Class: TinyXPathHelper

Inherits:
Object
  • Object
show all
Defined in:
lib/tiny_xpath_helper.rb

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(xml, options = {}) ⇒ TinyXPathHelper

Returns a new instance of TinyXPathHelper.



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# File 'lib/tiny_xpath_helper.rb', line 6

def initialize(xml, options = {})
  @xml  = xml
  @node = self.class.xml_node_for_xmlish(xml, options)
  @options = options.freeze
end

Instance Attribute Details

#node ⇒ Object (readonly)

Returns the value of attribute node.



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# File 'lib/tiny_xpath_helper.rb', line 4

def node
  @node
end

Class Method Details

.classes_that_are_xmlish ⇒ Object 



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# File 'lib/tiny_xpath_helper.rb', line 47

def self.classes_that_are_xmlish
  io_stream_classes + [ String, REXML::Document ]
end

.default_options ⇒ Object 



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# File 'lib/tiny_xpath_helper.rb', line 80

def self.default_options
  {:format => nil, :auto_text => true, :find => :first}.freeze
end

.find_xpath_from(element, path, options = {}, &blk) ⇒ Object 



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# File 'lib/tiny_xpath_helper.rb', line 84

def self.find_xpath_from(element, path, options = {}, &blk)
  if options[:with_indifferent_access]
    path = path.to_s
  end

  options = self.default_options.dup.update(options)
  format    = options[:format]
  auto_text = options[:auto_text]
  count     = options[:find]

  if format == :array
    count     = :all
    format    = nil
  elsif format == :text
    auto_text = true
    format    = nil
  elsif format == :xml or format == :rexml
    auto_text = false
    format    = nil
  elsif format == :xpath_helper or format == :tiny_xpath_helper
    auto_text = false
    format    = self.method(:new)
  end

  filter1 = auto_text ? self.method(:xml_node_to_text) : nil
  filter2 = format

  if count   == :all
    elements = REXML::XPath.match(element, path)

  elsif count == :first
    elements  = [ REXML::XPath.first(element, path) ].compact # Haskell hacker wishing for the Maybe monad

  else 
    raise "I don't know how to find #{count.inspect}"
  end

  elements = elements.map(&filter1).map(&filter2)

  if count == :all
    r = elements
  elsif count == :first
    r = elements.first
  end

  if(blk and elements.length > 0)
    return blk.call( r )
  end

  return r

end

.io_stream_classes ⇒ Object 



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# File 'lib/tiny_xpath_helper.rb', line 43

def self.io_stream_classes
  [ IOStream ] rescue [ IO, StringIO ] # thoughtbot-paperclip fixes the ducktype mess in StringIO
end

.xml_node_for_xmlish(xml, options = {}) ⇒ Object 



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# File 'lib/tiny_xpath_helper.rb', line 51

def self.xml_node_for_xmlish( xml, options = {} )
  if io_stream_classes.any?{|k| xml.is_a?(k) }
    xml = xml.read
  end
  if xml.is_a?(String)
    xml = REXML::Document.new(xml)
  end
  if xml.is_a?(REXML::Document)
    if options[:allow_empty_document] and ! xml.root
      xml = xml
    else
      xml = xml.root
    end
  end
  if not xml.is_a?(REXML::Element)
    raise TypeError.new("Expected REXML::Element, got #{xml.class}")
  end
  return xml
end

.xml_node_to_text(node) ⇒ Object 



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# File 'lib/tiny_xpath_helper.rb', line 71

def self.xml_node_to_text(node)
  if(node.respond_to? :text)
    # XML::Elements don't to_s in the way we want
    val = node.text
  else
    val = node.to_s
  end
end

Instance Method Details

#all(xpath_expr, options = {}, &blk) ⇒ Object Also known as: [] 



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# File 'lib/tiny_xpath_helper.rb', line 38

def all(xpath_expr, options = {}, &blk)
  self.find_xpath( xpath_expr, with_options(options, :find => :all), &blk)
end

#default_options ⇒ Object 



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# File 'lib/tiny_xpath_helper.rb', line 12

def default_options
  self.class.default_options.dup.update(@options)
end

#find_xpath(xpath_expr, options = {}, &blk) ⇒ Object 



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# File 'lib/tiny_xpath_helper.rb', line 29

def find_xpath(xpath_expr, options = {}, &blk)
  self.class.find_xpath_from( node, xpath_expr, with_options(options), &blk)
end

#first(xpath_expr, options = {}, &blk) ⇒ Object Also known as: at 



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# File 'lib/tiny_xpath_helper.rb', line 33

def first(xpath_expr, options = {}, &blk)
  self.find_xpath( xpath_expr, with_options(options, :find => :first), &blk)
end

#with_options(*options) ⇒ Object 



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# File 'lib/tiny_xpath_helper.rb', line 16

def with_options(*options)
  r = default_options.dup

  options.reverse.each do |option|
    if not option.is_a?( Hash )
      option = {:format => option}
    end
    r.update(option)
  end

  return r
end