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<h1 id="processor"><a class="header" href="#processor">Processor</a></h1>
<p>The processor replaces TODO comments in source files with GitHub issue links after issues are created.</p>
<h2 id="processor-1"><a class="header" href="#processor-1"><code>Processor</code></a></h2>
<pre><pre class="playground"><code class="language-rust"><span class="boring">#![allow(unused)]
</span><span class="boring">fn main() {
</span>pub struct Processor;
<span class="boring">}</span></code></pre></pre>
<p>Stateless processor that operates on batches of <code>(TodoComment, CreatedIssue)</code> pairs. All methods are associated functions (no <code>self</code>).</p>
<h3 id="replace_todos"><a class="header" href="#replace_todos"><code>replace_todos</code></a></h3>
<pre><pre class="playground"><code class="language-rust"><span class="boring">#![allow(unused)]
</span><span class="boring">fn main() {
</span>pub async fn replace_todos(
repo_root: &Path,
replacements: &[(TodoComment, CreatedIssue)],
) -> ProcessorResult
<span class="boring">}</span></code></pre></pre>
<p>Replaces TODO comments in source files with <code>GH_ISSUE: <issue_url></code> links.</p>
<p><strong>Behaviour:</strong></p>
<ol>
<li>Groups replacements by file path for efficient batch processing</li>
<li>For each file, validates the path stays within <code>repo_root</code></li>
<li>Reads file content, replaces each TODO line, writes back atomically</li>
<li>Returns a <code>ProcessorResult</code> with counts and per-file errors</li>
</ol>
<p><strong>Path safety:</strong></p>
<ul>
<li>Both the file path and repo root are canonicalised before comparison</li>
<li>Files outside the repo root are rejected with <code>PathOutsideRoot</code></li>
<li>Issue URLs must start with <code>https://github.com/</code> or are rejected</li>
</ul>
<p><strong>Replacement format:</strong></p>
<p>The comment prefix (e.g., <code>// </code>, <code># </code>, <code>/* </code>) is preserved. The TODO text after the prefix is replaced:</p>
<pre><code class="language-text">// TODO: Implement caching --> // GH_ISSUE: https://github.com/owner/repo/issues/42
# FIXME: Handle timeout --> # GH_ISSUE: https://github.com/owner/repo/issues/43
</code></pre>
<p><strong>Atomic writes:</strong></p>
<p>Files are written via a tempfile in the same directory, then atomically persisted. This prevents partial writes if the process is interrupted.</p>
<p><strong>Empty input:</strong></p>
<p>If <code>replacements</code> is empty, returns immediately with zero counts and no I/O.</p>
<h2 id="processorresult"><a class="header" href="#processorresult"><code>ProcessorResult</code></a></h2>
<pre><pre class="playground"><code class="language-rust"><span class="boring">#![allow(unused)]
</span><span class="boring">fn main() {
</span>pub struct ProcessorResult {
pub files_modified: usize,
pub todos_replaced: usize,
pub errors: Vec<(PathBuf, TowlProcessorError)>,
}
<span class="boring">}</span></code></pre></pre>
<p>Summary of a batch replacement operation. The <code>errors</code> field contains per-file errors that did not abort the overall operation -- other files continue processing.</p>
<h2 id="errors"><a class="header" href="#errors">Errors</a></h2>
<pre><pre class="playground"><code class="language-rust"><span class="boring">#![allow(unused)]
</span><span class="boring">fn main() {
</span>pub enum TowlProcessorError {
FileReadError(PathBuf, std::io::Error),
FileWriteError(PathBuf, std::io::Error),
LineOutOfBounds { path: PathBuf, line: usize, total_lines: usize },
CommentPrefixNotFound { path: PathBuf, line: usize },
PathOutsideRoot { path: PathBuf, root: PathBuf },
InvalidIssueUrl { url: String },
}
<span class="boring">}</span></code></pre></pre>
<div class="table-wrapper"><table><thead><tr><th>Variant</th><th>Cause</th></tr></thead><tbody>
<tr><td><code>FileReadError</code></td><td>Failed to read source file</td></tr>
<tr><td><code>FileWriteError</code></td><td>Failed to write modified file</td></tr>
<tr><td><code>LineOutOfBounds</code></td><td>TODO line number exceeds file length</td></tr>
<tr><td><code>CommentPrefixNotFound</code></td><td>Column offset points past end of line</td></tr>
<tr><td><code>PathOutsideRoot</code></td><td>File is outside the repository root</td></tr>
<tr><td><code>InvalidIssueUrl</code></td><td>URL does not start with <code>https://github.com/</code></td></tr>
</tbody></table>
</div>
<h2 id="example"><a class="header" href="#example">Example</a></h2>
<pre><pre class="playground"><code class="language-rust no_run"><span class="boring">#![allow(unused)]
</span><span class="boring">fn main() {
</span>use towl::processor::Processor;
let replacements = vec![(todo, created_issue)];
let result = Processor::replace_todos(repo_root, &replacements).await;
println!("Modified {} files, replaced {} TODOs", result.files_modified, result.todos_replaced);
for (path, err) in &result.errors {
eprintln!("Error in {}: {}", path.display(), err);
}
<span class="boring">}</span></code></pre></pre>
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