comparison lib/faster_csv.rb @ 0:513646585e45

* Import Redmine trunk SVN rev 3859

+#!/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
+  
+  # Alias for FasterCSV::read().
+  def self.readlines(*args)
+    read(*args)
+  end
+  
+  # 
+  # A shortcut for:
+  # 
+  #   FasterCSV.read( path, { :headers           => true,
+  #                           :converters        => :numeric,
+  #                           :header_converters => :symbol }.merge(options) )
+  # 
+  def self.table(path, options = Hash.new)
+    read( path, { :headers           => true,
+                  :converters        => :numeric,
+                  :header_converters => :symbol }.merge(options) )
+  end
+  
+  # 
+  # This constructor will wrap either a String or IO object passed in +data+ for
+  # reading and/or writing.  In addition to the FasterCSV instance methods, 
+  # several IO methods are delegated.  (See FasterCSV::open() for a complete 
+  # list.)  If you pass a String for +data+, you can later retrieve it (after
+  # writing to it, for example) with FasterCSV.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 
+  # FasterCSV::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:
+  # 
+  # <b><tt>:col_sep</tt></b>::            The String placed between each field.
+  # <b><tt>:row_sep</tt></b>::            The String appended to the end of each
+  #                                       row.  This can be set to the special
+  #                                       <tt>:auto</tt> setting, which requests
+  #                                       that FasterCSV automatically discover
+  #                                       this from the data.  Auto-discovery
+  #                                       reads ahead in the data looking for
+  #                                       the next <tt>"\r\n"</tt>,
+  #                                       <tt>"\n"</tt>, or <tt>"\r"</tt>
+  #                                       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
+  #                                       <tt>ARGF</tt>, <tt>STDIN</tt>,
+  #                                       <tt>STDOUT</tt>, or <tt>STDERR</tt>,
+  #                                       or the stream is only available for
+  #                                       output, the default
+  #                                       <tt>$INPUT_RECORD_SEPARATOR</tt>
+  #                                       (<tt>$/</tt>) is used.  Obviously,
+  #                                       discovery takes a little time.  Set
+  #                                       manually if speed is important.  Also
+  #                                       note that IO objects should be opened
+  #                                       in binary mode on Windows if this
+  #                                       feature will be used as the
+  #                                       line-ending translation can cause
+  #                                       problems with resetting the document
+  #                                       position to where it was before the
+  #                                       read ahead.
+  # <b><tt>:quote_char</tt></b>::         The character used to quote fields.
+  #                                       This has to be a single character
+  #                                       String.  This is useful for
+  #                                       application that incorrectly use
+  #                                       <tt>'</tt> as the quote character
+  #                                       instead of the correct <tt>"</tt>.
+  #                                       FasterCSV will always consider a
+  #                                       double sequence this character to be
+  #                                       an escaped quote.
+  # <b><tt>:encoding</tt></b>::           The encoding to use when parsing the
+  #                                       file. Defaults to your <tt>$KDOCE</tt>
+  #                                       setting. Valid values: <tt>`n’</tt> or
+  #                                       <tt>`N’</tt> for none, <tt>`e’</tt> or
+  #                                       <tt>`E’</tt> for EUC, <tt>`s’</tt> or
+  #                                       <tt>`S’</tt> for SJIS, and
+  #                                       <tt>`u’</tt> or <tt>`U’</tt> for UTF-8
+  #                                       (see Regexp.new()).
+  # <b><tt>:field_size_limit</tt></b>::   This is a maximum size FasterCSV 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 FasterCSV 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.
+  # <b><tt>:converters</tt></b>::         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.
+  # <b><tt>:unconverted_fields</tt></b>:: If set to +true+, an
+  #                                       unconverted_fields() method will be
+  #                                       added to all returned rows (Array or
+  #                                       FasterCSV::Row) that will return the
+  #                                       fields as they were before convertion.
+  #                                       Note that <tt>:headers</tt> supplied
+  #                                       by Array or String were not fields of
+  #                                       the document and thus will have an
+  #                                       empty Array attached.
+  # <b><tt>:headers</tt></b>::            If set to <tt>:first_row</tt> 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
+  #                                       FasterCSV::parse_line() with the same
+  #                                       <tt>:col_sep</tt>, <tt>:row_sep</tt>,
+  #                                       and <tt>:quote_char</tt> as this
+  #                                       instance to produce an Array of
+  #                                       headers.  This setting causes
+  #                                       FasterCSV.shift() to return rows as
+  #                                       FasterCSV::Row objects instead of
+  #                                       Arrays and FasterCSV.read() to return
+  #                                       FasterCSV::Table objects instead of
+  #                                       an Array of Arrays.
