep: row_sep)
#
# ###### Option `col_sep`
#
# Specifies the String field separator to be used for both parsing and
# generating. The String will be transcoded into the data's Encoding before use.
#
# Default value:
#     CSV::DEFAULT_OPTIONS.fetch(:col_sep) # => "," (comma)
#
# Using the default (comma):
#     str = CSV.generate do |csv|
#       csv << [:foo, 0]
#       csv << [:bar, 1]
#       csv << [:baz, 2]
#     end
#     str # => "foo,0\nbar,1\nbaz,2\n"
#     ary = CSV.parse(str)
#     ary # => [["foo", "0"], ["bar", "1"], ["baz", "2"]]
#
# Using `:` (colon):
#     col_sep = ':'
#     str = CSV.generate(col_sep: col_sep) do |csv|
#       csv << [:foo, 0]
#       csv << [:bar, 1]
#       csv << [:baz, 2]
#     end
#     str # => "foo:0\nbar:1\nbaz:2\n"
#     ary = CSV.parse(str, col_sep: col_sep)
#     ary # => [["foo", "0"], ["bar", "1"], ["baz", "2"]]
#
# Using `::` (two colons):
#     col_sep = '::'
#     str = CSV.generate(col_sep: col_sep) do |csv|
#       csv << [:foo, 0]
#       csv << [:bar, 1]
#       csv << [:baz, 2]
#     end
#     str # => "foo::0\nbar::1\nbaz::2\n"
#     ary = CSV.parse(str, col_sep: col_sep)
#     ary # => [["foo", "0"], ["bar", "1"], ["baz", "2"]]
#
# Using `''` (empty string):
#     col_sep = ''
#     str = CSV.generate(col_sep: col_sep) do |csv|
#       csv << [:foo, 0]
#       csv << [:bar, 1]
#       csv << [:baz, 2]
#     end
#     str # => "foo0\nbar1\nbaz2\n"
#
# ---
#
# Raises an exception if parsing with the empty String:
#     col_sep = ''
#     # Raises ArgumentError (:col_sep must be 1 or more characters: "")
#     CSV.parse("foo0\nbar1\nbaz2\n", col_sep: col_sep)
#
# Raises an exception if the given value is not String-convertible:
#     col_sep = BasicObject.new
#     # Raises NoMethodError (undefined method `to_s' for #<BasicObject:>)
#     CSV.generate(line, col_sep: col_sep)
#     # Raises NoMethodError (undefined method `to_s' for #<BasicObject:>)
#     CSV.parse(str, col_sep: col_sep)
#
# ###### Option `quote_char`
#
# Specifies the character (String of length 1) used used to quote fields in both
# parsing and generating. This String will be transcoded into the data's
# Encoding before use.
#
# Default value:
#     CSV::DEFAULT_OPTIONS.fetch(:quote_char) # => "\"" (double quote)
#
# This is useful for an application that incorrectly uses `'` (single-quote) to
# quote fields, instead of the correct `"` (double-quote).
#
# Using the default (double quote):
#     str = CSV.generate do |csv|
#       csv << ['foo', 0]
#       csv << ["'bar'", 1]
#       csv << ['"baz"', 2]
#     end
#     str # => "foo,0\n'bar',1\n\"\"\"baz\"\"\",2\n"
#     ary = CSV.parse(str)
#     ary # => [["foo", "0"], ["'bar'", "1"], ["\"baz\"", "2"]]
#
# Using `'` (single-quote):
#     quote_char = "'"
#     str = CSV.generate(quote_char: quote_char) do |csv|
#       csv << ['foo', 0]
#       csv << ["'bar'", 1]
#       csv << ['"baz"', 2]
#     end
#     str # => "foo,0\n'''bar''',1\n\"baz\",2\n"
#     ary = CSV.parse(str, quote_char: quote_char)
#     ary # => [["foo", "0"], ["'bar'", "1"], ["\"baz\"", "2"]]
#
# ---
#
# Raises an exception if the String length is greater than 1:
#     # Raises ArgumentError (:quote_char has to be nil or a single character String)
#     CSV.new('', quote_char: 'xx')
#
# Raises an exception if the value is not a String:
#     # Raises ArgumentError (:quote_char has to be nil or a single character String)
#     CSV.new('', quote_char: :foo)
#
# ###### Option `write_headers`
#
# Specifies the boolean that determines whether a header row is included in the
# output; ignored if there are no headers.
#
# Default value:
#     CSV::DEFAULT_OPTIONS.fetch(:write_headers) # => nil
#
# Without `write_headers`:
#     file_path = 't.csv'
#     CSV.open(file_path,'w',
#         :headers => ['Name','Value']
#       ) do |csv|
#         csv << ['foo', '0']
#     end
#     CSV.open(file_path) do |csv|
#       csv.shift
#     end # => ["foo", "0"]
#
# With `write_headers`":
#     CSV.open(file_path,'w',
#         :write_headers=> true,
#         :headers => ['Name','Value']
#       ) do |csv|
#         csv << ['foo', '0']
#     end
#     CSV.open(file_path) do |csv|
#       csv.shift
#     end # => ["Name", "Value"]
#
# ###### Option `force_quotes`
#
# Specifies the boolean that determines whether each output field is to be
# double-quoted.
#
# Default value:
#     CSV::DEFAULT_OPTIONS.fetch(:force_quotes) # => false
#
# For examples in this section:
#     ary = ['foo', 0, nil]
#
# Using the default, `false`:
#     str = CSV.generate_line(ary)
#     str # => "foo,0,\n"
#
# Using `true`:
#     str = CSV.generate_line(ary, force_quotes: true)
#     str # => "\"foo\",\"0\",\"\"\n"
#
# ###### Option `quote_empty`
#
# Specifies the boolean that determines whether an empty value is to be
# double-quoted.
#
# Default value:
#     CSV::DEFAULT_OPTIONS.fetch(:quote_empty) # => true
#
# With the default `true`:
#     CSV.generate_line(['"', ""]) # => "\"\"\"\",\"\"\n"
#
# With `false`:
#     CSV.generate_line(['"', ""], quote_empty: false) # => "\"\"\"\",\n"
#
# ###### Option `write_converters`
#
# Specifies converters to be used in generating fields. See [Write
# Converters](#class-CSV-label-Write+Converters)
#
# Default value:
#     CSV::DEFAULT_OPTIONS.fetch(:write_converters) # => nil
#
# With no write converter:
#     str = CSV.generate_line(["\na\n", "\tb\t", " c "])
#     str # => "\"\na\n\",\tb\t, c \n"
#
# With a write converter:
#     strip_converter = proc {|field| field.strip }
#     str = CSV.generate_line(["\na\n", "\tb\t", " c "], write_converters: strip_converter)
#     str # => "a,b,c\n"
#
# With two write converters (called in order):
#     upcase_converter = proc {|field| field.upcase }
#     downcase_converter = proc {|field| field.downcase }
#     write_converters = [upcase_converter, downcase_converter]
#     str = CSV.generate_line(['a', 'b', 'c'], write_converters: write_converters)
#     str # => "a,b,c\n"
#
# See also [Write Converters](#class-CSV-label-Write+Converters)
#
# ---
#
# Raises an exception if the converter returns a value that is neither `nil` nor
# String-convertible:
#     bad_converter = proc {|field| BasicObject.new }
#     # Raises NoMethodError (undefined method `is_a?' for #<BasicObject:>)
#     CSV.generate_line(['a', 'b', 'c'], write_converters: bad_converter)#
#
# ###### Option `write_nil_value`
#
# Specifies the object that is to be substituted for each `nil`-valued field.
#
# Default value:
#     CSV::DEFAULT_OPTIONS.fetch(:write_nil_value) # => nil
#
# Without the option:
#     str = CSV.generate_line(['a', nil, 'c', nil])
#     str # => "a,,c,\n"
#
# With the option:
#     str = CSV.generate_line(['a', nil, 'c', nil], write_nil_value: "x")
#     str # => "a,x,c,x\n"
#
# ###### Option `write_empty_value`
#
# Specifies the object that is to be substituted for each field that has an
# empty String.
#
# Default value:
#     CSV::DEFAULT_OPTIONS.fetch(:write_empty_value) # => ""
#
# Without the option:
#     str = CSV.generate_line(['a', '', 'c', ''])
#     str # => "a,\"\",c,\"\"\n"
#
# With the option:
#     str = CSV.generate_line(['a', '', 'c', ''], write_empty_value: "x")
#     str # => "a,x,c,x\n"
#
# ### CSV with Headers
#
# CSV allows to specify column names of CSV file, whether they are in data, or
# provided separately. If headers are specified, reading methods return an
# instance of CSV::Table, consisting of CSV::Row.
#
#     # Headers are part of data
#     data = CSV.parse(<<~ROWS, headers: true)
#       Name,Department,Salary
#       Bob,Engineering,1000
#       Jane,Sales,2000
#       John,Management,5000
#     ROWS
#
#     data.class      #=> CSV::Table
#     data.first      #=> #<CSV::Row "Name":"Bob" "Department":"Engineering" "Salary":"1000">
#     data.first.to_h #=> {"Name"=>"Bob", "Department"=>"Engineering", "Salary"=>"1000"}
#
#     # Headers provided by developer
#     data = CSV.parse('Bob,Engineering,1000', headers: %i[name department salary])
#     data.first      #=> #<CSV::Row name:"Bob" department:"Engineering" salary:"1000">
#
# ### Converters
#
# By default, each value (field or header) parsed by CSV is formed into a
# String. You can use a *field* *converter* or  *header* *converter* to
# intercept and modify the parsed values:
# *   See [Field Converters](#class-CSV-label-Field+Converters).
# *   See [Header Converters](#class-CSV-label-Header+Converters).
#
#
# Also by default, each value to be written during generation is written
# 'as-is'. You can use a *write* *converter* to modify values before writing.
# *   See [Write Converters](#class-CSV-label-Write+Converters).
#
#
# #### Specifying Converters
#
# You can specify converters for parsing or generating in the `options` argument
# to various CSV methods:
# *   Option `converters` for converting parsed field values.
# *   Option `header_converters` for converting parsed header values.
# *   Option `write_converters` for converting values to be written (generated).
#
#
# There are three forms for specifying converters:
# *   A converter proc: executable code to be used for conversion.
# *   A converter name: the name of a stored converter.
# *   A converter list: an array of converter procs, converter names, and
#     converter lists.
#
#
# ##### Converter Procs
#
# This converter proc, `strip_converter`, accepts a value `field` and returns
# `field.strip`:
#     strip_converter = proc {|field| field.strip }
#
# In this call to `CSV.parse`, the keyword argument `converters:
# string_converter` specifies that:
# *   Proc `string_converter` is to be called for each parsed field.
# *   The converter's return value is to replace the `field` value.
#
# Example:
#     string = " foo , 0 \n bar , 1 \n baz , 2 \n"
#     array = CSV.parse(string, converters: strip_converter)
#     array # => [["foo", "0"], ["bar", "1"], ["baz", "2"]]
#
# A converter proc can receive a second argument, `field_info`, that contains
# details about the field. This modified `strip_converter` displays its
# arguments:
#     strip_converter = proc do |field, field_info|
#       p [field, field_info]
#       field.strip
#     end
#     string = " foo , 0 \n bar , 1 \n baz , 2 \n"
#     array = CSV.parse(string, converters: strip_converter)
#     array # => [["foo", "0"], ["bar", "1"], ["baz", "2"]]
#
# Output:
#     [" foo ", #<struct CSV::FieldInfo index=0, line=1, header=nil>]
#     [" 0 ", #<struct CSV::FieldInfo index=1, line=1, header=nil>]
#     [" bar ", #<struct CSV::FieldInfo index=0, line=2, header=nil>]
#     [" 1 ", #<struct CSV::FieldInfo index=1, line=2, header=nil>]
#     [" baz ", #<struct CSV::FieldInfo index=0, line=3, header=nil>]
#     [" 2 ", #<struct CSV::FieldInfo index=1, line=3, header=nil>]
#
# Each CSV::FieldInfo object shows:
# *   The 0-based field index.
# *   The 1-based line index.
# *   The field header, if any.
#
#
# ##### Stored Converters
#
# A converter may be given a name and stored in a structure where the parsing
# methods can find it by name.
#
# The storage structure for field converters is the Hash CSV::Converters. It has
# several built-in converter procs:
# *   `:integer`: converts each String-embedded integer into a true Integer.
# *   `:float`: converts each String-embedded float into a true Float.
# *   `:date`: converts each String-embedded date into a true Date.
# *   `:date_time`: converts each String-embedded date-time into a true DateTime
#
# . This example creates a converter proc, then stores it:
#     strip_converter = proc {|field| field.strip }
#     CSV::Converters[:strip] = strip_converter
#
# Then the parsing method call can refer to the converter by its name, `:strip`:
#     string = " foo , 0 \n bar , 1 \n baz , 2 \n"
#     array = CSV.parse(string, converters: :strip)
#     array # => [["foo", "0"], ["bar", "1"], ["baz", "2"]]
#
# The storage structure for header converters is the Hash CSV::HeaderConverters,
# which works in the same way. It also has built-in converter procs:
# *   `:downcase`: Downcases each header.
# *   `:symbol`: Converts each header to a Symbol.
#
#
# There is no such storage structure for write headers.
#
# In order for the parsing methods to access stored converters in
# non-main-Ractors, the storage structure must be made shareable first.
# Therefore, `Ractor.make_shareable(CSV::Converters)` and
# `Ractor.make_shareable(CSV::HeaderConverters)` must be called before the
# creation of Ractors that use the converters stored in these structures. (Since
# making the storage structures shareable involves freezing them, any custom
# converters that are to be used must be added first.)
#
# ##### Converter Lists
#
# A *converter* *list* is an Array that may include any assortment of:
# *   Converter procs.
# *   Names of stored converters.
# *   Nested converter lists.
#
#
# Examples:
#     numeric_converters = [:integer, :float]
#     date_converters = [:date, :date_time]
#     [numeric_converters, strip_converter]
#     [strip_converter, date_converters, :float]
#
# Like a converter proc, a converter list may be named and stored in either
# CSV::Converters or CSV::HeaderConverters:
#     CSV::Converters[:custom] = [strip_converter, date_converters, :float]
#     CSV::HeaderConverters[:custom] = [:downcase, :symbol]
#
# There are two built-in converter lists:
#     CSV::Converters[:numeric] # => [:integer, :float]
#     CSV::Converters[:all] # => [:date_time, :numeric]
#
# #### Field Converters
#
# With no conversion, all parsed fields in all rows become Strings:
#     string = "foo,0\nbar,1\nbaz,2\n"
#     ary = CSV.parse(string)
#     ary # => # => [["foo", "0"], ["bar", "1"], ["baz", "2"]]
#
# When you specify a field converter, each parsed field is passed to the
# converter; its return value becomes the stored value for the field. A
# converter might, for example, convert an integer embedded in a String into a
# true Integer. (In fact, that's what built-in field converter `:integer` does.)
#
# There are three ways to use field converters.
#
# *   Using option [converters](#class-CSV-label-Option+converters) with a
#     parsing method:
#         ary = CSV.parse(string, converters: :integer)
#         ary # => [0, 1, 2] # => [["foo", 0], ["bar", 1], ["baz", 2]]
#
# *   Using option [converters](#class-CSV-label-Option+converters) with a new
#     CSV instance:
#         csv = CSV.new(string, converters: :integer)
#         # Field converters in effect:
#         csv.converters # => [:integer]
#         csv.read # => [["foo", 0], ["bar", 1], ["baz", 2]]
#
# *   Using method #convert to add a field converter to a CSV instance:
#         csv = CSV.new(string)
#         # Add a converter.
#         csv.convert(:integer)
#         csv.converters # => [:integer]
#         csv.read # => [["foo", 0], ["bar", 1], ["baz", 2]]
#
#
# Installing a field converter does not affect already-read rows:
#     csv = CSV.new(string)
#     csv.shift # => ["foo", "0"]
#     # Add a converter.
#     csv.convert(:integer)
#     csv.converters # => [:integer]
#     csv.read # => [["bar", 1], ["baz", 2]]
#
# There are additional built-in converters, and custom converters are also
# supported.
#
# ##### Built-In Field Converters
#
# The built-in field converters are in Hash CSV::Converters:
# *   Each key is a field converter name.
# *   Each value is one of:
#     *   A Proc field converter.
#     *   An Array of field converter names.
#
#
#
# Display:
#     CSV::Converters.each_pair do |name, value|
#       if value.kind_of?(Proc)
#         p [name, value.class]
#       else
#         p [name, value]
#       end
#     end
#
# Output:
#     [:integer, Proc]
#     [:float, Proc]
#     [:numeric, [:integer, :float]]
#     [:date, Proc]
#     [:date_time, Proc]
#     [:all, [:date_time, :numeric]]
#
# Each of these converters transcodes values to UTF-8 before attempting
# conversion. If a value cannot be transcoded to UTF-8 the conversion will fail
# and the value will remain unconverted.
#
# Converter `:integer` converts each field that Integer() accepts:
#     data = '0,1,2,x'
#     # Without the converter
#     csv = CSV.parse_line(data)
#     csv # => ["0", "1", "2", "x"]
#     # With the converter
#     csv = CSV.parse_line(data, converters: :integer)
#     csv # => [0, 1, 2, "x"]
#
# Converter `:float` converts each field that Float() accepts:
#     data = '1.0,3.14159,x'
#     # Without the converter
#     csv = CSV.parse_line(data)
#     csv # => ["1.0", "3.14159", "x"]
#     # With the converter
#     csv = CSV.parse_line(data, converters: :float)
#     csv # => [1.0, 3.14159, "x"]
#
# Converter `:numeric` converts with both `:integer` and `:float`..
#
# Converter `:date` converts each field that Date::parse accepts:
#     data = '2001-02-03,x'
#     # Without the converter
#     csv = CSV.parse_line(data)
#     csv # => ["2001-02-03", "x"]
#     # With the converter
#     csv = CSV.parse_line(data, converters: :date)
#     csv # => [#<Date: 2001-02-03 ((2451944j,0s,0n),+0s,2299161j)>, "x"]
#
# Converter `:date_time` converts each field that DateTime::parse accepts:
#     data = '2020-05-07T14:59:00-05:00,x'
#     # Without the converter
#     csv = CSV.parse_line(data)
#     csv # => ["2020-05-07T14:59:00-05:00", "x"]
#     # With the converter
#     csv = CSV.parse_line(data, converters: :date_time)
#     csv # => [#<DateTime: 2020-05-07T14:59:00-05:00 ((2458977j,71940s,0n),-18000s,2299161j)>, "x"]
#
# Converter `:numeric` converts with both `:date_time` and `:numeric`..
#
# As seen above, method #convert adds converters to a CSV instance, and method
# #converters returns an Array of the converters in effect:
#     csv = CSV.new('0,1,2')
#     csv.converters # => []
#     csv.convert(:integer)
#     csv.converters # => [:integer]
#     csv.convert(:date)
#     csv.converters # => [:integer, :date]
#
# ##### Custom Field Converters
#
# You can define a custom field converter:
#     strip_converter = proc {|field| field.strip }
#     string = " foo , 0 \n bar , 1 \n baz , 2 \n"
#     array = CSV.parse(string, converters: strip_converter)
#     array # => [["foo", "0"], ["bar", "1"], ["baz", "2"]]
#
# You can register the converter in Converters Hash, which allows you to refer
# to it by name:
#     CSV::Converters[:strip] = strip_converter
#     string = " foo , 0 \n bar , 1 \n baz , 2 \n"
#     array = CSV.parse(string, converters: :strip)
#     array # => [["foo", "0"], ["bar", "1"], ["baz", "2"]]
#
# #### Header Converters
#
# Header converters operate only on headers (and not on other rows).
#
# There are three ways to use header converters; these examples use built-in
# header converter `:dowhcase`, which downcases each parsed header.
#
# *   Option `header_converters` with a singleton parsing method:
#         string = "Name,Count\nFoo,0\n,Bar,1\nBaz,2"
#         tbl = CSV.parse(string, headers: true, header_converters: :downcase)
#         tbl.class # => CSV::Table
#         tbl.headers # => ["name", "count"]
#
# *   Option `header_converters` with a new CSV instance:
#         csv = CSV.new(string, header_converters: :downcase)
#         # Header converters in effect:
#         csv.header_converters # => [:downcase]
#         tbl = CSV.parse(string, headers: true)
#         tbl.headers # => ["Name", "Count"]
#
# *   Method #header_convert adds a header converter to a CSV instance:
#         csv = CSV.new(string)
#         # Add a header converter.
#         csv.header_convert(:downcase)
#         csv.header_converters # => [:downcase]
#         tbl = CSV.parse(string, headers: true)
#         tbl.headers # => ["Name", "Count"]
#
#
# ##### Built-In Header Converters
#
# The built-in header converters are in Hash CSV::HeaderConverters. The keys
# there are the names of the converters:
#     CSV::HeaderConverters.keys # => [:downcase, :symbol]
#
# Converter `:downcase` converts each header by downcasing it:
#     string = "Name,Count\nFoo,0\n,Bar,1\nBaz,2"
#     tbl = CSV.parse(string, headers: true, header_converters: :downcase)
#     tbl.class # => CSV::Table
#     tbl.headers # => ["name", "count"]
#
# Converter `:symbol` converts each header by making it into a Symbol:
#     string = "Name,Count\nFoo,0\n,Bar,1\nBaz,2"
#     tbl = CSV.parse(string, headers: true, header_converters: :symbol)
#     tbl.headers # => [:name, :count]
#
# Details:
# *   Strips leading and trailing whitespace.
# *   Downcases the header.
# *   Replaces embedded spaces with underscores.
# *   Removes non-word characters.
# *   Makes the string into a Symbol.
#
#
# ##### Custom Header Converters
#
# You can define a custom header converter:
#     upcase_converter = proc {|header| header.upcase }
#     string = "Name,Value\nfoo,0\nbar,1\nbaz,2\n"
#     table = CSV.parse(string, headers: true, header_converters: upcase_converter)
#     table # => #<CSV::Table mode:col_or_row row_count:4>
#     table.headers # => ["NAME", "VALUE"]
#
# You can register the converter in HeaderConverters Hash, which allows you to
# refer to it by name:
#     CSV::HeaderConverters[:upcase] = upcase_converter
#     table = CSV.parse(string, headers: true, header_converters: :upcase)
#     table # => #<CSV::Table mode:col_or_row row_count:4>
#     table.headers # => ["NAME", "VALUE"]
#
# ##### Write Converters
#
# When you specify a write converter for generating CSV, each field to be
# written is passed to the converter; its return value becomes the new value for
# the field. A converter might, for example, strip whitespace from a field.
#
# Using no write converter (all fields unmodified):
#     output_string = CSV.generate do |csv|
#       csv << [' foo ', 0]
#       csv << [' bar ', 1]
#       csv << [' baz ', 2]
#     end
#     output_string # => " foo ,0\n bar ,1\n baz ,2\n"
#
# Using option `write_converters` with two custom write converters:
#     strip_converter = proc {|field| field.respond_to?(:strip) ? field.strip : field }
#     upcase_converter = proc {|field| field.respond_to?(:upcase) ? field.upcase : field }
#     write_converters = [strip_converter, upcase_converter]
#     output_string = CSV.generate(write_converters: write_converters) do |csv|
#       csv << [' foo ', 0]
#       csv << [' bar ', 1]
#       csv << [' baz ', 2]
#     end
#     output_string # => "FOO,0\nBAR,1\nBAZ,2\n"
#
# ### Character Encodings (M17n or Multilingualization)
#
# This new CSV parser is m17n savvy.  The parser works in the Encoding of the IO
# or String object being read from or written to. Your data is never transcoded
# (unless you ask Ruby to transcode it for you) and will literally be parsed in
# the Encoding it is in. Thus CSV will return Arrays or Rows of Strings in the
# Encoding of your data. This is accomplished by transcoding the parser itself
# into your Encoding.
#
# Some transcoding must take place, of course, to accomplish this multiencoding
# support. For example, `:col_sep`, `:row_sep`, and `:quote_char` must be
# transcoded to match your data.  Hopefully this makes the entire process feel
# transparent, since CSV's defaults should just magically work for your data.
# However, you can set these values manually in the target Encoding to avoid the
# translation.
#
# It's also important to note that while all of CSV's core parser is now
# Encoding agnostic, some features are not. For example, the built-in converters
# will try to transcode data to UTF-8 before making conversions. Again, you can
# provide custom converters that are aware of your Encodings to avoid this
# translation. It's just too hard for me to support native conversions in all of
# Ruby's Encodings.
#
# Anyway, the practical side of this is simple: make sure IO and String objects
# passed into CSV have the proper Encoding set and everything should just work.
# CSV methods that allow you to open IO objects (CSV::foreach(), CSV::open(),
# CSV::read(), and CSV::readlines()) do allow you to specify the Encoding.
#
# One minor exception comes when generating CSV into a String with an Encoding
# that is not ASCII compatible. There's no existing data for CSV to use to
# prepare itself and thus you will probably need to manually specify the desired
# Encoding for most of those cases. It will try to guess using the fields in a
# row of output though, when using CSV::generate_line() or Array#to_csv().
#
# I try to point out any other Encoding issues in the documentation of methods
# as they come up.
#
# This has been tested to the best of my ability with all non-"dummy" Encodings
# Ruby ships with. However, it is brave new code and may have some bugs. Please
# feel free to [report](mailto:james@grayproductions.net) any issues you find
# with it.
#
class CSV < Object
  include Enumerable[untyped]
  extend Forwardable

