Lexbor

Fast HTML5 Parser with CSS selectors (based on lexborisov's HTML5 parser lexbor). This is successor of myhtml and expected to be faster and use less memory. Usage is almost equal to myhtml.

Installation

Install dependency cmake:

sudo apt install cmake

Install dependency build-essential:

sudo apt install build-essential

Add this to your application's shard.yml:

dependencies:
  lexbor:
    github: kostya/lexbor

Usage example

require "lexbor"

html = <<-HTML
  <html>
    <body>
      <div id="t1" class="red">
        <a href="/#">O_o</a>
      </div>
      <div id="t2"></div>
    </body>
  </html>
HTML

lexbor = Lexbor::Parser.new(html)

lexbor.nodes(:div).each do |node|
  id = node["id"]?

  if first_link = node.scope.nodes(:a).first?
    href = first_link["href"]?
    link_text = first_link.inner_text

    puts "div with id #{id} have link [#{link_text}](#{href})"
  else
    puts "div with id #{id} have no links"
  end
end

# Output:
#   div with id t1 have link [O_o](/#)
#   div with id t2 have no links

Css selectors example

require "lexbor"

html = <<-HTML
  <html>
    <body>
      <table id="t1">
        <tr><td>Hello</td></tr>
      </table>
      <table id="t2">
        <tr><td>123</td><td>other</td></tr>
        <tr><td>foo</td><td>columns</td></tr>
        <tr><td>bar</td><td>are</td></tr>
        <tr><td>xyz</td><td>ignored</td></tr>
      </table>
    </body>
  </html>
HTML

lexbor = Lexbor::Parser.new(html)

p lexbor.css("#t2 tr td:first-child").map(&.inner_text).to_a
# => ["123", "foo", "bar", "xyz"]

p lexbor.css("#t2 tr td:first-child").map(&.to_html).to_a
# => ["<td>123</td>", "<td>foo</td>", "<td>bar</td>", "<td>xyz</td>"]

More Examples

examples

Development Setup:

git clone https://github.com/kostya/lexbor.git
cd lexbor
crystal src/ext/build_ext.cr
crystal spec

Benchmark

Parse google results page(1.5Mb) 1000 times, and 5000 times css select.

lexbor-program myhtml-program crystagiri-program nokogiri-program

Running on Ryzen 3800x.

Lang	Lib	Parse time, s	Css time, s	Memory, MiB
Ruby 2.7	Nokolexbor(lexbor)	4.07	1.80	112.5
Crystal	lexbor	4.75	0.80	12.3
Crystal	myhtml(+modest)	5.98	1.22	12.2
Crystal	Crystagiri(libxml2)	14.20	-	31.7
Ruby 2.7	Nokogiri(libxml2)	18.67	92.69	398.4

Running on Apple M1.

Lang	Lib	Parse time, s	Css time, s	Memory, MiB
Crystal	lexbor	2.77	0.62	26.4
Ruby 2.7	Nokolexbor(lexbor)	3.41	1.11	268.8
Ruby 2.7	Nokogiri(libxml2)	18.22	87.21	232.8
Crystal	Crystagiri(libxml2)	126.25	-	26.8