Author: sebb
Date: Tue Dec 15 15:59:12 2009
New Revision: 890851
URL: http://svn.apache.org/viewvc?rev=890851&view=rev
Log:
Improve RE docs
Modified:
jakarta/jmeter/trunk/xdocs/usermanual/regular_expressions.xml
Modified: jakarta/jmeter/trunk/xdocs/usermanual/regular_expressions.xml
URL:
http://svn.apache.org/viewvc/jakarta/jmeter/trunk/xdocs/usermanual/regular_expressions.xml?rev=890851&r1=890850&r2=890851&view=diff
==============================================================================
--- jakarta/jmeter/trunk/xdocs/usermanual/regular_expressions.xml (original)
+++ jakarta/jmeter/trunk/xdocs/usermanual/regular_expressions.xml Tue Dec 15
15:59:12 2009
@@ -74,36 +74,51 @@
</p>
</subsection>
<subsection name="§-num;.2 Examples" anchor="examples">
+<h3>Extract single string</h3>
<p>
-Extract single string
-<br/>
Suppose you want to match the following portion of a web-page:
<br/>
-name="file" value="readme.txt" and you want to extract readme.txt.
+<code>name="file" value="readme.txt"></code>
<br/>
-A suitable reqular expression would be:
+and you want to extract <code>readme.txt</code>.
+<br/>
+A suitable regular expression would be:
<br/>
-name="file" value="(.+?)"
+<code>name="file" value="(.+?)"></code>
<p>
The special characters above are:
</p>
<ul>
<li>( and ) - these enclose the portion of the match string to be returned</li>
-<li>. - match any character. + - one or more times.
-? - don't be greedy, i.e. stop when first match succeeds</li>
+<li>. - match any character</li>
+<li>+ - one or more times</li>
+<li>? - don't be greedy, i.e. stop when first match succeeds</li>
</ul>
<p>
-Note: without the ?, the .+ would continue past the first " until it found the
last possible " - probably not what was intended.
+Note: without the ?, the .+ would continue past the first <code>"></code>
+until it found the last possible <code>"></code> - which is probably not what
was intended.
</p>
-<p>Extract multiple strings</p>
-
-Suppose you want to match the following portion of a web-page:
name="file.name" value="readme.txt" and you want to extract file.name and
readme.txt.
+<p>
+Note: although the above expression works, it's more efficient to use the
following expression:
+<br/>
+<code>name="file" value="([^"]+)"></code>
+where<br></br>
+[^"] - means match anything except "<br></br>
+In this case, the matching engine can stop looking as soon as it sees the
first <code>"</code>,
+whereas in the previous case the engine has to check that it has found
<code>"></code> rather than say <code>" ></code>.
+</p>
+<h3>Extract multiple strings</h3>
+<p>
+Suppose you want to match the following portion of a web-page:<br/>
+<code>name="file.name" value="readme.txt"</code>
+and you want to extract both <code>file.name</code> and
<code>readme.txt</code>.
<br/>
A suitable reqular expression would be:
<br/>
-name="(.+?)" value="(.+?)"
+<code>name="([^"]+)" value="([^"]+)"</code>
<br/>
This would create 2 groups, which could be used in the JMeter Regular
Expression Extractor template as $1$ and $2$.
+</p>
<p>
The JMeter Regex Extractor saves the values of the groups in additional
variables.
</p>
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