# 
  # Calls the block with each row read from source `path` or `io`.
  #
  # *   Argument `path`, if given, must be the path to a file.
  # *   Argument `io` should be an IO object that is:
  #     *   Open for reading; on return, the IO object will be closed.
  #     *   Positioned at the beginning. To position at the end, for appending,
  #         use method CSV.generate. For any other positioning, pass a preset
  #         StringIO object instead.
  #
  # *   Argument `mode`, if given, must be a File mode See [Open
  #     Mode](IO.html#method-c-new-label-Open+Mode).
  # *   Arguments `**options` must be keyword options. See [Options for
  #     Parsing](#class-CSV-label-Options+for+Parsing).
  # *   This method optionally accepts an additional `:encoding` option that you
  #     can use to specify the Encoding of the data read from `path` or `io`. You
  #     must provide this unless your data is in the encoding given by
  #     `Encoding::default_external`. Parsing will use this to determine how to
  #     parse the data. You may provide a second Encoding to have the data
  #     transcoded as it is read. For example,
  #         encoding: 'UTF-32BE:UTF-8'
  #
  #     would read `UTF-32BE` data from the file but transcode it to `UTF-8`
  #     before parsing.
  #
  #
  # ###### Without Option `headers`
  #
  # Without option `headers`, returns each row as an Array object.
  #
  # These examples assume prior execution of:
  #     string = "foo,0\nbar,1\nbaz,2\n"
  #     path = 't.csv'
  #     File.write(path, string)
  #
  # Read rows from a file at `path`:
  #     CSV.foreach(path) {|row| p row }
  #
  # Output:
  #     ["foo", "0"]
  #     ["bar", "1"]
  #     ["baz", "2"]
  #
  # Read rows from an IO object:
  #     File.open(path) do |file|
  #       CSV.foreach(file) {|row| p row }
  #     end
  #
  # Output:
  #     ["foo", "0"]
  #     ["bar", "1"]
  #     ["baz", "2"]
  #
  # Returns a new Enumerator if no block given:
  #     CSV.foreach(path) # => #<Enumerator: CSV:foreach("t.csv", "r")>
  #     CSV.foreach(File.open(path)) # => #<Enumerator: CSV:foreach(#<File:t.csv>, "r")>
  #
  # Issues a warning if an encoding is unsupported:
  #     CSV.foreach(File.open(path), encoding: 'foo:bar') {|row| }
  #
  # Output:
  #     warning: Unsupported encoding foo ignored
  #     warning: Unsupported encoding bar ignored
  #
  # ###### With Option `headers`
  #
  # With {option `headers`[}](#class-CSV-label-Option+headers), returns each row
  # as a CSV::Row object.
  #
  # These examples assume prior execution of:
  #     string = "Name,Count\nfoo,0\nbar,1\nbaz,2\n"
  #     path = 't.csv'
  #     File.write(path, string)
  #
  # Read rows from a file at `path`:
  #     CSV.foreach(path, headers: true) {|row| p row }
  #
  # Output:
  #     #<CSV::Row "Name":"foo" "Count":"0">
  #     #<CSV::Row "Name":"bar" "Count":"1">
  #     #<CSV::Row "Name":"baz" "Count":"2">
  #
  # Read rows from an IO object:
  #     File.open(path) do |file|
  #       CSV.foreach(file, headers: true) {|row| p row }
  #     end
  #
  # Output:
  #     #<CSV::Row "Name":"foo" "Count":"0">
  #     #<CSV::Row "Name":"bar" "Count":"1">
  #     #<CSV::Row "Name":"baz" "Count":"2">
  #
  # ---
  #
  # Raises an exception if `path` is a String, but not the path to a readable
  # file:
  #     # Raises Errno::ENOENT (No such file or directory @ rb_sysopen - nosuch.csv):
  #     CSV.foreach('nosuch.csv') {|row| }
  #
  # Raises an exception if `io` is an IO object, but not open for reading:
  #     io = File.open(path, 'w') {|row| }
  #     # Raises TypeError (no implicit conversion of nil into String):
  #     CSV.foreach(io) {|row| }
  #
  # Raises an exception if `mode` is invalid:
  #     # Raises ArgumentError (invalid access mode nosuch):
  #     CSV.foreach(path, 'nosuch') {|row| }
  #
  def self.foreach: [U] (String | IO | StringIO path, ?::Hash[Symbol, U] options) { (::Array[String?] arg0) -> void } -> void

