1 files changed, 59 insertions, 0 deletions
diff --git a/scripts/plugin-stub-generator/src/Project.php b/scripts/plugin-stub-generator/src/Project.php
new file mode 100644
index 00000000..13f1067d
--- /dev/null
+++ b/scripts/plugin-stub-generator/src/Project.php
@@ -0,0 +1,59 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Shirabe\PluginStubGenerator;
+
+use PhpParser\Parser;
+use PhpParser\ParserFactory;
+
+/**
+ * Locates and parses classes of the Composer checkout (composer/src and composer/vendor),
+ * using the checkout's own PSR-4 autoload map.
+ */
+final class Project
+{
+    private Parser $parser;
+
+    /** @var array<string, list<string>> namespace prefix => base dirs, longest prefix first */
+    private array $psr4;
+
+    /** @var array<string, SourceFile> */
+    private array $cache = [];
+
+    public function __construct(string $composerRoot)
+    {
+        $this->parser = (new ParserFactory())->createForNewestSupportedVersion();
+
+        $mapFile = $composerRoot . '/vendor/composer/autoload_psr4.php';
+        if (!is_file($mapFile)) {
+            throw new GenerationError(["missing $mapFile (run composer install in the checkout)"]);
+        }
+        $map = require $mapFile;
+        $map['Composer\\'] ??= [$composerRoot . '/src/Composer'];
+        uksort($map, static fn (string $a, string $b): int => strlen($b) <=> strlen($a));
+        $this->psr4 = $map;
+    }
+
+    public function sourceFor(string $fqcn): SourceFile
+    {
+        return $this->cache[$fqcn] ??= new SourceFile($this->fileFor($fqcn), $fqcn, $this->parser);
+    }
+
+    private function fileFor(string $fqcn): string
+    {
+        foreach ($this->psr4 as $prefix => $dirs) {
+            if (!str_starts_with($fqcn, $prefix)) {
+                continue;
+            }
+            $relative = str_replace('\\', '/', substr($fqcn, strlen($prefix))) . '.php';
+            foreach ($dirs as $dir) {
+                $path = $dir . '/' . $relative;
+                if (is_file($path)) {
+                    return $path;
+                }
+            }
+        }
+        throw new GenerationError(["cannot locate a source file for $fqcn"]);
+    }
+}