Form redesign backend technology

form/CMakeLists.txt

@@ -16,6 +16,14 @@ include_directories(${PROJECT_SOURCE_DIR}/form)
 option(FORM_USE_ROOT_STORAGE "Enable ROOT Storage" ON)
 option(FORM_USE_RNTUPLE_STORAGE "Enable RNTuple Storage" OFF)
 
+# RNTuple is a ROOT sub-technology and cannot be built without ROOT.
+if(FORM_USE_RNTUPLE_STORAGE AND NOT FORM_USE_ROOT_STORAGE)
+  message(
+    FATAL_ERROR
+    "FORM_USE_RNTUPLE_STORAGE requires FORM_USE_ROOT_STORAGE=ON (RNTuple is part of ROOT)."
+  )
+endif()
+
 # Add sub directories
 add_subdirectory(form)
 add_subdirectory(core)

form/core/placement.cpp

@@ -7,7 +7,7 @@
 using namespace form::detail::experimental;
 
 /// Constructor with initialization
-Placement::Placement(std::string fileName, std::string containerName, int technology) :
+Placement::Placement(std::string fileName, std::string containerName, technology::Id technology) :
   m_technology(technology),
   m_fileName(std::move(fileName)),
   m_containerName(std::move(containerName))
@@ -19,4 +19,4 @@ std::string const& Placement::fileName() const { return m_fileName; }
 /// Access container name
 std::string const& Placement::containerName() const { return m_containerName; }
 /// Access technology type
-int Placement::technology() const { return m_technology; }
+form::technology::Id Placement::technology() const { return m_technology; }

form/core/placement.hpp

@@ -3,6 +3,8 @@
 #ifndef FORM_CORE_PLACEMENT_HPP
 #define FORM_CORE_PLACEMENT_HPP
 
+#include "core/technology.hpp"
+
 #include <string>
 
 /* @class Placement
@@ -16,18 +18,18 @@ namespace form::detail::experimental {
     Placement() = default;
 
     /// Constructor with initialization
-    Placement(std::string fileName, std::string containerName, int technology);
+    Placement(std::string fileName, std::string containerName, technology::Id technology);
 
     /// Access file name
     std::string const& fileName() const;
     /// Access container name
     std::string const& containerName() const;
     /// Access technology type
-    int technology() const;
+    technology::Id technology() const;
 
   private:
     /// Technology identifier
-    int m_technology{};
+    technology::Id m_technology{};
     /// File name
     std::string m_fileName;
     /// Container name

form/core/technology.hpp

@@ -0,0 +1,67 @@
+#ifndef FORM_CORE_TECHNOLOGY_HPP
+#define FORM_CORE_TECHNOLOGY_HPP
+
+#include <compare>
+#include <stdexcept>
+#include <string>
+#include <string_view>
+
+/* A storage technology, identified by a (major, minor) pair */
+
+namespace form::technology {
+
+  // Major storage type (ROOT, HDF5, ...)
+  enum class Major {
+    generic = 0, // no specific technology requested
+    root = 1,
+    hdf5 = 2,
+  };
+
+  // Minor variant within a Major (e.g. TTree vs RNTuple within ROOT)
+  struct Id {
+    Major major{Major::generic};
+    int minor{0};
+
+    // Exact ordering over (major, minor): lets an Id be a std::map key and drives backend dispatch
+    constexpr auto operator<=>(Id const&) const = default;
+  };
+
+  // Backends: valid (major, minor) pairs, stable numeric values as a future Token may persist them
+  inline constexpr Id ROOT_TTREE{Major::root, 1};
+  inline constexpr Id ROOT_RNTUPLE{Major::root, 2};
+  inline constexpr Id HDF5{Major::hdf5, 1};
+
+  // Canonical string -> technology mapping: the single place a technology string is parsed, replacing the copies that used to live in each module/source/test
+  inline Id from_string(std::string_view name)
+  {
+    if (name == "ROOT_TTREE") {
+      return ROOT_TTREE;
+    }
+    if (name == "ROOT_RNTUPLE") {
+      return ROOT_RNTUPLE;
+    }
+    if (name == "HDF5") {
+      // HDF5 is a reserved technology but has no backend yet: reject it at parse time
+      throw std::runtime_error("Technology 'HDF5' is recognized but not yet implemented");
+    }
+    throw std::runtime_error("Unknown technology: " + std::string(name));
+  }
+
+  // Canonical technology -> string mapping
+  inline std::string to_string(Id tech)
+  {
+    if (tech == ROOT_TTREE) {
+      return "ROOT_TTREE";
+    }
+    if (tech == ROOT_RNTUPLE) {
+      return "ROOT_RNTUPLE";
+    }
+    if (tech == HDF5) {
+      return "HDF5";
+    }
+    return "UNKNOWN";
+  }
+
+} // namespace form::technology
+
+#endif // FORM_CORE_TECHNOLOGY_HPP

form/core/token.cpp

@@ -7,7 +7,7 @@
 using namespace form::detail::experimental;
 
