Memory optimization (~30% less)

Gemfile

@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 source 'https://rubygems.org'
 gemspec
 

Rakefile

@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require File.expand_path(File.dirname(__FILE__) + '/lib/axlsx/version.rb')
 
 task :build => :gendoc do

axlsx.gemspec

@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require File.expand_path('../lib/axlsx/version', __FILE__)
 
 Gem::Specification.new do |s|

lib/axlsx.rb

@@ -1,4 +1,5 @@
 # encoding: UTF-8
+# frozen_string_literal: true
 require 'htmlentities'
 require 'axlsx/version.rb'
 require 'mimemagic'
@@ -90,7 +91,7 @@ def self.name_to_indices(name)
   # @note This follows the standard spreadsheet convention of naming columns A to Z, followed by AA to AZ etc.
   # @return [String]
   def self.col_ref(index)
-    chars = ''
+    chars = String.new
     while index >= 26 do
       index, char = index.divmod(26)
       chars.prepend((char + 65).chr)
@@ -114,8 +115,8 @@ def self.range_to_a(range)
     range.match(/^(\w+?\d+)\:(\w+?\d+)$/)
     start_col, start_row = name_to_indices($1)
     end_col,   end_row   = name_to_indices($2)
-    (start_row..end_row).to_a.map do |row_num|
-      (start_col..end_col).to_a.map do |col_num|
+    (start_row..end_row).map do |row_num|
+      (start_col..end_col).map do |col_num|
         cell_r(col_num, row_num)
       end
     end
@@ -125,9 +126,10 @@ def self.range_to_a(range)
   # @param [String] s The snake case string to camelize
   # @return [String]
   def self.camel(s="", all_caps = true)
-    s = s.to_s
-    s = s.capitalize if all_caps
-    s.gsub(/_(.)/){ $1.upcase }
+    s_copy = s.to_s.dup
+    s_copy = s_copy.capitalize! if all_caps
+    s_copy.gsub!(/_(.)/){ $1.upcase }
+    s_copy
   end
 
   # returns the provided string with all invalid control charaters

lib/axlsx/content_type/abstract_content_type.rb

@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Axlsx
 
   # This class extracts the common parts from Default and Override
@@ -22,9 +23,9 @@ def content_type=(v) Axlsx::validate_content_type v; @content_type = v end
     alias :ContentType= :content_type=
 
     # Serialize the contenty type to xml
-    def to_xml_string(node_name = '', str = '')
-      str << "<#{node_name} "
-      str << instance_values.map { |key, value| Axlsx::camel(key) << '="' << value.to_s << '"' }.join(' ')
+    def to_xml_string(node_name = '', str = String.new)
+      str << "<#{node_name}"
+      instance_values.each { |key, value| str << " #{Axlsx::camel(key)}=\"#{value}\"" }
       str << '/>'
     end
 

lib/axlsx/content_type/content_type.rb

@@ -1,4 +1,5 @@
 # encoding: UTF-8
+# frozen_string_literal: true
 module Axlsx
   require 'axlsx/content_type/abstract_content_type.rb'
   require 'axlsx/content_type/default.rb'
@@ -14,9 +15,9 @@ def initialize
     # Serializes the object
     # @param [String] str
     # @return [String]
-    def to_xml_string(str = '')
-      str << '<?xml version="1.0" encoding="UTF-8"?>'
-      str << ('<Types xmlns="' << XML_NS_T << '">')
+    def to_xml_string(str = String.new)
+      str << '<?xml version="1.0" encoding="UTF-8"?>'\
+             "<Types xmlns=\"#{XML_NS_T}\">"
       each { |type| type.to_xml_string(str) }
       str << '</Types>'
     end

lib/axlsx/content_type/default.rb

@@ -1,4 +1,5 @@
 # encoding: UTF-8
+# frozen_string_literal: true
 module Axlsx
 
   # An default content part. These parts are automatically created by for you based on the content of your package.
@@ -17,7 +18,7 @@ def extension=(v) Axlsx::validate_string v; @extension = v end
     alias :Extension= :extension=
 
