Module: OM::XML::TermXpathGenerator

Defined in:
lib/om/xml/term_xpath_generator.rb

Class Method Summary collapse

Class Method Details

.add_node_index_predicate(xpath_query, array_index_value) ⇒ Object

Adds xpath xpath node index predicate to the end of your xpath query Example: add_node_index_predicate(“//oxns:titleInfo”,0)

=> "//oxns:titleInfo[1]"

add_node_index_predicate(“//oxns:titleInfo”,0)

=> "//oxns:titleInfo[@lang=\"finnish\"][1]"


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# File 'lib/om/xml/term_xpath_generator.rb', line 240

def self.add_node_index_predicate(xpath_query, array_index_value)
  modified_query = xpath_query.dup
  modified_query << "[#{array_index_value + 1}]"
end

.add_position_predicate(xpath_query, array_index_value) ⇒ Object

Adds xpath:position() method call to the end of your xpath query Examples:

add_position_predicate(“//oxns:titleInfo”,0)

> “//oxns:titleInfo

add_position_predicate(“//oxns:titleInfo”,0)

> “//oxns:titleInfo[@lang="finnish" and position()=1]”



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# File 'lib/om/xml/term_xpath_generator.rb', line 253

def self.add_position_predicate(xpath_query, array_index_value)
  position_function = "position()=#{array_index_value + 1}"
  self.add_predicate(xpath_query, position_function)
end

.add_predicate(xpath_query, predicate) ⇒ Object



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# File 'lib/om/xml/term_xpath_generator.rb', line 258

def self.add_predicate(xpath_query, predicate)
  modified_query = xpath_query.dup
  # if xpath_query.include?("]")
  if xpath_query[xpath_query.length-1..xpath_query.length] == "]"
    modified_query.insert(xpath_query.rindex("]"), " and #{predicate}")
  else
    modified_query << "[#{predicate}]"
  end
  return modified_query
end

.delimited_list(*args) ⇒ Object



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# File 'lib/om/xml/term_xpath_generator.rb', line 229

def self.delimited_list(*args)
  OM::XML.delimited_list(*args)
end

.generate_absolute_xpath(term) ⇒ Object

Generate absolute xpath for a Term Absolute xpaths always begin with “//”. They are generated by relying on the Term's relative xpath and the absolute xpath of its parent node.



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# File 'lib/om/xml/term_xpath_generator.rb', line 62

def self.generate_absolute_xpath(term)
  relative = generate_relative_xpath(term)
  if term.parent.nil?
    return "//#{relative}"
  else
    return term.parent.xpath_absolute + "/" + relative
  end
end

.generate_constrained_xpath(term) ⇒ Object



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# File 'lib/om/xml/term_xpath_generator.rb', line 71

def self.generate_constrained_xpath(term)
  if term.namespace_prefix.nil?
    complete_prefix = ""
  else
    complete_prefix = term.namespace_prefix + ":"
  end
  
  absolute = generate_absolute_xpath(term)
  constraint_predicates = []
  
  arguments_for_contains_function = []

  if !term.default_content_path.nil?
    arguments_for_contains_function << "#{complete_prefix}#{term.default_content_path}"
  end
    
  # If no subelements have been specified to search within, set contains function to search within the current node
  if arguments_for_contains_function.empty?
    arguments_for_contains_function << "."
  end
  
  arguments_for_contains_function << "\":::constraint_value:::\""

  contains_function = "contains(#{delimited_list(arguments_for_contains_function)})"

  template = add_predicate(absolute, contains_function)
  return template.gsub( /:::(.*?):::/ ) { '#{'+$1+'}' }.gsub('"', '\"')
end

.generate_relative_xpath(term) ⇒ Object

Generate relative xpath for a term In most cases, the resulting xpath will be the Term's path with the appropriate namespace appended to it. If the Term specifies any attributes, Special Case: attribute Terms If the Term's path is set to :attribute=>attr_name, the resulting xpath will points to a node attribute named attr_name ie. a path fo :attribute=>“lang” will result in a relative xpath of “@lang” Special Case: xpath functions If the Term's path variable is text(), it will be treated as an xpath function (no namespace) and turned into “text()



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# File 'lib/om/xml/term_xpath_generator.rb', line 13

def self.generate_relative_xpath(term)
  template = ""
  predicates = []
  
  if term.namespace_prefix.nil?
    complete_prefix = ""
  else
    complete_prefix = term.namespace_prefix + ":"
  end
  
  if term.path.kind_of?(Hash)
    if term.path.has_key?(:attribute)
      base_path = "@"+term.path[:attribute]
    else
      raise "#{term.path} is an invalid path for an OM::XML::Term.  You should provide either a string or {:attributes=>XXX}"
    end
  else
    if term.path == "text()"
      base_path = "#{term.path}[normalize-space(.)]"
    else
      unless term.namespace_prefix.nil?
        template << complete_prefix
      end
      base_path = term.path
    end
  end
  template << base_path
  
  unless term.attributes.nil?
    term.attributes.each_pair do |attr_name, attr_value|
      if attr_value == :none
        predicates << "not(@#{attr_name})"
      else
        predicates << "@#{attr_name}=\"#{attr_value}\""
      end
    end
  end
  
  unless predicates.empty? 
    template << "["+ delimited_list(predicates, " and ")+"]"
  end
  
  return template
end

.generate_xpath(term, type) ⇒ Object

Generate an xpath of the chosen type for the given Term.



