diff --git a/src/class_diagram/generators/json/class_diagram_generator.cc b/src/class_diagram/generators/json/class_diagram_generator.cc
index 9ff39d7d..581a5cfd 100644
--- a/src/class_diagram/generators/json/class_diagram_generator.cc
+++ b/src/class_diagram/generators/json/class_diagram_generator.cc
@@ -34,8 +34,8 @@ void to_json(nlohmann::json &j, const element &c)
         {"namespace", c.get_namespace().to_string()}, {"type", c.type_name()},
         {"display_name", c.full_name(false)}};
 
-    if (c.comment())
-        j["comment"] = c.comment().value();
+    if (const auto &comment = c.comment(); comment)
+        j["comment"] = comment.value();
 
     if (!c.file().empty())
         j["source_location"] =
@@ -50,8 +50,8 @@ void to_json(nlohmann::json &j, const template_parameter &c)
         j["default_value"] = c.default_value();
     j["is_template_parameter"] = c.is_template_parameter();
     j["is_template_template_parameter"] = c.is_template_template_parameter();
-    if (c.concept_constraint())
-        j["concept_constraint"] = c.concept_constraint().value();
+    if (const auto &constraint = c.concept_constraint(); constraint)
+        j["concept_constraint"] = constraint.value();
     j["is_variadic"] = c.is_variadic();
 }
 
@@ -67,11 +67,11 @@ void to_json(nlohmann::json &j, const relationship &c)
         j["access"] = to_string(c.access());
     if (!c.label().empty())
         j["label"] = c.label();
-    if (c.comment())
-        j["comment"] = c.comment().value();
+    if (const auto &comment = c.comment(); comment)
+        j["comment"] = comment.value();
 }
 
-}
+} // namespace clanguml::common::model
 
 namespace clanguml::class_diagram::model {
 using nlohmann::json;
@@ -84,8 +84,8 @@ void to_json(nlohmann::json &j, const class_element &c)
     if (!c.file().empty())
         j["source_location"] =
             dynamic_cast<const common::model::source_location &>(c);
-    if (c.comment())
-        j["comment"] = c.comment().value();
+    if (const auto &comment = c.comment(); comment)
+        j["comment"] = comment.value();
 }
 
 void to_json(nlohmann::json &j, const class_member &c)
@@ -154,7 +154,8 @@ void to_json(nlohmann::json &j, const concept_ &c)
     j["parameters"] = c.requires_parameters();
     j["statements"] = c.requires_statements();
 }
-}
+
+} // namespace clanguml::class_diagram::model
 
