An Element represents a element of an XML document. It has a name, attributes, and sub-nodes.
To access the child elements or attributes there are several options. One is to walk the nodes and attributes. Another is to use the locate() method. The easiest for simple regularly formatted XML is to reference the sub elements or attributes simply by name. Repeating elements with the same name can be referenced with an element count as well. A few examples should explain the 'easy' API more clearly.
Example
doc = Ox.parse(%Q{ <?xml?> <People> <Person age="58"> <given>Peter</given> <surname>Ohler</surname> </Person> <Person> <given>Makie</given> <surname>Ohler</surname> </Person> </People> }) doc.People.Person.given.text => "Peter" doc.People.Person(1).given.text => "Makie" doc.People.Person.age => "58"
Appends a Node to the Element's nodes array. Returns the element itself so multiple appends can be chained together.
node
[Node] Node to append to the
nodes array
# File lib/ox/element.rb, line 59 def <<(node) raise "argument to << must be a String or Ox::Node." unless node.is_a?(String) or node.is_a?(Node) @nodes = [] if !instance_variable_defined?(:@nodes) or @nodes.nil? @nodes << node self end
path
[Array] array of steps in a path
found
[Array] matching nodes
# File lib/ox/element.rb, line 191 def alocate(path, found) step = path[0] if step.start_with?('@') # attribute raise InvalidPath.new(path) unless 1 == path.size if instance_variable_defined?(:@attributes) step = step[1..-1] sym_step = step.to_sym @attributes.each do |k,v| found << v if ('?' == step or k == step or k == sym_step) end end else # element name if (i = step.index('[')).nil? # just name name = step qual = nil else name = step[0..i-1] raise InvalidPath.new(path) unless step.end_with?(']') i += 1 qual = step[i..i] # step[i] would be better but some rubies (jruby, ree, rbx) take that as a Fixnum. if '0' <= qual and qual <= '9' qual = '+' else i += 1 end index = step[i..-2].to_i end if '?' == name or '*' == name match = nodes elsif '^' == name[0..0] # 1.8.7 thinks name[0] is a fixnum case name[1..-1] when 'Element' match = nodes.select { |e| e.is_a?(Element) } when 'String', 'Text' match = nodes.select { |e| e.is_a?(String) } when 'Comment' match = nodes.select { |e| e.is_a?(Comment) } when 'CData' match = nodes.select { |e| e.is_a?(CData) } when 'DocType' match = nodes.select { |e| e.is_a?(DocType) } else #puts "*** no match on #{name}" match = [] end else match = nodes.select { |e| e.is_a?(Element) and name == e.name } end unless qual.nil? or match.empty? case qual when '+' match = index < match.size ? [match[index]] : [] when '-' match = index <= match.size ? [match[-index]] : [] when '<' match = 0 < index ? match[0..index - 1] : [] when '>' match = index <= match.size ? match[index + 1..-1] : [] else raise InvalidPath.new(path) end end if (1 == path.size) match.each { |n| found << n } elsif '*' == name match.each { |n| n.alocate(path, found) if n.is_a?(Element) } match.each { |n| n.alocate(path[1..-1], found) if n.is_a?(Element) } else match.each { |n| n.alocate(path[1..-1], found) if n.is_a?(Element) } end end end
Returns true if this Object and other are of the same type and have the equivalent value and the equivalent elements otherwise false is returned.
other
[Object] Object compare self to.
return [Boolean] true if both Objects are equivalent, otherwise false.
# File lib/ox/element.rb, line 70 def eql?(other) return false if (other.nil? or self.class != other.class) return false unless super(other) return false unless self.attributes == other.attributes return false unless self.nodes == other.nodes true end
Returns an array of Nodes or Strings that correspond to the locations specified by the path parameter. The path parameter describes the path to the return values which can be either nodes in the XML or attributes. The path is a relative description. There are similarities between the locate() method and XPath but locate does not follow the same rules as XPath. The syntax is meant to be simpler and more Ruby like.