 /// Constructor with initialization
-Token::Token(std::string fileName, std::string containerName, int technology, int id) :
+Token::Token(std::string fileName, std::string containerName, technology::Id technology, int id) :
   m_technology(technology),
   m_fileName(std::move(fileName)),
   m_containerName(std::move(containerName)),
@@ -20,7 +20,7 @@ std::string const& Token::fileName() const { return m_fileName; }
 /// Access container name
 std::string const& Token::containerName() const { return m_containerName; }
 /// Access technology type
-int Token::technology() const { return m_technology; }
+form::technology::Id Token::technology() const { return m_technology; }
 /// Set technology type
 /// Access identifier/entry number
 int Token::id() const { return m_id; }

form/core/token.hpp

@@ -3,6 +3,8 @@
 #ifndef FORM_CORE_TOKEN_HPP
 #define FORM_CORE_TOKEN_HPP
 
+#include "core/technology.hpp"
+
 #include <string>
 
 /* @class Token
@@ -12,24 +14,24 @@ namespace form::detail::experimental {
   class Token {
   public:
     /// Default constructor; delegates to the named constructor so the -1 sentinel for id is defined once
-    Token() : Token("", "", 0) {}
+    Token() : Token("", "", {}) {}
 
     /// Named constructor; id defaults to -1 as a "not set" sentinel
-    Token(std::string fileName, std::string containerName, int technology, int id = -1);
+    Token(std::string fileName, std::string containerName, technology::Id technology, int id = -1);
 
     /// Access file name
     std::string const& fileName() const;
     /// Access container name
     std::string const& containerName() const;
     /// Access technology type
-    int technology() const;
+    technology::Id technology() const;
 
     /// Access identifier/entry number
     int id() const;
 
   private:
     /// Technology identifier
-    int m_technology;
+    technology::Id m_technology;
     /// File name
     std::string m_fileName;
     /// Container name

form/form/config.cpp

@@ -16,7 +16,7 @@ namespace form::experimental::config {
 
   void ItemConfig::addItem(std::string const& product_name,
                            std::string const& file_name,
-                           int technology)
+                           technology::Id technology)
   {
     m_items.emplace_back(product_name, file_name, technology);
   }
@@ -31,15 +31,15 @@ namespace form::experimental::config {
     return std::nullopt;
   }
 
-  tech_setting_config::table_t tech_setting_config::getFileTable(int const technology,
+  tech_setting_config::table_t tech_setting_config::getFileTable(technology::Id const technology,
                                                                  std::string const& fileName) const
   {
     auto const per_tech = ::const_lookup(file_settings, technology);
     return ::const_lookup(per_tech, fileName);
   }
 
   tech_setting_config::table_t tech_setting_config::getContainerTable(
-    int const technology, std::string const& containerName) const
+    technology::Id const technology, std::string const& containerName) const
   {
     auto const per_tech = ::const_lookup(container_settings, technology);
     return ::const_lookup(per_tech, containerName);

form/form/config.hpp

@@ -1,6 +1,8 @@
 #ifndef FORM_FORM_CONFIG_HPP
 #define FORM_FORM_CONFIG_HPP
 
+#include "core/technology.hpp"
+
 #include <map>
 #include <memory>
 #include <optional>
@@ -12,13 +14,13 @@
 namespace form::experimental::config {
 
   struct PersistenceItem {
-    std::string product_name; // e.g. "trackStart", "trackNumberHits"
-    std::string file_name;    // e.g. "toy.root", "output.hdf5"
-    int technology{};         // Technology::ROOT_TTREE, Technology::ROOT_RNTUPLE, Technology::HDF5
+    std::string product_name;    // e.g. "trackStart", "trackNumberHits"
+    std::string file_name;       // e.g. "toy.root", "output.hdf5"
+    technology::Id technology{}; // technology::ROOT_TTREE, ROOT_RNTUPLE, HDF5
 
     PersistenceItem() = default;
 
-    PersistenceItem(std::string product, std::string file, int tech) :
+    PersistenceItem(std::string product, std::string file, technology::Id tech) :
       product_name(std::move(product)), file_name(std::move(file)), technology(tech)
     {
     }
@@ -30,7 +32,9 @@ namespace form::experimental::config {
     ~ItemConfig() = default;
 
     // Add a configuration item
-    void addItem(std::string const& product_name, std::string const& file_name, int technology);
+    void addItem(std::string const& product_name,
+                 std::string const& file_name,
+                 technology::Id technology);
 
