import: data frames are here!

Implemented a whole new class to represent the data that comes in from CSV and XLSX. See docs for more info.

Closes #153

lib/squib/api/data.rb

@@ -3,6 +3,7 @@ require 'csv'
 require_relative '../args/input_file'
 require_relative '../args/import'
 require_relative '../args/csv_opts'
+require_relative '../import/data_frame'
 
 module Squib
 
@@ -12,7 +13,7 @@ module Squib
     import = Args::Import.new.load!(opts)
     s = Roo::Excelx.new(input.file[0])
     s.default_sheet = s.sheets[input.sheet[0]]
-    data = {}
+    data = Squib::DataFrame.new
     s.first_column.upto(s.last_column) do |col|
       header = s.cell(s.first_row, col).to_s
       header.strip! if import.strip?
@@ -39,14 +40,14 @@ module Squib
     csv_opts = Args::CSV_Opts.new(opts)
     table = CSV.parse(data, csv_opts.to_hash)
     check_duplicate_csv_headers(table)
-    hash = Hash.new
+    hash = Squib::DataFrame.new
     table.headers.each do |header|
       new_header = header.to_s
       new_header = new_header.strip if import.strip?
       hash[new_header] ||= table[header]
     end
     if import.strip?
-      new_hash = Hash.new
+      new_hash = Squib::DataFrame.new
       hash.each do |header, col|
         new_hash[header] = col.map do |str|
           str = str.strip if str.respond_to?(:strip)
@@ -78,9 +79,9 @@ module Squib
 
   # @api private
   def explode_quantities(data, qty)
-    return data unless data.key? qty.to_s.strip
+    return data unless data.col? qty.to_s.strip
     qtys = data[qty]
-    new_data = {}
+    new_data = Squib::DataFrame.new
     data.each do |col, arr|
       new_data[col] = []
       qtys.each_with_index do |qty, index|

lib/squib/import/data_frame.rb

@@ -0,0 +1,108 @@
+# encoding: UTF-8
+
+require 'json'
+require 'forwardable'
+
+module Squib
+  class DataFrame
+    include Enumerable
+
+    def initialize(hash = {}, def_columns = true)
+      @hash = hash
+      columns.each { |col| def_column(col) } if def_columns
+    end
+
+    def each(&block)
+      @hash.each(&block)
+    end
+
+    def [](i)
+      @hash[i]
+    end
+
+    def []=(col, v)
+      @hash[col] = v
+      def_column(col)
+      return v
+    end
+
+    def columns
+      @hash.keys
+    end
+
+    def ncolumns
+      @hash.keys.size
+    end
+
+    def col?(col)
+      @hash.key? col
+    end
+
+    def row(i)
+      @hash.inject(Hash.new) { |ret, (name, arr)| ret[name] = arr[i]; ret }
+    end
+
+    def nrows
+      @hash.inject(0) { |max, (_n, col)| col.size > max ? col.size : max }
+    end
+
+    def to_json
+      @hash.to_json
+    end
+
+    def to_pretty_json
+      JSON.pretty_generate(@hash)
+    end
+
+    def to_h
+      @hash
+    end
+
+    def to_pretty_text
+      max_col = columns.inject(0) { |max, c | c.length > max ? c.length : max }
+      top    = " ╭#{'-' * 36}╮\n"
+      bottom = " ╰#{'-' * 36}╯\n"
+      str =  ''
+      0.upto(nrows - 1) do | i |
+        str += (' ' * max_col) + top
+        row(i).each do |col, data|
+          str += "#{col.rjust(max_col)} #{wrap_n_pad(data, max_col)}"
+        end
+        str += (' ' * max_col) + bottom
+      end
+      return str
+    end
+
+    private
+
+    def snake_case(str)
+      str.to_s.
+          strip.
+          gsub(/\s+/,'_').
+          gsub(/([A-Z]+)([A-Z][a-z])/,'\1_\2').
+          gsub(/([a-z]+)([A-Z])/,'\1_\2').
+          downcase.
+          to_sym
+    end
+
+    def wrap_n_pad(str, max_col)
+      str.to_s.
+          concat(' '). # handle nil & empty strings
+          scan(/.{1,34}/).
+          map { |s| (' ' * max_col) + " | " + s.ljust(34) }.
+          join(" |\n").
+          lstrip.      # initially no whitespace next to key
+          concat(" |\n")
+    end
+
+    def def_column(col)
+      raise "Column #{col} - does not exist" unless @hash.key? col
+      method_name = snake_case(col)
+      return if self.class.method_defined?(method_name) #warn people? or skip?
+      define_singleton_method method_name do
+        @hash[col]
+      end
+    end
+
+  end
+end