JSSpecCompiler: Add infrastructure to run compiler passes on AST

Meta/Lagom/Tools/CodeGenerators/JSSpecCompiler/Compiler/GenericASTPass.h

@@ -0,0 +1,46 @@
+/*
+ * Copyright (c) 2023, Dan Klishch <danilklishch@gmail.com>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/NonnullRefPtr.h>
+#include <AK/RecursionDecision.h>
+
+#include "Compiler/CompilerPass.h"
+
+namespace JSSpecCompiler {
+
+class RecursiveASTVisitor {
+public:
+    virtual ~RecursiveASTVisitor() = default;
+
+    void run_in_subtree(Tree& tree);
+
+protected:
+    virtual RecursionDecision on_entry(Tree) { return RecursionDecision::Recurse; }
+    virtual void on_leave(Tree) { }
+
+    void replace_current_node_with(Tree tree);
+
+private:
+    RecursionDecision recurse(Tree root, NodeSubtreePointer& pointer);
+
+    NodeSubtreePointer* m_current_subtree_pointer = nullptr;
+};
+
+class GenericASTPass
+    : public CompilerPass
+    , protected RecursiveASTVisitor {
+public:
+    GenericASTPass(FunctionRef function)
+        : CompilerPass(function)
+    {
+    }
+
+    void run() override;
+};
+
+}