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Class: REXML::Attributes

Relationships & Source Files
Super Chains via Extension / Inclusion / Inheritance
Class Chain:
self, Hash
Instance Chain:
self, Hash
Inherits: Hash
  • Object
Defined in: lib/rexml/element.rb

Overview

A class that defines the set of Attributes of an Element and provides operations for accessing elements in that set.

Class Method Summary

Instance Method Summary

Constructor Details

.new(element) ⇒ Attributes

Creates and returns a new REXML::Attributes object. The element given by argument element is stored, but its own attributes are not modified:

ele = REXML::Element.new('foo')
attrs = REXML::Attributes.new(ele)
attrs.object_id == ele.attributes.object_id # => false

Other instance methods in class REXML::Attributes may refer to:

  • element.document.

  • element.prefix.

  • element.expanded_name.

[ GitHub ] 

  


# File 'lib/rexml/element.rb', line 2160



def initialize element
  @element = element
end


  







Instance Method Details



  

    #<<(attribute)  
  



  

    

Alias for #add.


  



  [ GitHub ]


  

  


# File 'lib/rexml/element.rb', line 2541



alias :<< :add


  








  

    #[](name)  ⇒ attribute_value?   



  

    

Returns the value for the attribute given by name, if it exists; otherwise nil. The value returned is the unnormalized attribute value, with entities expanded:



xml_string = <<-EOT
  <root xmlns:foo="http://foo" xmlns:bar="http://bar">
     <ele foo:att='1' bar:att='2' att='&lt;'/>
  </root>
EOT
d = REXML::Document.new(xml_string)
ele = d.elements['//ele'] # => <a foo:att='1' bar:att='2' att='&lt;'/>
ele.attributes['att']     # => "<"
ele.attributes['bar:att'] # => "2"
ele.attributes['nosuch']  # => nil



Related: get_attribute (returns an Attribute object).


  



  [ GitHub ]


  

  


# File 'lib/rexml/element.rb', line 2185



def [](name)
  attr = get_attribute(name)
  return attr.value unless attr.nil?
  return nil
end


  








  

    #[]=(name, value)  ⇒ value   



  

    

When value is non-nil, assigns that to the attribute for the given name, overwriting the previous value if it exists:



xml_string = <<-EOT
  <root xmlns:foo="http://foo" xmlns:bar="http://bar">
     <ele foo:att='1' bar:att='2' att='&lt;'/>
  </root>
EOT
d = REXML::Document.new(xml_string)
ele = d.root.elements['//ele'] # => <a foo:att='1' bar:att='2' att='&lt;'/>
attrs = ele.attributes
attrs['foo:att'] = '2' # => "2"
attrs['baz:att'] = '3' # => "3"



When value is nil, deletes the attribute if it exists:



attrs['baz:att'] = nil
attrs.include?('baz:att') # => false


  



  [ GitHub ]


  

  


# File 'lib/rexml/element.rb', line 2369



def []=( name, value )
  if value.nil?             # Delete the named attribute
    attr = get_attribute(name)
    delete attr
    return
  end

  unless value.kind_of? Attribute
    if @element.document and @element.document.doctype
      value = Text::normalize( value, @element.document.doctype )
    else
      value = Text::normalize( value, nil )
    end
    value = Attribute.new(name, value)
  end
  value.element = @element
  old_attr = fetch(value.name, nil)
  if old_attr.nil?
    store(value.name, value)
  elsif old_attr.kind_of? Hash
    old_attr[value.prefix] = value
  elsif old_attr.prefix != value.prefix
    # Check for conflicting namespaces
    if value.prefix != "xmlns" and old_attr.prefix != "xmlns"
      old_namespace = old_attr.namespace
      new_namespace = value.namespace
      if old_namespace == new_namespace
        raise ParseException.new(
                "Namespace conflict in adding attribute \"#{value.name}\": "+
                "Prefix \"#{old_attr.prefix}\" = \"#{old_namespace}\" and "+
                "prefix \"#{value.prefix}\" = \"#{new_namespace}\"")
      end
    end
    store value.name, {old_attr.prefix => old_attr,
                       value.prefix    => value}
  else
    store value.name, value
  end
  return @element
end


