Merge pull request #9144 from github/alexdenisov/introduce-visitors

Swift: Introduce visitors

swift/extractor/BUILD.bazel

@@ -9,6 +9,12 @@ swift_cc_binary(
         "SwiftDispatcher.h",
         "SwiftTagTraits.h",
         "main.cpp",
+        "SwiftVisitor.h",
+        "visitors/DeclVisitor.h",
+        "visitors/ExprVisitor.h",
+        "visitors/StmtVisitor.h",
+        "visitors/TypeVisitor.h",
+        "visitors/PatternVisitor.h",
     ],
     visibility = ["//swift:__pkg__"],
     deps = [

swift/extractor/SwiftDispatcher.h

@@ -57,9 +57,18 @@ class SwiftDispatcher {
   SwiftDispatcher(const swift::SourceManager& sourceManager, TrapArena& arena, TrapOutput& trap)
       : sourceManager{sourceManager}, arena{arena}, trap{trap} {}
 
-  template <typename T>
-  void extract(T* entity) {
-    fetchLabel(entity);
+  // This is a helper method to emit TRAP entries for AST nodes that we don't fully support yet.
+  template <typename Parent, typename Child>
+  void TBD(Child* entity, const std::string& suffix) {
+    using namespace std::string_literals;
+    auto label = assignNewLabel(entity);
+    auto kind = detail::getKindName<Parent>(static_cast<const Parent*>(entity)->getKind());
+    auto name = "TBD ("s + kind + suffix + ")";
+    if constexpr (std::is_same_v<Parent, swift::TypeBase>) {
+      trap.emit(UnknownTypesTrap{label, name});
+    } else {
+      trap.emit(UnknownAstNodesTrap{label, name});
+    }
   }
 
  private:
@@ -105,20 +114,6 @@ class SwiftDispatcher {
     return arena.allocateLabel<Tag>();
   }
 
-  // This is a helper method to emit TRAP entries for AST nodes that we don't fully support yet.
-  template <typename Parent, typename Child>
-  void TBD(Child* entity, const std::string& suffix) {
-    using namespace std::string_literals;
-    auto label = assignNewLabel(entity);
-    auto kind = detail::getKindName<Parent>(static_cast<const Parent*>(entity)->getKind());
-    auto name = "TBD ("s + kind + suffix + ")";
-    if constexpr (std::is_same_v<Parent, swift::TypeBase>) {
-      trap.emit(UnknownTypesTrap{label, name});
-    } else {
-      trap.emit(UnknownAstNodesTrap{label, name});
-    }
-  }
-
   template <typename Locatable>
   void attachLocation(Locatable locatable, TrapLabel<LocatableTag> locatableLabel) {
     attachLocation(&locatable, locatableLabel);
@@ -162,12 +157,12 @@ class SwiftDispatcher {
 
   // TODO: The following methods are supposed to redirect TRAP emission to correpsonding visitors,
   // which are to be introduced in follow-up PRs
-  void visit(swift::Decl* decl) { TBD<swift::Decl>(decl, "Decl"); }
-  void visit(swift::Stmt* stmt) { TBD<swift::Stmt>(stmt, "Stmt"); }
-  void visit(swift::Expr* expr) { TBD<swift::Expr>(expr, "Expr"); }
-  void visit(swift::Pattern* pattern) { TBD<swift::Pattern>(pattern, "Pattern"); }
-  void visit(swift::TypeRepr* type) { TBD<swift::TypeRepr>(type, "TypeRepr"); }
-  void visit(swift::TypeBase* type) { TBD<swift::TypeBase>(type, "Type"); }
+  virtual void visit(swift::Decl* decl) = 0;
+  virtual void visit(swift::Stmt* stmt) = 0;
+  virtual void visit(swift::Expr* expr) = 0;
+  virtual void visit(swift::Pattern* pattern) = 0;
+  virtual void visit(swift::TypeRepr* type) = 0;
+  virtual void visit(swift::TypeBase* type) = 0;
 
   const swift::SourceManager& sourceManager;
   TrapArena& arena;

swift/extractor/SwiftExtractor.cpp

@@ -14,7 +14,7 @@
 
 #include "swift/extractor/trap/generated/TrapClasses.h"
 #include "swift/extractor/trap/TrapOutput.h"
-#include "swift/extractor/SwiftDispatcher.h"
+#include "swift/extractor/SwiftVisitor.h"
 
 using namespace codeql;
 