     # Serializes this object to xml
-    def to_xml_string(str ='')
+    def to_xml_string(str = String.new)
       super(NODE_NAME, str)
     end
   end

lib/axlsx/content_type/override.rb

@@ -1,5 +1,6 @@
 
 # encoding: UTF-8
+# frozen_string_literal: true
 module Axlsx
 
   # An override content part. These parts are automatically created by for you based on the content of your package.
@@ -18,7 +19,7 @@ def part_name=(v) Axlsx::validate_string v; @part_name = v end
     alias :PartName= :part_name=
 
     # Serializes this object to xml
-    def to_xml_string(str = '')
+    def to_xml_string(str = String.new)
       super(NODE_NAME, str)
     end
   end

lib/axlsx/doc_props/app.rb

@@ -1,4 +1,5 @@
 # encoding: UTF-8
+# frozen_string_literal: true
 module Axlsx
 
   # App represents the app.xml document. The attributes for this object are primarily managed by the application the end user uses to edit the document. None of the attributes are required to serialize a valid xlsx object.
@@ -220,9 +221,9 @@ def doc_security=(v) Axlsx::validate_int v; @doc_security = v; end
 
     # Serialize the app.xml document
     # @return [String]
-    def to_xml_string(str = '')
-      str << '<?xml version="1.0" encoding="UTF-8"?>'
-      str << ('<Properties xmlns="' << APP_NS << '" xmlns:vt="' << APP_NS_VT << '">')
+    def to_xml_string(str = String.new)
+      str << '<?xml version="1.0" encoding="UTF-8"?>'\
+             "<Properties xmlns=\"#{APP_NS}\" xmlns:vt=\"#{APP_NS_VT}\">"
       instance_values.each do |key, value|
         node_name = Axlsx.camel(key)
         str << "<#{node_name}>#{value}</#{node_name}>"

lib/axlsx/doc_props/core.rb

@@ -5,7 +5,7 @@ module Axlsx
   # @note Packages manage their own core object.
   # @see Package#core
   class Core
- 
+
     # Creates a new Core object.
     # @option options [String] creator
     # @option options [Time] created
@@ -24,14 +24,16 @@ def initialize(options={})
     # serializes the core.xml document
     # @return [String]
     def to_xml_string(str = '')
-      str << '<?xml version="1.0" encoding="UTF-8"?>'
-      str << ('<cp:coreProperties xmlns:cp="' << CORE_NS << '" xmlns:dc="' << CORE_NS_DC << '" ')
-      str << ('xmlns:dcmitype="' << CORE_NS_DCMIT << '" xmlns:dcterms="' << CORE_NS_DCT << '" ')
-      str << ('xmlns:xsi="' << CORE_NS_XSI << '">')
-      str << ('<dc:creator>' << self.creator << '</dc:creator>')
-      str << ('<dcterms:created xsi:type="dcterms:W3CDTF">' << (created || Time.now).strftime('%Y-%m-%dT%H:%M:%S') << 'Z</dcterms:created>')
-      str << '<cp:revision>0</cp:revision>'
-      str << '</cp:coreProperties>'
+      str << <<-XML.gsub!("\n", '')
+<?xml version="1.0" encoding="UTF-8"?>
+<cp:coreProperties xmlns:cp="#{CORE_NS}" xmlns:dc="#{CORE_NS_DC}"
+ xmlns:dcmitype="#{CORE_NS_DCMIT}" xmlns:dcterms="#{CORE_NS_DCT}"
+ xmlns:xsi="#{CORE_NS_XSI}">
+<dc:creator>#{self.creator}</dc:creator>
+<dcterms:created xsi:type="dcterms:W3CDTF">#{(created || Time.now).strftime('%Y-%m-%dT%H:%M:%S')}Z</dcterms:created>
+<cp:revision>0</cp:revision>
+</cp:coreProperties>
+XML
     end
 