+  # <b><tt>:return_headers</tt></b>::     When +false+, header rows are silently
+  #                                       swallowed.  If set to +true+, header
+  #                                       rows are returned in a FasterCSV::Row
+  #                                       object with identical headers and
+  #                                       fields (save that the fields do not go
+  #                                       through the converters).
+  # <b><tt>:write_headers</tt></b>::      When +true+ and <tt>:headers</tt> is
+  #                                       set, a header row will be added to the
+  #                                       output.
+  # <b><tt>:header_converters</tt></b>::  Identical in functionality to
+  #                                       <tt>:converters</tt> save that the
+  #                                       conversions are only made to header
+  #                                       rows.
+  # <b><tt>:skip_blanks</tt></b>::        When set to a +true+ value, FasterCSV
+  #                                       will skip over any rows with no
+  #                                       content.
+  # <b><tt>:force_quotes</tt></b>::       When set to a +true+ value, FasterCSV
+  #                                       will quote all CSV fields it creates.
+  # 
+  # See FasterCSV::DEFAULT_OPTIONS for the default settings.
+  # 
+  # Options cannot be overriden in the instance methods for performance reasons,
+  # so be sure to set what you want here.
+  # 
+  def initialize(data, options = Hash.new)
+    # build the options for this read/write
+    options = DEFAULT_OPTIONS.merge(options)
+    
+    # create the IO object we will read from
+    @io = if data.is_a? String then StringIO.new(data) else data end
+    
+    init_separators(options)
+    init_parsers(options)
+    init_converters(options)
+    init_headers(options)
+    
+    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
+  
+  # 
+  # The line number of the last row read from this file.  Fields with nested 
+  # line-end characters will not affect this count.
+  # 
+  attr_reader :lineno
+  
+  ### IO and StringIO Delegation ###
+  
+  extend Forwardable
+  def_delegators :@io, :binmode, :close, :close_read, :close_write, :closed?,
+                       :eof, :eof?, :fcntl, :fileno, :flush, :fsync, :ioctl,
+                       :isatty, :pid, :pos, :reopen, :seek, :stat, :string,
+                       :sync, :sync=, :tell, :to_i, :to_io, :tty?
+  
+  # Rewinds the underlying IO object and resets FasterCSV's lineno() counter.
+  def rewind
+    @headers = nil
+    @lineno  = 0
+    
+    @io.rewind
+  end
+
+  ### End Delegation ###
+  
+  # 
+  # The primary write method for wrapped Strings and IOs, +row+ (an Array or
+  # FasterCSV::Row) is converted to CSV and appended to the data source.  When a
+  # FasterCSV::Row is passed, only the row's fields() are appended to the
+  # output.
+  # 
+  # The data source must be open for writing.
+  # 
+  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 FasterCSV::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
+
+    @io << row.map(&@quote).join(@col_sep) + @row_sep  # quote and separate
+    
+    self  # for chaining
+  end
+  alias_method :add_row, :<<
+  alias_method :puts,    :<<
+  
+  # 
+  # :call-seq:
+  #   convert( name )
+  #   convert { |field| ... }
+  #   convert { |field, field_info| ... }
+  # 
+  # You can use this method to install a FasterCSV::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 FieldInfo Struct, 
+  # containing details about the field.  Again, the block should return a 
+  # converted field or the field itself.
+  # 
+  def convert(name = nil, &converter)
+    add_converter(:converters, self.class::Converters, name, &converter)
+  end
+
+  # 
+  # :call-seq:
+  #   header_convert( name )
+  #   header_convert { |field| ... }
+  #   header_convert { |field, field_info| ... }
+  # 
+  # Identical to FasterCSV.convert(), but for header rows.
+  # 
+  # Note that this method must be called before header rows are read to have any
+  # effect.
+  # 
+  def header_convert(name = nil, &converter)
+    add_converter( :header_converters,
+                   self.class::HeaderConverters,
+                   name,
+                   &converter )
+  end
+  
+  include Enumerable
+  
+  # 
+  # Yields each row of the data source in turn.
+  # 
+  # Support for Enumerable.
+  # 
+  # The data source must be open for reading.
+  # 
+  def each
+    while row = shift
+      yield row
+    end
+  end
+  
+  # 
+  # Slurps the remaining rows and returns an Array of Arrays.
+  # 
+  # The data source must be open for reading.
+  # 
+  def read
+    rows = to_a
+    if @use_headers
+      Table.new(rows)
+    else
+      rows
+    end
+  end
+  alias_method :readlines, :read
+  
+  # Returns +true+ if the next row read will be a header row.
+  def header_row?
+    @use_headers and @headers.nil?
