indexing
	description: "Objects that ..."
	author: ""
	date: "$Date$"
	revision: "$Revision$"

class
	XPATH

inherit
	TWO_WAY_LIST[LOCATION_STEP]
	export
		{NONE} all
	end

create
	make_from_path

feature -- Creation

	make_from_path (xpath: STRING) is
			-- creates a new xpath object from the given xpath string
		local
			steps: LIST[STRING]
		do
			has_error := False

			steps := split_xpath (xpath)

			steps.start
			if steps.item.is_empty then
				extend (create {LOCATION_STEP}.make_root_step)
				steps.forth
			end

			from until steps.off loop
				extend (create {LOCATION_STEP}.make (steps.item))
				steps.forth
			end
		end

feature -- Status Information

	has_error: BOOLEAN

feature -- Basic Operations

	select_nodes (node: XML_NODE) : XML_NODE_LIST is
			-- selects the nodes specified by this xpath instance from the given context node
		do
			create Result.make (Void)
			Result.append (node)

			from
				start
			until
				off
			loop
				Result := item.apply (Result)
				forth
			end
		end

	select_first_node (node: XML_NODE) : XML_NODE is
			-- selects the first node that matches this xpath starting from the given context node
		require
			valid_node: node /= Void
		local
			new: BOOLEAN
		do
			Result := node

			from
				start
				new := True
			until
				off or before
			loop
				Result := item.apply_single (Result, new)

				if Result = Void then
					back
					new := False
				else
					forth
					new := True
				end
			end
		end

feature {NONE} -- Implementation

	split_xpath (xpath: STRING) : LIST[STRING] is
			-- splits the given xpath expression into location step strings
		local
			steps: LIST[STRING]
		do
			Result := xpath.split ('/')
		end


end