class CSV

This class provides a complete interface to CSV files and data. It offers tools to enable you to read and write to and from Strings or IO objects, as needed.

Reading

From a File

A Line at a Time

CSV.foreach("path/to/file.csv") do |row|
  # use row here...
end

All at Once

arr_of_arrs = CSV.read("path/to/file.csv")

From a String

A Line at a Time

CSV.parse("CSV,data,String") do |row|
  # use row here...
end

All at Once

arr_of_arrs = CSV.parse("CSV,data,String")

Writing

To a File

CSV.open("path/to/file.csv", "wb") do |csv|
  csv << ["row", "of", "CSV", "data"]
  csv << ["another", "row"]
  # ...
end

To a String

csv_string = CSV.generate do |csv|
  csv << ["row", "of", "CSV", "data"]
  csv << ["another", "row"]
  # ...
end

Convert a Single Line

csv_string = ["CSV", "data"].to_csv   # to CSV
csv_array  = "CSV,String".parse_csv   # from CSV

Shortcut Interface

CSV             { |csv_out| csv_out << %w{my data here} }  # to $stdout
CSV(csv = "")   { |csv_str| csv_str << %w{my data here} }  # to a String
CSV($stderr)    { |csv_err| csv_err << %w{my data here} }  # to $stderr
CSV($stdin)     { |csv_in|  csv_in.each { |row| p row } }  # from $stdin

Advanced Usage

Wrap an IO Object

csv = CSV.new(io, options)
# ... read (with gets() or each()) from and write (with <<) to csv here ...

CSV and 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 you 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(), ::open, ::read, and ::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 ::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 any issues you find with it.

Constants

ConverterEncoding

The encoding used by all converters.

Converters

This Hash holds the built-in converters of CSV that can be accessed by name. You can select Converters with #convert or through the options Hash passed to ::new.

:integer

Converts any field Integer() accepts.

:float

Converts any field Float() accepts.

:numeric

A combination of :integer and :float.

:date

Converts any field Date.parse accepts.

:date_time

Converts any field DateTime.parse accepts.

:all

All built-in converters. A combination of :date_time and :numeric.

All built-in converters transcode field data to UTF-8 before attempting a conversion. If your data cannot be transcoded to UTF-8 the conversion will fail and the field will remain unchanged.

This Hash is intentionally left unfrozen and users should feel free to add values to it that can be accessed by all CSV objects.

To add a combo field, the value should be an Array of names. Combo fields can be nested with other combo fields.

DEFAULT_OPTIONS

The options used when no overrides are given by calling code. They are:

:col_sep

","

:row_sep

:auto

:quote_char

'"'

:field_size_limit

nil

:converters

nil

:unconverted_fields

nil

:headers

false

:return_headers

false

:header_converters

nil

:skip_blanks

false

:force_quotes

false

:skip_lines

nil

DateMatcher

A Regexp used to find and convert some common Date formats.

DateTimeMatcher

A Regexp used to find and convert some common DateTime formats.

FieldInfo

A FieldInfo Struct contains details about a field's position in the data source it was read from. CSV will pass this Struct to some blocks that make decisions based on field structure. See #convert_fields for an example.

index

The zero-based index of the field in its row.

line

The line of the data source this row is from.

header

The header for the column, when available.

HeaderConverters

This Hash holds the built-in header converters of CSV that can be accessed by name. You can select HeaderConverters with #header_convert or through the options Hash passed to ::new.

:downcase

Calls downcase() on the header String.

:symbol

The header String is downcased, spaces are replaced with underscores, non-word characters are dropped, and finally to_sym() is called.

All built-in header converters transcode header data to UTF-8 before attempting a conversion. If your data cannot be transcoded to UTF-8 the conversion will fail and the header will remain unchanged.

This Hash is intentionally left unfrozen and users should feel free to add values to it that can be accessed by all CSV objects.

To add a combo field, the value should be an Array of names. Combo fields can be nested with other combo fields.

VERSION

The version of the installed library.

Attributes

col_sep[R]

The encoded :col_sep used in parsing and writing. See ::new for details.

encoding[R]

The Encoding CSV is parsing or writing in. This will be the Encoding you receive parsed data in and/or the Encoding data will be written in.

field_size_limit[R]

The limit for field size, if any. See ::new for details.

lineno[R]

The line number of the last row read from this file. Fields with nested line-end characters will not affect this count.

quote_char[R]

The encoded :quote_char used in parsing and writing. See ::new for details.

row_sep[R]

The encoded :row_sep used in parsing and writing. See ::new for details.

skip_lines[R]

The regex marking a line as a comment. See ::new for details

Public Class Methods

filter( options = Hash.new ) { |row| ... } click to toggle source
filter( input, options = Hash.new ) { |row| ... }
filter( input, output, options = Hash.new ) { |row| ... }

This method is a convenience for building Unix-like filters for CSV data. Each row is yielded to the provided block which can alter it as needed. After the block returns, the row is appended to output altered or not.

The input and output arguments can be anything ::new accepts (generally String or IO objects). If not given, they default to ARGF and $stdout.