     // Find configuration for a product+creator combination
     std::optional<PersistenceItem> findItem(std::string const& product_name) const;
@@ -44,12 +48,12 @@ namespace form::experimental::config {
 
   struct tech_setting_config {
     using table_t = std::vector<std::pair<std::string, std::string>>;
-    using map_t = std::map<int, std::unordered_map<std::string, table_t>>;
+    using map_t = std::map<technology::Id, std::unordered_map<std::string, table_t>>;
     map_t file_settings;
     map_t container_settings;
 
-    table_t getFileTable(int technology, std::string const& fileName) const;
-    table_t getContainerTable(int technology, std::string const& containerName) const;
+    table_t getFileTable(technology::Id technology, std::string const& fileName) const;
+    table_t getContainerTable(technology::Id technology, std::string const& containerName) const;
   };
 
 } // namespace form::experimental::config

form/form_module.cpp

@@ -4,29 +4,27 @@
 
 // FORM headers - these need to be available via CMake configuration
 // need to set up the build system to find these headers
+#include "core/technology.hpp"
 #include "form/config.hpp"
 #include "form/form_writer.hpp"
-#include "form/technology.hpp"
 
 #include <cassert>
 #include <iostream>
 #include <stdexcept>
 #include <string>
-#include <string_view>
-#include <unordered_map>
 
 namespace {
 
   class FormOutputModule {
   public:
     FormOutputModule(std::string output_file,
-                     int technology,
+                     form::technology::Id technology,
                      std::vector<std::string> const& products_to_save) :
       m_output_file(std::move(output_file)), m_technology(technology)
     {
       std::cout << "FormOutputModule initialized\n";
       std::cout << "  Output file: " << m_output_file << "\n";
-      std::cout << "  Technology: " << m_technology << "\n";
+      std::cout << "  Technology: " << form::technology::to_string(m_technology) << "\n";
 
       // Build FORM configuration
       form::experimental::config::ItemConfig output_cfg;
@@ -104,7 +102,7 @@ namespace {
     // Algorithm configuration fixed at construction; intentionally immutable for object lifetime.
     // NOLINTBEGIN(cppcoreguidelines-avoid-const-or-ref-data-members)
     std::string const m_output_file;
-    int const m_technology;
+    form::technology::Id const m_technology;
     // NOLINTEND(cppcoreguidelines-avoid-const-or-ref-data-members)
     std::unique_ptr<form::experimental::form_writer_interface> m_form_interface;
   };
@@ -123,18 +121,7 @@ PHLEX_REGISTER_ALGORITHMS(m, config)
   std::cout << "  output_file: " << output_file << "\n";
   std::cout << "  technology: " << tech_string << "\n";
 
-  std::unordered_map<std::string_view, int> const tech_lookup = {
-    {"ROOT_TTREE", form::technology::ROOT_TTREE},
-    {"ROOT_RNTUPLE", form::technology::ROOT_RNTUPLE},
-    {"HDF5", form::technology::HDF5}};
-
-  auto it = tech_lookup.find(tech_string);
-
-  if (it == tech_lookup.end()) {
-    throw std::runtime_error("Unknown technology: " + tech_string);
-  }
-
-  int const technology = it->second;
+  auto const technology = form::technology::from_string(tech_string);
 
   auto products_to_save = config.get<std::vector<std::string>>("products");
 

form/form_source.cpp

@@ -1,9 +1,9 @@
 #include "phlex/source.hpp"
 
+#include "core/technology.hpp"
 #include "form/config.hpp"
 #include "form/form_reader.hpp"
 #include "form/form_source_type_registry.hpp"
-#include "form/technology.hpp"
 
 #include "phlex/model/data_cell_index.hpp"
 
@@ -13,7 +13,6 @@
 #include <sstream>
 #include <stdexcept>
 #include <string>
-#include <string_view>
 #include <utility>
 #include <vector>
 
@@ -176,16 +175,7 @@ PHLEX_REGISTER_SOURCE(s, config)
     actual_creator = *plugin + ":" + *algorithm;
   }
 
-  std::unordered_map<std::string_view, int> const tech_lookup = {
-    {"ROOT_TTREE", form::technology::ROOT_TTREE},
-    {"ROOT_RNTUPLE", form::technology::ROOT_RNTUPLE},
-    {"HDF5", form::technology::HDF5}};
-
-  auto it = tech_lookup.find(tech_string);
-  if (it == tech_lookup.end()) {
-    throw std::runtime_error("Unknown technology: " + tech_string);
-  }
-  int const technology = it->second;
+  auto const technology = form::technology::from_string(tech_string);
 
   form::experimental::config::ItemConfig input_cfg;
   form::experimental::config::tech_setting_config tech_cfg;