@@ -88,9 +88,9 @@ static void extractFile(const SwiftExtractorConfiguration& config,
   trap.assignKey(fileLabel, srcFilePath.str().str());
   trap.emit(FilesTrap{fileLabel, srcFilePath.str().str()});
 
-  SwiftDispatcher dispatcher(compiler.getSourceMgr(), arena, trap);
+  SwiftVisitor visitor(compiler.getSourceMgr(), arena, trap);
   for (swift::Decl* decl : file.getTopLevelDecls()) {
-    dispatcher.extract(decl);
+    visitor.extract(decl);
   }
 
   // TODO: Pick a better name to avoid collisions

swift/extractor/SwiftVisitor.h

@@ -0,0 +1,36 @@
+#pragma once
+
+#include "swift/extractor/SwiftDispatcher.h"
+#include "swift/extractor/visitors/DeclVisitor.h"
+#include "swift/extractor/visitors/ExprVisitor.h"
+#include "swift/extractor/visitors/StmtVisitor.h"
+#include "swift/extractor/visitors/TypeVisitor.h"
+#include "swift/extractor/visitors/PatternVisitor.h"
+
+namespace codeql {
+
+class SwiftVisitor : private SwiftDispatcher {
+ public:
+  using SwiftDispatcher::SwiftDispatcher;
+
+  template <typename T>
+  void extract(T* entity) {
+    fetchLabel(entity);
+  }
+
+ private:
+  void visit(swift::Decl* decl) override { declVisitor.visit(decl); }
+  void visit(swift::Stmt* stmt) override { stmtVisitor.visit(stmt); }
+  void visit(swift::Expr* expr) override { exprVisitor.visit(expr); }
+  void visit(swift::Pattern* pattern) override { patternVisitor.visit(pattern); }
+  void visit(swift::TypeRepr* type) override { TBD<swift::TypeRepr>(type, "TypeRepr"); }
+  void visit(swift::TypeBase* type) override { typeVisitor.visit(type); }
+
+  DeclVisitor declVisitor{*this};
+  ExprVisitor exprVisitor{*this};
+  StmtVisitor stmtVisitor{*this};
+  TypeVisitor typeVisitor{*this};
+  PatternVisitor patternVisitor{*this};
+};
+
+}  // namespace codeql

swift/extractor/visitors/DeclVisitor.h

@@ -0,0 +1,22 @@
+#pragma once
+
+#include "swift/extractor/SwiftDispatcher.h"
+#include <swift/AST/ASTVisitor.h>
+
+namespace codeql {
+
+class DeclVisitor : public swift::DeclVisitor<DeclVisitor> {
+ public:
+  // SwiftDispatcher should outlive the DeclVisitor
+  DeclVisitor(SwiftDispatcher& dispatcher) : dispatcher(dispatcher) {}
+
+  template <typename E>
+  void visitDecl(E* decl) {
+    dispatcher.TBD<swift::Decl>(decl, "Decl");
+  }
+
+ private:
+  SwiftDispatcher& dispatcher;
+};
+
+}  // namespace codeql

swift/extractor/visitors/ExprVisitor.h

@@ -0,0 +1,22 @@
+#pragma once
+
+#include "swift/extractor/SwiftDispatcher.h"
+#include <swift/AST/ASTVisitor.h>
+
+namespace codeql {
+
+class ExprVisitor : public swift::ExprVisitor<ExprVisitor> {
+ public:
+  // SwiftDispatcher should outlive the ExprVisitor
+  ExprVisitor(SwiftDispatcher& dispatcher) : dispatcher(dispatcher) {}
+
+  template <typename E>
+  void visitExpr(E* expr) {
+    dispatcher.TBD<swift::Expr>(expr, "Expr");
+  }
+
+ private:
+  SwiftDispatcher& dispatcher;
+};
+
+}  // namespace codeql

