1 files changed, 126 insertions, 0 deletions
diff --git a/scripts/plugin-class-classifier/src/BuiltinSignatures.php b/scripts/plugin-class-classifier/src/BuiltinSignatures.php
new file mode 100644
index 00000000..af3d77f3
--- /dev/null
+++ b/scripts/plugin-class-classifier/src/BuiltinSignatures.php
@@ -0,0 +1,126 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Shirabe\PluginClassifier;
+
+use JetBrains\PHPStormStub\PhpStormStubsMap;
+use PhpParser\Node;
+use PhpParser\NodeTraverser;
+use PhpParser\NodeVisitorAbstract;
+use PhpParser\Parser;
+use PhpParser\ParserFactory;
+
+/**
+ * By-ref parameter positions of PHP builtin functions, resolved from
+ * jetbrains/phpstorm-stubs instead of a hand-maintained table. Stub files
+ * are parsed lazily, one file per first lookup of any function it defines;
+ * a function absent from the stubs map is unknown and the caller must be
+ * conservative.
+ */
+final class BuiltinSignatures
+{
+    private Parser $parser;
+
+    /** @var array<string, string> lowercase function name => stub file relative path */
+    private array $functionFiles = [];
+
+    /** @var array<string, array{fixed: list<int>, variadicFrom: int|null}> lowercase function name => by-ref info */
+    private array $byRef = [];
+
+    /** @var array<string, true> */
+    private array $parsedFiles = [];
+
+    public function __construct()
+    {
+        $this->parser = (new ParserFactory())->createForNewestSupportedVersion();
+        foreach (PhpStormStubsMap::FUNCTIONS as $name => $file) {
+            $this->functionFiles[strtolower((string) $name)] = $file;
+        }
+    }
+
+    /**
+     * @return array{fixed: list<int>, variadicFrom: int|null}|null
+     *         null when the function is not a known builtin
+     */
+    public function byRefInfo(string $lowerName): ?array
+    {
+        if (isset($this->byRef[$lowerName])) {
+            return $this->byRef[$lowerName];
+        }
+
+        $file = $this->functionFiles[$lowerName] ?? null;
+        if ($file === null) {
+            return null;
+        }
+
+        $this->parseStubFile($file);
+
+        // Defined in the map but somehow absent from the parsed file:
+        // treat as unknown rather than silently non-by-ref.
+        return $this->byRef[$lowerName] ?? null;
+    }
+
+    private function parseStubFile(string $relativePath): void
+    {
+        if (isset($this->parsedFiles[$relativePath])) {
+            return;
+        }
+        $this->parsedFiles[$relativePath] = true;
+
+        $path = PhpStormStubsMap::DIR . '/' . $relativePath;
+        $code = file_get_contents($path);
+        if ($code === false) {
+            throw new \RuntimeException("cannot read stub file $path");
+        }
+        $stmts = $this->parser->parse($code);
+        if ($stmts === null) {
+            throw new \RuntimeException("cannot parse stub file $path");
+        }
+
+        $byRef = &$this->byRef;
+        $collector = new class($byRef) extends NodeVisitorAbstract {
+            /** @param array<string, array{fixed: list<int>, variadicFrom: int|null}> $byRef */
+            public function __construct(private array &$byRef)
+            {
+            }
+
+            public function enterNode(Node $node): null
+            {
+                if (!$node instanceof Node\Stmt\Function_) {
+                    return null;
+                }
+
+                $name = strtolower($node->name->toString());
+                $fixed = [];
+                $variadicFrom = null;
+                foreach ($node->params as $i => $param) {
+                    if (!$param->byRef) {
+                        continue;
+                    }
+                    if ($param->variadic) {
+                        $variadicFrom = $variadicFrom === null ? $i : min($variadicFrom, $i);
+                    } else {
+                        $fixed[] = $i;
+                    }
+                }
+
+                // Stub files occasionally declare a function more than once
+                // (per-version signatures); merge conservatively.
+                if (isset($this->byRef[$name])) {
+                    $fixed = array_values(array_unique(array_merge($this->byRef[$name]['fixed'], $fixed)));
+                    sort($fixed);
+                    $prev = $this->byRef[$name]['variadicFrom'];
+                    $variadicFrom = $prev === null ? $variadicFrom : ($variadicFrom === null ? $prev : min($prev, $variadicFrom));
+                }
+                $this->byRef[$name] = ['fixed' => $fixed, 'variadicFrom' => $variadicFrom];
+
+                return null;
+            }
+        };
+
+        $traverser = new NodeTraverser();
+        $traverser->addVisitor($collector);
+        $traverser->traverse($stmts);
+    }
+}