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#!/usr/local/bin/ruby -w

# = faster_csv.rb -- Faster CSV Reading and Writing

#

#  Created by James Edward Gray II on 2005-10-31.

#  Copyright 2005 Gray Productions. All rights reserved.

# 

# See FasterCSV for documentation.

if RUBY_VERSION >= "1.9"

  abort <<-VERSION_WARNING.gsub(/^\s+/, "")

  Please switch to Ruby 1.9's standard CSV library.  It's FasterCSV plus

  support for Ruby 1.9's m17n encoding engine.

  VERSION_WARNING

end

require "forwardable"

require "English"

require "enumerator"

require "date"

require "stringio"

# 

# 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

# 

#   FasterCSV.foreach("path/to/file.csv") do |row|

#     # use row here...

#   end

# 

# ==== All at Once

# 

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

# 

# === From a String

# 

# ==== A Line at a Time

# 

#   FasterCSV.parse("CSV,data,String") do |row|

#     # use row here...

#   end

# 

# ==== All at Once

# 

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

# 

# == Writing

# 

# === To a File

# 

#   FasterCSV.open("path/to/file.csv", "w") do |csv|

#     csv << ["row", "of", "CSV", "data"]

#     csv << ["another", "row"]

#     # ...

#   end

# 

# === To a String

# 

#   csv_string = FasterCSV.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

# 

#   FCSV             { |csv_out| csv_out << %w{my data here} }  # to $stdout

#   FCSV(csv = "")   { |csv_str| csv_str << %w{my data here} }  # to a String

#   FCSV($stderr)    { |csv_err| csv_err << %w{my data here} }  # to $stderr

# 

class FasterCSV

  # The version of the installed library.

  VERSION = "1.5.0".freeze

  # 

  # A FasterCSV::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 FasterCSV will be constructed from this class, if

  # header row processing is activated.

  # 

  class Row

    # 

    # Construct a new FasterCSV::Row from +headers+ and +fields+, which are

    # expected to be Arrays.  If one Array is shorter than the other, it will be

    # padded with +nil+ objects.

    # 

    # The optional +header_row+ parameter can be set to +true+ to indicate, via

    # FasterCSV::Row.header_row?() and FasterCSV::Row.field_row?(), that this is

    # a header row.  Otherwise, the row is assumes to be a field row.

    # 

    # A FasterCSV::Row object supports the following Array methods through

    # delegation:

    # 

    # * empty?()

    # * length()

    # * size()

    # 

    def initialize(headers, fields, header_row = false)

      @header_row = header_row

      # handle extra headers or fields

      @row = if headers.size > fields.size

        headers.zip(fields)

      else

        fields.zip(headers).map { |pair| pair.reverse }

      end

    end

    # Internal data format used to compare equality.

    attr_reader :row

    protected   :row

    ### Array Delegation ###

    extend Forwardable

    def_delegators :@row, :empty?, :length, :size

    # Returns +true+ if this is a header row.

    def header_row?

      @header_row

    end

    # Returns +true+ if this is a field row.

    def field_row?

      not header_row?

    end

    # Returns the headers of this row.

    def headers

      @row.map { |pair| pair.first }

    end

    # 

    # :call-seq:

    #   field( header )

    #   field( header, offset )

    #   field( index )

    # 

    # This method will fetch the field value by +header+ or +index+.  If a field

    # is not found, +nil+ is returned.

    # 

    # When provided, +offset+ ensures that a header match occurrs on or later

    # than the +offset+ index.  You can use this to find duplicate headers, 

    # without resorting to hard-coding exact indices.

    # 

    def field(header_or_index, minimum_index = 0)

      # locate the pair

      finder = header_or_index.is_a?(Integer) ? :[] : :assoc

      pair   = @row[minimum_index..-1].send(finder, header_or_index)