  








  

    #add(attribute)  ⇒ attribute     Also known as: #<<
  



  

    

Adds attribute attribute, replacing the previous attribute of the same name if it exists; returns attribute:



xml_string = <<-EOT
  <root xmlns:foo="http://foo" xmlns:bar="http://bar">
     <ele foo:att='1' bar:att='2' att='&lt;'/>
  </root>
EOT
d = REXML::Document.new(xml_string)
ele = d.root.elements['//ele'] # => <a foo:att='1' bar:att='2' att='&lt;'/>
attrs = ele.attributes
attrs # => {"att"=>{"foo"=>foo:att='1', "bar"=>bar:att='2', ""=>att='&lt;'}}
attrs.add(REXML::Attribute.new('foo:att', '2')) # => foo:att='2'
attrs.add(REXML::Attribute.new('baz', '3')) # => baz='3'
attrs.include?('baz') # => true


  



  [ GitHub ]


  

  


# File 'lib/rexml/element.rb', line 2537



def add( attribute )
  self[attribute.name] = attribute
end


  








  

    

      #delete(name)  ⇒ element 
      #delete(attribute)  ⇒ element 
    

  



  

    

Removes a specified attribute if it exists; returns the attributes’ element.



When string argument name is given, removes the attribute of that name if it exists:



xml_string = <<-EOT
  <root xmlns:foo="http://foo" xmlns:bar="http://bar">
     <ele foo:att='1' bar:att='2' att='&lt;'/>
  </root>
EOT
d = REXML::Document.new(xml_string)
ele = d.root.elements['//ele'] # => <a foo:att='1' bar:att='2' att='&lt;'/>
attrs = ele.attributes
attrs.delete('foo:att') # => <ele bar:att='2' att='&lt;'/>
attrs.delete('foo:att') # => <ele bar:att='2' att='&lt;'/>



When attribute argument attribute is given, removes that attribute if it exists:



attr = REXML::Attribute.new('bar:att', '2')
attrs.delete(attr) # => <ele att='&lt;'/> # => <ele att='&lt;'/>
attrs.delete(attr) # => <ele att='&lt;'/> # => <ele/>


  





  


  [ GitHub ]


  

  


# File 'lib/rexml/element.rb', line 2490



def delete( attribute )
  name = nil
  prefix = nil
  if attribute.kind_of? Attribute
    name = attribute.name
    prefix = attribute.prefix
  else
    attribute =~ Namespace::NAMESPLIT
    prefix, name = $1, $2
    prefix = '' unless prefix
  end
  old = fetch(name, nil)
  if old.kind_of? Hash # the supplied attribute is one of many
    old.delete(prefix)
    if old.size == 1
      repl = nil
      old.each_value{|v| repl = v}
      store name, repl
    end
  elsif old.nil?
    return @element
  else # the supplied attribute is a top-level one
    super(name)
  end
  @element
end


  








  

    #delete_all(name)  ⇒ Attributes   



  

    

Removes all attributes matching the given name; returns an array of the removed attributes:



xml_string = <<-EOT
  <root xmlns:foo="http://foo" xmlns:bar="http://bar">
     <ele foo:att='1' bar:att='2' att='&lt;'/>
  </root>
EOT
d = REXML::Document.new(xml_string)
ele = d.root.elements['//ele'] # => <a foo:att='1' bar:att='2' att='&lt;'/>
attrs = ele.attributes
attrs.delete_all('att') # => [att='&lt;']


  



  [ GitHub ]


  

  


# File 'lib/rexml/element.rb', line 2559



def delete_all( name )
  rv = []
  each_attribute { |attribute|
    rv << attribute if attribute.expanded_name == name
  }
  rv.each{ |attr| attr.remove }
  return rv
end


  








  

    #each {|expanded_name, value| ... }   



  

    

