Class: REXML::Attribute

Inherits:
Object show all
Includes:
Namespace, Node
Defined in:
lib/rexml/attribute.rb

Overview

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.

Constant Summary collapse

PATTERN =
/\s*(#{NAME_STR})\s*=\s*(["'])(.*?)\2/um
NEEDS_A_SECOND_CHECK =
/(<|&((#{Entity::NAME});|(#0*((?:\d+)|(?:x[a-fA-F0-9]+)));)?)/um

Constants included from Namespace

Namespace::NAMESPLIT

Constants included from XMLTokens

XMLTokens::NAME, XMLTokens::NAMECHAR, XMLTokens::NAME_CHAR, XMLTokens::NAME_START_CHAR, XMLTokens::NAME_STR, XMLTokens::NCNAME_STR, XMLTokens::NMTOKEN, XMLTokens::NMTOKENS, XMLTokens::REFERENCE

Instance Attribute Summary collapse

Attributes included from Namespace

#expanded_name, #name

Instance Method Summary collapse

Methods included from Namespace

#fully_expanded_name, #has_name?

Methods included from Node

#each_recursive, #find_first_recursive, #indent, #index_in_parent, #next_sibling_node, #parent?, #previous_sibling_node

Constructor Details

#initialize(first, second = nil, parent = nil) ⇒ Attribute

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 )

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# File '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

Instance Attribute Details

#elementObject

The element to which this attribute belongs


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# File 'lib/rexml/attribute.rb', line 15

def element
  @element
end

#normalized=(value) ⇒ Object (writeonly)

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


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# File 'lib/rexml/attribute.rb', line 18

def normalized=(value)
  @normalized = value
end

Instance Method Details

#==(other) ⇒ Object

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


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# File 'lib/rexml/attribute.rb', line 109

def ==( other )
  other.kind_of?(Attribute) and other.name==name and other.value==value
end

#cloneObject

Returns a copy of this attribute


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# File 'lib/rexml/attribute.rb', line 158

def clone
  Attribute.new self
end

#doctypeObject


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# File 'lib/rexml/attribute.rb', line 132

def doctype
  if @element
    doc = @element.document
    doc.doctype if doc
  end
end

#hashObject

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


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# File 'lib/rexml/attribute.rb', line 114

def hash
  name.hash + value.hash
end

#inspectObject


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# File 'lib/rexml/attribute.rb', line 192

def inspect
  rv = ""
  write( rv )
  rv
end

#namespace(arg = nil) ⇒ Object

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 # => ""

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# File 'lib/rexml/attribute.rb', line 98

def namespace arg=nil
  arg = prefix if arg.nil?
  if arg == ""
    ""
  else
    @element.namespace(arg)
  end
end

#node_typeObject


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# File 'lib/rexml/attribute.rb', line 188

def node_type
  :attribute
end

#prefixObject

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                                   # -> ""

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# File 'lib/rexml/attribute.rb', line 73

def prefix
  super
end

#removeObject

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

This method is usually not called directly.


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# File 'lib/rexml/attribute.rb', line 179

def remove
  @element.attributes.delete self.name unless @element.nil?
end

#to_sObject

Returns the attribute value, with entities replaced


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# File 'lib/rexml/attribute.rb', line 140

def to_s
  return @normalized if @normalized

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

#to_stringObject

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'"

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# File '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

#valueObject

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


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# File '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 )) ⇒ Object

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


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# File 'lib/rexml/attribute.rb', line 184

def write( output, indent=-1 )
  output << to_string
end

#xpathObject


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# File 'lib/rexml/attribute.rb', line 198

def xpath
  path = @element.xpath
  path += "/@#{self.expanded_name}"
  return path
end