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



993
994
995
 
# 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'



1008
1009
1010
1011
1012
 
# 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



1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
 
# 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



1231
1232
1233
 
# 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'/>"



1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
 
# 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



1241
1242
1243
1244
1245
1246
1247
1248
 
# 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 ⇒ Object

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 }



1051
1052
1053
1054
1055
1056
 
# 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 ⇒ Object

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
}



1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
 
# 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"



1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
 
# 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



1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
 
# 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 ⇒ Object 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



1021
1022
1023
1024
1025
 
# File 'lib/rexml/element.rb', line 1021

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

#namespaces ⇒ Object 



1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
 
# 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 ⇒ Object

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']



1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
 
# 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_a ⇒ Object 



1014
1015
1016
 
# File 'lib/rexml/element.rb', line 1014

def to_a
  enum_for(:each_attribute).to_a
end