Import CSV 3.0.2

This includes performance improvement especially writing. Writing is
about 2 times faster.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@66507 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 78 insertions, 0 deletions

diff --git a/lib/csv/fields_converter.rb b/lib/csv/fields_converter.rb
new file mode 100644
index 0000000000..c2fa5798ff
--- /dev/null
+++ b/lib/csv/fields_converter.rb
@@ -0,0 +1,78 @@
+# frozen_string_literal: true
+
+class CSV
+  class FieldsConverter
+    include Enumerable
+
+    def initialize(options={})
+      @converters = []
+      @nil_value = options[:nil_value]
+      @empty_value = options[:empty_value]
+      @empty_value_is_empty_string = (@empty_value == "")
+      @accept_nil = options[:accept_nil]
+      @builtin_converters = options[:builtin_converters]
+      @need_static_convert = need_static_convert?
+    end
+
+    def add_converter(name=nil, &converter)
+      if name.nil?  # custom converter
+        @converters << converter
+      else          # named converter
+        combo = @builtin_converters[name]
+        case combo
+        when Array  # combo converter
+          combo.each do |sub_name|
+            add_converter(sub_name)
+          end
+        else        # individual named converter
+          @converters << combo
+        end
+      end
+    end
+
+    def each(&block)
+      @converters.each(&block)
+    end
+
+    def empty?
+      @converters.empty?
+    end
+
+    def convert(fields, headers, lineno)
+      return fields unless need_convert?
+
+      fields.collect.with_index do |field, index|
+        if field.nil?
+          field = @nil_value
+        elsif field.empty?
+          field = @empty_value unless @empty_value_is_empty_string
+        end
+        @converters.each do |converter|
+          break if field.nil? and @accept_nil
+          if converter.arity == 1  # straight field converter
+            field = converter[field]
+          else                     # FieldInfo converter
+            if headers
+              header = headers[index]
+            else
+              header = nil
+            end
+            field = converter[field, FieldInfo.new(index, lineno, header)]
+          end
+          break unless field.is_a?(String)  # short-circuit pipeline for speed
+        end
+        field  # final state of each field, converted or original
+      end
+    end
+
+    private
+    def need_static_convert?
+      not (@nil_value.nil? and @empty_value_is_empty_string)
+    end
+
+    def need_convert?
+      @need_static_convert or
+        (not @converters.empty?)
+    end
+  end
+end