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  • rexml/element.rb

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REXML::Elements

A class which provides filtering of children for Elements, and XPath search support. You are expected to only encounter this class as the element.elements object. Therefore, you are not expected to instantiate this yourself.

Public Class Methods

new(parent) click to toggle source

Constructor

parent

the parent Element

 
               # File rexml/element.rb, line 727
def initialize parent
  @element = parent
end
            

Public Instance Methods

<<(element=nil) click to toggle source
Alias for: add
[]( index, name=nil) click to toggle source

Fetches a child element. Filters only Element children, regardless of the XPath match.

index

the search parameter. This is either an Integer, which will be used to find the index'th child Element, or an XPath, which will be used to search for the Element. Because of the nature of XPath searches, any element in the connected XML document can be fetched through any other element. The Integer index is 1-based, not 0-based. This means that the first child element is at index 1, not 0, and the +n+th element is at index n, not n-1. This is because XPath indexes element children starting from 1, not 0, and the indexes should be the same.

name

optional, and only used in the first argument is an Integer. In that case, the index'th child Element that has the supplied name will be returned. Note again that the indexes start at 1.

Returns

the first matching Element, or nil if no child matched

doc = Document.new '<a><b/><c id="1"/><c id="2"/><d/></a>'
doc.root.elements[1]       #-> <b/>
doc.root.elements['c']     #-> <c id="1"/>
doc.root.elements[2,'c']   #-> <c id="2"/>
 
               # File rexml/element.rb, line 752
def []( index, name=nil)
  if index.kind_of? Integer
    raise "index (#{index}) must be >= 1" if index < 1
    name = literalize(name) if name
    num = 0
    child = nil
    @element.find { |child|
      child.kind_of? Element and
      (name.nil? ? true : child.has_name?( name )) and 
      (num += 1) == index
    }
  else
    return XPath::first( @element, index )
    #{ |element| 
    #       return element if element.kind_of? Element
    #}
    #return nil
  end
end
            
[]=( index, element ) click to toggle source

Sets an element, replacing any previous matching element. If no existing element is found ,the element is added.

index

Used to find a matching element to replace. See []().

element

The element to replace the existing element with the previous element

Returns

nil if no previous element was found.

doc = Document.new '<a/>'
doc.root.elements[10] = Element.new('b')    #-> <a><b/></a>
doc.root.elements[1]                        #-> <b/>
doc.root.elements[1] = Element.new('c')     #-> <a><c/></a>
doc.root.elements['c'] = Element.new('d')   #-> <a><d/></a>
 
               # File rexml/element.rb, line 785
def []=( index, element )
  previous = self[index]
  if previous.nil?
    @element.add element
  else
    previous.replace_with element
  end
  return previous
end
            
add(element=nil) click to toggle source

Adds an element

element

if supplied, is either an Element, String, or Source (see Element.initialize). If not supplied or nil, a new, default Element will be constructed

Returns

the added Element

a = Element.new('a')
a.elements.add(Element.new('b'))  #-> <a><b/></a>
a.elements.add('c')               #-> <a><b/><c/></a>
 
               # File rexml/element.rb, line 861
def add element=nil
  rv = nil
  if element.nil?
    Element.new("", self, @element.context)
  elsif not element.kind_of?(Element)
    Element.new(element, self, @element.context)
  else
    @element << element
    element.context = @element.context
    element
  end
end
            
Also aliased as: <<
collect( xpath=nil, &block ) click to toggle source
 
               # File rexml/element.rb, line 894
def collect( xpath=nil, &block )
  collection = []
  XPath::each( @element, xpath ) {|e| 
    collection << yield(e)  if e.kind_of?(Element) 
  }
  collection
end
            
delete(element) click to toggle source

Deletes a child Element

element

Either an Element, which is removed directly; an xpath, where the first matching child is removed; or an Integer, where the n'th Element is removed.

