JSSpecCompiler: Add infrastructure to run compiler passes on AST

Author: https://github.com/DanShaders
Commit: https://github.com/SerenityOS/serenity/commit/198591cc20
Pull-request: https://github.com/SerenityOS/serenity/pull/20876
Reviewed-by: https://github.com/ADKaster

Meta/Lagom/Tools/CodeGenerators/JSSpecCompiler/AST/AST.cpp

@@ -0,0 +1,77 @@
+/*
+ * Copyright (c) 2023, Dan Klishch <danilklishch@gmail.com>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include "AST/AST.h"
+
+namespace JSSpecCompiler {
+
+Vector<NodeSubtreePointer> BinaryOperation::subtrees()
+{
+    return { { &m_left }, { &m_right } };
+}
+
+Vector<NodeSubtreePointer> UnaryOperation::subtrees()
+{
+    return { { &m_operand } };
+}
+
+Vector<NodeSubtreePointer> IsOneOfOperation::subtrees()
+{
+    Vector<NodeSubtreePointer> result = { { &m_operand } };
+    for (auto& child : m_compare_values)
+        result.append({ &child });
+    return result;
+}
+
+Vector<NodeSubtreePointer> ReturnExpression::subtrees()
+{
+    return { { &m_return_value } };
+}
+
+Vector<NodeSubtreePointer> AssertExpression::subtrees()
+{
+    return { { &m_condition } };
+}
+
+Vector<NodeSubtreePointer> IfBranch::subtrees()
+{
+    return { { &m_condition }, { &m_branch } };
+}
+
+Vector<NodeSubtreePointer> ElseIfBranch::subtrees()
+{
+    if (m_condition.has_value())
+        return { { &m_condition.value() }, { &m_branch } };
+    return { { &m_branch } };
+}
+
+Vector<NodeSubtreePointer> TreeList::subtrees()
+{
+    Vector<NodeSubtreePointer> result;
+    for (auto& expression : m_expressions)
+        result.append({ &expression });
+    return result;
+}
+
+Vector<NodeSubtreePointer> RecordDirectListInitialization::subtrees()
+{
+    Vector<NodeSubtreePointer> result { &m_type_reference };
+    for (auto& argument : m_arguments) {
+        result.append({ &argument.name });
+        result.append({ &argument.value });
+    }
+    return result;
+}
+
+Vector<NodeSubtreePointer> FunctionCall::subtrees()
+{
+    Vector<NodeSubtreePointer> result = { { &m_name } };
+    for (auto& child : m_arguments)
+        result.append({ &child });
+    return result;
+}
+
+}

Meta/Lagom/Tools/CodeGenerators/JSSpecCompiler/AST/AST.h

@@ -20,6 +20,21 @@ RefPtr<T> as(NullableTree const& tree)
     return dynamic_cast<T*>(tree.ptr());
 }
 
+class NodeSubtreePointer {
+public:
+    NodeSubtreePointer(Tree* tree_ptr)
+        : m_tree_ptr(tree_ptr)
+    {
+    }
+
+    Tree& get() { return *m_tree_ptr; }
+
+    void replace_subtree(Tree tree) { *m_tree_ptr = move(tree); }
+
+private:
+    Tree* m_tree_ptr;
+};
+
 // ===== Generic nodes =====
 class Node : public RefCounted<Node> {
 public:
@@ -27,6 +42,9 @@ public:
 
     void format_tree(StringBuilder& builder);
 
+    // For expressions, order must be the same as the evaluation order.
+    virtual Vector<NodeSubtreePointer> subtrees() { return {}; }
+
     virtual bool is_type() { return false; }
 
 protected:
@@ -128,6 +146,8 @@ public:
     {
     }
 
+    Vector<NodeSubtreePointer> subtrees() override;
+
     BinaryOperator m_operation;
     Tree m_left;
     Tree m_right;
@@ -144,6 +164,8 @@ public:
     {
     }
 