The options parameter is also filtered down to ::new after some clever key parsing. Any key beginning with :in_ or :input_ will have that leading identifier stripped and will only be used in the options Hash for the input object. Keys starting with :out_ or :output_ affect only output. All other keys are assigned to both objects.

The :output_row_sep option defaults to $INPUT_RECORD_SEPARATOR ($/).

# File lib/csv.rb, line 1077
def self.filter(*args)
  # parse options for input, output, or both
  in_options, out_options = Hash.new, {row_sep: $INPUT_RECORD_SEPARATOR}
  if args.last.is_a? Hash
    args.pop.each do |key, value|
      case key.to_s
      when /\Ain(?:put)?_(.+)\Z/
        in_options[$1.to_sym] = value
      when /\Aout(?:put)?_(.+)\Z/
        out_options[$1.to_sym] = value
      else
        in_options[key]  = value
        out_options[key] = value
      end
    end
  end
  # build input and output wrappers
  input  = new(args.shift || ARGF,    in_options)
  output = new(args.shift || $stdout, out_options)

  # read, yield, write
  input.each do |row|
    yield row
    output << row
  end
end
foreach(path, options = Hash.new, &block) click to toggle source

This method is intended as the primary interface for reading CSV files. You pass a path and any options you wish to set for the read. Each row of file will be passed to the provided block in turn.

The options parameter can be anything ::new understands. This method also understands an additional :encoding parameter that you can use to specify the Encoding of the data in the file to be read. You must provide this unless your data is in Encoding.default_external. CSV 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 CSV parses it.

# File lib/csv.rb, line 1118
def self.foreach(path, options = Hash.new, &block)
  return to_enum(__method__, path, options) unless block
  open(path, options) do |csv|
    csv.each(&block)
  end
end
generate( str, options = Hash.new ) { |csv| ... } click to toggle source
generate( options = Hash.new ) { |csv| ... }

This method wraps a String you provide, or an empty default String, in a CSV object which is passed to the provided block. You can use the block to append CSV rows to the String and when the block exits, the final String will be returned.

Note that a passed String is modified by this method. Call dup() before passing if you need a new String.

The options parameter can be anything ::new understands. This method understands an additional :encoding parameter when not passed a String to set the base Encoding for the output. CSV needs this hint if you plan to output non-ASCII compatible data.

# File lib/csv.rb, line 1143
def self.generate(*args)
  # add a default empty String, if none was given
  if args.first.is_a? String
    io = StringIO.new(args.shift)
    io.seek(0, IO::SEEK_END)
    args.unshift(io)
  else
    encoding = args[-1][:encoding] if args.last.is_a?(Hash)
    str      = ""
    str.force_encoding(encoding) if encoding
    args.unshift(str)
  end
  csv = new(*args)  # wrap
  yield csv         # yield for appending
  csv.string        # return final String
end
generate_line(row, options = Hash.new) click to toggle source

This method is a shortcut for converting a single row (Array) into a CSV String.

The options parameter can be anything ::new understands. This method understands an additional :encoding parameter to set the base Encoding for the output. This method will try to guess your Encoding from the first non-nil field in row, if possible, but you may need to use this parameter as a backup plan.

The :row_sep option defaults to $INPUT_RECORD_SEPARATOR ($/) when calling this method.

# File lib/csv.rb, line 1173
def self.generate_line(row, options = Hash.new)
  options  = {row_sep: $INPUT_RECORD_SEPARATOR}.merge(options)
  encoding = options.delete(:encoding)
  str      = ""
  if encoding
    str.force_encoding(encoding)
  elsif field = row.find { |f| not f.nil? }
    str.force_encoding(String(field).encoding)
  end
  (new(str, options) << row).string
end
instance(data = $stdout, options = Hash.new) { |instance| ... } click to toggle source

This method will return a CSV instance, just like ::new, but the instance will be cached and returned for all future calls to this method for the same data object (tested by Object#object_id) with the same options.

If a block is given, the instance is passed to the block and the return value becomes the return value of the block.

# File lib/csv.rb, line 1037
def self.instance(data = $stdout, options = Hash.new)
  # create a _signature_ for this method call, data object and options
  sig = [data.object_id] +
        options.values_at(*DEFAULT_OPTIONS.keys.sort_by { |sym| sym.to_s })

  # fetch or create the instance for this signature
  @@instances ||= Hash.new
  instance    =   (@@instances[sig] ||= new(data, options))

  if block_given?
    yield instance  # run block, if given, returning result
  else
    instance        # or return the instance
  end
end
new(data, options = Hash.new) click to toggle source

This constructor will wrap either a String or IO object passed in data for reading and/or writing. In addition to the CSV instance methods, several IO methods are delegated. (See ::open for a complete list.) If you pass a String for data, you can later retrieve it (after writing to it, for example) with CSV.string().

Note that a wrapped String will be positioned at at the beginning (for reading). If you want it at the end (for writing), use ::generate. If you want any other positioning, pass a preset StringIO object instead.

You may set any reading and/or writing preferences in the options Hash. Available options are:

:col_sep

The String placed between each field. This String will be transcoded into the data's Encoding before parsing.