Returns

the removed child

doc = Document.new '<a><b/><c/><c id="1"/></a>'
b = doc.root.elements[1]
doc.root.elements.delete b           #-> <a><c/><c id="1"/></a>
doc.elements.delete("a/c[@id='1']")  #-> <a><c/></a>
doc.root.elements.delete 1           #-> <a/>
 
               # File rexml/element.rb, line 825
def delete element
  if element.kind_of? Element
    @element.delete element
  else
    el = self[element]
    el.remove if el
  end
end
            
delete_all( xpath ) click to toggle source

Removes multiple elements. Filters for Element children, regardless of XPath matching.

xpath

all elements matching this String path are removed.

Returns

an Array of Elements that have been removed

doc = Document.new '<a><c/><c/><c/><c/></a>'
deleted = doc.elements.delete_all 'a/c' #-> [<c/>, <c/>, <c/>, <c/>]
 
               # File rexml/element.rb, line 840
def delete_all( xpath )
  rv = []
  XPath::each( @element, xpath) {|element| 
    rv << element if element.kind_of? Element
  }
  rv.each do |element|
    @element.delete element
    element.remove
  end
  return rv
end
            
each( xpath=nil, &block) click to toggle source

Iterates through all of the child Elements, optionally filtering them by a given XPath

xpath

optional. If supplied, this is a String XPath, and is used to filter the children, so that only matching children are yielded. Note that XPaths are automatically filtered for Elements, so that non-Element children will not be yielded

doc = Document.new '<a><b/><c/><d/>sean<b/><c/><d/></a>'
doc.root.each {|e|p e}       #-> Yields b, c, d, b, c, d elements
doc.root.each('b') {|e|p e}  #-> Yields b, b elements
doc.root.each('child::node()')  {|e|p e}
#-> Yields <b/>, <c/>, <d/>, <b/>, <c/>, <d/>
XPath.each(doc.root, 'child::node()', &block)
#-> Yields <b/>, <c/>, <d/>, sean, <b/>, <c/>, <d/>
 
               # File rexml/element.rb, line 890
def each( xpath=nil, &block)
  XPath::each( @element, xpath ) {|e| yield e if e.kind_of? Element }
end
            
empty?() click to toggle source

Returns true if there are no Element children, false otherwise

 
               # File rexml/element.rb, line 796
def empty?
  @element.find{ |child| child.kind_of? Element}.nil?
end
            
index(element) click to toggle source

Returns the index of the supplied child (starting at 1), or -1 if the element is not a child

element

an Element child

 
               # File rexml/element.rb, line 803
def index element
  rv = 0
  found = @element.find do |child| 
    child.kind_of? Element and
    (rv += 1) and
    child == element
  end
  return rv if found == element
  return -1
end
            
inject( xpath=nil, initial=nil, &block ) click to toggle source
 
               # File rexml/element.rb, line 902
def inject( xpath=nil, initial=nil, &block )
  first = true
  XPath::each( @element, xpath ) {|e|
    if (e.kind_of? Element)
      if (first and initial == nil)
        initial = e
        first = false
      else
        initial = yield( initial, e ) if e.kind_of? Element
      end
    end
  }
  initial
end
            
size() click to toggle source

Returns the number of Element children of the parent object.

doc = Document.new '<a>sean<b/>elliott<b/>russell<b/></a>'
doc.root.size            #-> 6, 3 element and 3 text nodes
doc.root.elements.size   #-> 3
 
               # File rexml/element.rb, line 921
def size
  count = 0
  @element.each {|child| count+=1 if child.kind_of? Element }
  count
end
            
to_a( xpath=nil ) click to toggle source

Returns an Array of Element children. An XPath may be supplied to filter the children. Only Element children are returned, even if the supplied XPath matches non-Element children.

doc = Document.new '<a>sean<b/>elliott<c/></a>'
doc.root.elements.to_a                  #-> [ <b/>, <c/> ]
doc.root.elements.to_a("child::node()") #-> [ <b/>, <c/> ] 
XPath.match(doc.root, "child::node()")  #-> [ sean, <b/>, elliott, <c/> ]
 
               # File rexml/element.rb, line 934
def to_a( xpath=nil )
  rv = XPath.match( @element, xpath )
  return rv.find_all{|e| e.kind_of? Element} if xpath
  rv
end