+  end
+  
+  # 
+  # 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 FasterCSV::Row (when header rows are used).
+  # 
+  # The data source must be open for reading.
+  # 
+  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
+    
+    # begin with a blank line, so we can always add to it
+    line = String.new
+
+    # 
+    # 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
+    # 
+    loop do
+      # add another read to the line
+      begin
+        line  += @io.gets(@row_sep)
+      rescue
+        return nil
+      end
+      # copy the line so we can chop it up in parsing
+      parse =  line.dup
+      parse.sub!(@parsers[:line_end], "")
+      
+      # 
+      # I believe a blank line should be an <tt>Array.new</tt>, not 
+      # CSV's <tt>[nil]</tt>
+      # 
+      if parse.empty?
+        @lineno += 1
+        if @skip_blanks
+          line = ""
+          next
+        elsif @unconverted_fields
+          return add_unconverted_fields(Array.new, Array.new)
+        elsif @use_headers
+          return FasterCSV::Row.new(Array.new, Array.new)
+        else
+          return Array.new
+        end
+      end
+
+      # parse the fields with a mix of String#split and regular expressions
+      csv           = Array.new
+      current_field = String.new
+      field_quotes  = 0
+      parse.split(@col_sep, -1).each do |match|
+        if current_field.empty? && match.count(@quote_and_newlines).zero?
+          csv           << (match.empty? ? nil : match)
+        elsif(current_field.empty? ? match[0] : current_field[0]) == @quote_char[0]
+          current_field << match
+          field_quotes += match.count(@quote_char)
+          if field_quotes % 2 == 0
+            in_quotes = current_field[@parsers[:quoted_field], 1]
+            raise MalformedCSVError unless in_quotes
+            current_field = in_quotes
+            current_field.gsub!(@quote_char * 2, @quote_char) # unescape contents
+            csv           << current_field
+            current_field =  String.new
+            field_quotes  =  0
+          else # we found a quoted field that spans multiple lines
+            current_field << @col_sep
+          end
+        elsif match.count("\r\n").zero?
+          raise MalformedCSVError, "Illegal quoting on line #{lineno + 1}."
+        else
+          raise MalformedCSVError, "Unquoted fields do not allow " +
+                                   "\\r or \\n (line #{lineno + 1})."
+        end
+      end
+
+      # if parse is empty?(), we found all the fields on the line...
+      if field_quotes % 2 == 0
+        @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 FasterCSV::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
+      # if we're not empty?() but 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 current_field.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
+    end
+  end
+  alias_method :gets,     :shift
+  alias_method :readline, :shift
+  
+  # Returns a simplified description of the key FasterCSV attributes.
+  def inspect
+    str = "<##{self.class} 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 other attributes
+    %w[ lineno     col_sep     row_sep
+        quote_char skip_blanks encoding ].each do |attr_name|
+      if a = instance_variable_get("@#{attr_name}")
+        str << " #{attr_name}:#{a.inspect}"
+      end
+    end
+    if @use_headers
+      str << " headers:#{(@headers || true).inspect}"
+    end
+    str << ">"
+  end
+  
+  private
+  
+  # 
+  # Stores the indicated separators for later use.
+  # 
+  # If auto-discovery was requested for <tt>@row_sep</tt>, this method will read
+  # ahead in the <tt>@io</tt> and try to find one.  +ARGF+, +STDIN+, +STDOUT+,
+  # +STDERR+ and any stream open for output only with a default
+  # <tt>@row_sep</tt> of <tt>$INPUT_RECORD_SEPARATOR</tt> (<tt>$/</tt>).
+  # 
+  # This method also establishes the quoting rules used for CSV output.
+  # 
+  def init_separators(options)
+    # store the selected separators
+    @col_sep            = options.delete(:col_sep)
+    @row_sep            = options.delete(:row_sep)
+    @quote_char         = options.delete(:quote_char)
+    @quote_and_newlines = "#{@quote_char}\r\n"
+
+    if @quote_char.length != 1
+      raise ArgumentError, ":quote_char has to be a single character String"
+    end
+    
+    # automatically discover row separator when requested
+    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
+          saved_pos = @io.pos  # remember where we were
+          while @row_sep == :auto
+            # 
+            # if we run out of data, it's probably a single line 
+            # (use a sensible default)
+            # 
+            if @io.eof?
+              @row_sep = $INPUT_RECORD_SEPARATOR
+              break
+            end
+      
+            # read ahead a bit
+            sample =  @io.read(1024)
+            sample += @io.read(1) if sample[-1..-1] == "\r" and not @io.eof?