:row_sep

The String appended to the end of each row. This can be set to the special :auto setting, which requests that CSV automatically discover this from the data. Auto-discovery reads ahead in the data looking for the next "\r\n", "\n", or "\r" sequence. A sequence will be selected even if it occurs in a quoted field, assuming that you would have the same line endings there. If none of those sequences is found, data is ARGF, STDIN, STDOUT, or STDERR, or the stream is only available for output, the default $INPUT_RECORD_SEPARATOR ($/) is used. 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. This String will be transcoded into the data's Encoding before parsing.

:quote_char

The character used to quote fields. This has to be a single character String. This is useful for application that incorrectly use ' as the quote character instead of the correct ". CSV will always consider a double sequence of this character to be an escaped quote. This String will be transcoded into the data's Encoding before parsing.

:field_size_limit

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 and thus is set to nil, or off, by default.

:converters

An Array of names from the Converters Hash and/or lambdas that handle custom conversion. A single converter doesn't have to be in an Array. All built-in converters try to transcode fields to UTF-8 before converting. The conversion will fail if the data cannot be transcoded, leaving the field unchanged.

:unconverted_fields

If set to true, an unconverted_fields() method will be added to all returned rows (Array or CSV::Row) that will return the fields as they were before conversion. Note that :headers supplied by Array or String were not fields of the document and thus will have an empty Array attached.

:headers

If set to :first_row or true, the initial row of the CSV file will be treated as a row of headers. If set to an Array, the contents will be used as the headers. If set to a String, the String is run through a call of ::parse_line with the same :col_sep, :row_sep, and :quote_char as this instance to produce an Array of headers. This setting causes #shift to return rows as CSV::Row objects instead of Arrays and #read to return CSV::Table objects instead of an Array of Arrays.

:return_headers

When false, header rows are silently swallowed. If set to true, header rows are returned in a CSV::Row object with identical headers and fields (save that the fields do not go through the converters).

:write_headers

When true and :headers is set, a header row will be added to the output.

:header_converters

Identical in functionality to :converters save that the conversions are only made to header rows. All built-in converters try to transcode headers to UTF-8 before converting. The conversion will fail if the data cannot be transcoded, leaving the header unchanged.

:skip_blanks

When set to a true value, CSV will skip over any empty rows. Note that this setting will not skip rows that contain column separators, even if the rows contain no actual data. If you want to skip rows that contain separators but no content, consider using :skip_lines, or inspecting fields.compact.empty? on each row.

:force_quotes

When set to a true value, CSV will quote all CSV fields it creates.

:skip_lines

When set to an object responding to match, every line matching it is considered a comment and ignored during parsing. When set to a String, it is first converted to a Regexp. When set to nil no line is considered a comment. If the passed object does not respond to match, ArgumentError is thrown.

See CSV::DEFAULT_OPTIONS for the default settings.

Options cannot be overridden in the instance methods for performance reasons, so be sure to set what you want here.

# File lib/csv.rb, line 1498
def initialize(data, options = Hash.new)
  if data.nil?
    raise ArgumentError.new("Cannot parse nil as CSV")
  end

  # build the options for this read/write
  options = DEFAULT_OPTIONS.merge(options)

  # create the IO object we will read from
  @io       = data.is_a?(String) ? StringIO.new(data) : data
  # honor the IO encoding if we can, otherwise default to ASCII-8BIT
  @encoding = raw_encoding(nil) ||
              ( if encoding = options.delete(:internal_encoding)
                  case encoding
                  when Encoding; encoding
                  else Encoding.find(encoding)
                  end
                end ) ||
              ( case encoding = options.delete(:encoding)
                when Encoding; encoding
                when /\A[^:]+/; Encoding.find($&)
                end ) ||
              Encoding.default_internal || Encoding.default_external
  #
  # prepare for building safe regular expressions in the target encoding,
  # if we can transcode the needed characters
  #
  @re_esc   =   "\\".encode(@encoding) rescue ""
  @re_chars =   /#{%"[-\\]\\[\\.^$?*+{}()|# \r\n\t\f\v]".encode(@encoding)}/

  init_separators(options)
  init_parsers(options)
  init_converters(options)
  init_headers(options)
  init_comments(options)

  @force_encoding = !!(encoding || options.delete(:encoding))
  options.delete(:internal_encoding)
  options.delete(:external_encoding)
  unless options.empty?
    raise ArgumentError, "Unknown options:  #{options.keys.join(', ')}."
  end

  # track our own lineno since IO gets confused about line-ends is CSV fields
  @lineno = 0
end
open( filename, mode = "rb", options = Hash.new ) { |faster_csv| ... } click to toggle source
open( filename, options = Hash.new ) { |faster_csv| ... }
open( filename, mode = "rb", options = Hash.new )
open( filename, options = Hash.new )

This method opens an IO object, and wraps that with CSV. This is intended as the primary interface for writing a CSV file.

You must pass a filename and may optionally add a mode for Ruby's open(). You may also pass an optional Hash containing any options ::new understands as the final argument.

This method works like Ruby's open() call, in that it will pass a CSV object to a provided block and close it when the block terminates, or it will return the CSV object when no block is provided. (Note: This is different from the Ruby 1.8 CSV library which passed rows to the block. Use ::foreach for that behavior.)

