Adds lazy JSON parsing

lib/simple/sql/helpers.rb

@@ -1,6 +1,7 @@
 module ::Simple::SQL::Helpers
 end
 
+require_relative "./json.rb"
 require_relative "helpers/decoder.rb"
 require_relative "helpers/encoder.rb"
 require_relative "helpers/row_converter.rb"

lib/simple/sql/helpers/decoder.rb

@@ -21,8 +21,8 @@ def decode_value(type, s)
     when :"timestamp without time zone" then ::Time.parse(s)
     when :"timestamp with time zone"    then ::Time.parse(s)
     when :hstore                        then HStore.parse(s)
-    when :json                          then ::JSON.parse(s)
-    when :jsonb                         then ::JSON.parse(s)
+    when :json                          then ::Simple::SQL::JSON.parse(s)
+    when :jsonb                         then ::Simple::SQL::JSON.parse(s)
     when :boolean                       then s == "t"
     else
       # unknown value, we just return the string here.

lib/simple/sql/json.rb

@@ -0,0 +1,37 @@
+# rubocop:disable Style/DoubleNegation
+
+# This class implements lazy JSON parsing. When enabled it should improve
+# performance if data is fetched from the database in a JSON format, and is
+# consumed via a JSON encoder.
+#
+# This seems a bit far-fetched, but that use case is actually quite common
+# when implementing a JSON API.
+class Simple::SQL::JSON < BasicObject
+  def self.parse(str)
+    new(str)
+  end
+
+  def initialize(json_string)
+    @json_string = json_string
+  end
+
+  def method_missing(sym, *args, &block)
+    parsed.send(sym, *args, &block) || super
+  end
+
+  def respond_to_missing?(name, include_private = false)
+    parsed.send(:respond_to_missing?, name, include_private) || super
+  end
+
+  def parsed
+    @parsed ||= ::JSON.parse(@json_string)
+  end
+
+  def ==(other)
+    super || (parsed == other)
+  end
+
+  def to_json(*_args)
+    @json_string
+  end
+end