shared string should be faster than non-shared string serialization

lib/axlsx/stylesheet/color.rb

@@ -72,5 +72,9 @@ def to_xml_string(str = '')
       str << "/>"
     end
 
+    def signature
+      "#{@rgb}:#{auto}:#{@tint}"
+    end
+
   end
 end

lib/axlsx/workbook/shared_strings_table.rb

@@ -30,8 +30,9 @@ def unique_count
     # @param [Array] cells This is an array of all of the cells in the workbook
     def initialize(cells)
       cells = cells.flatten.reject { |c| c.type != :string || c.value.nil? || c.value.start_with?('=') }
+      @index = 0
       @count = cells.size
-      @unique_cells = []
+      @unique_cells = {}
       @shared_xml_string = ""
       resolve(cells)
     end
@@ -53,15 +54,13 @@ def to_xml_string
     def resolve(cells)
       cells.each do |cell|
         cell_hash = cell.shareable_hash
-        index = @unique_cells.index do |item|
-          item == cell_hash
-        end
-        if index == nil
-          cell.send :ssti=, @unique_cells.size
-          @shared_xml_string << '<si>' << cell.run_xml_string << '</si>'
-          @unique_cells << cell_hash
-        else
+        if index = @unique_cells[cell_hash]
           cell.send :ssti=, index
+        else
+          cell.send :ssti=, @index
+          @shared_xml_string << '<si>' << cell.run_xml_string << '</si>'
+          @unique_cells[cell_hash] = @index
+          @index += 1
         end
       end
     end

lib/axlsx/workbook/worksheet/cell.rb

@@ -154,7 +154,7 @@ def u=(v) set_run_style :validate_boolean, :u, v; end
     # @param [String] The 8 character representation for an rgb color #FFFFFFFF"
     def color=(v)
       @color = v.is_a?(Color) ? v : Color.new(:rgb=>v)
-      @has_run_style = true
+      @is_text_run = true
     end
 
     # The inline sz property for the cell
@@ -203,6 +203,7 @@ def scheme=(v)
     # @option options [String] color an 8 letter rgb specification
     # @option options [Symbol] scheme must be one of :none, major, :minor
     def initialize(row, value="", options={})
+      @signature = 0
       self.row=row
       @font_name = @charset = @family = @b = @i = @strike = @outline = @shadow = nil
       @condense = @u = @vertAlign = @sz = @color = @scheme = @extend = @ssti = nil
@@ -223,10 +224,7 @@ def initialize(row, value="", options={})
     # equality comparison to test value, type and inline style attributes
     # this is how we work out if the cell needs to be added or already exists in the shared strings table
     def shareable_hash
-      self_hash = {}
-      INLINE_STYLES.each { |style| self_hash[style] = self.instance_variable_get("@" + style) }
-      self_hash['color'] = self_hash['color'].instance_values if self_hash['color']
-      self_hash
+      "#{@signature} & #{@value} & #{@color && @color.signature}"
     end
 
     # @return [Integer] The index of the cell in the containing row.
@@ -339,8 +337,9 @@ def to_xml_string(r_index, c_index, str = '')
 
     # Utility method for setting inline style attributes
     def set_run_style( validator, attr, value)
-      return unless INLINE_STYLES.include?(attr.to_s)
+      return unless idx = INLINE_STYLES.index(attr.to_s)
       Axlsx.send(validator, value) unless validator == nil
+      @signature += 2**idx
       self.instance_variable_set :"@#{attr.to_s}", value
       @is_text_run = true
     end

test/profile.rb

@@ -15,11 +15,12 @@
 row = []
 input = (32..126).to_a.pack('U*').chars.to_a
 20.times { row << input.shuffle.join}
-times = 1000
+times = 3000
 
 PerfTools::CpuProfiler.start("/tmp/axlsx_noautowidth") do
   p = Axlsx::Package.new
   p.use_autowidth = false
+  p.use_shared_strings = true
   wb = p.workbook
 
   #A Simple Workbook