      # return the field if we have a pair

      pair.nil? ? nil : pair.last

    end

    alias_method :[], :field

    # 

    # :call-seq:

    #   []=( header, value )

    #   []=( header, offset, value )

    #   []=( index, value )

    # 

    # Looks up the field by the semantics described in FasterCSV::Row.field()

    # and assigns the +value+.

    # 

    # Assigning past the end of the row with an index will set all pairs between

    # to <tt>[nil, nil]</tt>.  Assigning to an unused header appends the new

    # pair.

    # 

    def []=(*args)

      value = args.pop

      if args.first.is_a? Integer

        if @row[args.first].nil?  # extending past the end with index

          @row[args.first] = [nil, value]

          @row.map! { |pair| pair.nil? ? [nil, nil] : pair }

        else                      # normal index assignment

          @row[args.first][1] = value

        end

      else

        index = index(*args)

        if index.nil?             # appending a field

          self << [args.first, value]

        else                      # normal header assignment

          @row[index][1] = value

        end

      end

    end

    # 

    # :call-seq:

    #   <<( field )

    #   <<( header_and_field_array )

    #   <<( header_and_field_hash )

    # 

    # If a two-element Array is provided, it is assumed to be a header and field

    # and the pair is appended.  A Hash works the same way with the key being

    # the header and the value being the field.  Anything else is assumed to be

    # a lone field which is appended with a +nil+ header.

    # 

    # This method returns the row for chaining.

    # 

    def <<(arg)

      if arg.is_a?(Array) and arg.size == 2  # appending a header and name

        @row << arg

      elsif arg.is_a?(Hash)                  # append header and name pairs

        arg.each { |pair| @row << pair }

      else                                   # append field value

        @row << [nil, arg]

      end

      self  # for chaining

    end

    # 

    # A shortcut for appending multiple fields.  Equivalent to:

    # 

    #   args.each { |arg| faster_csv_row << arg }

    # 

    # This method returns the row for chaining.

    # 

    def push(*args)

      args.each { |arg| self << arg }

      self  # for chaining

    end

    # 

    # :call-seq:

    #   delete( header )

    #   delete( header, offset )

    #   delete( index )

    # 

    # Used to remove a pair from the row by +header+ or +index+.  The pair is

    # located as described in FasterCSV::Row.field().  The deleted pair is 

    # returned, or +nil+ if a pair could not be found.

    # 

    def delete(header_or_index, minimum_index = 0)

      if header_or_index.is_a? Integer  # by index

        @row.delete_at(header_or_index)

      else                              # by header

        @row.delete_at(index(header_or_index, minimum_index))

      end

    end

    # 

    # The provided +block+ is passed a header and field for each pair in the row

    # and expected to return +true+ or +false+, depending on whether the pair

    # should be deleted.

    # 

    # This method returns the row for chaining.

    # 

    def delete_if(&block)

      @row.delete_if(&block)

      self  # for chaining

    end

    # 

    # This method accepts any number of arguments which can be headers, indices,

    # Ranges of either, or two-element Arrays containing a header and offset.  

    # Each argument will be replaced with a field lookup as described in

    # FasterCSV::Row.field().

    # 

    # If called with no arguments, all fields are returned.

    # 

    def fields(*headers_and_or_indices)

      if headers_and_or_indices.empty?  # return all fields--no arguments

        @row.map { |pair| pair.last }

      else                              # or work like values_at()

        headers_and_or_indices.inject(Array.new) do |all, h_or_i|

          all + if h_or_i.is_a? Range

            index_begin = h_or_i.begin.is_a?(Integer) ? h_or_i.begin :

                                                        index(h_or_i.begin)

            index_end   = h_or_i.end.is_a?(Integer)   ? h_or_i.end :

                                                        index(h_or_i.end)

            new_range   = h_or_i.exclude_end? ? (index_begin...index_end) :

                                                (index_begin..index_end)

            fields.values_at(new_range)

          else

            [field(*Array(h_or_i))]

          end

        end

      end

    end

    alias_method :values_at, :fields

    # 

    # :call-seq:

    #   index( header )

    #   index( header, offset )

    # 

    # 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

    # FasterCSV::Row.field().

    # 

    def index(header, minimum_index = 0)

      # find the pair

      index = headers[minimum_index..-1].index(header)

      # return the index at the right offset, if we found one

      index.nil? ? nil : index + minimum_index

    end

    # Returns +true+ if +name+ is a header for this row, and +false+ otherwise.

    def header?(name)

      headers.include? name

    end

    alias_method :include?, :header?