 namespace clanguml::class_diagram::generators::json {
 
@@ -392,4 +393,4 @@ void generator::generate_relationships(
     }
 }
 
-} // namespace clanguml::class_diagram::generators::plantuml
+} // namespace clanguml::class_diagram::generators::json
diff --git a/src/common/generators/generators.cc b/src/common/generators/generators.cc
new file mode 100644
index 00000000..02823113
--- /dev/null
+++ b/src/common/generators/generators.cc
@@ -0,0 +1,224 @@
+/**
+ * src/common/generators/generators.cc
+ *
+ * Copyright (c) 2021-2023 Bartek Kryza <bkryza@gmail.com>
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "generators.h"
+
+namespace clanguml::common::generators {
+void find_translation_units_for_diagrams(
+    const std::vector<std::string> &diagram_names,
+    clanguml::config::config &config,
+    const std::vector<std::string> &compilation_database_files,
+    std::map<std::string, std::vector<std::string>> &translation_units_map)
+{
+    for (const auto &[name, diagram] : config.diagrams) {
+        // If there are any specific diagram names provided on the command line,
+        // and this diagram is not in that list - skip it
+        if (!diagram_names.empty() && !util::contains(diagram_names, name))
+            continue;
+
+        // If glob is not defined use all translation units from the
+        // compilation database
+        if (!diagram->glob.has_value) {
+            translation_units_map[name] = compilation_database_files;
+        }
+        // Otherwise, get all translation units matching the glob from diagram
+        // configuration
+        else {
+            const std::vector<std::string> translation_units =
+                diagram->get_translation_units();
+
+            std::vector<std::string> valid_translation_units{};
+            std::copy_if(compilation_database_files.begin(),
+                compilation_database_files.end(),
+                std::back_inserter(valid_translation_units),
+                [&translation_units](const auto &tu) {
+                    return util::contains(translation_units, tu);
+                });
+
+            translation_units_map[name] = std::move(valid_translation_units);
+        }
+    }
+}
+
+void generate_diagram(const std::string &od, const std::string &name,
+    std::shared_ptr<clanguml::config::diagram> diagram,
+    const clang::tooling::CompilationDatabase &db,
+    const std::vector<std::string> &translation_units,
+    const std::vector<clanguml::common::generator_type_t> &generators,
+    bool verbose)
+{
+    using clanguml::common::generator_type_t;
+    using clanguml::common::model::diagram_t;
+    using clanguml::config::class_diagram;
+    using clanguml::config::include_diagram;
+    using clanguml::config::package_diagram;
+    using clanguml::config::sequence_diagram;
+
+    if (diagram->type() == diagram_t::kClass) {
+        using diagram_config = class_diagram;
+        using diagram_model = clanguml::class_diagram::model::diagram;
+        using diagram_visitor =
+            clanguml::class_diagram::visitor::translation_unit_visitor;
+
+        auto model = clanguml::common::generators::generate<diagram_model,
+            diagram_config, diagram_visitor>(db, diagram->name,
+            dynamic_cast<diagram_config &>(*diagram), translation_units,
+            verbose);
+
+        for (const auto generator_type : generators) {
+            if (generator_type == generator_type_t::plantuml) {
+                auto path =
+                    std::filesystem::path{od} / fmt::format("{}.puml", name);
+                std::ofstream ofs;
+                ofs.open(path, std::ofstream::out | std::ofstream::trunc);
+                ofs << clanguml::class_diagram::generators::plantuml::generator(
+                    dynamic_cast<diagram_config &>(*diagram), *model);
+
+                ofs.close();
+
+                LOG_INFO("Written {} diagram to {}", name, path.string());
+            }
+            else if (generator_type == generator_type_t::json) {
+                auto path =
+                    std::filesystem::path{od} / fmt::format("{}.json", name);
+                std::ofstream ofs;
+                ofs.open(path, std::ofstream::out | std::ofstream::trunc);
+                ofs << clanguml::class_diagram::generators::json::generator(
+                    dynamic_cast<diagram_config &>(*diagram), *model);
+
+                ofs.close();
+
+                LOG_INFO("Written {} diagram to {}", name, path.string());
+            }
+        }
+    }
+    else if (diagram->type() == diagram_t::kSequence) {
+        using diagram_config = sequence_diagram;
+        using diagram_model = clanguml::sequence_diagram::model::diagram;
+        using diagram_visitor =
+            clanguml::sequence_diagram::visitor::translation_unit_visitor;
+
+        auto model = clanguml::common::generators::generate<diagram_model,
+            diagram_config, diagram_visitor>(db, diagram->name,
+            dynamic_cast<diagram_config &>(*diagram), translation_units,
+            verbose);
+
+        auto path = std::filesystem::path{od} / fmt::format("{}.puml", name);
+        std::ofstream ofs;
+
+        ofs.open(path, std::ofstream::out | std::ofstream::trunc);
+        ofs << clanguml::sequence_diagram::generators::plantuml::generator(
+            dynamic_cast<clanguml::config::sequence_diagram &>(*diagram),
+            *model);
+
+        ofs.close();
+
+        LOG_INFO("Written {} diagram to {}", name, path.string());
+    }