# 
  # Returns the new CSV object created using `string` or `io` and the specified
  # `options`.
  #
  # *   Argument `string` should be a String object; it will be put into a new
  #     StringIO object positioned at the beginning.
  # *   Argument `io` should be an IO object that is:
  #     *   Open for reading; on return, the IO object will be closed.
  #     *   Positioned at the beginning. To position at the end, for appending,
  #         use method CSV.generate. For any other positioning, pass a preset
  #         StringIO object instead.
  #
  # *   Argument `options`: See:
  #     *   [Options for Parsing](#class-CSV-label-Options+for+Parsing)
  #     *   [Options for Generating](#class-CSV-label-Options+for+Generating)
  #
  #     For performance reasons, the options cannot be overridden in a CSV object,
  #     so those specified here will endure.
  #
  #
  # In addition to the CSV instance methods, several IO methods are delegated. See
  # [Delegated Methods](#class-CSV-label-Delegated+Methods).
  #
  # ---
  #
  # Create a CSV object from a String object:
  #     csv = CSV.new('foo,0')
  #     csv # => #<CSV io_type:StringIO encoding:UTF-8 lineno:0 col_sep:"," row_sep:"\n" quote_char:"\"">
  #
  # Create a CSV object from a File object:
  #     File.write('t.csv', 'foo,0')
  #     csv = CSV.new(File.open('t.csv'))
  #     csv # => #<CSV io_type:File io_path:"t.csv" encoding:UTF-8 lineno:0 col_sep:"," row_sep:"\n" quote_char:"\"">
  #
  # ---
  #
  # Raises an exception if the argument is `nil`:
  #     # Raises ArgumentError (Cannot parse nil as CSV):
  #     CSV.new(nil)
  #
  def initialize: (?String | IO | StringIO io, ?::Hash[Symbol, untyped] options) -> void