You must provide a mode with an embedded Encoding designator unless your data is in Encoding.default_external. CSV will check the Encoding of the underlying IO object (set by the mode you pass) to determine how to parse the data. You may provide a second Encoding to have the data transcoded as it is read just as you can with a normal call to IO.open. For example, "rb:UTF-32BE:UTF-8" would read UTF-32BE data from the file but transcode it to UTF-8 before CSV parses it.

An opened CSV object will delegate to many IO methods for convenience. You may call:

  • binmode()

  • binmode?()

  • close()

  • close_read()

  • close_write()

  • closed?()

  • eof()

  • eof?()

  • external_encoding()

  • fcntl()

  • fileno()

  • flock()

  • flush()

  • fsync()

  • internal_encoding()

  • ioctl()

  • isatty()

  • path()

  • pid()

  • pos()

  • pos=()

  • reopen()

  • seek()

  • stat()

  • sync()

  • sync=()

  • tell()

  • to_i()

  • to_io()

  • truncate()

  • tty?()

# File lib/csv.rb, line 1248
def self.open(*args)
  # find the +options+ Hash
  options = if args.last.is_a? Hash then args.pop else Hash.new end
  # wrap a File opened with the remaining +args+ with no newline
  # decorator
  file_opts = {universal_newline: false}.merge(options)
  begin
    f = File.open(*args, file_opts)
  rescue ArgumentError => e
    raise unless /needs binmode/ =~ e.message and args.size == 1
    args << "rb"
    file_opts = {encoding: Encoding.default_external}.merge(file_opts)
    retry
  end
  begin
    csv = new(f, options)
  rescue Exception
    f.close
    raise
  end

  # handle blocks like Ruby's open(), not like the CSV library
  if block_given?
    begin
      yield csv
    ensure
      csv.close
    end
  else
    csv
  end
end
parse( str, options = Hash.new ) { |row| ... } click to toggle source
parse( str, options = Hash.new )

This method can be used to easily parse CSV out of a String. You may either provide a block which will be called with each row of the String in turn, or just use the returned Array of Arrays (when no block is given).

You pass your str to read from, and an optional options Hash containing anything ::new understands.

# File lib/csv.rb, line 1293
def self.parse(*args, &block)
  csv = new(*args)
  if block.nil?  # slurp contents, if no block is given
    begin
      csv.read
    ensure
      csv.close
    end
  else           # or pass each row to a provided block
    csv.each(&block)
  end
end
parse_line(line, options = Hash.new) click to toggle source

This method is a shortcut for converting a single line of a CSV String into an Array. Note that if line contains multiple rows, anything beyond the first row is ignored.

The options parameter can be anything ::new understands.

# File lib/csv.rb, line 1313
def self.parse_line(line, options = Hash.new)
  new(line, options).shift
end
read(path, *options) click to toggle source

Use to slurp a CSV file into an Array of Arrays. Pass the path to the file and any options ::new understands. This method also understands an additional :encoding parameter that you can use to specify the Encoding of the data in the file to be read. You must provide this unless your data is in Encoding.default_external. CSV 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 CSV parses it.

# File lib/csv.rb, line 1328
def self.read(path, *options)
  open(path, *options) { |csv| csv.read }
end
readlines(*args) click to toggle source

Alias for ::read.

# File lib/csv.rb, line 1333
def self.readlines(*args)
  read(*args)
end
table(path, options = Hash.new) click to toggle source

A shortcut for:

CSV.read( path, { headers:           true,
                  converters:        :numeric,
                  header_converters: :symbol }.merge(options) )
# File lib/csv.rb, line 1344
def self.table(path, options = Hash.new)
  read( path, { headers:           true,
                converters:        :numeric,
                header_converters: :symbol }.merge(options) )
end

Public Instance Methods

<<(row) click to toggle source

The primary write method for wrapped Strings and IOs, row (an Array or CSV::Row) is converted to CSV and appended to the data source. When a CSV::Row is passed, only the row's fields() are appended to the output.

The data source must be open for writing.

# File lib/csv.rb, line 1655
def <<(row)
  # make sure headers have been assigned
  if header_row? and [Array, String].include? @use_headers.class
    parse_headers  # won't read data for Array or String
    self << @headers if @write_headers
  end

  # handle CSV::Row objects and Hashes
  row = case row
        when self.class::Row then row.fields
        when Hash            then @headers.map { |header| row[header] }
        else                      row
        end

  @headers =  row if header_row?
  @lineno  += 1

  output = row.map(&@quote).join(@col_sep) + @row_sep  # quote and separate
  if @io.is_a?(StringIO)             and
     output.encoding != (encoding = raw_encoding)
    if @force_encoding
      output = output.encode(encoding)
    elsif (compatible_encoding = Encoding.compatible?(@io.string, output))
      @io.set_encoding(compatible_encoding)
      @io.seek(0, IO::SEEK_END)
    end
  end
  @io << output

  self  # for chaining
end
Also aliased as: add_row, puts
add_row(row)
Alias for: <<
convert( name ) click to toggle source
convert { |field| ... }
convert { |field, field_info| ... }

You can use this method to install a CSV::Converters built-in, or provide a block that handles a custom conversion.

