class REXML::Attribute

Defines an Element Attribute; IE, a attribute=value pair, as in: <element attribute=“value”/>. Attributes can be in their own namespaces. General users of REXML will not interact with the Attribute class much.

Constants

NEEDS_A_SECOND_CHECK
PATTERN

Attributes

element[R]

The element to which this attribute belongs

normalized[W]

The normalized value of this attribute. That is, the attribute with entities intact.

Public Class Methods

new( first, second=nil, parent=nil ) click to toggle source

Constructor. FIXME: The parser doesn’t catch illegal characters in attributes

first: Either: an Attribute, which this new attribute will become a clone of; or a String, which is the name of this attribute
second: If first is an Attribute, then this may be an Element, or nil. If nil, then the Element parent of this attribute is the parent of the first Attribute. If the first argument is a String, then this must also be a String, and is the content of the attribute. If this is the content, it must be fully normalized (contain no illegal characters).
parent: Ignored unless first is a String; otherwise, may be the Element parent of this attribute, or nil.

Attribute.new( attribute_to_clone )
Attribute.new( attribute_to_clone, parent_element )
Attribute.new( "attr", "attr_value" )
Attribute.new( "attr", "attr_value", parent_element )

# File rexml-3.2.5/lib/rexml/attribute.rb, line 45
def initialize( first, second=nil, parent=nil )
  @normalized = @unnormalized = @element = nil
  if first.kind_of? Attribute
    self.name = first.expanded_name
    @unnormalized = first.value
    if second.kind_of? Element
      @element = second
    else
      @element = first.element
    end
  elsif first.kind_of? String
    @element = parent
    self.name = first
    @normalized = second.to_s
  else
    raise "illegal argument #{first.class.name} to Attribute constructor"
  end
end

Public Instance Methods

==( other ) click to toggle source

Returns true if other is an Attribute and has the same name and value, false otherwise.

# File rexml-3.2.5/lib/rexml/attribute.rb, line 109
def ==( other )
  other.kind_of?(Attribute) and other.name==name and other.value==value
end

clone() click to toggle source

Returns a copy of this attribute

# File rexml-3.2.5/lib/rexml/attribute.rb, line 158
def clone
  Attribute.new self
end

doctype() click to toggle source

# File rexml-3.2.5/lib/rexml/attribute.rb, line 132
def doctype
  if @element
    doc = @element.document
    doc.doctype if doc
  end
end

element=( element ) click to toggle source

Sets the element of which this object is an attribute. Normally, this is not directly called.

Returns this attribute

# File rexml-3.2.5/lib/rexml/attribute.rb, line 166
def element=( element )
  @element = element

  if @normalized
    Text.check( @normalized, NEEDS_A_SECOND_CHECK, doctype )
  end

  self
end

hash() click to toggle source

Creates (and returns) a hash from both the name and value

# File rexml-3.2.5/lib/rexml/attribute.rb, line 114
def hash
  name.hash + value.hash
end

inspect() click to toggle source

# File rexml-3.2.5/lib/rexml/attribute.rb, line 192
def inspect
  rv = ""
  write( rv )
  rv
end

namespace(arg=nil) click to toggle source

Returns the namespace URL, if defined, or nil otherwise

e = Element.new("el")
e.add_namespace("ns", "http://url")
e.add_attribute("ns:a", "b")
e.add_attribute("nsx:a", "c")
e.attribute("ns:a").namespace # => "http://url"
e.attribute("nsx:a").namespace # => nil

This method always returns “” for no namespace attribute. Because the default namespace doesn’t apply to attribute names.

From www.w3.org/TR/xml-names/#uniqAttrs

> the default namespace does not apply to attribute names

e = REXML::Element.new("el")
e.add_namespace("", "http://example.com/")
e.namespace # => "http://example.com/"
e.add_attribute("a", "b")
e.attribute("a").namespace # => ""

# File rexml-3.2.5/lib/rexml/attribute.rb, line 98
def namespace arg=nil
  arg = prefix if arg.nil?
  if arg == ""
    ""
  else
    @element.namespace(arg)
  end
end

node_type() click to toggle source

# File rexml-3.2.5/lib/rexml/attribute.rb, line 188
def node_type
  :attribute
end

prefix() click to toggle source

Returns the namespace of the attribute.

e = Element.new( "elns:myelement" )
e.add_attribute( "nsa:a", "aval" )
e.add_attribute( "b", "bval" )
e.attributes.get_attribute( "a" ).prefix   # -> "nsa"
e.attributes.get_attribute( "b" ).prefix   # -> ""
a = Attribute.new( "x", "y" )
a.prefix                                   # -> ""

Calls superclass method

# File rexml-3.2.5/lib/rexml/attribute.rb, line 73
def prefix
  super
end

remove() click to toggle source

Removes this Attribute from the tree, and returns true if successful

This method is usually not called directly.

# File rexml-3.2.5/lib/rexml/attribute.rb, line 179
def remove
  @element.attributes.delete self.name unless @element.nil?
end

to_s() click to toggle source

Returns the attribute value, with entities replaced

# File rexml-3.2.5/lib/rexml/attribute.rb, line 140
def to_s
  return @normalized if @normalized

  @normalized = Text::normalize( @unnormalized, doctype )
  @unnormalized = nil
  @normalized
end

to_string() click to toggle source

Returns this attribute out as XML source, expanding the name

a = Attribute.new( "x", "y" )
a.to_string     # -> "x='y'"
b = Attribute.new( "ns:x", "y" )
b.to_string     # -> "ns:x='y'"

# File rexml-3.2.5/lib/rexml/attribute.rb, line 124
def to_string
  if @element and @element.context and @element.context[:attribute_quote] == :quote
    %Q^#@expanded_name="#{to_s().gsub(/"/, '&quot;')}"^
  else
    "#@expanded_name='#{to_s().gsub(/'/, '&apos;')}'"
  end
end

value() click to toggle source

Returns the UNNORMALIZED value of this attribute. That is, entities have been expanded to their values

# File rexml-3.2.5/lib/rexml/attribute.rb, line 150
def value
  return @unnormalized if @unnormalized
  @unnormalized = Text::unnormalize( @normalized, doctype )
  @normalized = nil
  @unnormalized
end

write( output, indent=-1 ) click to toggle source

Writes this attribute (EG, puts ‘key=“value”’ to the output)

# File rexml-3.2.5/lib/rexml/attribute.rb, line 184
def write( output, indent=-1 )
  output << to_string
end

xpath() click to toggle source

# File rexml-3.2.5/lib/rexml/attribute.rb, line 198
def xpath
  path = @element.xpath
  path += "/@#{self.expanded_name}"
  return path
end