# 
  # Parses `string` or `io` using the specified `options`.
  #
  # *   Argument `string` should be a String object; it will be put into a new
  #     StringIO object positioned at the beginning.
  # *   Argument `io` should be an IO object that is:
  #     *   Open for reading; on return, the IO object will be closed.
  #     *   Positioned at the beginning. To position at the end, for appending,
  #         use method CSV.generate. For any other positioning, pass a preset
  #         StringIO object instead.
  #
  # *   Argument `options`: see [Options for
  #     Parsing](#class-CSV-label-Options+for+Parsing)
  #
  #
  # ###### Without Option `headers`
  #
  # Without {option `headers`[}](#class-CSV-label-Option+headers) case.
  #
  # These examples assume prior execution of:
  #     string = "foo,0\nbar,1\nbaz,2\n"
  #     path = 't.csv'
  #     File.write(path, string)
  #
  # ---
  #
  # With no block given, returns an Array of Arrays formed from the source.
  #
  # Parse a String:
  #     a_of_a = CSV.parse(string)
  #     a_of_a # => [["foo", "0"], ["bar", "1"], ["baz", "2"]]
  #
  # Parse an open File:
  #     a_of_a = File.open(path) do |file|
  #       CSV.parse(file)
  #     end
  #     a_of_a # => [["foo", "0"], ["bar", "1"], ["baz", "2"]]
  #
  # ---
  #
  # With a block given, calls the block with each parsed row:
  #
  # Parse a String:
  #     CSV.parse(string) {|row| p row }
  #
  # Output:
  #     ["foo", "0"]
  #     ["bar", "1"]
  #     ["baz", "2"]
  #
  # Parse an open File:
  #     File.open(path) do |file|
  #       CSV.parse(file) {|row| p row }
  #     end
  #
  # Output:
  #     ["foo", "0"]
  #     ["bar", "1"]
  #     ["baz", "2"]
  #
  # ###### With Option `headers`
  #
  # With {option `headers`[}](#class-CSV-label-Option+headers) case.
  #
  # These examples assume prior execution of:
  #     string = "Name,Count\nfoo,0\nbar,1\nbaz,2\n"
  #     path = 't.csv'
  #     File.write(path, string)
  #
  # ---
  #
  # With no block given, returns a CSV::Table object formed from the source.
  #
  # Parse a String:
  #     csv_table = CSV.parse(string, headers: ['Name', 'Count'])
  #     csv_table # => #<CSV::Table mode:col_or_row row_count:5>
  #
  # Parse an open File:
  #     csv_table = File.open(path) do |file|
  #       CSV.parse(file, headers: ['Name', 'Count'])
  #     end
  #     csv_table # => #<CSV::Table mode:col_or_row row_count:4>
  #
  # ---
  #
  # With a block given, calls the block with each parsed row, which has been
  # formed into a CSV::Row object:
  #
  # Parse a String:
  #     CSV.parse(string, headers: ['Name', 'Count']) {|row| p row }
  #
  # Output:
  #     # <CSV::Row "Name":"foo" "Count":"0">
  #     # <CSV::Row "Name":"bar" "Count":"1">
  #     # <CSV::Row "Name":"baz" "Count":"2">
  #
  # Parse an open File:
  #     File.open(path) do |file|
  #       CSV.parse(file, headers: ['Name', 'Count']) {|row| p row }
  #     end
  #
  # Output:
  #     # <CSV::Row "Name":"foo" "Count":"0">
  #     # <CSV::Row "Name":"bar" "Count":"1">
  #     # <CSV::Row "Name":"baz" "Count":"2">
  #
  # ---
  #
  # Raises an exception if the argument is not a String object or IO object:
  #     # Raises NoMethodError (undefined method `close' for :foo:Symbol)
  #     CSV.parse(:foo)
  #
  def self.parse: (String str, ?::Hash[Symbol, untyped] options) ?{ (::Array[String?] arg0) -> void } -> ::Array[::Array[String?]]?

# 
  # Returns the data created by parsing the first line of `string` or `io` using
  # the specified `options`.
  #
  # *   Argument `string` should be a String object; it will be put into a new
  #     StringIO object positioned at the beginning.
  # *   Argument `io` should be an IO object that is:
  #     *   Open for reading; on return, the IO object will be closed.
  #     *   Positioned at the beginning. To position at the end, for appending,
  #         use method CSV.generate. For any other positioning, pass a preset
  #         StringIO object instead.
  #
  # *   Argument `options`: see [Options for
  #     Parsing](#class-CSV-label-Options+for+Parsing)
  #
  #
  # ###### Without Option `headers`
  #
  # Without option `headers`, returns the first row as a new Array.
  #
  # These examples assume prior execution of:
  #     string = "foo,0\nbar,1\nbaz,2\n"
  #     path = 't.csv'
  #     File.write(path, string)
  #
  # Parse the first line from a String object:
  #     CSV.parse_line(string) # => ["foo", "0"]
  #
  # Parse the first line from a File object:
  #     File.open(path) do |file|
  #       CSV.parse_line(file) # => ["foo", "0"]
  #     end # => ["foo", "0"]
  #
  # Returns `nil` if the argument is an empty String:
  #     CSV.parse_line('') # => nil
  #
  # ###### With Option `headers`
  #
  # With {option `headers`[}](#class-CSV-label-Option+headers), returns the first
  # row as a CSV::Row object.
  #
  # These examples assume prior execution of:
  #     string = "Name,Count\nfoo,0\nbar,1\nbaz,2\n"
  #     path = 't.csv'
  #     File.write(path, string)
  #
  # Parse the first line from a String object:
  #     CSV.parse_line(string, headers: true) # => #<CSV::Row "Name":"foo" "Count":"0">
  #
  # Parse the first line from a File object:
  #     File.open(path) do |file|
  #       CSV.parse_line(file, headers: true)
  #     end # => #<CSV::Row "Name":"foo" "Count":"0">
  #
  # ---
  #
  # Raises an exception if the argument is `nil`:
  #     # Raises ArgumentError (Cannot parse nil as CSV):
  #     CSV.parse_line(nil)
  #
  def self.parse_line: (String str, ?::Hash[Symbol, untyped] options) -> ::Array[String?]?

# 
  # Forms the remaining rows from `self` into:
  # *   A CSV::Table object, if headers are in use.
  # *   An Array of Arrays, otherwise.
  #
  #
  # The data source must be opened for reading.
  #
  # Without headers:
  #     string = "foo,0\nbar,1\nbaz,2\n"
  #     path = 't.csv'
  #     File.write(path, string)
  #     csv = CSV.open(path)
  #     csv.read # => [["foo", "0"], ["bar", "1"], ["baz", "2"]]
  #
  # With headers:
  #     string = "Name,Value\nfoo,0\nbar,1\nbaz,2\n"
  #     path = 't.csv'
  #     File.write(path, string)
  #     csv = CSV.open(path, headers: true)
  #     csv.read # => #<CSV::Table mode:col_or_row row_count:4>
  #
  # ---
  #
  # Raises an exception if the source is not opened for reading:
  #     string = "foo,0\nbar,1\nbaz,2\n"
  #     csv = CSV.new(string)
  #     csv.close
  #     # Raises IOError (not opened for reading)
  #     csv.read
  #
  def read: () -> ::Array[::Array[String?]]