If you provide a block that takes one argument, it will be passed the field and is expected to return the converted value or the field itself. If your block takes two arguments, it will also be passed a CSV::FieldInfo Struct, containing details about the field. Again, the block should return a converted field or the field itself.

# File lib/csv.rb, line 1704
def convert(name = nil, &converter)
  add_converter(:converters, self.class::Converters, name, &converter)
end
converters() click to toggle source

Returns the current list of converters in effect. See ::new for details. Built-in converters will be returned by name, while others will be returned as is.

# File lib/csv.rb, line 1571
def converters
  @converters.map do |converter|
    name = Converters.rassoc(converter)
    name ? name.first : converter
  end
end
each() { |row| ... } click to toggle source

Yields each row of the data source in turn.

Support for Enumerable.

The data source must be open for reading.

# File lib/csv.rb, line 1735
def each
  if block_given?
    while row = shift
      yield row
    end
  else
    to_enum
  end
end
force_quotes?() click to toggle source

Returns true if all output fields are quoted. See ::new for details.

# File lib/csv.rb, line 1614
def force_quotes?()       @force_quotes       end
gets()
Alias for: shift
header_convert( name ) click to toggle source
header_convert { |field| ... }
header_convert { |field, field_info| ... }

Identical to #convert, but for header rows.

Note that this method must be called before header rows are read to have any effect.

# File lib/csv.rb, line 1719
def header_convert(name = nil, &converter)
  add_converter( :header_converters,
                 self.class::HeaderConverters,
                 name,
                 &converter )
end
header_converters() click to toggle source

Returns the current list of converters in effect for headers. See ::new for details. Built-in converters will be returned by name, while others will be returned as is.

# File lib/csv.rb, line 1602
def header_converters
  @header_converters.map do |converter|
    name = HeaderConverters.rassoc(converter)
    name ? name.first : converter
  end
end
header_row?() click to toggle source

Returns true if the next row read will be a header row.

# File lib/csv.rb, line 1761
def header_row?
  @use_headers and @headers.nil?
end
headers() click to toggle source

Returns nil if headers will not be used, true if they will but have not yet been read, or the actual headers after they have been read. See ::new for details.

# File lib/csv.rb, line 1587
def headers
  @headers || true if @use_headers
end
inspect() click to toggle source

Returns a simplified description of the key CSV attributes in an ASCII compatible String.

# File lib/csv.rb, line 1922
def inspect
  str = ["<#", self.class.to_s, " io_type:"]
  # show type of wrapped IO
  if    @io == $stdout then str << "$stdout"
  elsif @io == $stdin  then str << "$stdin"
  elsif @io == $stderr then str << "$stderr"
  else                      str << @io.class.to_s
  end
  # show IO.path(), if available
  if @io.respond_to?(:path) and (p = @io.path)
    str << " io_path:" << p.inspect
  end
  # show encoding
  str << " encoding:" << @encoding.name
  # show other attributes
  %w[ lineno     col_sep     row_sep
      quote_char skip_blanks ].each do |attr_name|
    if a = instance_variable_get("@#{attr_name}")
      str << " " << attr_name << ":" << a.inspect
    end
  end
  if @use_headers
    str << " headers:" << headers.inspect
  end
  str << ">"
  begin
    str.join('')
  rescue  # any encoding error
    str.map do |s|
      e = Encoding::Converter.asciicompat_encoding(s.encoding)
      e ? s.encode(e) : s.force_encoding("ASCII-8BIT")
    end.join('')
  end
end
puts(row)
Alias for: <<
read() click to toggle source

Slurps the remaining rows and returns an Array of Arrays.

The data source must be open for reading.

# File lib/csv.rb, line 1750
def read
  rows = to_a
  if @use_headers
    Table.new(rows)
  else
    rows
  end
end
Also aliased as: readlines
readline()
Alias for: shift
readlines()
Alias for: read
return_headers?() click to toggle source

Returns true if headers will be returned as a row of results. See ::new for details.

# File lib/csv.rb, line 1594
def return_headers?()     @return_headers     end
rewind() click to toggle source

Rewinds the underlying IO object and resets CSV's lineno() counter.

# File lib/csv.rb, line 1639
def rewind
  @headers = nil
  @lineno  = 0

  @io.rewind
end
shift() click to toggle source

The primary read method for wrapped Strings and IOs, a single row is pulled from the data source, parsed and returned as an Array of fields (if header rows are not used) or a CSV::Row (when header rows are used).

The data source must be open for reading.