Calls the given block with each expanded-name/value pair:



xml_string = <<-EOT
  <root xmlns:foo="http://foo" xmlns:bar="http://bar">
     <ele foo:att='1' bar:att='2' att='&lt;'/>
  </root>
EOT
d = REXML::Document.new(xml_string)
ele = d.root.elements['//ele']   # => <a foo:att='1' bar:att='2' att='&lt;'/>
ele.attributes.each do |expanded_name, value|
  p [expanded_name, value]
end



Output:



["foo:att", "1"]
["bar:att", "2"]
["att", "<"]


  



  [ GitHub ]


  

  


# File 'lib/rexml/element.rb', line 2287



def each
  return to_enum(__method__) unless block_given?
  each_attribute do |attr|
    yield [attr.expanded_name, attr.value]
  end
end


  








  

    #each_attribute {|attr| ... }   



  

    

Calls the given block with each REXML::Attribute object:



xml_string = <<-EOT
  <root xmlns:foo="http://foo" xmlns:bar="http://bar">
     <ele foo:att='1' bar:att='2' att='&lt;'/>
  </root>
EOT
d = REXML::Document.new(xml_string)
ele = d.root.elements['//ele']   # => <a foo:att='1' bar:att='2' att='&lt;'/>
ele.attributes.each_attribute do |attr|
  p [attr.class, attr]
end



Output:



[REXML::Attribute, foo:att='1']
[REXML::Attribute, bar:att='2']
[REXML::Attribute, att='&lt;']


  



  [ GitHub ]


  

  


# File 'lib/rexml/element.rb', line 2254



def each_attribute # :yields: attribute
  return to_enum(__method__) unless block_given?
  each_value do |val|
    if val.kind_of? Attribute
      yield val
    else
      val.each_value { |atr| yield atr }
    end
  end
end


  








  

    #get_attribute(name)  ⇒ attribute_object?   



  

    

Returns the REXML::Attribute object for the given name:



xml_string = <<-EOT
  <root xmlns:foo="http://foo" xmlns:bar="http://bar">
     <ele foo:att='1' bar:att='2' att='&lt;'/>
  </root>
EOT
d = REXML::Document.new(xml_string)
ele = d.root.elements['//ele'] # => <a foo:att='1' bar:att='2' att='&lt;'/>
attrs = ele.attributes
attrs.get_attribute('foo:att')       # => foo:att='1'
attrs.get_attribute('foo:att').class # => REXML::Attribute
attrs.get_attribute('bar:att')       # => bar:att='2'
attrs.get_attribute('att')           # => att='&lt;'
attrs.get_attribute('nosuch')        # => nil


  



  [ GitHub ]


  

  


# File 'lib/rexml/element.rb', line 2313



def get_attribute( name )
  attr = fetch( name, nil )
  if attr.nil?
    return nil if name.nil?
    # Look for prefix
    name =~ Namespace::NAMESPLIT
    prefix, n = $1, $2
    if prefix
      attr = fetch( n, nil )
      # check prefix
      if attr == nil
      elsif attr.kind_of? Attribute
        return attr if prefix == attr.prefix
      else
        attr = attr[ prefix ]
        return attr
      end
    end
    element_document = @element.document
    if element_document and element_document.doctype
      expn = @element.expanded_name
      expn = element_document.doctype.name if expn.size == 0
      attr_val = element_document.doctype.attribute_of(expn, name)
      return Attribute.new( name, attr_val ) if attr_val
    end
    return nil
  end
  if attr.kind_of? Hash
    attr = attr[ @element.prefix ]
  end
  return attr
end


  








  

    #get_attribute_ns(namespace, name)    



  

    

Returns the REXML::Attribute object among the attributes that matches the given namespace and name:



xml_string = <<-EOT
  <root xmlns:foo="http://foo" xmlns:bar="http://bar">
     <ele foo:att='1' bar:att='2' att='&lt;'/>
  </root>
EOT
d = REXML::Document.new(xml_string)
ele = d.root.elements['//ele'] # => <a foo:att='1' bar:att='2' att='&lt;'/>
attrs = ele.attributes
attrs.get_attribute_ns('http://foo', 'att')    # => foo:att='1'
attrs.get_attribute_ns('http://foo', 'nosuch') # => nil