# 
  #
  def readline: () -> ::Array[String?]?

# 
  # Opens the given `source` with the given `options` (see CSV.open), reads the
  # source (see CSV#read), and returns the result, which will be either an Array
  # of Arrays or a CSV::Table.
  #
  # Without headers:
  #     string = "foo,0\nbar,1\nbaz,2\n"
  #     path = 't.csv'
  #     File.write(path, string)
  #     CSV.read(path) # => [["foo", "0"], ["bar", "1"], ["baz", "2"]]
  #
  # With headers:
  #     string = "Name,Value\nfoo,0\nbar,1\nbaz,2\n"
  #     path = 't.csv'
  #     File.write(path, string)
  #     CSV.read(path, headers: true) # => #<CSV::Table mode:col_or_row row_count:4>
  #
  def self.read: (String path, ?::Hash[Symbol, untyped] options) -> ::Array[::Array[String?]]

# 
  # Appends a row to `self`.
  #
  # *   Argument `row` must be an Array object or a CSV::Row object.
  # *   The output stream must be open for writing.
  #
  #
  # ---
  #
  # Append Arrays:
  #     CSV.generate do |csv|
  #       csv << ['foo', 0]
  #       csv << ['bar', 1]
  #       csv << ['baz', 2]
  #     end # => "foo,0\nbar,1\nbaz,2\n"
  #
  # Append CSV::Rows:
  #     headers = []
  #     CSV.generate do |csv|
  #       csv << CSV::Row.new(headers, ['foo', 0])
  #       csv << CSV::Row.new(headers, ['bar', 1])
  #       csv << CSV::Row.new(headers, ['baz', 2])
  #     end # => "foo,0\nbar,1\nbaz,2\n"
  #
  # Headers in CSV::Row objects are not appended:
  #     headers = ['Name', 'Count']
  #     CSV.generate do |csv|
  #       csv << CSV::Row.new(headers, ['foo', 0])
  #       csv << CSV::Row.new(headers, ['bar', 1])
  #       csv << CSV::Row.new(headers, ['baz', 2])
  #     end # => "foo,0\nbar,1\nbaz,2\n"
  #
  # ---
  #
  # Raises an exception if `row` is not an Array or CSV::Row:
  #     CSV.generate do |csv|
  #       # Raises NoMethodError (undefined method `collect' for :foo:Symbol)
  #       csv << :foo
  #     end
  #
  # Raises an exception if the output stream is not opened for writing:
  #     path = 't.csv'
  #     File.write(path, '')
  #     File.open(path) do |file|
  #       CSV.open(file) do |csv|
  #         # Raises IOError (not opened for writing)
  #         csv << ['foo', 0]
  #       end
  #     end
  #
  def <<: (::Array[untyped] | CSV::Row row) -> void

# 
  # *   Argument `csv_string`, if given, must be a String object; defaults to a
  #     new empty String.
  # *   Arguments `options`, if given, should be generating options. See [Options
  #     for Generating](#class-CSV-label-Options+for+Generating).
  #
  #
  # ---
  #
  # Creates a new CSV object via `CSV.new(csv_string, **options)`; calls the block
  # with the CSV object, which the block may modify; returns the String generated
  # from the CSV object.
  #
  # Note that a passed String **is** modified by this method. Pass
  # `csv_string`.dup if the String must be preserved.
  #
  # This method has one additional option: `:encoding`, which sets the base
  # Encoding for the output if no no `str` is specified. CSV needs this hint if
  # you plan to output non-ASCII compatible data.
  #
  # ---
  #
  # Add lines:
  #     input_string = "foo,0\nbar,1\nbaz,2\n"
  #     output_string = CSV.generate(input_string) do |csv|
  #       csv << ['bat', 3]
  #       csv << ['bam', 4]
  #     end
  #     output_string # => "foo,0\nbar,1\nbaz,2\nbat,3\nbam,4\n"
  #     input_string # => "foo,0\nbar,1\nbaz,2\nbat,3\nbam,4\n"
  #     output_string.equal?(input_string) # => true # Same string, modified
  #
  # Add lines into new string, preserving old string:
  #     input_string = "foo,0\nbar,1\nbaz,2\n"
  #     output_string = CSV.generate(input_string.dup) do |csv|
  #       csv << ['bat', 3]
  #       csv << ['bam', 4]
  #     end
  #     output_string # => "foo,0\nbar,1\nbaz,2\nbat,3\nbam,4\n"
  #     input_string # => "foo,0\nbar,1\nbaz,2\n"
  #     output_string.equal?(input_string) # => false # Different strings
  #
  # Create lines from nothing:
  #     output_string = CSV.generate do |csv|
  #       csv << ['foo', 0]
  #       csv << ['bar', 1]
  #       csv << ['baz', 2]
  #     end
  #     output_string # => "foo,0\nbar,1\nbaz,2\n"
  #
  # ---
  #
  # Raises an exception if `csv_string` is not a String object:
  #     # Raises TypeError (no implicit conversion of Integer into String)
  #     CSV.generate(0)
  #
  def self.generate: (?String str, **untyped options) { (CSV csv) -> void } -> String

# 
  # Calls the block with each successive row. The data source must be opened for
  # reading.
  #
  # Without headers:
  #     string = "foo,0\nbar,1\nbaz,2\n"
  #     csv = CSV.new(string)
  #     csv.each do |row|
  #       p row
  #     end
  #
  # Output:
  #     ["foo", "0"]
  #     ["bar", "1"]
  #     ["baz", "2"]
  #
  # With headers:
  #     string = "Name,Value\nfoo,0\nbar,1\nbaz,2\n"
  #     csv = CSV.new(string, headers: true)
  #     csv.each do |row|
  #       p row
  #     end
  #
  # Output:
  #     <CSV::Row "Name":"foo" "Value":"0">
  #     <CSV::Row "Name":"bar" "Value":"1">
  #     <CSV::Row "Name":"baz" "Value":"2">
  #
  # ---
  #
  # Raises an exception if the source is not opened for reading:
  #     string = "foo,0\nbar,1\nbaz,2\n"
  #     csv = CSV.new(string)
  #     csv.close
  #     # Raises IOError (not opened for reading)
  #     csv.each do |row|
  #       p row
  #     end
  #
  def each: () -> Enumerator[untyped, Integer]
          | () { (untyped) -> void } -> Integer
end

# 
# Default values for method options.
#
CSV::DEFAULT_OPTIONS: ::Hash[untyped, untyped]

# 
# The version of the installed library.
#
CSV::VERSION: String

# 
# A CSV::Row is part Array and part Hash. It retains an order for the fields and
# allows duplicates just as an Array would, but also allows you to access fields
# by name just as you could if they were in a Hash.
#
# All rows returned by CSV will be constructed from this class, if header row
# processing is activated.
#
class CSV::Row < Object
  include Enumerable[Array[String]]
  extend Forwardable

# 
  # Adds a field to `self`; returns `self`:
  #
  # If the argument is a 2-element Array `[header, value]`, a field is added with
  # the given `header` and `value`:
  #     source = "Name,Name,Name\nFoo,Bar,Baz\n"
  #     table = CSV.parse(source, headers: true)
  #     row = table[0]
  #     row << ['NAME', 'Bat']
  #     row # => #<CSV::Row "Name":"Foo" "Name":"Bar" "Name":"Baz" "NAME":"Bat">
  #
  # If the argument is a Hash, each `key-value` pair is added as a field with
  # header `key` and value `value`.
  #     source = "Name,Name,Name\nFoo,Bar,Baz\n"
  #     table = CSV.parse(source, headers: true)
  #     row = table[0]
  #     row << {NAME: 'Bat', name: 'Bam'}
  #     row # => #<CSV::Row "Name":"Foo" "Name":"Bar" "Name":"Baz" NAME:"Bat" name:"Bam">
  #
  # Otherwise, the given `value` is added as a field with no header.
  #     source = "Name,Name,Name\nFoo,Bar,Baz\n"
  #     table = CSV.parse(source, headers: true)
  #     row = table[0]
  #     row << 'Bag'
  #     row # => #<CSV::Row "Name":"Foo" "Name":"Bar" "Name":"Baz" nil:"Bag">
  #
  def <<: (untyped arg) -> untyped

# 
  # Returns `true` if this row contains the same headers and fields in the same
  # order as `other`.
  #
  def ==: (untyped other) -> bool

# 
  #
  alias [] field

# 
  # Assigns the field value for the given `index` or `header`; returns `value`.
  #
  # ---
  #
  # Assign field value by Integer index:
  #     source = "Name,Value\nfoo,0\nbar,1\nbaz,2\n"
  #     table = CSV.parse(source, headers: true)
  #     row = table[0]
  #     row[0] = 'Bat'
  #     row[1] = 3
  #     row # => #<CSV::Row "Name":"Bat" "Value":3>
  #
  # Counts backward from the last column if `index` is negative:
  #     row[-1] = 4
  #     row[-2] = 'Bam'
  #     row # => #<CSV::Row "Name":"Bam" "Value":4>
  #
  # Extends the row with `nil:nil` if positive `index` is not in the row:
  #     row[4] = 5
  #     row # => #<CSV::Row "Name":"bad" "Value":4 nil:nil nil:nil nil:5>
  #
  # Raises IndexError if negative `index` is too small (too far from zero).
  #
  # ---
  #
  # Assign field value by header (first found):
  #     source = "Name,Name,Name\nFoo,Bar,Baz\n"
  #     table = CSV.parse(source, headers: true)
  #     row = table[0]
  #     row['Name'] = 'Bat'
  #     row # => #<CSV::Row "Name":"Bat" "Name":"Bar" "Name":"Baz">
  #
  # Assign field value by header, ignoring `offset` leading fields:
  #     source = "Name,Name,Name\nFoo,Bar,Baz\n"
  #     table = CSV.parse(source, headers: true)
  #     row = table[0]
  #     row['Name', 2] = 4
  #     row # => #<CSV::Row "Name":"Foo" "Name":"Bar" "Name":4>
  #
  # Append new field by (new) header:
  #     source = "Name,Value\nfoo,0\nbar,1\nbaz,2\n"
  #     table = CSV.parse(source, headers: true)
  #     row = table[0]
  #     row['New'] = 6
  #     row# => #<CSV::Row "Name":"foo" "Value":"0" "New":6>
  #
  def []=: (*untyped args) -> untyped