+      
+            # try to find a standard separator
+            if sample =~ /\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  # stream not opened for reading
+          @row_sep = $INPUT_RECORD_SEPARATOR
+        end
+      end
+    end
+    
+    # establish quoting rules
+    do_quote = lambda do |field|
+      @quote_char                                      +
+      String(field).gsub(@quote_char, @quote_char * 2) +
+      @quote_char
+    end
+    @quote = if options.delete(: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("\r\n#{@col_sep}#{@quote_char}").nonzero?
+            do_quote.call(field)
+          else
+            field  # unquoted field
+          end
+        end
+      end
+    end
+  end
+  
+  # Pre-compiles parsers and stores them by name for access during reads.
+  def init_parsers(options)
+    # store the parser behaviors
+    @skip_blanks      = options.delete(:skip_blanks)
+    @encoding         = options.delete(:encoding)  # nil will use $KCODE
+    @field_size_limit = options.delete(:field_size_limit)
+
+    # prebuild Regexps for faster parsing
+    esc_col_sep = Regexp.escape(@col_sep)
+    esc_row_sep = Regexp.escape(@row_sep)
+    esc_quote   = Regexp.escape(@quote_char)
+    @parsers = {
+      :any_field      => Regexp.new( "[^#{esc_col_sep}]+",
+                                     Regexp::MULTILINE,
+                                     @encoding ),
+      :quoted_field   => Regexp.new( "^#{esc_quote}(.*)#{esc_quote}$",
+                                     Regexp::MULTILINE,
+                                     @encoding ),
+      # safer than chomp!()
+      :line_end       => Regexp.new("#{esc_row_sep}\\z", nil, @encoding)
+    }
+  end
+  
+  # 
+  # Loads any converters requested during construction.
+  # 
+  # If +field_name+ is set <tt>:converters</tt> (the default) field converters
+  # are set.  When +field_name+ is <tt>:header_converters</tt> header converters
+  # are added instead.
+  # 
+  # The <tt>:unconverted_fields</tt> option is also actived for 
+  # <tt>:converters</tt> calls, if requested.
+  # 
+  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 coverters
+    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
+  
+  # Stores header row settings and loads header converters, if needed.
+  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
+  
+  # 
+  # The actual work method for adding converters, used by both 
+  # FasterCSV.convert() and FasterCSV.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 FasterCSV.convert() and FasterCSV.header_convert()
+  # methods.
+  # 
+  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
+  
+  # 
+  # Processes +fields+ with <tt>@converters</tt>, or <tt>@header_converters</tt>
+  # 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.
+  # 
+  def convert_fields(fields, headers = false)
+    # see if we are converting headers or fields
+    converters = headers ? @header_converters : @converters
+    
+    fields.enum_for(:each_with_index).map do |field, index|  # map_with_index
+      converters.each do |converter|
+        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-curcuit pipeline for speed
+      end
+      field  # return final state of each field, converted or original
+    end
+  end
+  
+  # 
+  # This methods is used to turn a finished +row+ into a FasterCSV::Row.  Header
+  # rows are also dealt with here, either by returning a FasterCSV::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 <tt>@headers</tt> for use in future rows.
+  # 
+  # When +nil+, +row+ is assumed to be a header row not based on an actual row
+  # of the stream.
+  # 
+  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)
+      
+      if @return_headers                                     # return headers
+        return FasterCSV::Row.new(@headers, row, true)
+      elsif not [Array, String].include? @use_headers.class  # skip to field row
+        return shift
+      end
+    end
+
+    FasterCSV::Row.new(@headers, convert_fields(row))  # field row
+  end
+  
+  # 
+  # Thiw methods injects an instance variable <tt>unconverted_fields</tt> into
+  # +row+ and an accessor method for it called unconverted_fields().  The
+  # variable is set to the contents of +fields+.
+  # 
+  def add_unconverted_fields(row, fields)
+    class << row
+      attr_reader :unconverted_fields
+    end
+    row.instance_eval { @unconverted_fields = fields }
+    row
+  end
+end
+
+# Another name for FasterCSV.
+FCSV = FasterCSV
+
+# Another name for FasterCSV::instance().
+def FasterCSV(*args, &block)
+  FasterCSV.instance(*args, &block)
+end
+
+# Another name for FCSV::instance().
+def FCSV(*args, &block)
+  FCSV.instance(*args, &block)
+end
+
+class Array
+  # Equivalent to <tt>FasterCSV::generate_line(self, options)</tt>.
+  def to_csv(options = Hash.new)
+    FasterCSV.generate_line(self, options)
+  end
+end
+
+class String
+  # Equivalent to <tt>FasterCSV::parse_line(self, options)</tt>.
+  def parse_csv(options = Hash.new)
+    FasterCSV.parse_line(self, options)
+  end
+end