CSS selectors for HTML5 Parser myhtml (Crystal wrapper for https://github.com/lexborisov/Modest).
Add this to your application's shard.yml:
dependencies:
modest:
github: kostya/modestrequire "modest"
page = <<-PAGE
<html>
<div class=aaa><p id=bbb><a href="http://..." class=ccc>bla</a></div>
</html>
PAGE
myhtml = Myhtml::Parser.new(page)
# css select from the root! scope (equal with myhtml.root!.css("..."))
iterator = myhtml.css("div.aaa p#bbb a.ccc") # => Iterator(Myhtml::Node), methods: .each, .to_a, ...
iterator.each do |node|
p node.tag_id # MyHTML_TAG_A
p node.tag_name # "a"
p node.tag_sym # :a
p node.attributes["href"]? # "http://..."
p node.inner_text # "bla"
puts node.to_html # <a href="http://..." class="ccc">bla</a>
end
# css select from node scope
if p_node = myhtml.css("div.aaa p#bbb").first?
p_node.css("a.ccc").each do |node|
p node.tag_sym # :a
end
end
require "modest"
html = <<-PAGE
<div>
<p id=p1>
<p id=p2 class=jo>
<p id=p3>
<a href="some.html" id=a1>link1</a>
<a href="some.png" id=a2>link2</a>
<div id=bla>
<p id=p4 class=jo>
<p id=p5 class=bu>
<p id=p6 class=jo>
</div>
</div>
PAGE
parser = Myhtml::Parser.new(html)
# select all p nodes which id like `*p*`
p parser.css("p[id*=p]").map(&.attribute_by("id")).to_a # => ["p1", "p2", "p3", "p4", "p5", "p6"]
# select all nodes with class "jo"
p parser.css("p.jo").map(&.attribute_by("id")).to_a # => ["p2", "p4", "p6"]
p parser.css(".jo").map(&.attribute_by("id")).to_a # => ["p2", "p4", "p6"]
# select odd child tag inside div, which not contain a
p parser.css("div > :nth-child(2n+1):not(:has(a))").map(&.attribute_by("id")).to_a # => ["p1", "p4", "p6"]
# all elements with class=jo inside last div tag
p parser.css("div").to_a.last.css(".jo").map(&.attribute_by("id")).to_a # => ["p4", "p6"]
# a element with href ends like .png
p parser.css(%q{a[href$=".png"]}).map(&.attribute_by("id")).to_a # => ["a2"]
# find all a tags inside <p id=p3>, which href contain `html`
p parser.css(%q{p[id=p3] > a[href*="html"]}).map(&.attribute_by("id")).to_a # => ["a1"]
# find all a tags inside <p id=p3>, which href contain `html` or ends_with `.png`
p parser.css(%q{p[id=p3] > a:matches([href *= "html"], [href $= ".png"])}).map(&.attribute_by("id")).to_a # => ["a1", "a2"]
# create finder and use it in many places, this is faster, than create it many times
finder = Modest::Finder.new(".jo")
p parser.css(finder).map(&.attribute_by("id")).to_a # => ["p2", "p4", "p6"]require "modest"
html = <<-PAGE
<html><body>
<table id="t1"><tbody>
<tr><td>Hello</td></tr>
</tbody></table>
<table id="t2"><tbody>
<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>
</tbody></table>
</body></html>
PAGE
parser = Myhtml::Parser.new(html)
p parser.css("#t2 tr td:first-child").map(&.inner_text).to_a # => ["123", "foo", "bar", "xyz"]
p parser.css("#t2 tr td:first-child").map(&.to_html).to_a # => ["<td>123</td>", "<td>foo</td>", "<td>bar</td>", "<td>xyz</td>"]Comparing with nokorigi(libxml), and crystagiri(libxml). Parse 1000 times google page, code: https://github.com/kostya/modest/tree/master/bench
require "modest"
page = File.read("./google.html")
s = 0
links = [] of String
1000.times do
myhtml = Myhtml::Parser.new(page)
links = myhtml.css("div.g h3.r a").map(&.attribute_by("href")).to_a
s += links.size
myhtml.free
end
p links.last
p sParse + Selectors
| Lang | Package | Time, s | Memory, MiB |
|---|---|---|---|
| Crystal | modest(myhtml) | 2.52 | 7.7 |
| Crystal | Crystagiri(LibXML) | 19.89 | 14.3 |
| Ruby 2.2 | Nokogiri(LibXML) | 45.05 | 136.2 |
Selectors Only (files with suffix 2)
| Lang | Package | Time, s | Memory, MiB |
|---|---|---|---|
| Crystal | modest(myhtml) | 0.18 | 4.6 |
| Crystal | Crystagiri(LibXML) | 12.30 | 6.6 |
| Ruby 2.2 | Nokogiri(LibXML) | 28.06 | 68.8 |