晋太元中，武陵人捕鱼为业。缘溪行，忘路之远近。忽逢桃花林，夹岸数百步，中无杂树，芳草鲜美，落英缤纷。渔人甚异之，复前行，欲穷其林。 　　林尽水源，便得一山，山有小口，仿佛若有光。便舍船，从口入。初极狭，才通人。复行数十步，豁然开朗。土地平旷，屋舍俨然，有良田、美池、桑竹之属。阡陌交通，鸡犬相闻。其中往来种作，男女衣着，悉如外人。黄发垂髫，并怡然自乐。 　　见渔人，乃大惊，问所从来。具答之。便要还家，设酒杀鸡作食。村中闻有此人，咸来问讯。自云先世避秦时乱，率妻子邑人来此绝境，不复出焉，遂与外人间隔。问今是何世，乃不知有汉，无论魏晋。此人一一为具言所闻，皆叹惋。余人各复延至其家，皆出酒食。停数日，辞去。此中人语云：“不足为外人道也。”(间隔 一作：隔绝) 　　既出，得其船，便扶向路，处处志之。及郡下，诣太守，说如此。太守即遣人随其往，寻向所志，遂迷，不复得路。 　　南阳刘子骥，高尚士也，闻之，欣然规往。未果，寻病终。后遂无问津者。 sh-3ll

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DIR:/opt/alt/ruby27/share/ruby/rexml/
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Current File : //opt/alt/ruby27/share/ruby/rexml/xpath.rb
# frozen_string_literal: false
require_relative 'functions'
require_relative 'xpath_parser'

module REXML
  # Wrapper class.  Use this class to access the XPath functions.
  class XPath
    include Functions
    # 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.
    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.
    # 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"})
    def XPath::first(element, path=nil, namespaces=nil, variables={}, options={})
      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(**options)
      parser.namespaces = namespaces
      parser.variables = variables
      path = "*" unless path
      element = [element] unless element.kind_of? Array
      parser.parse(path, element).flatten[0]
    end

    # 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| ... }
    def XPath::each(element, path=nil, namespaces=nil, variables={}, options={}, &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(**options)
      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={}, options={})
      parser = XPathParser.new(**options)
      parser.namespaces = namespaces
      parser.variables = variables
      path = "*" unless path
      element = [element] unless element.kind_of? Array
      parser.parse(path,element)
    end
  end
end