1 files changed, 78 insertions, 0 deletions
diff --git a/lib/roo/utils.rb b/lib/roo/utils.rb
new file mode 100644
index 0000000..17b672d
--- /dev/null
+++ b/lib/roo/utils.rb
@@ -0,0 +1,78 @@
+module Roo
+  module Utils
+    extend self
+
+    LETTERS = ('A'..'Z').to_a
+
+    def split_coordinate(str)
+      @split_coordinate ||= {}
+
+      @split_coordinate[str] ||= begin
+        letter, number = split_coord(str)
+        x = letter_to_number(letter)
+        y = number
+        [y, x]
+      end
+    end
+
+    alias_method :ref_to_key, :split_coordinate
+
+    def split_coord(s)
+      if s =~ /([a-zA-Z]+)([0-9]+)/
+        letter = Regexp.last_match[1]
+        number = Regexp.last_match[2].to_i
+      else
+        fail ArgumentError
+      end
+      [letter, number]
+    end
+
+    # convert a number to something like 'AB' (1 => 'A', 2 => 'B', ...)
+    def number_to_letter(num)
+      result = ""
+
+      until num.zero?
+        num, index = (num - 1).divmod(26)
+        result.prepend(LETTERS[index])
+      end
+
+      result
+    end
+
+    def letter_to_number(letters)
+      @letter_to_number ||= {}
+      @letter_to_number[letters] ||= begin
+         result = 0
+
+         # :bytes method returns an enumerator in 1.9.3 and an array in 2.0+
+         letters.bytes.to_a.map{|b| b > 96 ? b - 96 : b - 64 }.reverse.each_with_index{ |num, i| result += num * 26 ** i }
+
+         result
+      end
+    end
+
+    # Compute upper bound for cells in a given cell range.
+    def num_cells_in_range(str)
+      cells = str.split(':')
+      return 1 if cells.count == 1
+      raise ArgumentError.new("invalid range string: #{str}. Supported range format 'A1:B2'") if cells.count != 2
+      x1, y1 = split_coordinate(cells[0])
+      x2, y2 = split_coordinate(cells[1])
+      (x2 - (x1 - 1)) * (y2 - (y1 - 1))
+    end
+
+    def load_xml(path)
+      ::File.open(path, 'rb') do |file|
+        ::Nokogiri::XML(file)
+      end
+    end
+
+    # Yield each element of a given type ('row', 'c', etc.) to caller
+    def each_element(path, elements)
+      Nokogiri::XML::Reader(::File.open(path, 'rb'), nil, nil, Nokogiri::XML::ParseOptions::NOBLANKS).each do |node|
+        next unless node.node_type == Nokogiri::XML::Reader::TYPE_ELEMENT && Array(elements).include?(node.name)
+        yield Nokogiri::XML(node.outer_xml).root if block_given?
+      end
+    end
+  end
+end