+    else if (diagram->type() == diagram_t::kPackage) {
+        using diagram_config = package_diagram;
+        using diagram_model = clanguml::package_diagram::model::diagram;
+        using diagram_visitor =
+            clanguml::package_diagram::visitor::translation_unit_visitor;
+
+        auto model = clanguml::common::generators::generate<diagram_model,
+            diagram_config, diagram_visitor>(db, diagram->name,
+            dynamic_cast<diagram_config &>(*diagram), translation_units,
+            verbose);
+
+        auto path = std::filesystem::path{od} / fmt::format("{}.puml", name);
+        std::ofstream ofs;
+        ofs.open(path, std::ofstream::out | std::ofstream::trunc);
+
+        ofs << clanguml::package_diagram::generators::plantuml::generator(
+            dynamic_cast<diagram_config &>(*diagram), *model);
+
+        ofs.close();
+
+        LOG_INFO("Written {} diagram to {}", name, path.string());
+    }
+    else if (diagram->type() == diagram_t::kInclude) {
+        using diagram_config = include_diagram;
+        using diagram_model = clanguml::include_diagram::model::diagram;
+        using diagram_visitor =
+            clanguml::include_diagram::visitor::translation_unit_visitor;
+
+        auto model = clanguml::common::generators::generate<diagram_model,
+            diagram_config, diagram_visitor>(db, diagram->name,
+            dynamic_cast<diagram_config &>(*diagram), translation_units,
+            verbose);
+
+        auto path = std::filesystem::path{od} / fmt::format("{}.puml", name);
+        std::ofstream ofs;
+        ofs.open(path, std::ofstream::out | std::ofstream::trunc);
+
+        ofs << clanguml::include_diagram::generators::plantuml::generator(
+            dynamic_cast<diagram_config &>(*diagram), *model);
+
+        ofs.close();
+
+        LOG_INFO("Written {} diagram to {}", name, path.string());
+    }
+}
+
+void generate_diagrams(const std::vector<std::string> &diagram_names,
+    clanguml::config::config &config, const std::string &od,
+    const std::unique_ptr<clang::tooling::CompilationDatabase> &db,
+    const int verbose, const unsigned int thread_count,
+    const std::vector<clanguml::common::generator_type_t> &generators,
+    const std::map<std::string, std::vector<std::string>>
+        &translation_units_map)
+{
+    util::thread_pool_executor generator_executor{thread_count};
+    std::vector<std::future<void>> futs;
+
+    for (const auto &[name, diagram] : config.diagrams) {
+        // If there are any specific diagram names provided on the command line,
+        // and this diagram is not in that list - skip it
+        if (!diagram_names.empty() && !util::contains(diagram_names, name))
+            continue;
+
+        const auto &valid_translation_units = translation_units_map.at(name);
+
+        if (valid_translation_units.empty()) {
+            LOG_ERROR(
+                "Diagram {} generation failed: no translation units found",
+                name);
+            continue;
+        }
+
+        futs.emplace_back(generator_executor.add(
+            [&od, &generators, &name = name, &diagram = diagram,
+                db = std::ref(*db), translation_units = valid_translation_units,
+                verbose]() {
+                try {
+                    generate_diagram(od, name, diagram, db, translation_units,
+                        generators, verbose != 0);
+                }
+                catch (std::runtime_error &e) {
+                    LOG_ERROR(e.what());
+                }
+            }));
+    }
+
+    for (auto &fut : futs) {
+        fut.get();
+    }
+}
+
+} // namespace clanguml::common::generators
\ No newline at end of file
diff --git a/src/common/generators/generators.h b/src/common/generators/generators.h
index 5e260619..8cf7874a 100644
--- a/src/common/generators/generators.h
+++ b/src/common/generators/generators.h
@@ -49,37 +49,7 @@ void find_translation_units_for_diagrams(
     const std::vector<std::string> &diagram_names,
     clanguml::config::config &config,
     const std::vector<std::string> &compilation_database_files,
-    std::map<std::string, std::vector<std::string>> &translation_units_map)
-{
-    for (const auto &[name, diagram] : config.diagrams) {
-        // If there are any specific diagram names provided on the command line,
-        // and this diagram is not in that list - skip it
-        if (!diagram_names.empty() && !util::contains(diagram_names, name))
-            continue;
-
-        // If glob is not defined use all translation units from the
-        // compilation database
-        if (!diagram->glob.has_value) {
-            translation_units_map[name] = compilation_database_files;
-        }
-        // Otherwise, get all translation units matching the glob from diagram
-        // configuration
-        else {
-            const std::vector<std::string> translation_units =
-                diagram->get_translation_units();
-
-            std::vector<std::string> valid_translation_units{};
-            std::copy_if(compilation_database_files.begin(),
-                compilation_database_files.end(),
-                std::back_inserter(valid_translation_units),
-                [&translation_units](const auto &tu) {
-                    return util::contains(translation_units, tu);
-                });
-
-            translation_units_map[name] = std::move(valid_translation_units);
-        }
-    }
-}
+    std::map<std::string, std::vector<std::string>> &translation_units_map);
 
