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<!DOCTYPE html>
<html lang="en">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
<title>Diggernaut: Documentation for Meta-Language | Working with DOM | Sequences</title>
<meta name="description" content="Splitting the content into logical blocks using sequences.">
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<h1>Methods for Working with DOM</h1>
<div>
<h2>Sequences</h2>
<p class="flow-text">
Sometimes it is required to divide the sequence of nodes into logical blocks using the header
(the leading node of the logical block) or the footer (the final node of the logical block). For this operation
you can use the <span class = "hlt2">sequence</span> command. This command, unlike a <span class = "hlt2">split</span> command, works with the nodes
of the current block, so as parameters you will have to pass CSS selectors.
</p>
<p class="flow-text">
Following parameters can be used with the command:
</p>
<table class="responsive-table highlight">
<thead>
<tr>
<th data-field="parameter">Parameter</th>
<th data-field="description">Description</th>
</tr>
</thead>
<tbody>
<tr>
<td class="centered">selector</td>
<td>Selectors for nodes that must be selected in the current block. Bear in mind that the nodes,
used as a header or a footer, should also be selected by selectors in this parameter.
</td>
</tr>
<tr>
<td>header</td>
<td>A selector for nodes that will be used as header of logical blocks. If you are using
this parameter, the <span class = "hlt">footer</span> parameter will be ignored if it is also passed.
</td>
</tr>
<tr>
<td>footer</td>
<td>A selector for nodes that will be used as footer of logical blocks. If you are passing also the <span class = "hlt">header</span>
parameter, this parameter will be ignored.
</td>
</tr>
</tbody>
</table>
<p class="flow-text">
Let's use following HTML source for our examples:
</p>
<pre class="language-markup">
<code class="language-markup"><div>
<h1>Some title</h1>
<p>Some text 1</p>
<p>Some text 1 - 1</p>
<p class="footer">My footer</p>
<h1>Some other title</h1>
<p>Some text 2</p>
<p class="footer">My other footer</p>
<h1>Another title</h1>
<p>Some text 2</p>
<p>Final p</p>
<p class="footer">My last footer</p>
</div>
</code></pre>
<p class="flow-text">
As you can see, we can take the tag <span class = "hlt">h1</span> as a header node for splitting into additional
blocks in this example, or <span class = "hlt">p</span> tag with the <span class = "hlt">footer</span> class as a footer.
</p>
<p class="flow-text">
Now, let's try to split the common <span class = "hlt">div</span> block into a set of separate, independent blocks. <br/>
Let's take a closer look at the examples:
</p>
<div class="row">
<div class="col s12">
<ul class="tabs excdark">
<li class="tab col s6"><a class="active" href="#header">Split by header</a></li>
<li class="tab col s6"><a href="#footer">Split by footer</a></li>
</ul>
</div>
<div id="header" class="col s12">
<pre class="language-yaml">
<code class="language-yaml">- find:
path: div
do:
- sequence:
selector: p,h1
header: h1
# WE WILL GET NEW BLOCK CREATED BY COMMAND `sequence`
# WITH FOLLOWING HTML CONTENTS:
# <div class="sequence element_0">
# <h1>Some title</h1>
# <p>Some text 1</p>
# <p>Some text 1 - 1</p>
# <p class="footer">My footer</p>
# </div>
# <div class="sequence element_1">
# <h1>Some other title</h1>
# <p>Some text 2</p>
# <p class="footer">My other footer</p>
# </div>
# <div class="sequence element_2">
# <h1>Another title</h1>
# <p>Some text 2</p>
# <p>Final p</p>
# <p class="footer">My last footer</p>
# </div>
# LETS EXTRACT HEADER OF LAST ELEMENT OF SPLITTED BLOCKS
- find:
path: .sequence > h1
slice: -1
do:
- parse
# REGISTER VALUE: Another title
</code></pre>
</div>
<div id="footer" class="col s12">
<pre class="language-yaml">
<code class="language-yaml">- find:
path: div
do:
- sequence:
selector: p
footer: p.footer
# WE WILL GET NEW BLOCK CREATED BY COMMAND `sequence`
# WITH FOLLOWING HTML CONTENTS:
# <div class="sequence element_0">
# <p>Some text 1</p>
# <p>Some text 1 - 1</p>
# <p class="footer">My footer</p>
# </div>
# <div class="sequence element_1">
# <p>Some text 2</p>
# <p class="footer">My other footer</p>
# </div>
# <div class="sequence element_2">
# <p>Some text 2</p>
# <p>Final p</p>
# <p class="footer">My last footer</p>
# </div>
# LETS EXTRACT FOOTER OF LAST ELEMENT OF SPLITTED BLOCKS
- find:
path: .sequence > p.footer
slice: -1
do:
- parse
# REGISTER VALUE: My last footer
</code></pre>
</div>
</div>
<p class="flow-text">
In the next chapter, we will learn how to create a new block from the contents of the register.
</p>
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