Add the ASTExecutionInfo class handle cleanly execution information

The purpose of this is to provide some global execution info to parts
of execution.

This defines a singleton that is only constructable in the `parse`
function. The instance thus only leave during the execution of the
script.

As a first stored, the ugly `p_root_node` static pointer has been
encapsulated in this container.

src/language/PugsParser.cpp

@@ -14,6 +14,7 @@
 #include <language/ast/ASTSymbolInitializationChecker.hpp>
 #include <language/ast/ASTSymbolTableBuilder.hpp>
 #include <language/utils/ASTDotPrinter.hpp>
+#include <language/utils/ASTExecutionInfo.hpp>
 #include <language/utils/ASTPrinter.hpp>
 #include <language/utils/SymbolTable.hpp>
 #include <utils/PugsAssert.hpp>
@@ -32,8 +33,6 @@
 #include <unordered_map>
 #include <variant>
 
-const std::unique_ptr<ASTNode>* p_root_node = nullptr;
-
 void
 parser(const std::string& filename)
 {
@@ -50,7 +49,6 @@ parser(const std::string& filename)
 
   auto parse_and_execute = [](auto& input) {
     std::unique_ptr<ASTNode> root_node = ASTBuilder::build(input);
-    p_root_node                        = &root_node;
 
     ASTModulesImporter{*root_node};
     ASTNodeTypeCleaner<language::import_instruction>{*root_node};
@@ -77,11 +75,12 @@ parser(const std::string& filename)
     std::cout << "-------------------------------------------------------\n";
     std::cout << rang::style::bold << "Executing AST..." << rang::style::reset << '\n';
 
+    ASTExecutionInfo execution_info{*root_node};
+
     ExecutionPolicy exec_all;
     root_node->execute(exec_all);
 
     root_node->m_symbol_table->clearValues();
-    p_root_node = nullptr;
   };
 
   if (not SignalManager::pauseOnError()) {

src/language/modules/UtilsModule.cpp

 #include <language/modules/UtilsModule.hpp>
 
 #include <language/utils/ASTDotPrinter.hpp>
+#include <language/utils/ASTExecutionInfo.hpp>
 #include <language/utils/ASTPrinter.hpp>
 #include <language/utils/BuiltinFunctionEmbedder.hpp>
 #include <language/utils/SymbolTable.hpp>
 #include <utils/PugsUtils.hpp>
 
-extern const std::unique_ptr<ASTNode>* p_root_node;
-
 UtilsModule::UtilsModule()
 {
   this->_addBuiltinFunction("getPugsVersion", std::make_shared<BuiltinFunctionEmbedder<std::string(void)>>(
@@ -25,11 +24,10 @@ UtilsModule::UtilsModule()
   this->_addBuiltinFunction("getAST", std::make_shared<BuiltinFunctionEmbedder<std::string(void)>>(
 
                                         []() -> std::string {
-                                          Assert(p_root_node != nullptr, "unable to find AST's root node");
+                                          const auto& root_node = ASTExecutionInfo::current().rootNode();
 
-                                          const auto& root_node = *p_root_node;
                                           std::ostringstream os;
-                                          os << ASTPrinter{*root_node};
+                                          os << ASTPrinter{root_node};
 
                                           return os.str();
                                         }
@@ -39,9 +37,7 @@ UtilsModule::UtilsModule()
   this->_addBuiltinFunction("saveASTDot", std::make_shared<BuiltinFunctionEmbedder<void(const std::string&)>>(
 
                                             [](const std::string& dot_filename) -> void {
-                                              Assert(p_root_node != nullptr, "unable to find AST's root node");
-
-                                              const auto& root_node = *p_root_node;
+                                              const auto& root_node = ASTExecutionInfo::current().rootNode();
 
                                               std::ofstream fout(dot_filename);
 
@@ -51,7 +47,7 @@ UtilsModule::UtilsModule()
                                                 throw NormalError(os.str());
                                               }
 
-                                              ASTDotPrinter dot_printer{*root_node};
+                                              ASTDotPrinter dot_printer{root_node};
                                               fout << dot_printer;
 
                                               if (not fout) {

src/language/utils/ASTExecutionInfo.cpp

+#include <language/utils/ASTExecutionInfo.hpp>
+
+#include <language/ast/ASTNode.hpp>
+
+const ASTExecutionInfo* ASTExecutionInfo::m_current_execution_info = nullptr;
+
+ASTExecutionInfo::ASTExecutionInfo(const ASTNode& root_node) : m_root_node(root_node)
+{
+  Assert(m_current_execution_info == nullptr, "Can only define one ASTExecutionInfo");
+
+  m_current_execution_info = this;
+}
+
+const ASTExecutionInfo&
+ASTExecutionInfo::current()
+{
+  Assert(m_current_execution_info != nullptr, "ASTExecutionInfo is not defined!");
+  return *m_current_execution_info;
+}
+
+ASTExecutionInfo::~ASTExecutionInfo()
+{
+  m_current_execution_info = nullptr;
+}

src/language/utils/ASTExecutionInfo.hpp

+#ifndef AST_EXECUTION_INFO_HPP
+#define AST_EXECUTION_INFO_HPP
+
+#include <string>
+
+class ASTNode;
+class ASTExecutionInfo
+{
+ private:
+  static const ASTExecutionInfo* m_current_execution_info;
+
+  const ASTNode& m_root_node;
+
+  // The only place where the ASTExecutionInfo can be built
+  friend void parser(const std::string& filename);
+
+  ASTExecutionInfo(const ASTNode& root_node);
+
+ public:
+  const ASTNode&
+  rootNode() const
+  {
+    return m_root_node;
+  }
+
+  static const ASTExecutionInfo& current();
+
+  ASTExecutionInfo() = delete;
+
+  ~ASTExecutionInfo();
+};
+
+#endif   // AST_EXECUTION_INFO_HPP

src/language/utils/CMakeLists.txt

@@ -2,6 +2,7 @@
 
 add_library(PugsLanguageUtils
   ASTDotPrinter.cpp
+  ASTExecutionInfo.cpp
   ASTPrinter.cpp
   DataVariant.cpp
   EmbeddedData.cpp