# 
  # Removes a specified field from `self`; returns the 2-element Array `[header,
  # value]` if the field exists.
  #
  # If an Integer argument `index` is given, removes and returns the field at
  # offset `index`, or returns `nil` if the field does not exist:
  #     source = "Name,Name,Name\nFoo,Bar,Baz\n"
  #     table = CSV.parse(source, headers: true)
  #     row = table[0]
  #     row.delete(1) # => ["Name", "Bar"]
  #     row.delete(50) # => nil
  #
  # Otherwise, if the single argument `header` is given, removes and returns the
  # first-found field with the given header, of returns a new empty Array if the
  # field does not exist:
  #     source = "Name,Name,Name\nFoo,Bar,Baz\n"
  #     table = CSV.parse(source, headers: true)
  #     row = table[0]
  #     row.delete('Name') # => ["Name", "Foo"]
  #     row.delete('NAME') # => []
  #
  # If argument `header` and Integer argument `offset` are given, removes and
  # returns the first-found field with the given header whose `index` is at least
  # as large as `offset`:
  #     source = "Name,Name,Name\nFoo,Bar,Baz\n"
  #     table = CSV.parse(source, headers: true)
  #     row = table[0]
  #     row.delete('Name', 1) # => ["Name", "Bar"]
  #     row.delete('NAME', 1) # => []
  #
  def delete: (untyped header_or_index, ?untyped minimum_index) -> untyped

# 
  # Removes fields from `self` as selected by the block; returns `self`.
  #
  # Removes each field for which the block returns a truthy value:
  #     source = "Name,Name,Name\nFoo,Bar,Baz\n"
  #     table = CSV.parse(source, headers: true)
  #     row = table[0]
  #     row.delete_if {|header, value| value.start_with?('B') } # => true
  #     row # => #<CSV::Row "Name":"Foo">
  #     row.delete_if {|header, value| header.start_with?('B') } # => false
  #
  # If no block is given, returns a new Enumerator:
  #     row.delete_if # => #<Enumerator: #<CSV::Row "Name":"Foo">:delete_if>
  #
  def delete_if: () { (*untyped) -> untyped } -> untyped

# 
  # Finds and returns the object in nested object that is specified by
  # `index_or_header` and `specifiers`.
  #
  # The nested objects may be instances of various classes. See [Dig
  # Methods](https://docs.ruby-lang.org/en/master/doc/dig_methods_rdoc.html).
  #
  # Examples:
  #     source = "Name,Value\nfoo,0\nbar,1\nbaz,2\n"
  #     table = CSV.parse(source, headers: true)
  #     row = table[0]
  #     row.dig(1) # => "0"
  #     row.dig('Value') # => "0"
  #     row.dig(5) # => nil
  #
  def dig: (untyped index_or_header, *untyped indexes) -> untyped

# 
  # Yields each pair of the row as header and field tuples (much like iterating
  # over a Hash). This method returns the row for chaining.
  #
  # If no block is given, an Enumerator is returned.
  #
  # Support for Enumerable.
  #
  def each: () -> Enumerator[Array[String], self]
          | () { (Array[String]) -> void } -> self

# 
  #
  alias each_pair each

def empty?: (*untyped args) { (*untyped) -> untyped } -> bool

# 
  # Returns the field value as specified by `header`.
  #
  # ---
  #
  # With the single argument `header`, returns the field value for that header
  # (first found):
  #     source = "Name,Name,Name\nFoo,Bar,Baz\n"
  #     table = CSV.parse(source, headers: true)
  #     row = table[0]
  #     row.fetch('Name') # => "Foo"
  #
  # Raises exception `KeyError` if the header does not exist.
  #
  # ---
  #
  # With arguments `header` and `default` given, returns the field value for the
  # header (first found) if the header exists, otherwise returns `default`:
  #     source = "Name,Name,Name\nFoo,Bar,Baz\n"
  #     table = CSV.parse(source, headers: true)
  #     row = table[0]
  #     row.fetch('Name', '') # => "Foo"
  #     row.fetch(:nosuch, '') # => ""
  #
  # ---
  #
  # With argument `header` and a block given, returns the field value for the
  # header (first found) if the header exists; otherwise calls the block and
  # returns its return value:
  #     source = "Name,Name,Name\nFoo,Bar,Baz\n"
  #     table = CSV.parse(source, headers: true)
  #     row = table[0]
  #     row.fetch('Name') {|header| fail 'Cannot happen' } # => "Foo"
  #     row.fetch(:nosuch) {|header| "Header '#{header} not found'" } # => "Header 'nosuch not found'"
  #
  def fetch: (untyped header, *untyped varargs) ?{ (*untyped) -> untyped } -> untyped

# 
  # Returns the field value for the given `index` or `header`.
  #
  # ---
  #
  # Fetch field value by Integer index:
  #     source = "Name,Value\nfoo,0\nbar,1\nbaz,2\n"
  #     table = CSV.parse(source, headers: true)
  #     row = table[0]
  #     row.field(0) # => "foo"
  #     row.field(1) # => "bar"
  #
  # Counts backward from the last column if `index` is negative:
  #     row.field(-1) # => "0"
  #     row.field(-2) # => "foo"
  #
  # Returns `nil` if `index` is out of range:
  #     row.field(2) # => nil
  #     row.field(-3) # => nil
  #
  # ---
  #
  # Fetch field value by header (first found):
  #     source = "Name,Name,Name\nFoo,Bar,Baz\n"
  #     table = CSV.parse(source, headers: true)
  #     row = table[0]
  #     row.field('Name') # => "Foo"
  #
  # Fetch field value by header, ignoring `offset` leading fields:
  #     source = "Name,Name,Name\nFoo,Bar,Baz\n"
  #     table = CSV.parse(source, headers: true)
  #     row = table[0]
  #     row.field('Name', 2) # => "Baz"
  #
  # Returns `nil` if the header does not exist.
  #
  def field: (untyped header_or_index, ?untyped minimum_index) -> untyped

# 
  # Returns `true` if `data` matches a field in this row, and `false` otherwise.
  #
  def field?: (untyped data) -> bool

# 
  # Returns `true` if this is a field row, `false` otherwise.
  #
  def field_row?: () -> bool

# 
  # Returns field values per the given `specifiers`, which may be any mixture of:
  # *   Integer index.
  # *   Range of Integer indexes.
  # *   2-element Array containing a header and offset.
  # *   Header.
  # *   Range of headers.
  #
  #
  # For `specifier` in one of the first four cases above, returns the result of
  # `self.field(specifier)`;  see #field.
  #
  # Although there may be any number of `specifiers`, the examples here will
  # illustrate one at a time.
  #
  # When the specifier is an Integer `index`, returns `self.field(index)`L
  #     source = "Name,Name,Name\nFoo,Bar,Baz\n"
  #     table = CSV.parse(source, headers: true)
  #     row = table[0]
  #     row.fields(1) # => ["Bar"]
  #
  # When the specifier is a Range of Integers `range`, returns
  # `self.field(range)`:
  #     row.fields(1..2) # => ["Bar", "Baz"]
  #
  # When the specifier is a 2-element Array `array`, returns `self.field(array)`L
  #     row.fields('Name', 1) # => ["Foo", "Bar"]
  #
  # When the specifier is a header `header`, returns `self.field(header)`L
  #     row.fields('Name') # => ["Foo"]
  #
  # When the specifier is a Range of headers `range`, forms a new Range
  # `new_range` from the indexes of `range.start` and `range.end`, and returns
  # `self.field(new_range)`:
  #     source = "Name,NAME,name\nFoo,Bar,Baz\n"
  #     table = CSV.parse(source, headers: true)
  #     row = table[0]
  #     row.fields('Name'..'NAME') # => ["Foo", "Bar"]
  #
  # Returns all fields if no argument given:
  #     row.fields # => ["Foo", "Bar", "Baz"]
  #
  def fields: (*untyped headers_and_or_indices) -> untyped

# 
  # Returns `true` if there is a field with the given `header`, `false` otherwise.
  #
  def has_key?: (untyped header) -> bool

# 
  #
  alias header? has_key?

# 
  # Returns `true` if this is a header row, `false` otherwise.
  #
  def header_row?: () -> bool

# 
  # Returns the headers for this row:
  #     source = "Name,Value\nfoo,0\nbar,1\nbaz,2\n"
  #     table = CSV.parse(source, headers: true)
  #     row = table.first
  #     row.headers # => ["Name", "Value"]
  #
  def headers: () -> untyped

# 
  #
  alias include? has_key?

# 
  # This method will return the index of a field with the provided `header`. The
  # `offset` can be used to locate duplicate header names, as described in
  # CSV::Row.field().
  #
  def index: (untyped header, ?untyped minimum_index) -> untyped

# 
  # Returns an ASCII-compatible String showing:
  # *   Class CSV::Row.
  # *   Header-value pairs.
  #
  # Example:
  #     source = "Name,Value\nfoo,0\nbar,1\nbaz,2\n"
  #     table = CSV.parse(source, headers: true)
  #     row = table[0]
  #     row.inspect # => "#<CSV::Row \"Name\":\"foo\" \"Value\":\"0\">"
  #
  def inspect: () -> String