# File lib/csv.rb, line 1772
def shift
  #########################################################################
  ### This method is purposefully kept a bit long as simple conditional ###
  ### checks are faster than numerous (expensive) method calls.         ###
  #########################################################################

  # handle headers not based on document content
  if header_row? and @return_headers and
     [Array, String].include? @use_headers.class
    if @unconverted_fields
      return add_unconverted_fields(parse_headers, Array.new)
    else
      return parse_headers
    end
  end

  #
  # it can take multiple calls to <tt>@io.gets()</tt> to get a full line,
  # because of \r and/or \n characters embedded in quoted fields
  #
  in_extended_col = false
  csv             = Array.new

  loop do
    # add another read to the line
    unless parse = @io.gets(@row_sep)
      return nil
    end

    parse.sub!(@parsers[:line_end], "")

    if csv.empty?
      #
      # I believe a blank line should be an <tt>Array.new</tt>, not Ruby 1.8
      # CSV's <tt>[nil]</tt>
      #
      if parse.empty?
        @lineno += 1
        if @skip_blanks
          next
        elsif @unconverted_fields
          return add_unconverted_fields(Array.new, Array.new)
        elsif @use_headers
          return self.class::Row.new(Array.new, Array.new)
        else
          return Array.new
        end
      end
    end

    next if @skip_lines and @skip_lines.match parse

    parts =  parse.split(@col_sep, -1)
    if parts.empty?
      if in_extended_col
        csv[-1] << @col_sep   # will be replaced with a @row_sep after the parts.each loop
      else
        csv << nil
      end
    end

    # This loop is the hot path of csv parsing. Some things may be non-dry
    # for a reason. Make sure to benchmark when refactoring.
    parts.each do |part|
      if in_extended_col
        # If we are continuing a previous column
        if part[-1] == @quote_char && part.count(@quote_char) % 2 != 0
          # extended column ends
          csv.last << part[0..-2]
          if csv.last =~ @parsers[:stray_quote]
            raise MalformedCSVError,
                  "Missing or stray quote in line #{lineno + 1}"
          end
          csv.last.gsub!(@quote_char * 2, @quote_char)
          in_extended_col = false
        else
          csv.last << part
          csv.last << @col_sep
        end
      elsif part[0] == @quote_char
        # If we are staring a new quoted column
        if part[-1] != @quote_char || part.count(@quote_char) % 2 != 0
          # start an extended column
          csv             << part[1..-1]
          csv.last        << @col_sep
          in_extended_col =  true
        else
          # regular quoted column
          csv << part[1..-2]
          if csv.last =~ @parsers[:stray_quote]
            raise MalformedCSVError,
                  "Missing or stray quote in line #{lineno + 1}"
          end
          csv.last.gsub!(@quote_char * 2, @quote_char)
        end
      elsif part =~ @parsers[:quote_or_nl]
        # Unquoted field with bad characters.
        if part =~ @parsers[:nl_or_lf]
          raise MalformedCSVError, "Unquoted fields do not allow " +
                                   "\\r or \\n (line #{lineno + 1})."
        else
          raise MalformedCSVError, "Illegal quoting in line #{lineno + 1}."
        end
      else
        # Regular ole unquoted field.
        csv << (part.empty? ? nil : part)
      end
    end

    # Replace tacked on @col_sep with @row_sep if we are still in an extended
    # column.
    csv[-1][-1] = @row_sep if in_extended_col

    if in_extended_col
      # if we're at eof?(), a quoted field wasn't closed...
      if @io.eof?
        raise MalformedCSVError,
              "Unclosed quoted field on line #{lineno + 1}."
      elsif @field_size_limit and csv.last.size >= @field_size_limit
        raise MalformedCSVError, "Field size exceeded on line #{lineno + 1}."
      end
      # otherwise, we need to loop and pull some more data to complete the row
    else
      @lineno += 1

      # save fields unconverted fields, if needed...
      unconverted = csv.dup if @unconverted_fields

      # convert fields, if needed...
      csv = convert_fields(csv) unless @use_headers or @converters.empty?
      # parse out header rows and handle CSV::Row conversions...
      csv = parse_headers(csv)  if     @use_headers

      # inject unconverted fields and accessor, if requested...
      if @unconverted_fields and not csv.respond_to? :unconverted_fields
        add_unconverted_fields(csv, unconverted)
      end

      # return the results
      break csv
    end
  end
end
Also aliased as: gets, readline
skip_blanks?() click to toggle source

Returns true blank lines are skipped by the parser. See ::new for details.

# File lib/csv.rb, line 1612
def skip_blanks?()        @skip_blanks        end
unconverted_fields?() click to toggle source

Returns true if unconverted_fields() to parsed results. See ::new for details.

# File lib/csv.rb, line 1581
def unconverted_fields?() @unconverted_fields end
write_headers?() click to toggle source

Returns true if headers are written in output. See ::new for details.

# File lib/csv.rb, line 1596
def write_headers?()      @write_headers      end

Private Instance Methods

add_converter(var_name, const, name = nil, &converter) click to toggle source

The actual work method for adding converters, used by both #convert and #header_convert.

This method requires the var_name of the instance variable to place the converters in, the const Hash to lookup named converters in, and the normal parameters of the #convert and #header_convert methods.

# File lib/csv.rb, line 2161
def add_converter(var_name, const, name = nil, &converter)
  if name.nil?  # custom converter
    instance_variable_get("@#{var_name}") << converter
  else          # named converter
    combo = const[name]
    case combo
    when Array  # combo converter
      combo.each do |converter_name|
        add_converter(var_name, const, converter_name)
      end
    else        # individual named converter
      instance_variable_get("@#{var_name}") << combo
    end
  end
end
add_unconverted_fields(row, fields) click to toggle source

This method injects an instance variable unconverted_fields into row and an accessor method for row called unconverted_fields(). The variable is set to the contents of fields.