 template <typename DiagramModel, typename DiagramConfig,
     typename TranslationUnitVisitor>
@@ -203,166 +173,15 @@ void generate_diagram(const std::string &od, const std::string &name,
     std::shared_ptr<clanguml::config::diagram> diagram,
     const clang::tooling::CompilationDatabase &db,
     const std::vector<std::string> &translation_units,
-    const std::vector<clanguml::common::generator_type_t> generators,
-    bool verbose)
-{
-    using clanguml::common::generator_type_t;
-    using clanguml::common::model::diagram_t;
-    using clanguml::config::class_diagram;
-    using clanguml::config::include_diagram;
-    using clanguml::config::package_diagram;
-    using clanguml::config::sequence_diagram;
-
-    if (diagram->type() == diagram_t::kClass) {
-        using diagram_config = class_diagram;
-        using diagram_model = clanguml::class_diagram::model::diagram;
-        using diagram_visitor =
-            clanguml::class_diagram::visitor::translation_unit_visitor;
-
-        auto model = clanguml::common::generators::generate<diagram_model,
-            diagram_config, diagram_visitor>(db, diagram->name,
-            dynamic_cast<diagram_config &>(*diagram), translation_units,
-            verbose);
-
-        for (const auto generator_type : generators) {
-            if (generator_type == generator_type_t::plantuml) {
-                auto path =
-                    std::filesystem::path{od} / fmt::format("{}.puml", name);
-                std::ofstream ofs;
-                ofs.open(path, std::ofstream::out | std::ofstream::trunc);
-                ofs << clanguml::class_diagram::generators::plantuml::generator(
-                    dynamic_cast<diagram_config &>(*diagram), *model);
-
-                ofs.close();
-
-                LOG_INFO("Written {} diagram to {}", name, path.string());
-            }
-            else if (generator_type == generator_type_t::json) {
-                auto path =
-                    std::filesystem::path{od} / fmt::format("{}.json", name);
-                std::ofstream ofs;
-                ofs.open(path, std::ofstream::out | std::ofstream::trunc);
-                ofs << clanguml::class_diagram::generators::json::generator(
-                    dynamic_cast<diagram_config &>(*diagram), *model);
-
-                ofs.close();
-
-                LOG_INFO("Written {} diagram to {}", name, path.string());
-            }
-        }
-    }
-    else if (diagram->type() == diagram_t::kSequence) {
-        using diagram_config = sequence_diagram;
-        using diagram_model = clanguml::sequence_diagram::model::diagram;
-        using diagram_visitor =
-            clanguml::sequence_diagram::visitor::translation_unit_visitor;
-
-        auto model = clanguml::common::generators::generate<diagram_model,
-            diagram_config, diagram_visitor>(db, diagram->name,
-            dynamic_cast<diagram_config &>(*diagram), translation_units,
-            verbose);
-
-        auto path = std::filesystem::path{od} / fmt::format("{}.puml", name);
-        std::ofstream ofs;
-
-        ofs.open(path, std::ofstream::out | std::ofstream::trunc);
-        ofs << clanguml::sequence_diagram::generators::plantuml::generator(
-            dynamic_cast<clanguml::config::sequence_diagram &>(*diagram),
-            *model);
-
-        ofs.close();
-
-        LOG_INFO("Written {} diagram to {}", name, path.string());
-    }
-    else if (diagram->type() == diagram_t::kPackage) {
-        using diagram_config = package_diagram;
-        using diagram_model = clanguml::package_diagram::model::diagram;
-        using diagram_visitor =
-            clanguml::package_diagram::visitor::translation_unit_visitor;
-
-        auto model = clanguml::common::generators::generate<diagram_model,
-            diagram_config, diagram_visitor>(db, diagram->name,
-            dynamic_cast<diagram_config &>(*diagram), translation_units,
-            verbose);
-
-        auto path = std::filesystem::path{od} / fmt::format("{}.puml", name);
-        std::ofstream ofs;
-        ofs.open(path, std::ofstream::out | std::ofstream::trunc);
-
-        ofs << clanguml::package_diagram::generators::plantuml::generator(
-            dynamic_cast<diagram_config &>(*diagram), *model);
-
-        ofs.close();
-
-        LOG_INFO("Written {} diagram to {}", name, path.string());
-    }
-    else if (diagram->type() == diagram_t::kInclude) {
-        using diagram_config = include_diagram;
-        using diagram_model = clanguml::include_diagram::model::diagram;
-        using diagram_visitor =
-            clanguml::include_diagram::visitor::translation_unit_visitor;
-
-        auto model = clanguml::common::generators::generate<diagram_model,
-            diagram_config, diagram_visitor>(db, diagram->name,
-            dynamic_cast<diagram_config &>(*diagram), translation_units,
-            verbose);
-
-        auto path = std::filesystem::path{od} / fmt::format("{}.puml", name);
-        std::ofstream ofs;
-        ofs.open(path, std::ofstream::out | std::ofstream::trunc);
-
-        ofs << clanguml::include_diagram::generators::plantuml::generator(
-            dynamic_cast<diagram_config &>(*diagram), *model);
-
-        ofs.close();
-
-        LOG_INFO("Written {} diagram to {}", name, path.string());
-    }
-}
+    const std::vector<clanguml::common::generator_type_t> &generators,
+    bool verbose);
 
