Class: REXML::Attributes

Relationships & Source Files
Super Chains via Extension / Inclusion / Inheritance
Class Chain: self, Hash
Instance Chain: self, Hash
Inherits:	Hash `::Object` Hash REXML::Attributes
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

.new(element) ⇒ Attributes constructor

Constructor element
the Element of which this is an Attribute.

Instance Method Summary

#<<(attribute)

Alias for #add.
#[](name)

Fetches an attribute value.
#[]=(name, value)

Sets an attribute, overwriting any existing attribute value by the same name.
#add(attribute) (also: #<<)

Adds an attribute, overriding any existing attribute by the same name.
#delete(attribute)

Removes an attribute attribute
#delete_all(name)

Deletes all attributes matching a name.
#each

Iterates over each attribute of an Element, yielding the expanded name and value as a pair of Strings.
#each_attribute

Iterates over the attributes of an Element.
#get_attribute(name)

Fetches an attribute name
#get_attribute_ns(namespace, name)

The get_attribute_ns method retrieves a method by its namespace and name.
#length (also: #size)

Returns the number of attributes the owning Element contains.
#namespaces
#prefixes

Returns an array of Strings containing all of the prefixes declared by this set of # attributes.
#size

Alias for #length.
#to_a

Constructor Details

.new(element) ⇒ `Attributes`

Constructor

element: the Element of which this is an Attribute

[ GitHub ]

# File 'lib/rexml/element.rb', line 993


def initialize element
  @element = element
end

Instance Method Details

#<<(attribute)

Alias for #add.

[ GitHub ]

# File 'lib/rexml/element.rb', line 1235


alias :<< :add

#[](name)

Fetches an attribute value. If you want to get the Attribute itself, use get_attribute()

name: an XPath attribute name. Namespaces are relevant here.
Returns: the String value of the matching attribute, or nil if no matching attribute was found. This is the unnormalized value (with entities expanded).

doc = Document.new "<a foo:att='1' bar:att='2' att='&lt;'/>"
doc.root.attributes['att']         #-> '<'
doc.root.attributes['bar:att']     #-> '2'

[ GitHub ]

# File 'lib/rexml/element.rb', line 1008


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

#[]=(name, value)

Sets an attribute, overwriting any existing attribute value by the same name. Namespace is significant.

name: the name of the attribute
value: (optional) If supplied, the value of the attribute. If nil, any existing matching attribute is deleted.
Returns: Owning element

doc = Document.new "<a x:foo='1' foo='3'/>"
doc.root.attributes['y:foo'] = '2'
doc.root.attributes['foo'] = '4'
doc.root.attributes['x:foo'] = nil

[ GitHub ]

# File 'lib/rexml/element.rb', line 1112


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) Also known as: #<<

Adds an attribute, overriding any existing attribute by the same name. Namespaces are significant.

attribute: An Attribute

[ GitHub ]

# File 'lib/rexml/element.rb', line 1231


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

#delete(attribute)

Removes an attribute

attribute: either a String, which is the name of the attribute to remove – namespaces are significant here – or the attribute to remove.
Returns: the owning element

doc = Document.new "<a y:foo='0' x:foo='1' foo='3' z:foo='4'/>"
doc.root.attributes.delete 'foo'   #-> <a y:foo='0' x:foo='1' z:foo='4'/>"
doc.root.attributes.delete 'x:foo' #-> <a y:foo='0' z:foo='4'/>"
attr = doc.root.attributes.get_attribute('y:foo')
doc.root.attributes.delete attr    #-> <a z:foo='4'/>"

[ GitHub ]

# File 'lib/rexml/element.rb', line 1201


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)

Deletes all attributes matching a name. Namespaces are significant.

name: A String; all attributes that match this path will be removed
Returns: an ::Array of the Attributes that were removed

[ GitHub ]

# File 'lib/rexml/element.rb', line 1241


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

#each

Iterates over each attribute of an Element, yielding the expanded name and value as a pair of Strings.

doc = Document.new '<a x="1" y="2"/>'
doc.root.attributes.each {|name, value| p name+" => "+value }

[ GitHub ]

# File 'lib/rexml/element.rb', line 1051


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

#each_attribute

Iterates over the attributes of an Element. Yields actual Attribute nodes, not String values.

doc = Document.new '<a x="1" y="2"/>'
doc.root.attributes.each_attribute {|attr|
  p attr.expanded_name+" => "+attr.value
}

[ GitHub ]

# File 'lib/rexml/element.rb', line 1035


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)

Fetches an attribute

name: the name by which to search for the attribute. Can be a prefix:name namespace name.
Returns: The first matching attribute, or nil if there was none. This

value is an Attribute node, not the String value of the attribute.

doc = Document.new '<a x:foo="1" foo="2" bar="3"/>'
doc.root.attributes.get_attribute("foo").value    #-> "2"
doc.root.attributes.get_attribute("x:foo").value  #-> "1"

[ GitHub ]

# File 'lib/rexml/element.rb', line 1067


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)

The get_attribute_ns method retrieves a method by its namespace and name. Thus it is possible to reliably identify an attribute even if an XML processor has changed the prefix.

Method contributed by Henrik Martensson

[ GitHub ]

# File 'lib/rexml/element.rb', line 1255


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 number of attributes the owning Element contains.

doc = Document "<a x='1' y='2' foo:x='3'/>"
doc.root.attributes.length        #-> 3

[ GitHub ]

# File 'lib/rexml/element.rb', line 1021


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

#namespaces

[ GitHub ]

# File 'lib/rexml/element.rb', line 1175


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

Returns an array of Strings containing all of the prefixes declared by this set of # attributes. The array does not include the default namespace declaration, if one exists.

doc = Document.new("<a xmlns='foo' xmlns:x='bar' xmlns:y='twee' "+
      "z='glorp' p:k='gru'/>")
prefixes = doc.root.attributes.prefixes    #-> ['x', 'y']

[ GitHub ]

# File 'lib/rexml/element.rb', line 1159


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 1026


alias :size :length

#to_a

[ GitHub ]

# File 'lib/rexml/element.rb', line 1014


def to_a
  enum_for(:each_attribute).to_a
end

Class: REXML::Attributes

Overview

Class Method Summary

Instance Method Summary

Constructor Details

.new(element) ⇒ Attributes

Instance Method Details

#<<(attribute)

#[](name)

#[]=(name, value)

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

#delete(attribute)

#delete_all(name)

#each

#each_attribute

#get_attribute(name)

#get_attribute_ns(namespace, name)

#length Also known as: #size

#namespaces

#prefixes

#size

#to_a

.new(element) ⇒ `Attributes`