Class: Nokogiri::XML::XPathContext

Inherits:
Object
  • Object
show all
Defined in:
lib/nokogiri/xml/xpath_context.rb,
lib/nokogiri/ffi/xml/xpath_context.rb,
ext/nokogiri/xml_xpath_context.c

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Instance Attribute Details

#cstruct ⇒ Object

:nodoc:



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# File 'lib/nokogiri/ffi/xml/xpath_context.rb', line 5

def cstruct
  @cstruct
end

Class Method Details

.new(node) ⇒ Object

Create a new XPathContext with node as the reference point.



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# File 'lib/nokogiri/ffi/xml/xpath_context.rb', line 50

def self.new(node) # :nodoc:
  LibXML.xmlXPathInit()

  ptr = LibXML.xmlXPathNewContext(node.cstruct[:doc])

  ctx = allocate
  ctx.cstruct = LibXML::XmlXpathContext.new(ptr)
  ctx.cstruct[:node] = node.cstruct
  ctx
end

Instance Method Details

#evaluate(search_path) ⇒ Object

Evaluate the search_path returning an XML::XPath object.



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# File 'lib/nokogiri/ffi/xml/xpath_context.rb', line 11

def evaluate(search_path, xpath_handler=nil) # :nodoc:
  lookup = nil # to keep lambda in scope long enough to avoid a possible GC tragedy
  query = search_path.to_s

  if xpath_handler
    lookup = lambda do |ctx, name, uri|
      return nil unless xpath_handler.respond_to?(name)
      ruby_funcall name, xpath_handler
    end
    LibXML.xmlXPathRegisterFuncLookup(cstruct, lookup, nil);
  end

  exception_handler = lambda do |ctx, error|
    raise XPath::SyntaxError.wrap(error)
  end
  LibXML.xmlResetLastError()
  LibXML.xmlSetStructuredErrorFunc(nil, exception_handler)

  generic_exception_handler = lambda do |ctx, msg|
    raise RuntimeError.new(msg) # TODO: varargs
  end
  LibXML.xmlSetGenericErrorFunc(nil, generic_exception_handler)

  xpath_ptr = LibXML.xmlXPathEvalExpression(query, cstruct)

  LibXML.xmlSetStructuredErrorFunc(nil, nil)
  LibXML.xmlSetGenericErrorFunc(nil, nil)

  if xpath_ptr.null?
    error = LibXML.xmlGetLastError()
    raise XPath::SyntaxError.wrap(error)
  end

  xpath = XML::XPath.new
  xpath.cstruct = LibXML::XmlXpathObject.new(xpath_ptr)
  xpath.document = cstruct[:doc]
  xpath
end

#register_namespaces(namespaces) ⇒ Object

Register namespaces in namespaces



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# File 'lib/nokogiri/xml/xpath_context.rb', line 7

def register_namespaces(namespaces)
  namespaces.each do |k, v|
    k = k.gsub(/.*:/,'') # strip off 'xmlns:' or 'xml:'
    register_ns(k, v)
  end
end

#register_ns(prefix, uri) ⇒ Object

Register the namespace with prefix and uri.



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# File 'lib/nokogiri/ffi/xml/xpath_context.rb', line 7

def register_ns(prefix, uri) # :nodoc:
  LibXML.xmlXPathRegisterNs(cstruct, prefix, uri)
end