# File lib/csv.rb, line 2248
def add_unconverted_fields(row, fields)
  class << row
    attr_reader :unconverted_fields
  end
  row.instance_eval { @unconverted_fields = fields }
  row
end
convert_fields(fields, headers = false) click to toggle source

Processes fields with @converters, or @header_converters if headers is passed as true, returning the converted field set. Any converter that changes the field into something other than a String halts the pipeline of conversion for that field. This is primarily an efficiency shortcut.

# File lib/csv.rb, line 2184
def convert_fields(fields, headers = false)
  # see if we are converting headers or fields
  converters = headers ? @header_converters : @converters

  fields.map.with_index do |field, index|
    converters.each do |converter|
      break if field.nil?
      field = if converter.arity == 1  # straight field converter
        converter[field]
      else                             # FieldInfo converter
        header = @use_headers && !headers ? @headers[index] : nil
        converter[field, FieldInfo.new(index, lineno, header)]
      end
      break unless field.is_a? String  # short-circuit pipeline for speed
    end
    field  # final state of each field, converted or original
  end
end
encode_re(*chunks) click to toggle source

Builds a regular expression in @encoding. All chunks will be transcoded to that encoding.

# File lib/csv.rb, line 2271
def encode_re(*chunks)
  Regexp.new(encode_str(*chunks))
end
encode_str(*chunks) click to toggle source

Builds a String in @encoding. All chunks will be transcoded to that encoding.

# File lib/csv.rb, line 2279
def encode_str(*chunks)
  chunks.map { |chunk| chunk.encode(@encoding.name) }.join('')
end
escape_re(str) click to toggle source

This method is an encoding safe version of Regexp.escape. It will escape any characters that would change the meaning of a regular expression in the encoding of str. Regular expression characters that cannot be transcoded to the target encoding will be skipped and no escaping will be performed if a backslash cannot be transcoded.

# File lib/csv.rb, line 2263
def escape_re(str)
  str.gsub(@re_chars) {|c| @re_esc + c}
end
init_comments(options) click to toggle source

Stores the pattern of comments to skip from the provided options.

The pattern must respond to .match, else ArgumentError is raised. Strings are converted to a Regexp.

See also ::new

# File lib/csv.rb, line 2146
def init_comments(options)
  @skip_lines = options.delete(:skip_lines)
  @skip_lines = Regexp.new(@skip_lines) if @skip_lines.is_a? String
  if @skip_lines and not @skip_lines.respond_to?(:match)
    raise ArgumentError, ":skip_lines has to respond to matches"
  end
end
init_converters(options, field_name = :converters) click to toggle source

Loads any converters requested during construction.

If field_name is set :converters (the default) field converters are set. When field_name is :header_converters header converters are added instead.

The :unconverted_fields option is also actived for :converters calls, if requested.

# File lib/csv.rb, line 2099
def init_converters(options, field_name = :converters)
  if field_name == :converters
    @unconverted_fields = options.delete(:unconverted_fields)
  end

  instance_variable_set("@#{field_name}", Array.new)

  # find the correct method to add the converters
  convert = method(field_name.to_s.sub(/ers\Z/, ""))

  # load converters
  unless options[field_name].nil?
    # allow a single converter not wrapped in an Array
    unless options[field_name].is_a? Array
      options[field_name] = [options[field_name]]
    end
    # load each converter...
    options[field_name].each do |converter|
      if converter.is_a? Proc  # custom code block
        convert.call(&converter)
      else                     # by name
        convert.call(converter)
      end
    end
  end

  options.delete(field_name)
end
init_headers(options) click to toggle source

Stores header row settings and loads header converters, if needed.

# File lib/csv.rb, line 2129
def init_headers(options)
  @use_headers    = options.delete(:headers)
  @return_headers = options.delete(:return_headers)
  @write_headers  = options.delete(:write_headers)

  # headers must be delayed until shift(), in case they need a row of content
  @headers = nil

  init_converters(options, :header_converters)
end
init_parsers(options) click to toggle source

Pre-compiles parsers and stores them by name for access during reads.

# File lib/csv.rb, line 2068
def init_parsers(options)
  # store the parser behaviors
  @skip_blanks      = options.delete(:skip_blanks)
  @field_size_limit = options.delete(:field_size_limit)

  # prebuild Regexps for faster parsing
  esc_row_sep = escape_re(@row_sep)
  esc_quote   = escape_re(@quote_char)
  @parsers = {
    # for detecting parse errors
    quote_or_nl:    encode_re("[", esc_quote, "\r\n]"),
    nl_or_lf:       encode_re("[\r\n]"),
    stray_quote:    encode_re( "[^", esc_quote, "]", esc_quote,
                               "[^", esc_quote, "]" ),
    # safer than chomp!()
    line_end:       encode_re(esc_row_sep, "\\z"),
    # illegal unquoted characters
    return_newline: encode_str("\r\n")
  }
end
init_separators(options) click to toggle source

Stores the indicated separators for later use.

