1 files changed, 37 insertions, 0 deletions
diff --git a/activesupport/lib/active_support/core_ext/big_decimal/conversions.rb b/activesupport/lib/active_support/core_ext/big_decimal/conversions.rb
new file mode 100644
index 0000000000..bc9d578f38
--- /dev/null
+++ b/activesupport/lib/active_support/core_ext/big_decimal/conversions.rb
@@ -0,0 +1,37 @@
+require 'yaml'
+
+module ActiveSupport #:nodoc:
+  module CoreExtensions #:nodoc:
+    module BigDecimal #:nodoc:
+      module Conversions
+        DEFAULT_STRING_FORMAT = 'F'.freeze
+        YAML_TAG = 'tag:yaml.org,2002:float'.freeze
+        YAML_MAPPING = { 'Infinity' => '.Inf', '-Infinity' => '-.Inf', 'NaN' => '.NaN' }
+
+        def self.included(base) #:nodoc:
+          base.class_eval do
+            alias_method :_original_to_s, :to_s
+            alias_method :to_s, :to_formatted_s
+
+            yaml_as YAML_TAG
+          end
+        end
+
+        def to_formatted_s(format = DEFAULT_STRING_FORMAT)
+          _original_to_s(format)
+        end
+
+        # This emits the number without any scientific notation.
+        # This is better than self.to_f.to_s since it doesn't lose precision.
+        #
+        # Note that reconstituting YAML floats to native floats may lose precision.
+        def to_yaml(opts = {})
+          YAML.quick_emit(nil, opts) do |out|
+            string = to_s
+            out.scalar(YAML_TAG, YAML_MAPPING[string] || string, :plain)
+          end
+        end
+      end
+    end
+  end
+end