+    Vector<NodeSubtreePointer> subtrees() override;
+
     UnaryOperator m_operation;
     Tree m_operand;
 
@@ -159,6 +181,8 @@ public:
     {
     }
 
+    Vector<NodeSubtreePointer> subtrees() override;
+
     Tree m_operand;
     Vector<Tree> m_compare_values;
 
@@ -186,6 +210,8 @@ public:
     {
     }
 
+    Vector<NodeSubtreePointer> subtrees() override;
+
     Tree m_return_value;
 
 protected:
@@ -199,6 +225,8 @@ public:
     {
     }
 
+    Vector<NodeSubtreePointer> subtrees() override;
+
     Tree m_condition;
 
 protected:
@@ -213,6 +241,8 @@ public:
     {
     }
 
+    Vector<NodeSubtreePointer> subtrees() override;
+
     Tree m_condition;
     Tree m_branch;
 
@@ -228,6 +258,8 @@ public:
     {
     }
 
+    Vector<NodeSubtreePointer> subtrees() override;
+
     Optional<Tree> m_condition;
     Tree m_branch;
 
@@ -242,6 +274,8 @@ public:
     {
     }
 
+    Vector<NodeSubtreePointer> subtrees() override;
+
     Vector<Tree> m_expressions;
 
 protected:
@@ -261,6 +295,8 @@ public:
     {
     }
 
+    Vector<NodeSubtreePointer> subtrees() override;
+
     Tree m_type_reference;
     Vector<Argument> m_arguments;
 
@@ -276,6 +312,8 @@ public:
     {
     }
 
+    Vector<NodeSubtreePointer> subtrees() override;
+
     Tree m_name;
     Vector<Tree> m_arguments;
 

Meta/Lagom/Tools/CodeGenerators/JSSpecCompiler/CMakeLists.txt

@@ -1,5 +1,7 @@
 set(SOURCES
+    AST/AST.cpp
     AST/ASTPrinting.cpp
+    Compiler/GenericASTPass.cpp
     Parser/Lexer.cpp
     Parser/ParseError.cpp
     Parser/SpecParser.cpp

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

@@ -0,0 +1,31 @@
+/*
+ * 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 "Forward.h"
+
+namespace JSSpecCompiler {
+
+class CompilerPass {
+public:
+    CompilerPass(FunctionRef function)
+        : m_function(function)
+    {
+    }
+
+    virtual ~CompilerPass() = default;
+
+    virtual void run() = 0;
+
+protected:
+    FunctionRef m_function;
+};
+
+}

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

@@ -0,0 +1,49 @@
+/*
+ * Copyright (c) 2023, Dan Klishch <danilklishch@gmail.com>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include "Compiler/GenericASTPass.h"
+#include "AST/AST.h"
+#include "Function.h"
+
+namespace JSSpecCompiler {
+
+void RecursiveASTVisitor::run_in_subtree(Tree& tree)
+{
+    NodeSubtreePointer pointer { &tree };
+    recurse(tree, pointer);
+}
+
+void RecursiveASTVisitor::replace_current_node_with(Tree tree)
+{
+    m_current_subtree_pointer->replace_subtree(move(tree));
+}
+
+RecursionDecision RecursiveASTVisitor::recurse(Tree root, NodeSubtreePointer& pointer)
+{
+    RecursionDecision decision;
+
+    m_current_subtree_pointer = &pointer;
+    decision = on_entry(root);
+
+    if (decision == RecursionDecision::Recurse) {
+        for (auto& child : root->subtrees()) {
+            if (recurse(child.get(), child) == RecursionDecision::Break)
+                return RecursionDecision::Break;
+        }
+    }
+
+    m_current_subtree_pointer = &pointer;
+    on_leave(root);
+
+    return RecursionDecision::Continue;
+}
+
+void GenericASTPass::run()
+{
+    run_in_subtree(m_function->m_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;
+};
+
+}