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» How PMD Works
<a
target="_blank"
href="https://github.com/pmd/pmd/blob/main/docs/pages/pmd/devdocs/how_pmd_works.md"
class="float-right"
role="button"
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>
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<div class="post-header">
<h1 class="post-title-main">How PMD Works</h1>
</div>
<div class="post-content" data-github-edit-url="https://github.com/pmd/pmd/blob/main/docs/pages/pmd/devdocs/how_pmd_works.md">
<div class="summary">Processing overview of the different steps taken by PMD.</div>
<details id="inline-toc-details">
<summary>Table of Contents</summary>
<div id="inline-toc"><!-- empty, move TOC here when screen size too small --></div>
</details>
<h2 id="overview">Overview</h2>
<p>The processing starts with the main class <a href="https://docs.pmd-code.org/apidocs/pmd-core/7.8.0-SNAPSHOT/net/sourceforge/pmd/PmdAnalysis.html#"><code>PmdAnalysis</code></a>.</p>
<ul>
<li>Parse command line parameters (see net.sourceforge.pmd.cli.PMDParameters)
Also load the incremental analysis cache file</li>
<li>Load rulesets/rules</li>
<li>Determine languages (rules of different languages might be mixed in rulesets)</li>
<li>Determine files (uses the given source directory, filter by the languages file extensions)</li>
<li>Prepare the renderer</li>
<li>Sort the files by name</li>
<li>Check whether we can use the incremental analysis cache (if the rulesets changed, it will be invalid)</li>
<li>Prepare the SourceCodeProcessor based on the configuration</li>
<li>Analyze the files. Either single threaded or multi-threaded parallel. This task is encapsulated
in <code class="language-plaintext highlighter-rouge">net.sourceforge.pmd.processor.PMDRunnable</code>:
<ul>
<li>Create input stream</li>
<li>Call source code processor (<code class="language-plaintext highlighter-rouge">net.sourceforge.pmd.SourceCodeProcessor</code>):
<ol>
<li>Determine the language</li>
<li>Check whether the file is already analyzed and a result is available from the analysis cache</li>
<li>Parse the source code. Result is the root AST node.</li>
<li>Always run the SymbolFacade visitor. It builds scopes, finds declarations and usages.</li>
<li>Run DFA (data flow analysis) visitor (if at least one rule requires it) for building
control flow graphs and data flow nodes.</li>
<li>Run TypeResolution visitor (if at least one rule requires it)</li>
<li>FUTURE: Run multifile analysis (if at least one rule requires it)</li>
<li>Execute the rules:
<ul>
<li>First run the rules that opted in for the rule chain mechanism</li>
<li>Run all the other rules and let them traverse the AST. The rules can use the symbol table,
type resolution information and DFA nodes.</li>
<li>The rules will report found problems as RuleViolations.</li>
</ul>
</li>
</ol>
</li>
</ul>
</li>
<li>Render the found violations into the wanted format (XML, text, HTML, …)</li>
<li>Store the incremental analysis cache</li>
<li>Depending on the number of violations found, exit with code 0 or 4.</li>
</ul>
<div class="tags">
<b>Tags: </b>
<a href="tag_devdocs.html" class="btn btn-outline-secondary navbar-btn cursorNorm" role="button">devdocs</a>
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This documentation is written in markdown. <br />
If there is something missing or can be improved, edit this page on
github and create a PR:
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