   end

lib/axlsx/drawing/area_chart.rb

@@ -1,4 +1,5 @@
 # encoding: UTF-8
+# frozen_string_literal: true
 module Axlsx
 
   # The AreaChart is a two dimentional line chart (who would have guessed?) that you can add to your worksheet.
@@ -75,16 +76,16 @@ def node_name
     # Serializes the object
     # @param [String] str
     # @return [String]
-    def to_xml_string(str = '')
+    def to_xml_string(str = String.new)
       super(str) do
-        str << ("<c:" << node_name << ">")
-        str << ('<c:grouping val="' << grouping.to_s << '"/>')
-        str << ('<c:varyColors val="' << vary_colors.to_s << '"/>')
+        str << "<c:#{node_name}>"\
+               "<c:grouping val=\"#{grouping}\"/>"\
+               "<c:varyColors val=\"#{vary_colors}\"/>"
         @series.each { |ser| ser.to_xml_string(str) }
         @d_lbls.to_xml_string(str) if @d_lbls
         yield if block_given?
         axes.to_xml_string(str, :ids => true)
-        str << ("</c:" << node_name << ">")
+        str << "</c:#{node_name}>"
         axes.to_xml_string(str)
       end
     end

lib/axlsx/drawing/area_series.rb

@@ -1,4 +1,5 @@
 # encoding: UTF-8
+# frozen_string_literal: true
 module Axlsx
   # A AreaSeries defines the title, data and labels for line charts
   # @note The recommended way to manage series is to use Chart#add_series
@@ -71,30 +72,30 @@ def smooth=(v)
     # Serializes the object
     # @param [String] str
     # @return [String]
-    def to_xml_string(str = '')
+    def to_xml_string(str = String.new)
       super(str) do
         if color
-          str << '<c:spPr><a:solidFill>'
-          str << ('<a:srgbClr val="' << color << '"/>')
-          str << '</a:solidFill>'
-          str << '<a:ln w="28800">'
-          str << '<a:solidFill>'
-          str << ('<a:srgbClr val="' << color << '"/>')
-          str << '</a:solidFill>'
-          str << '</a:ln>'
-          str << '<a:round/>'
-          str << '</c:spPr>'
+          str << '<c:spPr><a:solidFill>'\
+                 "<a:srgbClr val=\"#{color}\"/>"\
+                 '</a:solidFill>'\
+                 '<a:ln w="28800">'\
+                 '<a:solidFill>'\
+                 "<a:srgbClr val=\"#{color}\"/>"\
+                 '</a:solidFill>'\
+                 '</a:ln>'\
+                 '<a:round/>'\
+                 '</c:spPr>'
         end
 
         if !@show_marker
           str << '<c:marker><c:symbol val="none"/></c:marker>'
         elsif @marker_symbol != :default
-          str << '<c:marker><c:symbol val="' + @marker_symbol.to_s + '"/></c:marker>'
+          str << "<c:marker><c:symbol val=\"#{@marker_symbol}\"/></c:marker>"
         end
 
         @labels.to_xml_string(str) unless @labels.nil?
         @data.to_xml_string(str) unless @data.nil?
-        str << ('<c:smooth val="' << ((smooth) ? '1' : '0') << '"/>')
+        str << "<c:smooth val=\"#{smooth ? 1 : 0}\"/>"
       end
     end
 

lib/axlsx/drawing/ax_data_source.rb

@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Axlsx
 
   # An axis data source that can contain referenced or literal strings or numbers

lib/axlsx/drawing/axes.rb

@@ -1,5 +1,6 @@
+# frozen_string_literal: true
 module Axlsx
-  
+
   # The Axes class creates and manages axis information and
   # serialization for charts.
   class Axes
@@ -16,7 +17,7 @@ def initialize(options={})
     end
 
     # [] provides assiciative access to a specic axis store in an axes
-    # instance. 
+    # instance.
     # @return [Axis]
     def [](name)
       axes.assoc(name)[1]
@@ -27,12 +28,12 @@ def [](name)
     # @param [Hash] options
     # @option options ids
     # If the ids option is specified only the axis identifier is
-    # serialized. Otherwise, each axis is serialized in full. 
-    def to_xml_string(str = '', options = {})
+    # serialized. Otherwise, each axis is serialized in full.
+    def to_xml_string(str = String.new, options = {})
       if options[:ids]
         # CatAxis must come first in the XML (for Microsoft Excel at least)
         sorted = axes.sort_by { |name, axis| axis.kind_of?(CatAxis) ? 0 : 1 }
-        sorted.each { |axis| str << ('<c:axId val="' << axis[1].id.to_s << '"/>') }        
+        sorted.each { |axis| str << "<c:axId val=\"#{axis[1].id}\"/>" }
       else
         axes.each { |axis| axis[1].to_xml_string(str) }
       end

lib/axlsx/drawing/axis.rb

@@ -1,4 +1,5 @@
 # encoding: UTF-8
+# frozen_string_literal: true
 module Axlsx
 
   # the access class defines common properties and values for a chart axis.
@@ -83,14 +84,14 @@ def initialize(options={})
     # the title for the axis. This can be a cell or a fixed string.
     attr_reader :title
 