Like XPath the path delimiters are the slash (/) character. The path is split on the delimiter and each element of the path then describes the child of the current Element to traverse.
Attributes are specified with an @ prefix.
Each element name in the path can be followed by a bracket expression that narrows the paths to traverse. Supported expressions are numbers with a preceeding qualifier. Qualifiers are -, +, <, and >. The + qualifier is the default. A - qualifier indicates the index begins at the end of the children just like for Ruby Arrays. The < and > qualifiers indicates all elements either less than or greater than should be matched. Note that unlike XPath, the element index starts at 0 similar to Ruby be contrary to XPath.
Element names can also be wildcard characters. A * indicates any decendent should be followed. A ? indicates any single Element can match the wildcard. A ^ character followed by the name of a Class will match any node of the specified class. Valid class names are Element, Comment, String (or Text), CData, DocType.
Examples are:
element.locate("Family/Pete ")
returns all children
of the Pete Element.
element.locate("Family/?[1]")
returns the first element
in the Family Element.
element.locate("Family/?[<3]")
returns the first 3
elements in the Family Element.
element.locate("Family/?/@age")
returns the arg
attribute for each child in the Family Element.
element.locate("Family/ @type")
returns the type
attribute value for decendents of the Family.
element.locate("Family/^Comment")
returns any
comments that are a child of Family.
path
[String] path to the Nodes to locate
# File lib/ox/element.rb, line 131 def locate(path) return [self] if path.nil? found = [] pa = path.split('/') if '*' == path[0] # a bit of a hack but it allows self to be checked as well e = Element.new('') e << self e.alocate(pa, found) else alocate(pa, found) end found end
Handles the 'easy' API that allows navigating a simple XML by referencing elements and attributes by name.
id
[Symbol] element or attribute name
return [Element|Node|String|nil] the element, attribute value, or Node identifed by the name
raise [NoMethodError] if no match is found
# File lib/ox/element.rb, line 152 def method_missing(id, *args, &block) has_some = false ids = id.to_s i = args[0].to_i # will be 0 if no arg or parsing fails nodes.each do |n| if (n.is_a?(Element) || n.is_a?(Instruct)) && (n.value == id || n.value == ids) return n if 0 == i has_some = true i -= 1 end end if instance_variable_defined?(:@attributes) return @attributes[id] if @attributes.has_key?(id) return @attributes[ids] if @attributes.has_key?(ids) end return nil if has_some raise NoMethodError.new("#{ids} not found", name) end
Returns the Element's nodes array. These are the sub-elements of this Element. return [Array] all child Nodes.
# File lib/ox/element.rb, line 51 def nodes @nodes = [] if !instance_variable_defined?(:@nodes) or @nodes.nil? @nodes end
Clears any child nodes of an element and replaces those with a single Text (String) node. Note the existing nodes array is modified and not replaced.
txt
[String] to become the only element of the nodes array
# File lib/ox/element.rb, line 89 def replace_text(txt) raise "the argument to replace_text() must be a String" unless txt.is_a?(String) @nodes.clear() @nodes << txt end
id
[String|Symbol] identifer of the attribute or method
ignored
inc_all [Boolean]
return true if the element has a member that matches the provided name.
# File lib/ox/element.rb, line 174 def respond_to?(id, inc_all=false) return true if super id_str = id.to_s id_sym = id.to_sym nodes.each do |n| next if n.is_a?(String) return true if n.value == id_str || n.value == id_sym end if instance_variable_defined?(:@attributes) && !@attributes.nil? return true if @attributes.has_key?(id_str) return true if @attributes.has_key?(id_sym) end false end
Returns the first String in the elements nodes array or nil if there is no String node.
# File lib/ox/element.rb, line 81 def text() nodes.each { |n| return n if n.is_a?(String) } nil end