<stránka

	xmlns="https://trac.frantovo.cz/xml-web-generator/wiki/xmlns/strana"

	xmlns:m="https://trac.frantovo.cz/xml-web-generator/wiki/xmlns/makro">

	<nadpis>Using relpipe-tr-sed with groups and backreferences</nadpis>

	<perex>sed-like substitution with regex groups and backreferences</perex>

	<m:pořadí-příkladu>00800</m:pořadí-příkladu>

	<text xmlns="http://www.w3.org/1999/xhtml">

		<p>

			This tool also support regex groups and backreferences. Thus we can use parts of the matched string in our replacement string:

		</p>

		<m:pre jazyk="bash"><![CDATA[relpipe-in-cli \

	--relation 'r' \

		--attribute 'a' string \

		--record 'some string xxx_123 some zzz_456 other' \

	| relpipe-tr-sed \

		--relation 'r' \

			--attribute 'a' \

			--value '([a-z]{3})_([0-9]+)' \

			--replacement '$2:$1' \

	| relpipe-out-tabular]]></m:pre>

		<p>Which would convert this:</p>

		<pre><![CDATA[r:

 ╭────────────────────────────────────────╮

 │ a                             (string) │

 ├────────────────────────────────────────┤

 │ some string xxx_123 some zzz_456 other │

 ╰────────────────────────────────────────╯

Record count: 1]]></pre>

		<p>into this:</p>

		<pre><![CDATA[r:

 ╭────────────────────────────────────────╮

 │ a                             (string) │

 ├────────────────────────────────────────┤

 │ some string 123:xxx some 456:zzz other │

 ╰────────────────────────────────────────╯

Record count: 1]]></pre>

		<p>

			If there were any other relations or attributes in the stream, they would be unaffected by this transformation,

			becase we specified <code>'r' 'a'</code> instead of some wider regular expression that would match more relations or attributes.

		</p>

	</text>

</stránka>