    # 

    # Returns +true+ if +data+ matches a field in this row, and +false+

    # otherwise.

    # 

    def field?(data)

      fields.include? data

    end

    include Enumerable

    # 

    # Yields each pair of the row as header and field tuples (much like

    # iterating over a Hash).

    # 

    # Support for Enumerable.

    # 

    # This method returns the row for chaining.

    # 

    def each(&block)

      @row.each(&block)

      self  # for chaining

    end

    # 

    # Returns +true+ if this row contains the same headers and fields in the 

    # same order as +other+.

    # 

    def ==(other)

      @row == other.row

    end

    # 

    # Collapses the row into a simple Hash.  Be warning that this discards field

    # order and clobbers duplicate fields.

    # 

    def to_hash

      # flatten just one level of the internal Array

      Hash[*@row.inject(Array.new) { |ary, pair| ary.push(*pair) }]

    end

    # 

    # Returns the row as a CSV String.  Headers are not used.  Equivalent to:

    # 

    #   faster_csv_row.fields.to_csv( options )

    # 

    def to_csv(options = Hash.new)

      fields.to_csv(options)

    end

    alias_method :to_s, :to_csv

    # A summary of fields, by header.

    def inspect

      str = "#<#{self.class}"

      each do |header, field|

        str << " #{header.is_a?(Symbol) ? header.to_s : header.inspect}:" <<

               field.inspect

      end

      str << ">"

    end

  end

  # 

  # A FasterCSV::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 FasterCSV will be constructed from this class, if

  # header row processing is activated.

  # 

  class Table

    # 

    # Construct a new FasterCSV::Table from +array_of_rows+, which are expected

    # to be FasterCSV::Row objects.  All rows are assumed to have the same 

    # headers.

    # 

    # A FasterCSV::Table object supports the following Array methods through

    # delegation:

    # 

    # * empty?()

    # * length()

    # * size()

    # 

    def initialize(array_of_rows)

      @table = array_of_rows

      @mode  = :col_or_row

    end

    # The current access mode for indexing and iteration.

    attr_reader :mode

    # Internal data format used to compare equality.

    attr_reader :table

    protected   :table

    ### Array Delegation ###

    extend Forwardable

    def_delegators :@table, :empty?, :length, :size

    # 

    # 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

      self.class.new(@table.dup).by_col!

    end

    # 

    # 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!

      @mode = :col

      self

    end

    # 

    # 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

      self.class.new(@table.dup).by_col_or_row!

    end

    # 

    # 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!

      @mode = :col_or_row

      self

    end

    # 

    # 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

      self.class.new(@table.dup).by_row!

    end

    # 

    # 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!

      @mode = :row

      self

    end

    # 

    # Returns the headers for the first row of this table (assumed to match all

    # other rows).  An empty Array is returned for empty tables.

    # 

    def headers

      if @table.empty?

        Array.new

      else

        @table.first.headers

      end

    end

    # 

    # In the default mixed mode, this method returns rows for index access and

    # columns for header access.  You can force the index association by first

    # calling by_col!() or by_row!().

    # 

    # Columns are returned as an Array of values.  Altering that Array has no

    # effect on the table.

    # 

    def [](index_or_header)

      if @mode == :row or  # by index

         (@mode == :col_or_row and index_or_header.is_a? Integer)

        @table[index_or_header]

      else                 # by header

        @table.map { |row| row[index_or_header] }

      end

    end

    # 

    # 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 FasterCSV::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 []=(index_or_header, value)

      if @mode == :row or  # by index

         (@mode == :col_or_row and index_or_header.is_a? Integer)

        if value.is_a? Array

          @table[index_or_header] = Row.new(headers, value)

        else

          @table[index_or_header] = value

        end

      else                 # set column

        if value.is_a? Array  # multiple values

          @table.each_with_index do |row, i|

            if row.header_row?

