Class: XriResolver::SEPSelector

Inherits:

Object

• Object
• XriResolver::SEPSelector

Defined in:

lib/xri_resolver.rb

Constant Summary

@@sel_categories =

usage: SEPList = XriResolver::SEPSelector.select(xrds, xrd, inputs)

where xrds is a valid XriResolver::AuthorityResolver object where inputs is a valid XriResolver::ParseInputParameters object

Returns an SEPList object corresponding to the selected SEPs, ordered by priority

(literally implements pseudocode in XRI Resolution 2.0 WD11 ED03 Section 10.6)

['Path', 'Type', 'MediaType'].freeze

@@match_types =

['Positive', 'Default', 'Matched'].freeze

Class Method Summary

• .select(xrds, xrd, inputs) ⇒ Object

Class Method Details

.select(xrds, xrd, inputs) ⇒ Object

# File 'lib/xri_resolver.rb', line 723

def SEPSelector.select(xrds, xrd, inputs)
  ## initialize arrays
  selected_set = SEPList.new(xrds, xrd)
  default_set = SEPList.new(xrds, xrd)

  ## initialize nodefault to false
  nodefault = Hash.new
  @@sel_categories.each do |sel_category|
    nodefault[sel_category] = false
  end

  ## set nodefault according to subparameters
  nodefault['Path'] = inputs.nodefault_p
  nodefault['Type'] = inputs.nodefault_t
  nodefault['MediaType'] = inputs.nodefault_m

  ## normalize path
  path = (xrds.xri.path[0] == ?/) ? xrds.xri.path[1..-1] : xrds.xri.path ## remove leading '/'
  path = nil if path.empty? ## per XRI Resolution WD11 ED03 Section 6.1.1
  
  ## set content values
  content = Hash.new
  content['Path'] = path
  content['Type'] = inputs.service_type
  content['MediaType'] = inputs.service_media_type

  ## "FOR EACH SEP"
  REXML::XPath.match(xrd, "*[local-name()='Service']", XRDNS).each do |sep|
    ## "CREATE set of SEL match flags"
    ## "SET all flags to FALSE"
    flag = Hash.new
    @@match_types.each do |match_type|
      flag[match_type] = Hash.new
      @@sel_categories.each do |sel_category|
        flag[match_type][sel_category] = false
      end
    end
    
    ## we now have
    ## flag = {"Default"=>{"MediaType"=>false, "Type"=>false, "Path"=>false}, 
    ##         "Positive"=>{"MediaType"=>false, "Type"=>false, "Path"=>false}, 
    ##         "Matched"=>{"MediaType"=>false, "Type"=>false, "Path"=>false}}

    ## "FOR EACH SEL of category x (where x=Type, Path or Mediatype)"
    REXML::XPath.match(sep, "*[(local-name()='Type')|(local-name()='Path')|(local-name()='MediaType')]", XRDNS).each do |sel|
      ## record match result on this sel
      this_sel_positive_match = false
      this_sel_default_match = false
      
      ## "SET Matched.x=TRUE"
      flag['Matched'][sel.name] = true

      ## XRI Resolution WD11 ED07 Section 13.3.4
      unless sel.text or sel.attributes['match']
        sel.attributes << REXML::Attribute.new('match', 'null')
      end

      ## determine match
      if sel.attributes['match'] and sel.attributes['match'] != 'content'
        ## determine match per XRI Resolution WD11 ED03 Section 10.3.2
        case sel.attributes['match']
        when 'any'
          this_sel_positive_match = true
        when 'default'
          this_sel_default_match = true
        when 'non-null'
          if content[sel.name]
            this_sel_positive_match = true
          end
        when 'null'
          unless content[sel.name]
            this_sel_positive_match = true
          end
        end
      else
        ## if no match attribute, see if there's a content match per 10.3.6, 10.3.7 and 10.3.8
        ## TODO: implement normalization and other rules per these three sections
        if sel.text and content[sel.name]
          if sel.text.downcase == content[sel.name].downcase
            this_sel_positive_match = true
          end
        end
      end

      ## "IF match on this SEL is POSITIVE"
      if this_sel_positive_match
        if sel.attributes['select'] == 'true'
          ## sec 10.4.2
          selected_set << [sep]
          break
        else
          flag['Positive'][sel.name] = true
          next
        end
      elsif this_sel_default_match
        ## if we have already found a positive SEL with the same name - sec. 10.3.5
        if flag['Positive'][sel.name]
          next
        elsif nodefault[sel.name]
          next
        else
          flag['Default'][sel.name] = true
          next
        end
      else
        next
      end

    ## "End FOR EACH SEL"
    end
    
    ## "IF Matched.x=FALSE" (Sec 10.3.3)
    flag['Matched'].each do |selname, value|
      unless value ## this SEL hasn't been matched, i.e. was missing
        flag['Default'][selname] = true unless nodefault[selname]
      end
    end

    ## "IF Positive.Type=TRUE AND [...]"
    if flag['Positive']['Type'] and
       flag['Positive']['Path'] and
       flag['Positive']['MediaType']
      selected_set << [sep]
      next
    end
    
    if (flag['Positive']['Type'] or flag['Default']['Type']) and
          (flag['Positive']['Path'] or flag['Default']['Path']) and
          (flag['Positive']['MediaType'] or flag['Default']['MediaType'])
      default_set << [sep, flag.dup]
    end

  ## "END FOR EACH SEP"
  end

  ## "IF SELECTED SET != EMPTY
  unless selected_set.empty?
    return selected_set
  end

  ## "IF DEFAULT SET != EMPTY	;see 10.5.2"
  unless default_set.empty?
    default_set.each do |sep, flag|
      ## two positive flags
      if (flag['Positive']['Type'] and flag['Positive']['Path']) or
         (flag['Positive']['Type'] and flag['Positive']['MediaType']) or
         (flag['Positive']['Path'] and flag['Positive']['MediaType'])
        selected_set << [sep]
      end
    end

    ## "IF SELECTED SET != EMPTY
    unless selected_set.empty?
      return selected_set
    end

    ## "FOR EACH SEP IN DEFAULT SET"
    default_set.each do |sep, flag|
      ## one positive flag
      if flag['Positive']['Type'] or 
         flag['Positive']['Path'] or 
         flag['Positive']['MediaType']
        selected_set << [sep]
      end
    end
  end

  ## "IF SELECTED SET != EMPTY
  unless selected_set.empty?
    ## there was one positive flag in the default set
    return selected_set
  else
    ## all default flags
    return default_set
  end
  ## "RETURN EMPTY SET"
  return []
end