swift/extractor/visitors/PatternVisitor.h

@@ -0,0 +1,38 @@
+#pragma once
+
+#include "swift/extractor/SwiftDispatcher.h"
+#include <swift/AST/ASTVisitor.h>
+
+namespace codeql {
+
+namespace detail {
+// swift code lacks default implementations of visitor for some entities. We can add those here
+// while we do not have yet all implemented. This is a simplified version of the corresponding Expr
+// code in swift/AST/ASTVisitor.h
+template <typename CrtpSubclass>
+class PatchedPatternVisitor : public swift::PatternVisitor<CrtpSubclass> {
+ public:
+#define PATTERN(CLASS, PARENT)                                 \
+  void visit##CLASS##Pattern(swift::CLASS##Pattern* E) {       \
+    return static_cast<CrtpSubclass*>(this)->visit##PARENT(E); \
+  }
+#include "swift/AST/PatternNodes.def"
+};
+
+}  // namespace detail
+
+class PatternVisitor : public detail::PatchedPatternVisitor<PatternVisitor> {
+ public:
+  // SwiftDispatcher should outlive the PatternVisitor
+  PatternVisitor(SwiftDispatcher& dispatcher) : dispatcher(dispatcher) {}
+
+  template <typename E>
+  void visitPattern(E* pattern) {
+    dispatcher.TBD<swift::Pattern>(pattern, "Pattern");
+  }
+
+ private:
+  SwiftDispatcher& dispatcher;
+};
+
+}  // namespace codeql

swift/extractor/visitors/StmtVisitor.h

@@ -0,0 +1,39 @@
+#pragma once
+
+#include "swift/extractor/SwiftDispatcher.h"
+#include <swift/AST/ASTVisitor.h>
+
+namespace codeql {
+
+namespace detail {
+// swift code lacks default implementations of visitor for some entities. We can add those here
+// while we do not have yet all implemented. This is a simplified version of the corresponding Expr
+// code in swift/AST/ASTVisitor.h
+template <typename CrtpSubclass>
+class PatchedStmtVisitor : public swift::StmtVisitor<CrtpSubclass> {
+ public:
+#define ABSTRACT_STMT(CLASS, PARENT)                           \
+  void visit##CLASS##Stmt(swift::CLASS##Stmt* E) {             \
+    return static_cast<CrtpSubclass*>(this)->visit##PARENT(E); \
+  }
+#define STMT(CLASS, PARENT) ABSTRACT_STMT(CLASS, PARENT)
+#include "swift/AST/StmtNodes.def"
+};
+
+}  // namespace detail
+
+class StmtVisitor : public detail::PatchedStmtVisitor<StmtVisitor> {
+ public:
+  // SwiftDispatcher should outlive the StmtVisitor
+  StmtVisitor(SwiftDispatcher& dispatcher) : dispatcher(dispatcher) {}
+
+  template <typename E>
+  void visitStmt(E* stmt) {
+    dispatcher.TBD<swift::Stmt>(stmt, "Stmt");
+  }
+
+ private:
+  SwiftDispatcher& dispatcher;
+};
+
+}  // namespace codeql

swift/extractor/visitors/TypeVisitor.h

@@ -0,0 +1,22 @@
+#pragma once
+
+#include "swift/extractor/SwiftDispatcher.h"
+#include <swift/AST/TypeVisitor.h>
+
+namespace codeql {
+
+class TypeVisitor : public swift::TypeVisitor<TypeVisitor> {
+ public:
+  // SwiftDispatcher should outlive the TypeVisitor
+  TypeVisitor(SwiftDispatcher& dispatcher) : dispatcher(dispatcher) {}
+
+  template <typename E>
+  void visitType(E* type) {
+    dispatcher.TBD<swift::TypeBase>(type, "Type");
+  }
+
+ private:
+  SwiftDispatcher& dispatcher;
+};
+
+}  // namespace codeql