Class: PackerFiles::Utils::HashSerializer

Inherits:
Object
  • Object
show all
Defined in:
lib/PackerFiles/Utils/HashSerializer.rb

Overview

The Hash serializer is a meta-class that allows tracking of objects that needs to be converted into Hash objects, w/o having to hand-write lot of code.

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

.hash_attributes ⇒ Object

Return the attributes that are tracked so that it can be used for serialization.



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# File 'lib/PackerFiles/Utils/HashSerializer.rb', line 59

def hash_attributes
  @attrs
end

.hash_variable(name, type = String, method = nil, nil_emit = false) ⇒ Object

Specify that a list of methods are tracked for serialization. Name is the attribute name, Type is the object type that it belongs to. Method is the name of the conversion function that returns the value of the object serialized for JSON.



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# File 'lib/PackerFiles/Utils/HashSerializer.rb', line 21

def hash_variable(name, type = String, method = nil, nil_emit=false)
   @attrs ||= []
   @attrs +=  [Hash["name",     name,   "type",     type, 
	     "method",   method, "nil_emit", nil_emit]
       ]
   self.class_eval do
    
     # Read accessor
     define_method(name) do
instance_variable_get("@#{name}")
     end

     # Write accessor
     define_method("#{name}=") do |value|
 if value.is_a? type
   instance_variable_set("@#{name}", value)
 else
   raise ArgumentError.new("Invalid Type")
 end
     end

     # Converter function. We need to first get the
     # variable and then call a function on it by binding
     # first. (See Module::instance_method example in Ruby man page) 
     define_method("to_hash_value_#{name}") do
var = instance_variable_get("@#{name}")
if (method.nil? || var.nil?)
  var
else
  self.method(method).call
end
     end

   end
end

Instance Method Details

#merge_hs(other) ⇒ Object

Merge a hash serializer object with the current object.



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# File 'lib/PackerFiles/Utils/HashSerializer.rb', line 66

def merge_hs(other)

   # Do nothing if the other is not a Hash Serializer
	  return unless other.kind_of?(HashSerializer)

	  # Get the attributes set in other and if the same attribute
	  # is not set in self, then replace it. Otherwise ignore
	  other.class.hash_attributes.each do |attr|
	     name         = attr['name']
	     other_value  = other.method(name).call
	     self_value   = self.method(name).call
	     if !other_value.nil? && self_value.nil?
  self.method("#{name}=").call(other_value)
	     end
	  end
end

#to_hash(*args) ⇒ Object

Hash Converter which iterates through all the tracked objects and outputs the hash. This function is NOT a meta-class function but instead operates on the object level.



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# File 'lib/PackerFiles/Utils/HashSerializer.rb', line 86

def to_hash(*args)
	
	  # Return value 
	  hash = Hash.new

	  # Get all classes in the class hierarchy until HashSerializer
	  index = self.class.ancestors.index(HashSerializer)
	  cl_list  = self.class.ancestors.slice(0, index)
	  cl_list.each do |klass|
	     next if !klass.respond_to?(:hash_attributes)
	     klass.hash_attributes.each do |attr|
 name       = attr['name']
 nil_emit   = attr['nil_emit']
 value      = method("to_hash_value_#{name}").call
 hash[name] = value if (!value.nil? || (value.nil? && nil_emit))
	     end
	  end
	  return hash
end