              row[index_or_header] = index_or_header

            else

              row[index_or_header] = value[i]

            end

          end

        else                  # repeated value

          @table.each do |row|

            if row.header_row?

              row[index_or_header] = index_or_header

            else

              row[index_or_header] = value

            end

          end

        end

      end

    end

    # 

    # The mixed mode default is to treat a list of indices as row access,

    # returning the rows indicated.  Anything else is considered columnar

    # access.  For columnar access, the return set has an Array for each row

    # with the values indicated by the headers in each Array.  You can force

    # column or row mode using by_col!() or by_row!().

    # 

    # You cannot mix column and row access.

    # 

    def values_at(*indices_or_headers)

      if @mode == :row or  # by indices

         ( @mode == :col_or_row and indices_or_headers.all? do |index|

                                      index.is_a?(Integer)         or

                                      ( index.is_a?(Range)         and

                                        index.first.is_a?(Integer) and

                                        index.last.is_a?(Integer) )

                                    end )

        @table.values_at(*indices_or_headers)

      else                 # by headers

        @table.map { |row| row.values_at(*indices_or_headers) }

      end

    end

    # 

    # Adds a new row to the bottom end of this table.  You can provide an Array,

    # which will be converted to a FasterCSV::Row (inheriting the table's

    # headers()), or a FasterCSV::Row.

    # 

    # This method returns the table for chaining.

    # 

    def <<(row_or_array)

      if row_or_array.is_a? Array  # append Array

        @table << Row.new(headers, row_or_array)

      else                         # append Row

        @table << row_or_array

      end

      self  # for chaining

    end

    # 

    # A shortcut for appending multiple rows.  Equivalent to:

    # 

    #   rows.each { |row| self << row }

    # 

    # This method returns the table for chaining.

    # 

    def push(*rows)

      rows.each { |row| self << row }

      self  # for chaining

    end

    # 

    # Removes and returns the indicated column or row.  In the default mixed

    # mode indices refer to rows and everything else is assumed to be a column

    # header.  Use by_col!() or by_row!() to force the lookup.

    # 

    def delete(index_or_header)

      if @mode == :row or  # by index

         (@mode == :col_or_row and index_or_header.is_a? Integer)

        @table.delete_at(index_or_header)

      else                 # by header

        @table.map { |row| row.delete(index_or_header).last }

      end

    end

    # 

    # Removes any column or row for which the block returns +true+.  In the

    # default mixed mode or row mode, iteration is the standard row major

    # walking of rows.  In column mode, interation will +yield+ two element

    # tuples containing the column name and an Array of values for that column.

    # 

    # This method returns the table for chaining.

    # 

    def delete_if(&block)

      if @mode == :row or @mode == :col_or_row  # by index

        @table.delete_if(&block)

      else                                      # by header

        to_delete = Array.new

        headers.each_with_index do |header, i|

          to_delete << header if block[[header, self[header]]]

        end

        to_delete.map { |header| delete(header) }

      end

      self  # for chaining

    end

    include Enumerable

    # 

    # In the default mixed mode or row mode, iteration is the standard row major

    # walking of rows.  In column mode, interation will +yield+ two element

    # tuples containing the column name and an Array of values for that column.

    # 

    # This method returns the table for chaining.

    # 

    def each(&block)

      if @mode == :col

        headers.each { |header| block[[header, self[header]]] }

      else

        @table.each(&block)

      end

      self  # for chaining

    end

    # Returns +true+ if all rows of this table ==() +other+'s rows.

    def ==(other)

      @table == other.table

    end

    # 

    # 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

      @table.inject([headers]) do |array, row|

        if row.header_row?

          array

        else

          array + [row.fields]

        end

      end

    end

    # 

    # Returns the table as a complete CSV String.  Headers will be listed first,

    # then all of the field rows.

    # 

    def to_csv(options = Hash.new)

