Build json::Object on-the-fly

Author: lucic71

cpp2rust/converter/rule_src_parser.cpp

@@ -69,7 +69,7 @@ struct LookupInfo {
 
 class Callback : public clang::ast_matchers::MatchFinder::MatchCallback {
 public:
-  explicit Callback(SrcStrings &strings) : strings_(strings) {}
+  explicit Callback(llvm::json::Object &out) : out_(out) {}
 
   void init(clang::Sema &sema) {
     sema_ = &sema;
@@ -87,13 +87,15 @@ class Callback : public clang::ast_matchers::MatchFinder::MatchCallback {
       } else {
         type = var->getUnderlyingType();
       }
-      strings_.types[var->getQualifiedNameAsString()] = Mapper::ToString(type);
+      out_[var->getQualifiedNameAsString()] =
+          llvm::json::Object{{"to_string", Mapper::ToString(type)}};
       return;
     }
 
     if (auto func = R.Nodes.getNodeAs<clang::FunctionDecl>("func")) {
       auto add = [&](std::string &&src) {
-        strings_.functions[func->getQualifiedNameAsString()] = std::move(src);
+        out_[func->getQualifiedNameAsString()] =
+            llvm::json::Object{{"to_string", std::move(src)}};
       };
 
       if (const auto *fcall = R.Nodes.getNodeAs<clang::CallExpr>("fcall")) {
@@ -168,7 +170,7 @@ class Callback : public clang::ast_matchers::MatchFinder::MatchCallback {
   }
 
 private:
-  SrcStrings &strings_;
+  llvm::json::Object &out_;
   clang::Sema *sema_ = nullptr;
   clang::SourceLocation loc_;
 
@@ -644,7 +646,7 @@ class Callback : public clang::ast_matchers::MatchFinder::MatchCallback {
 
 class ActionFactory : public clang::tooling::FrontendActionFactory {
 public:
-  explicit ActionFactory(SrcStrings &strings) : cb_(strings) {
+  explicit ActionFactory(llvm::json::Object &out) : cb_(out) {
     using namespace clang::ast_matchers;
     finder_.addMatcher(
         returnStmt(
@@ -719,16 +721,14 @@ class ActionFactory : public clang::tooling::FrontendActionFactory {
 
 } // namespace
 
-SrcStrings Extract(const std::filesystem::path &src_path) {
-  SrcStrings strings;
+void Extract(const std::filesystem::path &src_path, llvm::json::Object &out) {
   auto flags = getPlatformClangBeginFlags();
   auto end_flags = getPlatformClangEndFlags();
   flags.insert(flags.end(), end_flags.begin(), end_flags.end());
   clang::tooling::FixedCompilationDatabase compilations(".", flags);
-  ActionFactory factory(strings);
+  ActionFactory factory(out);
   clang::tooling::ClangTool tool(compilations, {src_path.string()});
   tool.run(&factory);
-  return strings;
 }
 
 } // namespace cpp2rust::RuleSrcParser

cpp2rust/converter/rule_src_parser.h

@@ -1,19 +1,16 @@
-#pragma once
-
 // Copyright (c) 2022-present INESC-ID.
 // Distributed under the MIT license that can be found in the LICENSE file.
 
+#pragma once
+
+#include <llvm/Support/JSON.h>
+
 #include <filesystem>
-#include <string>
-#include <unordered_map>
 
 namespace cpp2rust::RuleSrcParser {
 
-struct SrcStrings {
-  std::unordered_map<std::string, std::string> functions; // f<n> -> ToString
-  std::unordered_map<std::string, std::string> types;     // t<n> -> ToString
-};
-
-SrcStrings Extract(const std::filesystem::path &src_path);
+// Visit every f<n> / t<n> declaration in `src_path`:
+// f<n> / t<n>: { "to_string": <Mapper::ToString> }
+void Extract(const std::filesystem::path &src_path, llvm::json::Object &out);
 
 } // namespace cpp2rust::RuleSrcParser

cpp2rust/cpp_rule_preprocessor.cpp

@@ -8,7 +8,6 @@
 
 #include <cstdlib>
 #include <filesystem>
-#include <map>
 #include <string>
 
 #include "converter/rule_src_parser.h"
@@ -32,23 +31,8 @@ int main(int argc, char *argv[]) {
 
   fs::path src = SrcFile.getValue();
   llvm::errs() << "Preprocessing " << src.string() << '\n';
-  auto strings = cpp2rust::RuleSrcParser::Extract(src);
-
-  // Sort by name for deterministic output.
-  std::map<std::string, std::string> sorted;
-  for (auto &[k, v] : strings.functions) {
-    sorted.emplace(k, v);
-  }
-  for (auto &[k, v] : strings.types) {
-    sorted.emplace(k, v);
-  }
-
   llvm::json::Object root;
-  for (auto &[k, v] : sorted) {
-    llvm::json::Object entry;
-    entry["to_string"] = v;
-    root.try_emplace(k, std::move(entry));
-  }
+  cpp2rust::RuleSrcParser::Extract(src, root);
 
   auto out_path = src.parent_path() / "ir_src.json";
   std::error_code ec;