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# File 'lib/om/xml/term_xpath_generator.rb', line 103

def self.generate_xpath(term, type)
  case type
  when :relative
    self.generate_relative_xpath(term)
  when :absolute
    self.generate_absolute_xpath(term)
  when :constrained
    self.generate_constrained_xpath(term)
  end
end

.generate_xpath_with_indexes(terminology, *pointers) ⇒ Object

Use the given terminology to generate an xpath with (optional) node indexes for each of the term pointers. Ex. OM::XML::TermXpathGenerator.xpath_with_indexes(my_terminology, :conference=>0, :role=>1, :text )

will yield an xpath similar to this: '//oxns:name[@type="conference"][1]/oxns:role[2]/oxns:roleTerm[@type="text"]'


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# File 'lib/om/xml/term_xpath_generator.rb', line 119

def self.generate_xpath_with_indexes(terminology, *pointers)
  if pointers.first.nil?
    root_term = terminology.root_terms.first
    if root_term.nil?
      return "/"
    else
      return root_term.xpath
    end
  end
  
  query_constraints = nil
  
  if pointers.length > 1 && pointers.last.kind_of?(Hash)
    constraints = pointers.pop
    unless constraints.empty?
      query_constraints = constraints
    end 
  end

  if pointers.length == 1 && pointers.first.instance_of?(String)
    return xpath_query = pointers.first
  end
    
  # if pointers.first.kind_of?(String)
  #   return pointers.first
  # end
  
  keys = []
  xpath = "//"

  pointers = OM.destringify(pointers)
  pointers.each_with_index do |pointer, pointer_index|
    
    if pointer.kind_of?(Hash)
      k = pointer.keys.first
      index = pointer[k]
    else
      k = pointer
      index = nil
    end
    
    keys << k
    
    term = terminology.retrieve_term(*keys)  
    # Return nil if there is no term to work with
    return if term.nil?
    
    # If we've encountered a NamedTermProxy, insert path sections corresponding to each entry in its proxy_pointer (rather than just the final term that it points to).
    # TODO Looks like this only works if the last key is a NamedTermProxy, what if we cross proxies on the way there?
    if term.kind_of? OM::XML::NamedTermProxy
      OM.logger.warn "You attempted to call an index value of #{index} on the term \"#{k.inspect}\". However \"#{k.inspect}\" is a proxy so we are ignoring the index. See https://jira.duraspace.org/browse/HYDRA-643" if index && OM.logger
      current_location = term.parent.nil? ? term.terminology : term.parent
      relative_path = ""
      term.proxy_pointer.each_with_index do |proxy_pointer, proxy_pointer_index|
        begin
        proxy_term = current_location.retrieve_term(proxy_pointer)
        if proxy_term.nil?
          proxy_term = terminology.retrieve_term(proxy_pointer)
        end
        proxy_relative_path = proxy_term.xpath_relative
        if proxy_pointer_index > 0
          proxy_relative_path = "/"+proxy_relative_path
        end
        relative_path << proxy_relative_path
        current_location = proxy_term
        rescue Exception => e
          raise "There's a problem with the #{term.name} OM::XML::NamedTermProxy, whose proxy pointer is #{term.proxy_pointer}.  The #{proxy_pointer} pointer is returning #{proxy_term.inspect}"
        end
      end
    else  
      relative_path = term.xpath_relative
    
      unless index.nil?
        relative_path = add_node_index_predicate(relative_path, index)
      end
    end
    
    if pointer_index > 0
      relative_path = "/"+relative_path
    end
    xpath << relative_path 
  end
    
  final_term = terminology.retrieve_term(*keys) 
  
  if query_constraints.kind_of?(Hash)
    contains_functions = []
    query_constraints.each_pair do |k,v|

      if v.is_a?(Integer) || v == "0" || v.to_i != 0
        # lookup sub element 
        xpath = '(' + xpath +  '/' + final_term.children[query_constraints.keys.first].xpath_relative + ")[#{v.to_i + 1}]"
      else
        if k.instance_of?(Symbol)
          constraint_path = final_term.children[k].xpath_relative
        else
          constraint_path = k
        end
        # match for text
        contains_functions << "#{constraint_path}[text()=\"#{v}\"]"
        xpath = add_predicate(xpath, delimited_list(contains_functions, " and ") )
      end
    end
    
  end
  # 
  return xpath
end