Class: REXML::Attributes

Inherits:
Hash
  • Object
show all
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.

Instance Method Summary collapse

Constructor Details

#initialize(element) ⇒ Attributes

Constructor

element

the Element of which this is an Attribute


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

def initialize element
  @element = element
end

Instance Method Details

#[](name) ⇒ Object

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'

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

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

#[]=(name, value) ⇒ Object

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

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# 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) ⇒ Object Also known as: <<

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

attribute

An Attribute


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

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

#delete(attribute) ⇒ Object

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'/>"

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# 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) ⇒ Object

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


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# 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

#eachObject

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 }

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# 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_attributeObject

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
}

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# 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) ⇒ Object

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"

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# 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) ⇒ Object

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


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# 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

#lengthObject 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

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

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

#namespacesObject


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# 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

#prefixesObject

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']

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# 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

#to_aObject


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

def to_a
  enum_for(:each_attribute).to_a
end