source: extensions/gsdl-video/trunk/installed/cmdline/lib/ruby/1.8/rexml/xpath.rb@ 18425

require 'rexml/functions'
require 'rexml/xpath_parser'

module REXML
    # Wrapper class.  Use this class to access the XPath functions.
    class XPath
        include Functions
        EMPTY_HASH = {}

        # 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.
        #
        #  XPath.first( node )
        #  XPath.first( doc, "//b"} )
        #  XPath.first( node, "a/x:b", { "x"=>"http://doofus" } )
    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

        # Itterates 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
        #
        #  XPath.each( node ) { |el| ... }
        #  XPath.each( node, '/*[@attr='v']' ) { |el| ... }
        #  XPath.each( node, 'ancestor::x' ) { |el| ... }
        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

        # Returns an array of nodes matching a given XPath.  
        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
    end
end