-    # The color for this axis. This value is used when rendering the axis line in the chart. 
+    # The color for this axis. This value is used when rendering the axis line in the chart.
     # colors should be in 6 character rbg format
     # @return [String] the rbg color assinged.
     # @see color
     def color=(color_rgb)
       @color = color_rgb
     end
-    
+
     # The crossing axis for this axis
     # @param [Axis] axis
     def cross_axis=(axis)
@@ -149,40 +150,40 @@ def title=(v)
     # Serializes the object
     # @param [String] str
     # @return [String]
-    def to_xml_string(str = '')
-      str << ('<c:axId val="' << @id.to_s << '"/>')
+    def to_xml_string(str = String.new)
+      str << "<c:axId val=\"#{@id}\"/>"
       @scaling.to_xml_string str
-      str << ('<c:delete val="' << @delete.to_s << '"/>')
-      str << ('<c:axPos val="' << @ax_pos.to_s << '"/>')
-      str << '<c:majorGridlines>'
+      str << "<c:delete val=\"#{@delete}\"/>"\
+             "<c:axPos val=\"#{@ax_pos}\"/>"\
+             '<c:majorGridlines>'
       # TODO shape properties need to be extracted into a class
       if gridlines == false
-        str << '<c:spPr>'
-        str << '<a:ln>'
-        str << '<a:noFill/>'
-        str << '</a:ln>'
-        str << '</c:spPr>'
+        str << '<c:spPr>'\
+               '<a:ln>'\
+               '<a:noFill/>'\
+               '</a:ln>'\
+               '</c:spPr>'
       end
       str << '</c:majorGridlines>'
       @title.to_xml_string(str) unless @title == nil
       # Need to set sourceLinked to 0 if we're setting a format code on this row
       # otherwise it will never take, as it will always prefer the 'General' formatting
       # of the cells themselves
-      str << ('<c:numFmt formatCode="' << @format_code << '" sourceLinked="' << (@format_code.eql?('General') ? '1' : '0') << '"/>')
-      str << '<c:majorTickMark val="none"/>'
-      str << '<c:minorTickMark val="none"/>'
-      str << ('<c:tickLblPos val="' << @tick_lbl_pos.to_s << '"/>')
+      str << "<c:numFmt formatCode=\"#{@format_code}\" sourceLinked=\"#{@format_code.eql?('General') ? 1 : 0}\"/>"\
+             '<c:majorTickMark val="none"/>'\
+             '<c:minorTickMark val="none"/>'\
+             "<c:tickLblPos val=\"#{@tick_lbl_pos}\"/>"
       # TODO - this is also being used for series colors
       # time to extract this into a class spPr - Shape Properties
       if @color
-        str << '<c:spPr><a:ln><a:solidFill>'
-        str << ('<a:srgbClr val="' << @color << '"/>')
-        str << '</a:solidFill></a:ln></c:spPr>'
+        str << '<c:spPr><a:ln><a:solidFill>'\
+               "<a:srgbClr val=\"#{@color}\"/>"\
+               '</a:solidFill></a:ln></c:spPr>'
       end
       # some potential value in implementing this in full. Very detailed!
-      str << ('<c:txPr><a:bodyPr rot="' << @label_rotation.to_s << '"/><a:lstStyle/><a:p><a:pPr><a:defRPr/></a:pPr><a:endParaRPr/></a:p></c:txPr>')
-      str << ('<c:crossAx val="' << @cross_axis.id.to_s << '"/>')
-      str << ('<c:crosses val="' << @crosses.to_s << '"/>')
+      str << "<c:txPr><a:bodyPr rot=\"#{@label_rotation}\"/><a:lstStyle/><a:p><a:pPr><a:defRPr/></a:pPr><a:endParaRPr/></a:p></c:txPr>"\
+             "<c:crossAx val=\"#{@cross_axis.id}\"/>"\
+             "<c:crosses val=\"#{@crosses}\"/>"
     end
 
   end