Extending Coding Rules

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Sonar provides a quick and easy way to add new coding rules directly via the web interface for certain languages (C, /C++, C#, Cobol, Flex, JavaScript, PL/I, PL/SQL, Python and PythonVB.NET).

The rules have to be written in XPath to navigate the Abstract Syntax Tree (AST). For each language, an SSLR Toolkit is provided to navigate the AST. This SSLR Toolkit is a standalone application that displays the AST for a provided piece of code source. So that you quickly get the nodes names and attributes to write your XPath expression from your code sample. The proper SSLR Toolkit can be downloaded from the language plugin page. So, finally, knowing the XPath language is the only prerequisite. A lot of tutorials on XPath can be found online (see http://www.w3schools.com/xpath/ for example).

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1. Register definitions of coding rules, when the server is started.
2. Optionally define some templates of quality profiles, when the server is started.
3. Analyze source code and inject results in database 

1. Registering

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Coding Rules

This step relates to the extension point org.sonar.api.rules.RuleRepository. A RuleRepository defines a set of coding rules. It usually loads data from a XML file:

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 <rules> 
  <!-- the format used before sonar 2.3 is still supported : attributes key and priority on the node <rule> -->
  <rule>
    <!-- unique key within this repository -->
    <key>com.puppycrawl.tools.checkstyle.checks.header.HeaderCheck</key>
    <name>Header</name>
    <!-- default priority when the rule is activated (optional, default value is MAJOR). Values are INFO, MINOR,
         MAJOR, CRITICAL, BLOCKER -->
    <priority>MAJOR</priority>

    <!-- this key is used later by the sensor to configure the code analyzer --> 
    <configKey>Checker/Header</configKey>
   
    <!-- available ISO categories : Reliability, Portability, Maintainability, Efficiency, Usability -->
    <category name="Usability"/>

    <!--
    This node is optional: default value is SINGLE.
    MULTIPLE: the rule can be activated many times with different parameters and priority.
    SINGLE: the rule can be activated once
    --> 
    <cardinality>SINGLE</cardinality>

    <description><![CDATA[Checks that ...]]></description>
    <param>
      <key>header</key>
      <description><![CDATA[the required header specified inline. Individual header lines must be separated by the string "\n" (even on platforms with a different line separator)]]></description>
    </param>
    <param>
      <key>ignore</key>
      <description>...</description>
      <defaultValue>false</defaultValue>
    </param>
  </rule>
</rules>

2. Defining

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Quality Profiles

This step relates to the extension point org.sonar.api.profiles.ProfileDefinition. Profiles Quality profiles provided by plugins are registered at server startup  and can't be edited by users:Image Removedstartup.

3. Analyzing

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Source Code

This step relates to the extension point org.sonar.api.batch.Sensor.