Class: GRel::QL::BGP

Inherits:
Object
  • Object
show all
Defined in:
lib/grel/ql.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(data, context, inverse = false) ⇒ BGP

Returns a new instance of BGP.



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# File 'lib/grel/ql.rb', line 654

def initialize(data, context, inverse=false)
  @data = data
  @context = context
  @bgp_id = nil
  @inverse = inverse
end

Instance Attribute Details

#bgp_id ⇒ Object (readonly)

Returns the value of attribute bgp_id.



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# File 'lib/grel/ql.rb', line 652

def bgp_id
  @bgp_id
end

#context ⇒ Object (readonly)

Returns the value of attribute context.



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# File 'lib/grel/ql.rb', line 652

def context
  @context
end

#data ⇒ Object (readonly)

Returns the value of attribute data.



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# File 'lib/grel/ql.rb', line 652

def data
  @data
end

Instance Method Details

#parse_property(k) ⇒ Object 



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# File 'lib/grel/ql.rb', line 732

def parse_property(k)
  if(k.is_a?(String))
    k.gsub(":@type","<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>").
      gsub(":$inv_","^:")
  else
    QL.to_query(k, context)
  end
end

#to_query ⇒ Object 



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# File 'lib/grel/ql.rb', line 661

def to_query
  acum = []

  node_id = @context.next_node_id
  id = @data[:@id]
  id = "@id(#{id})" if id && id.is_a?(String) && id.index("@id(").nil?        
  id = QL.to_query(id, context) if id
  subject_var_id,pred_var_id, obj_var_id = @context.register_node(id,node_id,@inverse)

  filters = []

  @data.inject([]) do |ac,(k,v)| 
    # $optional can point to an array of conditions that must be handled separetedly
    if(k.to_s == "$optional" && v.is_a?(Array))
      v.each{ |c| ac << [k,c] }
    else
      ac << [k,v]
    end
    ac
  end.each do |(k,v)|
    # process each property in the query hash
    inverse = false
    optional = false
    unless(k == :@id)
      prop = if(k.to_s.index("$inv_"))
               inverse = true
               k.to_s                     
             elsif(k.to_s == "$optional")
               context.optional = true
               optional = true
             else
               parse_property(k)
             end
      value = QL.to_query(v,context,inverse)
      if(value.is_a?(Array))
        context.append(value,false)
        value = value.triples_id
      elsif(value.is_a?(Filter))
        filters << value
        value = value.variable
      elsif(value == context) # It was a nested hash, retrieve the subject as object value
        if(optional)
          subject_to_replace = value.last_registered_subject
          context.node_to_optional(subject_to_replace)#, subject_var_id)
          context.optional_triples = context.optional_triples.map do |(s,p,o)|
            s = (s == subject_to_replace ? subject_var_id : s)
            o = (o == subject_to_replace ? subject_var_id : o)
            [s, p, o]
          end
          context.optional = false
        else
          value = context.last_registered_subject
        end
      end
      acum << [prop,value] unless optional
    end
  end

  bgp_id = subject_var_id
  acum = acum.map do |(p,o)| 
    if(p.index("$inv_"))
      [o,QL.to_query(p.to_sym,@context),subject_var_id]
    else
      [subject_var_id,p,o]
    end
  end
  acum << [subject_var_id, pred_var_id, obj_var_id] if acum.empty?
  acum += filters
  acum
end