# 
  #
  alias key? has_key?

def length: (*untyped args) { (*untyped) -> untyped } -> untyped

# 
  #
  alias member? has_key?

# 
  # Appends each of the given `values` to `self` as a field; returns `self`:
  #     source = "Name,Name,Name\nFoo,Bar,Baz\n"
  #     table = CSV.parse(source, headers: true)
  #     row = table[0]
  #     row.push('Bat', 'Bam')
  #     row # => #<CSV::Row "Name":"Foo" "Name":"Bar" "Name":"Baz" nil:"Bat" nil:"Bam">
  #
  def push: (*untyped args) -> untyped

def size: (*untyped args) { (*untyped) -> untyped } -> untyped

# 
  # Returns the row as a CSV String. Headers are not included:
  #     source = "Name,Value\nfoo,0\nbar,1\nbaz,2\n"
  #     table = CSV.parse(source, headers: true)
  #     row = table[0]
  #     row.to_csv # => "foo,0\n"
  #
  def to_csv: (**untyped) -> untyped

# 
  # Returns the new Hash formed by adding each header-value pair in `self` as a
  # key-value pair in the Hash.
  #     source = "Name,Value\nfoo,0\nbar,1\nbaz,2\n"
  #     table = CSV.parse(source, headers: true)
  #     row = table[0]
  #     row.to_h # => {"Name"=>"foo", "Value"=>"0"}
  #
  # Header order is preserved, but repeated headers are ignored:
  #     source = "Name,Name,Name\nFoo,Bar,Baz\n"
  #     table = CSV.parse(source, headers: true)
  #     row = table[0]
  #     row.to_h # => {"Name"=>"Foo"}
  #
  def to_h: () -> untyped

# 
  #
  alias to_hash to_h

# 
  #
  alias to_s to_csv

# 
  #
  alias values_at fields
end

class CSV::FieldInfo < Struct[untyped]
end

# 
# The error thrown when the parser encounters illegal CSV formatting.
#
class CSV::MalformedCSVError < RuntimeError
end

# 
# A CSV::Table is a two-dimensional data structure for representing CSV
# documents. Tables allow you to work with the data by row or column, manipulate
# the data, and even convert the results back to CSV, if needed.
#
# All tables returned by CSV will be constructed from this class, if header row
# processing is activated.
#
class CSV::Table[out Elem] < Object
  include Enumerable[untyped]
  extend Forwardable

# 
  # Constructs a new CSV::Table from `array_of_rows`, which are expected to be
  # CSV::Row objects. All rows are assumed to have the same headers.
  #
  # The optional `headers` parameter can be set to Array of headers. If headers
  # aren't set, headers are fetched from CSV::Row objects. Otherwise, headers()
  # method will return headers being set in headers argument.
  #
  # A CSV::Table object supports the following Array methods through delegation:
  #
  # *   empty?()
  # *   length()
  # *   size()
  #
  def initialize: (untyped array_of_rows, ?headers: untyped) -> untyped

# 
  # If `row_or_array` is a CSV::Row object, it is appended to the table:
  #     source = "Name,Value\nfoo,0\nbar,1\nbaz,2\n"
  #     table = CSV.parse(source, headers: true)
  #     table << CSV::Row.new(table.headers, ['bat', 3])
  #     table[3] # => #<CSV::Row "Name":"bat" "Value":3>
  #
  # If `row_or_array` is an Array, it is used to create a new CSV::Row object
  # which is then appended to the table:
  #     table << ['bam', 4]
  #     table[4] # => #<CSV::Row "Name":"bam" "Value":4>
  #
  def <<: (untyped row_or_array) -> untyped

# 
  # Returns `true` if all each row of `self` `==` the corresponding row of
  # `other_table`, otherwise, `false`.
  #
  # The access mode does no affect the result.
  #
  # Equal tables:
  #     source = "Name,Value\nfoo,0\nbar,1\nbaz,2\n"
  #     table = CSV.parse(source, headers: true)
  #     other_table = CSV.parse(source, headers: true)
  #     table == other_table # => true
  #
  # Different row count:
  #     other_table.delete(2)
  #     table == other_table # => false
  #
  # Different last row:
  #     other_table << ['bat', 3]
  #     table == other_table # => false
  #
  def ==: (untyped other) -> bool

# 
  # Returns data from the table;  does not modify the table.
  #
  # ---
  #
  # The expression `table[n]`, where `n` is a non-negative Integer, returns the
  # +n+th row of the table, if that row exists, and if the access mode is `:row`
  # or `:col_or_row`:
  #     source = "Name,Value\nfoo,0\nbar,1\nbaz,2\n"
  #     table = CSV.parse(source, headers: true)
  #     table.by_row! # => #<CSV::Table mode:row row_count:4>
  #     table[1] # => #<CSV::Row "Name":"bar" "Value":"1">
  #     table.by_col_or_row! # => #<CSV::Table mode:col_or_row row_count:4>
  #     table[1] # => #<CSV::Row "Name":"bar" "Value":"1">
  #
  # Counts backward from the last row if `n` is negative:
  #     table[-1] # => #<CSV::Row "Name":"baz" "Value":"2">
  #
  # Returns `nil` if `n` is too large or too small:
  #     table[4] # => nil
  #     table[-4] => nil
  #
  # Raises an exception if the access mode is `:row` and `n` is not an
  # [Integer-convertible
  # object](https://docs.ruby-lang.org/en/master/implicit_conversion_rdoc.html#lab
  # el-Integer-Convertible+Objects).
  #     table.by_row! # => #<CSV::Table mode:row row_count:4>
  #     # Raises TypeError (no implicit conversion of String into Integer):
  #     table['Name']
  #
  # ---
  #
  # The expression `table[range]`, where `range` is a Range object, returns rows
  # from the table, beginning at row `range.first`, if those rows exist, and if
  # the access mode is `:row` or `:col_or_row`:
  #     source = "Name,Value\nfoo,0\nbar,1\nbaz,2\n"
  #     table = CSV.parse(source, headers: true)
  #     table.by_row! # => #<CSV::Table mode:row row_count:4>
  #     rows = table[1..2] # => #<CSV::Row "Name":"bar" "Value":"1">
  #     rows # => [#<CSV::Row "Name":"bar" "Value":"1">, #<CSV::Row "Name":"baz" "Value":"2">]
  #     table.by_col_or_row! # => #<CSV::Table mode:col_or_row row_count:4>
  #     rows = table[1..2] # => #<CSV::Row "Name":"bar" "Value":"1">
  #     rows # => [#<CSV::Row "Name":"bar" "Value":"1">, #<CSV::Row "Name":"baz" "Value":"2">]
  #
  # If there are too few rows, returns all from `range.first` to the end:
  #     rows = table[1..50] # => #<CSV::Row "Name":"bar" "Value":"1">
  #     rows # => [#<CSV::Row "Name":"bar" "Value":"1">, #<CSV::Row "Name":"baz" "Value":"2">]
  #
  # Special case:  if `range.start == table.size`, returns an empty Array:
  #     table[table.size..50] # => []
  #
  # If `range.end` is negative, calculates the ending index from the end:
  #     rows = table[0..-1]
  #     rows # => [#<CSV::Row "Name":"foo" "Value":"0">, #<CSV::Row "Name":"bar" "Value":"1">, #<CSV::Row "Name":"baz" "Value":"2">]
  #
  # If `range.start` is negative, calculates the starting index from the end:
  #     rows = table[-1..2]
  #     rows # => [#<CSV::Row "Name":"baz" "Value":"2">]
  #
  # If `range.start` is larger than `table.size`, returns `nil`:
  #     table[4..4] # => nil
  #
  # ---
  #
  # The expression `table[header]`, where `header` is a String, returns column
  # values (Array of Strings) if the column exists and if the access mode is
  # `:col` or `:col_or_row`:
  #     source = "Name,Value\nfoo,0\nbar,1\nbaz,2\n"
  #     table = CSV.parse(source, headers: true)
  #     table.by_col! # => #<CSV::Table mode:col row_count:4>
  #     table['Name'] # => ["foo", "bar", "baz"]
  #     table.by_col_or_row! # => #<CSV::Table mode:col_or_row row_count:4>
  #     col = table['Name']
  #     col # => ["foo", "bar", "baz"]
  #
  # Modifying the returned column values does not modify the table:
  #     col[0] = 'bat'
  #     col # => ["bat", "bar", "baz"]
  #     table['Name'] # => ["foo", "bar", "baz"]
  #
  # Returns an Array of `nil` values if there is no such column:
  #     table['Nosuch'] # => [nil, nil, nil]
  #
  def []: (untyped index_or_header) -> untyped

# 
  # In the default mixed mode, this method assigns rows for index access and
  # columns for header access. You can force the index association by first
  # calling by_col!() or by_row!().
  #
  # Rows may be set to an Array of values (which will inherit the table's
  # headers()) or a CSV::Row.
  #
  # Columns may be set to a single value, which is copied to each row of the
  # column, or an Array of values. Arrays of values are assigned to rows top to
  # bottom in row major order. Excess values are ignored and if the Array does not
  # have a value for each row the extra rows will receive a `nil`.
  #
  # Assigning to an existing column or row clobbers the data. Assigning to new
  # columns creates them at the right end of the table.
  #
  def []=: (untyped index_or_header, untyped value) -> untyped

# 
  # Returns a duplicate table object, in column mode. This is handy for chaining
  # in a single call without changing the table mode, but be aware that this
  # method can consume a fair amount of memory for bigger data sets.
  #
  # This method returns the duplicate table for chaining. Don't chain destructive
  # methods (like []=()) this way though, since you are working with a duplicate.
  #
  def by_col: () -> untyped