      @table.inject([headers.to_csv(options)]) do |rows, row|

        if row.header_row?

          rows

        else

          rows + [row.fields.to_csv(options)]

        end

      end.join

    end

    alias_method :to_s, :to_csv

    def inspect

      "#<#{self.class} mode:#{@mode} row_count:#{to_a.size}>"

    end

  end

  # The error thrown when the parser encounters illegal CSV formatting.

  class MalformedCSVError < RuntimeError; end

  # 

  # A FieldInfo Struct contains details about a field's position in the data

  # source it was read from.  FasterCSV will pass this Struct to some blocks

  # that make decisions based on field structure.  See 

  # FasterCSV.convert_fields() for an example.

  # 

  # <b><tt>index</tt></b>::  The zero-based index of the field in its row.

  # <b><tt>line</tt></b>::   The line of the data source this row is from.

  # <b><tt>header</tt></b>:: The header for the column, when available.

  # 

  FieldInfo = Struct.new(:index, :line, :header)

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

  DateMatcher     = / \A(?: (\w+,?\s+)?\w+\s+\d{1,2},?\s+\d{2,4} |

                            \d{4}-\d{2}-\d{2} )\z /x

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

  DateTimeMatcher =

    / \A(?: (\w+,?\s+)?\w+\s+\d{1,2}\s+\d{1,2}:\d{1,2}:\d{1,2},?\s+\d{2,4} |

            \d{4}-\d{2}-\d{2}\s\d{2}:\d{2}:\d{2} )\z /x

  # 

  # This Hash holds the built-in converters of FasterCSV that can be accessed by

  # name.  You can select Converters with FasterCSV.convert() or through the

  # +options+ Hash passed to FasterCSV::new().

  # 

  # <b><tt>:integer</tt></b>::    Converts any field Integer() accepts.

  # <b><tt>:float</tt></b>::      Converts any field Float() accepts.

  # <b><tt>:numeric</tt></b>::    A combination of <tt>:integer</tt> 

  #                               and <tt>:float</tt>.

  # <b><tt>:date</tt></b>::       Converts any field Date::parse() accepts.

  # <b><tt>:date_time</tt></b>::  Converts any field DateTime::parse() accepts.

  # <b><tt>:all</tt></b>::        All built-in converters.  A combination of 

  #                               <tt>:date_time</tt> and <tt>:numeric</tt>.

  # 

  # This Hash is intetionally left unfrozen and users should feel free to add

  # values to it that can be accessed by all FasterCSV objects.

  # 

  # To add a combo field, the value should be an Array of names.  Combo fields

  # can be nested with other combo fields.

  # 

  Converters  = { :integer   => lambda { |f| Integer(f)        rescue f },

                  :float     => lambda { |f| Float(f)          rescue f },

                  :numeric   => [:integer, :float],

                  :date      => lambda { |f|

                    f =~ DateMatcher ? (Date.parse(f) rescue f) : f

                  },

                  :date_time => lambda { |f|

                    f =~ DateTimeMatcher ? (DateTime.parse(f) rescue f) : f

                  },

                  :all       => [:date_time, :numeric] }

  # 

  # This Hash holds the built-in header converters of FasterCSV that can be

  # accessed by name.  You can select HeaderConverters with

  # FasterCSV.header_convert() or through the +options+ Hash passed to

  # FasterCSV::new().

  # 

  # <b><tt>:downcase</tt></b>::  Calls downcase() on the header String.

  # <b><tt>:symbol</tt></b>::    The header String is downcased, spaces are

  #                              replaced with underscores, non-word characters

  #                              are dropped, and finally to_sym() is called.

  # 

  # This Hash is intetionally left unfrozen and users should feel free to add

  # values to it that can be accessed by all FasterCSV objects.

  # 

  # To add a combo field, the value should be an Array of names.  Combo fields

  # can be nested with other combo fields.

  # 

  HeaderConverters = {

