Class: ASIR::Coder::XML

Inherits:
ASIR::Coder show all
Includes:
ObjectResolving
Defined in:
lib/asir/coder/xml.rb

Overview

!SLIDE XML

Encode/Decode objects as XML.

Defined Under Namespace

Classes: Error

Constant Summary collapse

CC = 
'::'.freeze
D = 
'.'.freeze
B = 
'<'.freeze
S = 
' '.freeze
E = 
'>'.freeze
SE = 
'/>'.freeze
BS = 
'</'.freeze
A = 
'='.freeze
DECODER = 
{
  'NilClass'   => lambda { | _, dom | nil },
  'TrueClass'  => lambda { | _, dom | true },
  'FalseClass' => lambda { | _, dom | false },
  'String'     => lambda { | _, dom | (dom.attributes[:v] || dom.content) },
  'Symbol'     => lambda { | _, dom | (dom.attributes[:v] || dom.content).to_sym },
  'Integer'    => lambda { | _, dom | (dom.attributes[:v] || dom.content).to_i },
  'Float'      => lambda { | _, dom | (dom.attributes[:v] || dom.content).to_f },
  "Array" => lambda { | _, dom | 
    obj = [ ]
    _.map_dom_id_to_obj! dom, obj
    dom.each_element do | elem |
      obj << _.decode_dom(elem)
    end
    obj
  },
  'Hash' => lambda { | _, dom |
    obj = { }
    _.map_dom_id_to_obj! dom, obj
    key = nil
    dom.each_element do | val |
      if key
        obj[_.decode_dom(key)] = _.decode_dom(val)
        key = nil
      else
        key = val
      end
    end
    obj
  },
  'Object' => lambda { | _, dom |
    cls_name = dom.name
    # $stderr.puts "cls_name = #{cls_name.inspect}"
    cls = _.tag_cls(cls_name)
    obj = cls.allocate
    _.map_dom_id_to_obj! dom, obj
    dom.each_element do | child |
      key = child.name
      val = _.decode_dom child.first
      obj.instance_variable_set("@#{key}", val)
    end
    obj
  },
}

Instance Method Summary collapse

Instance Method Details

#_decode(obj) ⇒ Object 



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# File 'lib/asir/coder/xml.rb', line 25

def _decode obj
  @stream = obj
  @decoder ||= DECODER; @decoder_object = nil
  @dom_id_map = { }
  @dom_id = 0
  @cls_tag_map = { }
  @parser = ::XML::Parser.string(@stream)
  @dom = @parser.parse
  decode_dom @dom.root
end

#_decode_dom(dom) ⇒ Object

Raises:



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# File 'lib/asir/coder/xml.rb', line 141

def _decode_dom dom
  cls_name = dom.name
  decoder = @decoder[cls_name] || 
    (@decoder_object ||= @decoder['Object'])
  raise Error, "BUG: " unless decoder
  decoder.call(self, dom)
end

#_encode(obj) ⇒ Object 



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# File 'lib/asir/coder/xml.rb', line 16

def _encode obj
  @stream = ''
  @dom_id_map = { }
  @dom_id = 0
  @cls_tag_map = { }
  encode_dom obj
  @stream
end

#_encode_dom(obj) ⇒ Object 



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# File 'lib/asir/coder/xml.rb', line 44

def _encode_dom obj
  case obj
  when NilClass, TrueClass, FalseClass
    tag_obj(obj)
  when Numeric
    tag_obj(obj, nil, :v => obj.to_s)
  when Symbol
    tag_obj(obj) do
      @stream << obj.to_s
    end
  when String
    tag_obj(obj, :id) do 
      @stream << obj.to_s
    end
  when Array
    tag_obj(obj, :id) do 
      obj.each do | elem |
        encode_dom elem
      end
    end
  when Hash
    tag_obj(obj, :id) do 
      obj.each do | key, val |
        encode_dom key
        encode_dom val
      end
    end
  else
    tag_obj(obj, :id) do 
      obj.instance_variables.each do | attr |
        val = obj.instance_variable_get(attr)
        key = attr.to_s.sub(/^@/, '')
        tag(key) do 
          encode_dom val
        end
      end
    end
  end
end

#cls_tag(obj) ⇒ Object 



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# File 'lib/asir/coder/xml.rb', line 95

def cls_tag obj
  obj = obj.class
  @cls_tag_map[obj] ||= obj.name.gsub(CC, D).freeze
end

#decode_dom(dom) ⇒ Object 



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# File 'lib/asir/coder/xml.rb', line 128

def decode_dom dom
  if dom_id = dom.attributes[:idref]
    unless obj = @dom_id_map[dom_id]
      raise Error::BadIdref, "in element #{dom}"
    end
    obj
  else
    obj = _decode_dom(dom)
    map_dom_id_to_obj! dom, obj if dom.attributes[:id]
    obj
  end
end

#encode_dom(obj) ⇒ Object 



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# File 'lib/asir/coder/xml.rb', line 36

def encode_dom obj
  if dom_id = @dom_id_map[obj.object_id]
    tag_obj(obj, nil, :idref => dom_id.first)
  else
    _encode_dom obj
  end
end

#map_dom_id_to_obj!(dom, obj) ⇒ Object

Raises:



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# File 'lib/asir/coder/xml.rb', line 195

def map_dom_id_to_obj! dom, obj
  dom_id = dom.attributes[:id]
  debugger unless dom_id
  raise Error, "no :id attribute in #{dom}" unless dom_id
  if (other_obj = @dom_id_map[dom_id]) and other_obj.object_id != obj.object_id
    raise Error, "BUG: :id #{dom_id} already used for #{other_obj.class.name} #{other_obj.inspect}"
  end
  @dom_id_map[dom_id] = obj
end

#map_obj_to_dom_id!(obj) ⇒ Object 



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# File 'lib/asir/coder/xml.rb', line 100

def map_obj_to_dom_id! obj
  if dom_id = @dom_id_map[obj.object_id]
    dom_id.first
  else
    @dom_id_map[obj.object_id] = [ @dom_id += 1, obj ]
    @dom_id
  end
end

#prepare ⇒ Object

This coder is stateful.



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# File 'lib/asir/coder/xml.rb', line 211

def prepare; dup; end

#tag(tag, attrs = nil) ⇒ Object 



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# File 'lib/asir/coder/xml.rb', line 111

def tag tag, attrs = nil
  tag = tag.to_s
  @stream << B << tag << S
  if attrs
    attrs.each do | key, val |
      @stream << key.to_s << A << val.to_s.inspect << S
    end
  end
  if block_given?
    @stream << E; yield; @stream << BS << tag << E
  else
    @stream << SE
  end
end

#tag_cls(cls_name) ⇒ Object 



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# File 'lib/asir/coder/xml.rb', line 206

def tag_cls cls_name
  @cls_tag_map[cls_name.freeze] ||= resolve_object(cls_name.gsub('.', '::'))
end

#tag_obj(obj, with_id = false, attrs = nil) ⇒ Object 



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# File 'lib/asir/coder/xml.rb', line 84

def tag_obj obj, with_id = false, attrs = nil
  if block_given?
    tag(cls_tag(obj), with_id ? { with_id => map_obj_to_dom_id!(obj) } : nil) do
      yield
    end
  else
    tag(cls_tag(obj), attrs)
  end
end