If auto-discovery was requested for @row_sep, this method will read ahead in the @io and try to find one. ARGF, STDIN, STDOUT, STDERR and any stream open for output only with a default @row_sep of $INPUT_RECORD_SEPARATOR ($/).

This method also establishes the quoting rules used for CSV output.

# File lib/csv.rb, line 1969
def init_separators(options)
  # store the selected separators
  @col_sep    = options.delete(:col_sep).to_s.encode(@encoding)
  @row_sep    = options.delete(:row_sep)  # encode after resolving :auto
  @quote_char = options.delete(:quote_char).to_s.encode(@encoding)

  if @quote_char.length != 1
    raise ArgumentError, ":quote_char has to be a single character String"
  end

  #
  # automatically discover row separator when requested
  # (not fully encoding safe)
  #
  if @row_sep == :auto
    if [ARGF, STDIN, STDOUT, STDERR].include?(@io) or
       (defined?(Zlib) and @io.class == Zlib::GzipWriter)
      @row_sep = $INPUT_RECORD_SEPARATOR
    else
      begin
        #
        # remember where we were (pos() will raise an exception if @io is pipe
        # or not opened for reading)
        #
        saved_pos = @io.pos
        while @row_sep == :auto
          #
          # if we run out of data, it's probably a single line
          # (ensure will set default value)
          #
          break unless sample = @io.gets(nil, 1024)
          # extend sample if we're unsure of the line ending
          if sample.end_with? encode_str("\r")
            sample << (@io.gets(nil, 1) || "")
          end

          # try to find a standard separator
          if sample =~ encode_re("\r\n?|\n")
            @row_sep = $&
            break
          end
        end

        # tricky seek() clone to work around GzipReader's lack of seek()
        @io.rewind
        # reset back to the remembered position
        while saved_pos > 1024  # avoid loading a lot of data into memory
          @io.read(1024)
          saved_pos -= 1024
        end
        @io.read(saved_pos) if saved_pos.nonzero?
      rescue IOError         # not opened for reading
        # do nothing:  ensure will set default
      rescue NoMethodError   # Zlib::GzipWriter doesn't have some IO methods
        # do nothing:  ensure will set default
      rescue SystemCallError # pipe
        # do nothing:  ensure will set default
      ensure
        #
        # set default if we failed to detect
        # (stream not opened for reading, a pipe, or a single line of data)
        #
        @row_sep = $INPUT_RECORD_SEPARATOR if @row_sep == :auto
      end
    end
  end
  @row_sep = @row_sep.to_s.encode(@encoding)

  # establish quoting rules
  @force_quotes   = options.delete(:force_quotes)
  do_quote        = lambda do |field|
    field         = String(field)
    encoded_quote = @quote_char.encode(field.encoding)
    encoded_quote                                +
    field.gsub(encoded_quote, encoded_quote * 2) +
    encoded_quote
  end
  quotable_chars = encode_str("\r\n", @col_sep, @quote_char)
  @quote         = if @force_quotes
    do_quote
  else
    lambda do |field|
      if field.nil?  # represent +nil+ fields as empty unquoted fields
        ""
      else
        field = String(field)  # Stringify fields
        # represent empty fields as empty quoted fields
        if field.empty? or
           field.count(quotable_chars).nonzero?
          do_quote.call(field)
        else
          field  # unquoted field
        end
      end
    end
  end
end
parse_headers(row = nil) click to toggle source

This method is used to turn a finished row into a CSV::Row. Header rows are also dealt with here, either by returning a CSV::Row with identical headers and fields (save that the fields do not go through the converters) or by reading past them to return a field row. Headers are also saved in @headers for use in future rows.

When nil, row is assumed to be a header row not based on an actual row of the stream.

# File lib/csv.rb, line 2213
def parse_headers(row = nil)
  if @headers.nil?                # header row
    @headers = case @use_headers  # save headers
               # Array of headers
               when Array then @use_headers
               # CSV header String
               when String
                 self.class.parse_line( @use_headers,
                                        col_sep:    @col_sep,
                                        row_sep:    @row_sep,
                                        quote_char: @quote_char )
               # first row is headers
               else            row
               end

    # prepare converted and unconverted copies
    row      = @headers                       if row.nil?
    @headers = convert_fields(@headers, true)
    @headers.each { |h| h.freeze if h.is_a? String }

    if @return_headers                                     # return headers
      return self.class::Row.new(@headers, row, true)
    elsif not [Array, String].include? @use_headers.class  # skip to field row
      return shift
    end
  end

  self.class::Row.new(@headers, convert_fields(row))  # field row
end
raw_encoding(default = Encoding::ASCII_8BIT) click to toggle source

Returns the encoding of the internal IO object or the default if the encoding cannot be determined.

# File lib/csv.rb, line 2289
def raw_encoding(default = Encoding::ASCII_8BIT)
  if @io.respond_to? :internal_encoding
    @io.internal_encoding || @io.external_encoding
  elsif @io.is_a? StringIO
    @io.string.encoding
  elsif @io.respond_to? :encoding
    @io.encoding
  else
    default
  end
end