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  • rexml/element.rb

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REXML::Attributes

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

Public Class Methods

new(element) click to toggle source

Constructor

element

the Element of which this is an Attribute

 
               # File rexml/element.rb, line 971
def initialize element
  @element = element
end
            

Public Instance Methods

<<( attribute ) click to toggle source
Alias for: add
[](name) click to toggle source

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'
 
               # File rexml/element.rb, line 986
def [](name)
  attr = get_attribute(name)
  return attr.value unless attr.nil?
  return nil
end
            
[]=( name, value ) click to toggle source

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
 
               # File rexml/element.rb, line 1088
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
    raise ParseException.new(
      "Namespace conflict in adding attribute \"#{value.name}\": "+
      "Prefix \"#{old_attr.prefix}\" = "+
      "\"#{@element.namespace(old_attr.prefix)}\" and prefix "+
      "\"#{value.prefix}\" = \"#{@element.namespace(value.prefix)}\"") if
      value.prefix != "xmlns" and old_attr.prefix != "xmlns" and
      @element.namespace( old_attr.prefix ) ==
        @element.namespace( value.prefix )
      store value.name, { old_attr.prefix   => old_attr,
        value.prefix                => value }
  else
    store value.name, value
  end
  return @element
end
            
add( attribute ) click to toggle source

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

attribute

An Attribute

 
               # File rexml/element.rb, line 1207
def add( attribute )
  self[attribute.name] = attribute
end
            
Also aliased as: <<
delete( attribute ) click to toggle source

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'/>"
 
               # File rexml/element.rb, line 1175
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)
  attr = nil
  if old.kind_of? Hash # the supplied attribute is one of many
    attr = 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
    attr = old
    super(name)
  end
  @element
end
            
delete_all( name ) click to toggle source

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

 
               # File rexml/element.rb, line 1217
def delete_all( name )
  rv = []
  each_attribute { |attribute|
    rv << attribute if attribute.expanded_name == name
  }
  rv.each{ |attr| attr.remove }
  return rv
end
            
each() click to toggle source

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 }
 
               # File rexml/element.rb, line 1028
def each
  each_attribute do |attr|
    yield [attr.expanded_name, attr.value]
  end
end
            
each_attribute() click to toggle source

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
}
 
               # File rexml/element.rb, line 1013
def each_attribute # :yields: attribute
  each_value do |val|
    if val.kind_of? Attribute
      yield val
    else
      val.each_value { |atr| yield atr }
    end
  end
end
            
get_attribute( name ) click to toggle source

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"
 
               # File rexml/element.rb, line 1043
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) click to toggle source

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

 
               # File rexml/element.rb, line 1231
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() click to toggle source

Returns the number of attributes the owning Element contains.

doc = Document "<a x='1' y='2' foo:x='3'/>"
doc.root.attributes.length        #-> 3
 
               # File rexml/element.rb, line 999
def length
  c = 0
  each_attribute { c+=1 }
  c
end
            
Also aliased as: size
namespaces() click to toggle source
 
               # File rexml/element.rb, line 1149
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() click to toggle source

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']
 
               # File rexml/element.rb, line 1133
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() click to toggle source
Alias for: length
to_a() click to toggle source
 
               # File rexml/element.rb, line 992
def to_a
  values.flatten
end
            

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