Nokolexbor

Nokolexbor is a drop-in replacement for Nokogiri. It's 5.2x faster at parsing HTML and up to 997x faster at CSS selectors.

It's a performance-focused HTML5 parser for Ruby based on Lexbor. It supports both CSS selectors and XPath. Nokolexbor's API is designed to be 1:1 compatible as much as possible with Nokogiri's API.

Requirements

Nokolexbor is shipped with pre-compiled gems on most common platforms:

Linux: x86_64, with glibc >= 2.17
macOS: x86_64 and arm64
Windows: ucrt64, mingw32 and mingw64

If you are on a supported platform, just jump to the Installation section. Otherwise, you need to install CMake to compile C extensions:

macOS

brew install cmake

Linux (Debian, Ubuntu, etc.)

sudo apt-get install cmake

Installation

Add to your Gemfile:

gem 'nokolexbor'

Then, run bundle install.

Or, install the gem directly:

gem install nokolexbor

Quick start

require 'nokolexbor'
require 'open-uri'

# Parse HTML document
doc = Nokolexbor::HTML(URI.open('https://github.com/serpapi/nokolexbor'))

# Search for nodes by css
doc.css('#readme h1', 'article h2', 'p[dir=auto]').each do |node|
  puts node.content
end

# Search for text nodes by css
doc.css('#readme p > ::text').each do |text|
  puts text.content
end

# Search for nodes by xpath
doc.xpath('//div[@id="readme"]//h1', '//article//h2').each do |node|
  puts node.content
end

Features

Nokogiri-compatible APIs.
High performance HTML parsing, DOM manipulation and CSS selectors engine.
XPath search engine (ported from libxml2).
Text nodes CSS selector support: ::text.

Searching methods overview

css and at_css
- Based on Lexbor.
- Only accepts CSS selectors, doesn't support mixed syntax like div#abc /text().
- To select text nodes, use pseudo element ::text. e.g. div#abc > ::text.
- Performance is much higher than libxml2 based methods.
xpath and at_xpath
- Based on libxml2.
- Only accepts XPath syntax.
- Works in the same way as Nokogiri's xpath and at_xpath.
nokogiri_css and nokogiri_at_css (requires Nokogiri installed)
- Based on libxml2.
- Accept mixed syntax like div#abc /text().
- Works in the same way as Nokogiri's css and at_css.

Different behaviors from Nokogiri

For selector :nth-of-type(n), n is not affected by prior filter. For example, if we want to select the 3rd div excluding class a and class b, which will be the last div in the following HTML:
```
<body>
  <div></div>
  <div class="a"></div>
  <div class="b"></div>
  <div></div>
  <div></div>
</body>
```
In Nokogiri, the selector should be div:not(.a):not(.b):nth-of-type(3)

In Nokolexbor, :not does affect the place of the last div (same in browsers), the selector should be div:not(.a):not(.b):nth-of-type(5), but this losts the purpose of filtering though.

Benchmarks

Benchmark parsing google result page (368 KB) and selecting nodes using CSS and XPath. Run on MacBook Pro (2019) 2.3 GHz 8-Core Intel Core i9.

Run with: ruby bench/bench.rb

	Nokolexbor (iters/s)	Nokogiri (iters/s)	Diff
parsing	487.6	93.5	5.22x faster
at_css	50798.8	50.9	997.87x faster
css	7437.6	52.3	142.11x faster
at_xpath	57.077	53.176	same-ish
xpath	51.523	58.438	same-ish

Raw data

Warming up --------------------------------------
    Nokolexbor parse    56.000  i/100ms
      Nokogiri parse     8.000  i/100ms
Calculating -------------------------------------
    Nokolexbor parse    487.564  (±10.9%) i/s -      9.688k in  20.117173s
      Nokogiri parse     93.470  (±21.4%) i/s -      1.736k in  20.024163s

Comparison:
    Nokolexbor parse:      487.6 i/s
      Nokogiri parse:       93.5 i/s - 5.22x  (± 0.00) slower

Warming up --------------------------------------
   Nokolexbor at_css     5.548k i/100ms
     Nokogiri at_css     6.000  i/100ms
Calculating -------------------------------------
   Nokolexbor at_css     50.799k (±13.8%) i/s -    987.544k in  20.018481s
     Nokogiri at_css     50.907  (±35.4%) i/s -    828.000  in  20.666258s

Comparison:
   Nokolexbor at_css:    50798.8 i/s
     Nokogiri at_css:       50.9 i/s - 997.87x  (± 0.00) slower

Warming up --------------------------------------
      Nokolexbor css   709.000  i/100ms
        Nokogiri css     4.000  i/100ms
Calculating -------------------------------------
      Nokolexbor css      7.438k (±14.7%) i/s -    145.345k in  20.083833s
        Nokogiri css     52.338  (±36.3%) i/s -    816.000  in  20.042053s

Comparison:
      Nokolexbor css:     7437.6 i/s
        Nokogiri css:       52.3 i/s - 142.11x  (± 0.00) slower

Warming up --------------------------------------
 Nokolexbor at_xpath     2.000  i/100ms
   Nokogiri at_xpath     4.000  i/100ms
Calculating -------------------------------------
 Nokolexbor at_xpath     57.077  (±31.5%) i/s -    920.000  in  20.156393s
   Nokogiri at_xpath     53.176  (±35.7%) i/s -    876.000  in  20.036717s

Comparison:
 Nokolexbor at_xpath:       57.1 i/s
   Nokogiri at_xpath:       53.2 i/s - same-ish: difference falls within error

Warming up --------------------------------------
    Nokolexbor xpath     3.000  i/100ms
      Nokogiri xpath     3.000  i/100ms
Calculating -------------------------------------
    Nokolexbor xpath     51.523  (±31.1%) i/s -    903.000  in  20.102568s
      Nokogiri xpath     58.438  (±35.9%) i/s -    852.000  in  20.001408s

Comparison:
      Nokogiri xpath:       58.4 i/s
    Nokolexbor xpath:       51.5 i/s - same-ish: difference falls within error

serpapi/nokolexbor

serpapi

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