    :downcase => lambda { |h| h.downcase },

    :symbol   => lambda { |h|

      h.downcase.tr(" ", "_").delete("^a-z0-9_").to_sym

    }

  }

  # 

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

  # 

  # <b><tt>:col_sep</tt></b>::            <tt>","</tt>

  # <b><tt>:row_sep</tt></b>::            <tt>:auto</tt>

  # <b><tt>:quote_char</tt></b>::         <tt>'"'</tt>

  # <b><tt>:converters</tt></b>::         +nil+

  # <b><tt>:unconverted_fields</tt></b>:: +nil+

  # <b><tt>:headers</tt></b>::            +false+

  # <b><tt>:return_headers</tt></b>::     +false+

  # <b><tt>:header_converters</tt></b>::  +nil+

  # <b><tt>:skip_blanks</tt></b>::        +false+

  # <b><tt>:force_quotes</tt></b>::       +false+

  # 

  DEFAULT_OPTIONS = { :col_sep            => ",",

                      :row_sep            => :auto,

                      :quote_char         => '"', 

                      :converters         => nil,

                      :unconverted_fields => nil,

                      :headers            => false,

                      :return_headers     => false,

                      :header_converters  => nil,

                      :skip_blanks        => false,

                      :force_quotes       => false }.freeze

  # 

  # This method will build a drop-in replacement for many of the standard CSV

  # methods.  It allows you to write code like:

  # 

  #   begin

  #     require "faster_csv"

  #     FasterCSV.build_csv_interface

  #   rescue LoadError

  #     require "csv"

  #   end

  #   # ... use CSV here ...

  # 

  # This is not a complete interface with completely identical behavior.

  # However, it is intended to be close enough that you won't notice the

  # difference in most cases.  CSV methods supported are:

  # 

  # * foreach()

  # * generate_line()

  # * open()

  # * parse()

  # * parse_line()

  # * readlines()

  # 

  # Be warned that this interface is slower than vanilla FasterCSV due to the

  # extra layer of method calls.  Depending on usage, this can slow it down to 

  # near CSV speeds.

  # 

  def self.build_csv_interface

    Object.const_set(:CSV, Class.new).class_eval do

      def self.foreach(path, rs = :auto, &block)  # :nodoc:

        FasterCSV.foreach(path, :row_sep => rs, &block)

      end

      def self.generate_line(row, fs = ",", rs = "")  # :nodoc:

        FasterCSV.generate_line(row, :col_sep => fs, :row_sep => rs)

      end

      def self.open(path, mode, fs = ",", rs = :auto, &block)  # :nodoc:

        if block and mode.include? "r"

          FasterCSV.open(path, mode, :col_sep => fs, :row_sep => rs) do |csv|

            csv.each(&block)

          end

        else

          FasterCSV.open(path, mode, :col_sep => fs, :row_sep => rs, &block)

        end

      end

      def self.parse(str_or_readable, fs = ",", rs = :auto, &block)  # :nodoc:

        FasterCSV.parse(str_or_readable, :col_sep => fs, :row_sep => rs, &block)

      end

      def self.parse_line(src, fs = ",", rs = :auto)  # :nodoc:

        FasterCSV.parse_line(src, :col_sep => fs, :row_sep => rs)

      end

      def self.readlines(path, rs = :auto)  # :nodoc:

        FasterCSV.readlines(path, :row_sep => rs)