# 
  # Switches the mode of this table to column mode. All calls to indexing and
  # iteration methods will work with columns until the mode is changed again.
  #
  # This method returns the table and is safe to chain.
  #
  def by_col!: () -> untyped

# 
  # Returns a duplicate table object, in mixed mode. This is handy for chaining in
  # a single call without changing the table mode, but be aware that this method
  # can consume a fair amount of memory for bigger data sets.
  #
  # This method returns the duplicate table for chaining.  Don't chain destructive
  # methods (like []=()) this way though, since you are working with a duplicate.
  #
  def by_col_or_row: () -> untyped

# 
  # Switches the mode of this table to mixed mode. All calls to indexing and
  # iteration methods will use the default intelligent indexing system until the
  # mode is changed again. In mixed mode an index is assumed to be a row reference
  # while anything else is assumed to be column access by headers.
  #
  # This method returns the table and is safe to chain.
  #
  def by_col_or_row!: () -> untyped

# 
  # Returns a duplicate table object, in row mode.  This is handy for chaining in
  # a single call without changing the table mode, but be aware that this method
  # can consume a fair amount of memory for bigger data sets.
  #
  # This method returns the duplicate table for chaining.  Don't chain destructive
  # methods (like []=()) this way though, since you are working with a duplicate.
  #
  def by_row: () -> untyped

# 
  # Switches the mode of this table to row mode. All calls to indexing and
  # iteration methods will work with rows until the mode is changed again.
  #
  # This method returns the table and is safe to chain.
  #
  def by_row!: () -> untyped

# 
  # If the access mode is `:row` or `:col_or_row`, and each argument is either an
  # Integer or a Range, returns deleted rows. Otherwise, returns deleted columns
  # data.
  #
  # In either case, the returned values are in the order specified by the
  # arguments.  Arguments may be repeated.
  #
  # ---
  #
  # Returns rows as an Array of CSV::Row objects.
  #
  # One index:
  #     source = "Name,Value\nfoo,0\nbar,1\nbaz,2\n"
  #     table = CSV.parse(source, headers: true)
  #     deleted_values = table.delete(0)
  #     deleted_values # => [#<CSV::Row "Name":"foo" "Value":"0">]
  #
  # Two indexes:
  #     table = CSV.parse(source, headers: true)
  #     deleted_values = table.delete(2, 0)
  #     deleted_values # => [#<CSV::Row "Name":"baz" "Value":"2">, #<CSV::Row "Name":"foo" "Value":"0">]
  #
  # ---
  #
  # Returns columns data as column Arrays.
  #
  # One header:
  #     table = CSV.parse(source, headers: true)
  #     deleted_values = table.delete('Name')
  #     deleted_values # => ["foo", "bar", "baz"]
  #
  # Two headers:
  #     table = CSV.parse(source, headers: true)
  #     deleted_values = table.delete('Value', 'Name')
  #     deleted_values # => [["0", "1", "2"], ["foo", "bar", "baz"]]
  #
  def delete: (*untyped indexes_or_headers) -> untyped

# 
  # Removes rows or columns for which the block returns a truthy value; returns
  # `self`.
  #
  # Removes rows when the access mode is `:row` or `:col_or_row`; calls the block
  # with each CSV::Row object:
  #     source = "Name,Value\nfoo,0\nbar,1\nbaz,2\n"
  #     table = CSV.parse(source, headers: true)
  #     table.by_row! # => #<CSV::Table mode:row row_count:4>
  #     table.size # => 3
  #     table.delete_if {|row| row['Name'].start_with?('b') }
  #     table.size # => 1
  #
  # Removes columns when the access mode is `:col`; calls the block with each
  # column as a 2-element array containing the header and an Array of column
  # fields:
  #     source = "Name,Value\nfoo,0\nbar,1\nbaz,2\n"
  #     table = CSV.parse(source, headers: true)
  #     table.by_col! # => #<CSV::Table mode:col row_count:4>
  #     table.headers.size # => 2
  #     table.delete_if {|column_data| column_data[1].include?('2') }
  #     table.headers.size # => 1
  #
  # Returns a new Enumerator if no block is given:
  #     source = "Name,Value\nfoo,0\nbar,1\nbaz,2\n"
  #     table = CSV.parse(source, headers: true)
  #     table.delete_if # => #<Enumerator: #<CSV::Table mode:col_or_row row_count:4>:delete_if>
  #
  def delete_if: () { (*untyped) -> untyped } -> untyped

# 
  # Extracts the nested value specified by the sequence of `index` or `header`
  # objects by calling dig at each step, returning nil if any intermediate step is
  # nil.
  #
  def dig: (untyped index_or_header, *untyped index_or_headers) -> untyped

# 
  # Calls the block with each row or column; returns `self`.
  #
  # When the access mode is `:row` or `:col_or_row`, calls the block with each
  # CSV::Row object:
  #     source = "Name,Value\nfoo,0\nbar,1\nbaz,2\n"
  #     table = CSV.parse(source, headers: true)
  #     table.by_row! # => #<CSV::Table mode:row row_count:4>
  #     table.each {|row| p row }
  #
  # Output:
  #     #<CSV::Row "Name":"foo" "Value":"0">
  #     #<CSV::Row "Name":"bar" "Value":"1">
  #     #<CSV::Row "Name":"baz" "Value":"2">
  #
  # When the access mode is `:col`, calls the block with each column as a
  # 2-element array containing the header and an Array of column fields:
  #     table.by_col! # => #<CSV::Table mode:col row_count:4>
  #     table.each {|column_data| p column_data }
  #
  # Output:
  #     ["Name", ["foo", "bar", "baz"]]
  #     ["Value", ["0", "1", "2"]]
  #
  # Returns a new Enumerator if no block is given:
  #     table.each # => #<Enumerator: #<CSV::Table mode:col row_count:4>:each>
  #
  def each: () -> Enumerator[untyped, self]
          | () { (untyped) -> void } -> self
          | () { (*untyped) -> void } -> self

def empty?: (*untyped args) { (*untyped) -> untyped } -> untyped

# 
  # Returns the headers for the first row of this table (assumed to match all
  # other rows). The headers Array passed to CSV::Table.new is returned for empty
  # tables.
  #
  def headers: () -> untyped

# 
  # Shows the mode and size of this table in a US-ASCII String.
  #
  def inspect: () -> String

def length: (*untyped args) { (*untyped) -> untyped } -> untyped

# 
  # The current access mode for indexing and iteration.
  #
  def mode: () -> untyped

# 
  # A shortcut for appending multiple rows. Equivalent to:
  #     rows.each {|row| self << row }
  #
  # Each argument may be either a CSV::Row object or an Array:
  #     source = "Name,Value\nfoo,0\nbar,1\nbaz,2\n"
  #     table = CSV.parse(source, headers: true)
  #     rows = [
  #       CSV::Row.new(table.headers, ['bat', 3]),
  #       ['bam', 4]
  #     ]
  #     table.push(*rows)
  #     table[3..4] # => [#<CSV::Row "Name":"bat" "Value":3>, #<CSV::Row "Name":"bam" "Value":4>]
  #
  def push: (*untyped rows) -> untyped

def size: (*untyped args) { (*untyped) -> untyped } -> untyped

# 
  # Returns the table as an Array of Arrays. Headers will be the first row, then
  # all of the field rows will follow.
  #
  def to_a: () -> untyped

# 
  # Returns the table as a complete CSV String. Headers will be listed first, then
  # all of the field rows.
  #
  # This method assumes you want the Table.headers(), unless you explicitly pass
  # `:write_headers => false`.
  #
  def to_csv: (?write_headers: boolish, **untyped) -> untyped

# 
  #
  alias to_s to_csv

# 
  # If the access mode is `:row` or `:col_or_row`, and each argument is either an
  # Integer or a Range, returns rows. Otherwise, returns columns data.
  #
  # In either case, the returned values are in the order specified by the
  # arguments.  Arguments may be repeated.
  #
  # ---
  #
  # Returns rows as an Array of CSV::Row objects.
  #
  # No argument:
  #     source = "Name,Value\nfoo,0\nbar,1\nbaz,2\n"
  #     table = CSV.parse(source, headers: true)
  #     table.values_at # => []
  #
  # One index:
  #     values = table.values_at(0)
  #     values # => [#<CSV::Row "Name":"foo" "Value":"0">]
  #
  # Two indexes:
  #     values = table.values_at(2, 0)
  #     values # => [#<CSV::Row "Name":"baz" "Value":"2">, #<CSV::Row "Name":"foo" "Value":"0">]
  #
  # One Range:
  #     values = table.values_at(1..2)
  #     values # => [#<CSV::Row "Name":"bar" "Value":"1">, #<CSV::Row "Name":"baz" "Value":"2">]
  #
  # Ranges and indexes:
  #     values = table.values_at(0..1, 1..2, 0, 2)
  #     pp values
  #
  # Output:
  #     [#<CSV::Row "Name":"foo" "Value":"0">,
  #      #<CSV::Row "Name":"bar" "Value":"1">,
  #      #<CSV::Row "Name":"bar" "Value":"1">,
  #      #<CSV::Row "Name":"baz" "Value":"2">,
  #      #<CSV::Row "Name":"foo" "Value":"0">,
  #      #<CSV::Row "Name":"baz" "Value":"2">]
  #
  # ---
  #
  # Returns columns data as row Arrays, each consisting of the specified columns
  # data for that row:
  #     values = table.values_at('Name')
  #     values # => [["foo"], ["bar"], ["baz"]]
  #     values = table.values_at('Value', 'Name')
  #     values # => [["0", "foo"], ["1", "bar"], ["2", "baz"]]
  #
  def values_at: (*untyped indices_or_headers) -> untyped
end

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Edit File: csv.rbs

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