class Ox::Element

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(%{
<?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"

Public Class Methods

new(name) click to toggle source

Creates a new Element with the specified name.

name [String] name of the Element

Calls superclass method

# File lib/ox/element.rb, line 41
def initialize(name)
  super
  @attributes = {}
  @nodes = []
end

Public Instance Methods

<<(node) click to toggle source

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 60
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

==(other)

Alias for: eql?

alocate(path, found) click to toggle source

path [Array] array of steps in a path
found [Array] matching nodes

# File lib/ox/element.rb, line 246
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] : []
      when '@'
        k,v = step[i..-2].split('=')
        if v
          match = match.select { |n| n.is_a?(Element) && (v == n.attributes[k.to_sym] || v == n.attributes[k]) }
        else
          match = match.select { |n| n.is_a?(Element) && (n.attributes[k.to_sym] || n.attributes[k]) }
        end
      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

attr_match(cond) click to toggle source

Return true if all the key-value pairs in the cond Hash match the @attributes key-values.

# File lib/ox/element.rb, line 107
def attr_match(cond)
  cond.each_pair { |k,v| return false unless v == @attributes[k.to_sym] || v == @attributes[k.to_s] }
  true
end

del_locate(path) click to toggle source

path [Array] array of steps in a path

# File lib/ox/element.rb, line 327
def del_locate(path)
  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.delete_if { |k,v| '?' == step || k.to_sym == sym_step }
    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] : []
      when '@'
        k,v = step[i..-2].split('=')
        if v
          match = match.select { |n| n.is_a?(Element) && (v == n.attributes[k.to_sym] || v == n.attributes[k]) }
        else
          match = match.select { |n| n.is_a?(Element) && (n.attributes[k.to_sym] || n.attributes[k]) }
        end
      else
        raise InvalidPath.new(path)
      end
    end
    if (1 == path.size)
      nodes.delete_if { |n| match.include?(n) }
    elsif '*' == name
      match.each { |n| n.del_locate(path) if n.is_a?(Element) }
      match.each { |n| n.del_locate(path[1..-1]) if n.is_a?(Element) }
    else
      match.each { |n| n.del_locate(path[1..-1]) if n.is_a?(Element) }
    end
  end
end

each(cond=nil, &block) click to toggle source

Iterate over each child of the instance yielding according to the cond argument value. If the cond argument is nil then all child nodes are yielded to. If cond is a string then only the child Elements with a matching name will be yielded to. If the cond is a Hash then the keys-value pairs in the cond must match the child attribute values with the same keys. Any other cond type will yield to nothing.

# File lib/ox/element.rb, line 118
def each(cond=nil, &block)
  build_enumerator(cond).each(&block)
end

eql?(other) click to toggle source

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.

Calls superclass method

# File lib/ox/element.rb, line 81
def eql?(other)
  return false unless super(other)
  return false unless self.attributes == other.attributes
  return false unless self.nodes == other.nodes
  true
end

Also aliased as: ==

locate(path) click to toggle source

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 elements with an age attribute defined in the Family Element.
element.locate("Family/Kid[@age]") returns the Kid elements with an age attribute defined in the Family Element.
element.locate("Family/?[@age=32]") returns the elements with an age attribute equal to 32 in the Family Element.
element.locate("Family/Kid[@age=32]") returns the Kid elements with an age attribute equal to 32 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 162
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

method_missing(id, *args, &block) click to toggle source

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 207
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 || name_matchs?(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

nodes() click to toggle source

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 52
def nodes
  @nodes = [] if !instance_variable_defined?(:@nodes) or @nodes.nil?
  @nodes
end

prepend_child(node) click to toggle source

Prepend a Node to the Element's nodes array. Returns the element itself so multiple appends can be chained together.

node [Node] Node to prepend to the nodes array

# File lib/ox/element.rb, line 70
def prepend_child(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.unshift(node)
  self
end

remove_children(*children) click to toggle source

Remove all the children matching the path provided

Examples are:

element.remove_children(Ox:Element) removes the element passed as argument if child of the element.
element.remove_children(Ox:Element, Ox:Element) removes the list of elements passed as argument if children of the element.
children [Array] array of OX

# File lib/ox/element.rb, line 184
def remove_children(*children)
  return self if children.compact.empty?
  recursive_children_removal(children.compact.map { |c| c.object_id })
  self
end

remove_children_by_path(path) click to toggle source

Remove all the children matching the path provided

Examples are:

element.remove_children_by_path("*") removes all children attributes.
element.remove_children_by_path("Family/Kid[@age=32]") removes the Kid elements with an age attribute equal to 32 in the Family Element.
path [String] path to the Nodes to locate

# File lib/ox/element.rb, line 197
def remove_children_by_path(path)
  del_locate(path.split('/')) unless path.nil?
  self
end

replace_text(txt) click to toggle source

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 99
def replace_text(txt)
  raise "the argument to replace_text() must be a String" unless txt.is_a?(String)
  @nodes.clear()
  @nodes << txt
end

respond_to?(id, inc_all=false) click to toggle source

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.

Calls superclass method

# File lib/ox/element.rb, line 229
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 || name_matchs?(n.value, id_str)
  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

text() click to toggle source

Returns the first String in the elements nodes array or nil if there is no String node.

# File lib/ox/element.rb, line 91
def text()
  nodes.each { |n| return n if n.is_a?(String) }
  nil
end