      end

    end

  end

  # 

  # This method allows you to serialize an Array of Ruby objects to a String or

  # File of CSV data.  This is not as powerful as Marshal or YAML, but perhaps

  # useful for spreadsheet and database interaction.

  # 

  # Out of the box, this method is intended to work with simple data objects or

  # Structs.  It will serialize a list of instance variables and/or

  # Struct.members().

  # 

  # If you need need more complicated serialization, you can control the process

  # by adding methods to the class to be serialized.

  # 

  # A class method csv_meta() is responsible for returning the first row of the

  # document (as an Array).  This row is considered to be a Hash of the form

  # key_1,value_1,key_2,value_2,...  FasterCSV::load() expects to find a class

  # key with a value of the stringified class name and FasterCSV::dump() will

  # create this, if you do not define this method.  This method is only called

  # on the first object of the Array.

  # 

  # The next method you can provide is an instance method called csv_headers().

  # This method is expected to return the second line of the document (again as

  # an Array), which is to be used to give each column a header.  By default,

  # FasterCSV::load() will set an instance variable if the field header starts

  # with an @ character or call send() passing the header as the method name and

  # the field value as an argument.  This method is only called on the first

  # object of the Array.

  # 

  # Finally, you can provide an instance method called csv_dump(), which will

  # be passed the headers.  This should return an Array of fields that can be

  # serialized for this object.  This method is called once for every object in

  # the Array.

  # 

  # The +io+ parameter can be used to serialize to a File, and +options+ can be

  # anything FasterCSV::new() accepts.

  # 

  def self.dump(ary_of_objs, io = "", options = Hash.new)

    obj_template = ary_of_objs.first

    csv = FasterCSV.new(io, options)

    # write meta information

    begin

      csv << obj_template.class.csv_meta

    rescue NoMethodError

      csv << [:class, obj_template.class]

    end

    # write headers

    begin

      headers = obj_template.csv_headers

    rescue NoMethodError

      headers = obj_template.instance_variables.sort

      if obj_template.class.ancestors.find { |cls| cls.to_s =~ /\AStruct\b/ }

        headers += obj_template.members.map { |mem| "#{mem}=" }.sort

      end

    end

    csv << headers

    # serialize each object

    ary_of_objs.each do |obj|

      begin

        csv << obj.csv_dump(headers)

      rescue NoMethodError

        csv << headers.map do |var|

          if var[0] == ?@

            obj.instance_variable_get(var)

          else

            obj[var[0..-2]]

          end

        end

      end

    end

    if io.is_a? String

      csv.string

    else

      csv.close

    end

  end

  # 

  # :call-seq:

  #   filter( options = Hash.new ) { |row| ... }

  #   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 FasterCSV::new() accepts

  # (generally String or IO objects).  If not given, they default to 

  # <tt>ARGF</tt> and <tt>$stdout</tt>.

  # 

  # The +options+ parameter is also filtered down to FasterCSV::new() after some

  # clever key parsing.  Any key beginning with <tt>:in_</tt> or 

  # <tt>:input_</tt> will have that leading identifier stripped and will only

  # be used in the +options+ Hash for the +input+ object.  Keys starting with

  # <tt>:out_</tt> or <tt>:output_</tt> affect only +output+.  All other keys 

  # are assigned to both objects.

  # 

  # The <tt>:output_row_sep</tt> +option+ defaults to

  # <tt>$INPUT_RECORD_SEPARATOR</tt> (<tt>$/</tt>).

  # 

  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   = FasterCSV.new(args.shift || ARGF,    in_options)

    output  = FasterCSV.new(args.shift || $stdout, out_options)

    # read, yield, write

    input.each do |row|

      yield row

      output << row

    end

  end

  # 

  # 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 FasterCSV::new() understands.

  # 

  def self.foreach(path, options = Hash.new, &block)

    open(path, "rb", options) do |csv|

      csv.each(&block)

    end

  end

  # 

  # :call-seq:

  #   generate( str, options = Hash.new ) { |faster_csv| ... }

  #   generate( options = Hash.new ) { |faster_csv| ... }

  # 

  # This method wraps a String you provide, or an empty default String, in a 

  # FasterCSV 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* modfied by this method.  Call dup() before

  # passing if you need a new String.

  # 

  # The +options+ parameter can be anthing FasterCSV::new() understands.

  # 

  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

      args.unshift("")

    end

    faster_csv = new(*args)  # wrap

    yield faster_csv         # yield for appending

    faster_csv.string        # return final String

  end

  # 

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

  # String.

  # 

  # The +options+ parameter can be anthing FasterCSV::new() understands.

  # 

  # The <tt>:row_sep</tt> +option+ defaults to <tt>$INPUT_RECORD_SEPARATOR</tt>

  # (<tt>$/</tt>) when calling this method.

  # 

  def self.generate_line(row, options = Hash.new)

    options = {:row_sep => $INPUT_RECORD_SEPARATOR}.merge(options)

    (new("", options) << row).string

  end

  # 

  # This method will return a FasterCSV instance, just like FasterCSV::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.