 void generate_diagrams(const std::vector<std::string> &diagram_names,
     clanguml::config::config &config, const std::string &od,
-    const std::unique_ptr<clang::tooling::CompilationDatabase> &db,
-    const int verbose, const unsigned int thread_count,
-    const std::vector<clanguml::common::generator_type_t> generators,
+    const std::unique_ptr<clang::tooling::CompilationDatabase> &db, int verbose,
+    unsigned int thread_count,
+    const std::vector<clanguml::common::generator_type_t> &generators,
     const std::map<std::string, std::vector<std::string>>
-        &translation_units_map)
-{
-    util::thread_pool_executor generator_executor{thread_count};
-    std::vector<std::future<void>> futs;
-
-    for (const auto &[name, diagram] : config.diagrams) {
-        // If there are any specific diagram names provided on the command line,
-        // and this diagram is not in that list - skip it
-        if (!diagram_names.empty() && !util::contains(diagram_names, name))
-            continue;
-
-        const auto &valid_translation_units = translation_units_map.at(name);
-
-        if (valid_translation_units.empty()) {
-            LOG_ERROR(
-                "Diagram {} generation failed: no translation units found",
-                name);
-            continue;
-        }
-
-        futs.emplace_back(generator_executor.add(
-            [&od, &generators, &name = name, &diagram = diagram,
-                db = std::ref(*db), translation_units = valid_translation_units,
-                verbose]() {
-                try {
-                    generate_diagram(od, name, diagram, db, translation_units,
-                        generators, verbose != 0);
-                }
-                catch (std::runtime_error &e) {
-                    LOG_ERROR(e.what());
-                }
-            }));
-    }
-
-    for (auto &fut : futs) {
-        fut.get();
-    }
-}
+        &translation_units_map);
 
 } // namespace clanguml::common::generators
\ No newline at end of file