SXRB aims to provide nice DSL for ruby developers to cope with XML files that
are too big to be loaded at once with Nokogiri or other parser. It is based on
external SAX implementation.
DSL instructing SXRB how to treat encountered entities is very similar to one
that would be usually used to build parsed document, which makes it very easy
to represent business logic behind the code.
With SXRB one can write readable code that handles XML data, which later runs
fast and has low memory usage. DSL combines SAX robustness with DOM simplicity.
For quick start install SXRB with:
gem install sxrb
Given html variable containing string with any webpage code this piece of
code builds links Hash that contains arrays of anchor texts related to each
link.
require 'sxrb'
html = <<-HTML
<html>
<body>
<a href="https://github.com/samuil/sxrb">SXRB</a>
</body>
</html>
HTML
links = Hash.new {|h,k| h[k] = []}
SXRB::Parser.new(html) do |html|
html.descendant 'body' do |body|
body.descendant 'a' do |a|
a.on_element do |element|
links[element.attributes['href']] << element.content
end
end
end
endIf you have ever used SAX before you should be familiar with idea of event
that it provides. SXRB wraps those events, so usually you won't need them,
but they are still available. Elements in DSL provide on_start and on_end
methods, that call provided block whenever matching element is encountered (at
beginning and end of the tag respectively).
counter = 0
SXRB::Parser.new(file, :mode => :file) do |xml|
xml.descendant 'test_element' do |el|
el.on_start {counter += 1}
end
endAs you could see in above examples DSL provides on_element method which is
easy-to-use wrapper of internal SAX events. This method changes the way
parser treats incoming data when matching element is encountered. All events
within this element are used to build small DOM-like structure, which is more
comfortable than typical series of events. Please note that without additional
memory usage you can define nested on_element blocks.
- Latest SXRB gem build at rubygems.org
- SXRB documentation at yard
- Browse SXRB code at github
Right now SXRB is using LibXML implementation of SAX. Next important step
(and probably last before 1.0.0) is integration with other backends (REXML,
Nokogiri). It would also be nice to test current code against xml using
namespaces.
SXRB is in early development stage (currently released version is 0.3.0). It is not yet
production-ready, because of a bit unstable API (versioning convention is
maintained though -- minor upgrades don't break compatibility). I'm planning to
end wild development, stabilize API and have full test suite with version 1.0.0.
SXRB is distributed under MIT license (see LICENSE for details).