# class REXML::XPath

Wrapper class. Use this class to access the XPath functions.

### Constants

EMPTY_HASH

  A base Hash object, supposing to be used when initializing a default empty namespaces set, but is currently unused. TODO: either set the namespaces=EMPTY_HASH, or deprecate this.

### Public Class Methods

each(element, path=nil, namespaces=nil, variables={}) click to toggle source

Iterates over nodes that match the given path, calling the supplied block with the match.

element

  The context element

path

  The xpath to search for. If not supplied or nil, defaults to '*'

namespaces

  If supplied, a Hash which defines a namespace mapping

variables

  If supplied, a Hash which maps $variables in the query to values. This can be used to avoid XPath injection attacks or to automatically handle escaping string values.

    XPath.each( node ) { |el| ... }
    XPath.each( node, '/*[@attr='v']' ) { |el| ... }
    XPath.each( node, 'ancestor::x' ) { |el| ... }
    XPath.each( node, '/book/publisher/text()=$publisher', {}, {"publisher"=>"O'Reilly"}) \
      {|el| ... }

    # File lib/rexml/xpath.rb, line 59
    def XPath::each element, path=nil, namespaces=nil, variables={}, &block
      raise "The namespaces argument, if supplied, must be a hash object." unless namespaces.nil? or namespaces.kind_of?(Hash)
      raise "The variables argument, if supplied, must be a hash object." unless variables.kind_of?(Hash)
      parser = XPathParser.new
      parser.namespaces = namespaces
      parser.variables = variables
      path = "*" unless path
      element = [element] unless element.kind_of? Array
      parser.parse(path, element).each( &block )
    end

first(element, path=nil, namespaces=nil, variables={}) click to toggle source

Finds and returns the first node that matches the supplied xpath.

element

  The context element

path

  The xpath to search for. If not supplied or nil, returns the first node matching '*'.

namespaces

  If supplied, a Hash which defines a namespace mapping.

variables

  If supplied, a Hash which maps $variables in the query to values. This can be used to avoid XPath injection attacks or to automatically handle escaping string values.

    XPath.first( node )
    XPath.first( doc, "//b"} )
    XPath.first( node, "a/x:b", { "x"=>"http://doofus" } )
    XPath.first( node, '/book/publisher/text()=$publisher', {}, {"publisher"=>"O'Reilly"})

    # File lib/rexml/xpath.rb, line 30
    def XPath::first element, path=nil, namespaces=nil, variables={}
      raise "The namespaces argument, if supplied, must be a hash object." unless namespaces.nil? or namespaces.kind_of?(Hash)
      raise "The variables argument, if supplied, must be a hash object." unless variables.kind_of?(Hash)
      parser = XPathParser.new
      parser.namespaces = namespaces
      parser.variables = variables
      path = "*" unless path
      element = [element] unless element.kind_of? Array
      parser.parse(path, element).flatten[0]
    end

match(element, path=nil, namespaces=nil, variables={}) click to toggle source

Returns an array of nodes matching a given XPath.

    # File lib/rexml/xpath.rb, line 71
    def XPath::match element, path=nil, namespaces=nil, variables={}
      parser = XPathParser.new
      parser.namespaces = namespaces
      parser.variables = variables
      path = "*" unless path
      element = [element] unless element.kind_of? Array
      parser.parse(path,element)
    end