  # 

  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

  # 

  # This method is the reading counterpart to FasterCSV::dump().  See that

  # method for a detailed description of the process.

  # 

  # You can customize loading by adding a class method called csv_load() which 

  # will be passed a Hash of meta information, an Array of headers, and an Array

  # of fields for the object the method is expected to return.

  # 

  # Remember that all fields will be Strings after this load.  If you need

  # something else, use +options+ to setup converters or provide a custom

  # csv_load() implementation.

  # 

  def self.load(io_or_str, options = Hash.new)

    csv = FasterCSV.new(io_or_str, options)

    # load meta information

    meta = Hash[*csv.shift]

    cls  = meta["class"].split("::").inject(Object) do |c, const|

      c.const_get(const)

    end

    # load headers

    headers = csv.shift

    # unserialize each object stored in the file

    results = csv.inject(Array.new) do |all, row|

      begin

        obj = cls.csv_load(meta, headers, row)

      rescue NoMethodError

        obj = cls.allocate

        headers.zip(row) do |name, value|

          if name[0] == ?@

            obj.instance_variable_set(name, value)

          else

            obj.send(name, value)

          end

        end

      end

      all << obj

    end

    csv.close unless io_or_str.is_a? String

    results

  end

  # 

  # :call-seq:

  #   open( filename, mode="rb", options = Hash.new ) { |faster_csv| ... }

  #   open( filename, mode="rb", options = Hash.new )

  # 

  # This method opens an IO object, and wraps that with FasterCSV.  This is

  # intended as the primary interface for writing a CSV file.

  # 

  # You may pass any +args+ Ruby's open() understands followed by an optional

  # Hash containing any +options+ FasterCSV::new() understands.

  # 

  # This method works like Ruby's open() call, in that it will pass a FasterCSV

  # object to a provided block and close it when the block termminates, or it

  # will return the FasterCSV object when no block is provided.  (*Note*: This

  # is different from the standard CSV library which passes rows to the block.  

  # Use FasterCSV::foreach() for that behavior.)

  # 

  # An opened FasterCSV object will delegate to many IO methods, for 

  # convenience.  You may call:

  # 

  # * binmode()

  # * close()

  # * close_read()

  # * close_write()

  # * closed?()

  # * eof()

  # * eof?()

  # * fcntl()

  # * fileno()

  # * flush()

  # * fsync()

  # * ioctl()

  # * isatty()

  # * pid()

  # * pos()

  # * reopen()

  # * seek()

  # * stat()

  # * sync()

  # * sync=()

  # * tell()

  # * to_i()

  # * to_io()

  # * tty?()

  # 

  def self.open(*args)

    # find the +options+ Hash

    options = if args.last.is_a? Hash then args.pop else Hash.new end

    # default to a binary open mode

    args << "rb" if args.size == 1

    # wrap a File opened with the remaining +args+

    csv     = new(File.open(*args), options)

    # 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

  # 

  # :call-seq:

  #   parse( str, options = Hash.new ) { |row| ... }

  #   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 FasterCSV::new() understands.

  # 

  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

  # 

  # This method is a shortcut for converting a single line of a CSV String into 

  # a into an Array.  Note that if +line+ contains multiple rows, anything 

  # beyond the first row is ignored.

  # 

  # The +options+ parameter can be anthing FasterCSV::new() understands.

  # 

  def self.parse_line(line, options = Hash.new)

    new(line, options).shift

  end

  # 

  # Use to slurp a CSV file into an Array of Arrays.  Pass the +path+ to the 

  # file and any +options+ FasterCSV::new() understands.

  # 

  def self.read(path, options = Hash.new)

    open(path, "rb", options) { |csv| csv.read }

  end