  



  [ GitHub ]


  

  


# File 'lib/rexml/element.rb', line 2585



def get_attribute_ns(namespace, name)
  result = nil
  each_attribute() { |attribute|
    if name == attribute.name &&
      namespace == attribute.namespace() &&
      ( !namespace.empty? || !attribute.fully_expanded_name.index(':') )
      # foo will match xmlns:foo, but only if foo isn't also an attribute
      result = attribute if !result or !namespace.empty? or
                            !attribute.fully_expanded_name.index(':')
    end
  }
  result
end


  








  

    #length      Also known as: #size
  



  

    

Returns the count of attributes:



xml_string = <<-EOT
  <root xmlns:foo="http://foo" xmlns:bar="http://bar">
     <ele foo:att='1' bar:att='2' att='&lt;'/>
  </root>
EOT
d = REXML::Document.new(xml_string)
ele = d.root.elements['//ele']   # => <a foo:att='1' bar:att='2' att='&lt;'/>
ele.attributes.length # => 3


  



  [ GitHub ]


  

  


# File 'lib/rexml/element.rb', line 2225



def length
  c = 0
  each_attribute { c+=1 }
  c
end


  








  

    #namespaces    



  

    

Returns a hash of name/value pairs for the namespaces:



xml_string = '<a xmlns="foo" xmlns:x="bar" xmlns:y="twee" z="glorp"/>'
d = REXML::Document.new(xml_string)
d.root.attributes.namespaces # => {"xmlns"=>"foo", "x"=>"bar", "y"=>"twee"}


  



  [ GitHub ]


  

  


# File 'lib/rexml/element.rb', line 2446



def namespaces
  namespaces = {}
  each_attribute do |attribute|
    namespaces[attribute.name] = attribute.value if attribute.prefix == 'xmlns' or attribute.name == 'xmlns'
  end
  if @element.document and @element.document.doctype
    expn = @element.expanded_name
    expn = @element.document.doctype.name if expn.size == 0
    @element.document.doctype.attributes_of(expn).each {
      |attribute|
      namespaces[attribute.name] = attribute.value if attribute.prefix == 'xmlns' or attribute.name == 'xmlns'
    }
  end
  namespaces
end


  








  

    #prefixes  ⇒ array_of_prefix_strings   



  

    

Returns an array of prefix strings in the attributes. The array does not include the default namespace declaration, if one exists.



xml_string = '<a xmlns="foo" xmlns:x="bar" xmlns:y="twee" z="glorp"/>'
d = REXML::Document.new(xml_string)
d.root.attributes.prefixes # => ["x", "y"]


  



  [ GitHub ]


  

  


# File 'lib/rexml/element.rb', line 2421



def prefixes
  ns = []
  each_attribute do |attribute|
    ns << attribute.name if attribute.prefix == 'xmlns'
  end
  if @element.document and @element.document.doctype
    expn = @element.expanded_name
    expn = @element.document.doctype.name if expn.size == 0
    @element.document.doctype.attributes_of(expn).each {
      |attribute|
      ns << attribute.name if attribute.prefix == 'xmlns'
    }
  end
  ns
end


  








  

    #size  
  



  

    

Alias for #length.


  



  [ GitHub ]


  

  


# File 'lib/rexml/element.rb', line 2230



alias :size :length


  








  

    #to_a  ⇒ array_of_attribute_objects   



  

    

Returns an array of REXML::Attribute objects representing the attributes:



xml_string = <<-EOT
  <root xmlns:foo="http://foo" xmlns:bar="http://bar">
     <ele foo:att='1' bar:att='2' att='&lt;'/>
  </root>
EOT
d = REXML::Document.new(xml_string)
ele = d.root.elements['//ele']   # => <a foo:att='1' bar:att='2' att='&lt;'/>
attrs = ele.attributes.to_a      # => [foo:att='1', bar:att='2', att='&lt;']
attrs.first.class                # => REXML::Attribute


  



  [ GitHub ]


  

  


# File 'lib/rexml/element.rb', line 2207



def to_a
  enum_for(:each_attribute).to_a
end