Cleanups

AGENTS.md

@@ -42,6 +42,20 @@ ctest --output-on-failure
 ./test/integration/integration_tests
 ```
 
+### Formatting
+The project uses `clang-format` for code formatting.
+
+To format all files:
+```bash
+# From the build directory
+cmake --build . --target format
+```
+
+To format only changed files (requires `git`):
+```bash
+./scripts/format_changed.sh
+```
+
 ### Building Documentation
 If Doxygen is found, you can generate the HTML documentation:
 ```bash
@@ -63,11 +77,14 @@ Or simply copy the `include/deferred` directory to your project's include path.
   - **Indentation**: 2 spaces.
   - **Pointer Alignment**: Left (`Type* ptr`).
   - **Brace Wrapping**: Custom (check `.clang-format` for details).
+  - **Formatting**: All code must be formatted using `clang-format` before being committed. Use the `format` CMake target or the `scripts/format_changed.sh` script.
 - **Naming**: 
   - Namespaces: `deferred`
   - Files: `.hpp` for headers, `.cpp` for tests/examples.
 - **Testing**: New features must include unit tests in `test/unit/` and integration tests in `test/integration/`. Tests use the Catch2 v3 framework.
   - **Catch2 v3**: Uses `#include <catch2/catch_test_macros.hpp>` and requires a custom `main` in `main.cpp` using `Catch::Session().run()`.
+  - **Verification**: All changes must be verified by ensuring that all tests pass (`ctest`).
+- **Project Documentation**: After any code changes, `README.md` and `AGENTS.md` must be reviewed and updated if necessary to reflect the current state of the project.
 - **License**: MIT License. All source files should include the standard MIT license header.
 - **Header Guards**: Use `#ifndef DEFERRED_FILENAME_HPP` format.
 - **CI**: GitHub Actions workflow (`.github/workflows/c-cpp.yml`) builds the project on Ubuntu, Windows (MSVC), and macOS.

CMakeLists.txt

@@ -95,3 +95,18 @@ if(CMAKE_PROJECT_NAME STREQUAL PROJECT_NAME AND BUILD_TESTING)
   enable_testing()
   add_subdirectory(test)
 endif()
+
+# formatting
+
+find_program(CLANG_FORMAT clang-format)
+if(CLANG_FORMAT)
+  file(GLOB_RECURSE ALL_SOURCE_FILES
+    "include/*.h*"
+    "test/*.c*"
+    "examples/*.c*")
+  add_custom_target(format
+    COMMAND ${CLANG_FORMAT} -i ${ALL_SOURCE_FILES}
+    WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}
+    COMMENT "Formatting code with clang-format"
+    VERBATIM)
+endif()

README.md

@@ -92,8 +92,18 @@ To run tests after building:
 ctest --output-on-failure
 ```
 
-Known Issues
-------------
+Formatting
+----------
+
+The project uses `clang-format` for code formatting.
+
+To format all files:
+```bash
+# From the build directory
+cmake --build . --target format
+```
 
-* Using callable objects and functions with side-effects in ``invoke()`` and ``if_then_else()`` will result in a constant expression, assignable to ``constant_``.
-* Using ``deferred`` with other expression template based classes (e.g., `std::valarray`) may not be possible.
+To format only changed files (requires `git`):
+```bash
+./scripts/format_changed.sh
+```

examples/saxpy/saxpy_valarray.cpp

@@ -1,10 +1,5 @@
-/*
- * Copyright (c) 2019-2020 Yiannis Papadopoulos
- *
- * Distributed under the terms of the MIT License.
- *
- * (See accompanying file LICENSE or copy at http://opensource.org/licenses/MIT)
- */
+// SPDX-FileCopyrightText: 2019-2026 Yiannis Papadopoulos <giannis.papadopoulos@gmail.com>
+// SPDX-License-Identifier: MIT
 
 #include <algorithm>
 #include <iostream>

examples/saxpy/saxpy_vector.cpp

@@ -1,10 +1,5 @@
-/*
- * Copyright (c) 2019-2020 Yiannis Papadopoulos
- *
- * Distributed under the terms of the MIT License.
- *
- * (See accompanying file LICENSE or copy at http://opensource.org/licenses/MIT)
- */
+// SPDX-FileCopyrightText: 2019-2026 Yiannis Papadopoulos <giannis.papadopoulos@gmail.com>
+// SPDX-License-Identifier: MIT
 
 #include <algorithm>
 #include <iostream>

examples/trivial/main.cpp

@@ -1,10 +1,5 @@
-/*
- * Copyright (c) 2019-2020 Yiannis Papadopoulos
- *
- * Distributed under the terms of the MIT License.
- *
- * (See accompanying file LICENSE or copy at http://opensource.org/licenses/MIT)
- */
+// SPDX-FileCopyrightText: 2019-2026 Yiannis Papadopoulos <giannis.papadopoulos@gmail.com>
+// SPDX-License-Identifier: MIT
 
 #include <deferred/deferred.hpp>
 #include <iostream>

include/deferred/apply.hpp

@@ -1,11 +1,5 @@
-/** @file */
-/*
- * Copyright (c) 2019-2020 Yiannis Papadopoulos
- *
- * Distributed under the terms of the MIT License.
- *
- * (See accompanying file LICENSE or copy at http://opensource.org/licenses/MIT)
- */
+// SPDX-FileCopyrightText: 2019-2026 Yiannis Papadopoulos <giannis.papadopoulos@gmail.com>
+// SPDX-License-Identifier: MIT
 
 #ifndef DEFERRED_APPLY_HPP
 #define DEFERRED_APPLY_HPP
@@ -20,13 +14,9 @@ namespace detail {
 
 /**
  * @brief Helper function to apply a callable to the elements of a tuple.
- * @tparam F Type of the callable.
- * @tparam Tuple Type of the tuple.
+ * @copydoc apply(F&&, Tuple&&)
  * @tparam I Index sequence for tuple elements.
- * @param f The callable to apply.
- * @param t The tuple containing deferred objects.
  * @param I Index sequence for tuple elements.
- * @return The result of applying @p f to the evaluated elements of @p t.
  */
 template<typename F, typename Tuple, std::size_t... I>
 constexpr decltype(auto) apply_impl(F&& f, Tuple&& t, std::index_sequence<I...>)

include/deferred/conditional.hpp

@@ -1,11 +1,5 @@
-/** @file */
-/*
- * Copyright (c) 2019-2020 Yiannis Papadopoulos
- *
- * Distributed under the terms of the MIT License.
- *
- * (See accompanying file LICENSE or copy at http://opensource.org/licenses/MIT)
- */
+// SPDX-FileCopyrightText: 2019-2026 Yiannis Papadopoulos <giannis.papadopoulos@gmail.com>
+// SPDX-License-Identifier: MIT
 
 #ifndef DEFERRED_CONDITIONAL_HPP
 #define DEFERRED_CONDITIONAL_HPP
@@ -31,9 +25,6 @@ namespace deferred {
 template<typename ConditionExpression, typename ThenExpression, typename ElseExpression>
 class if_then_else_expression
 {
-  [[no_unique_address]] std::tuple<ConditionExpression, ThenExpression, ElseExpression>
-    m_expressions;
-
 public:
   using condition_expression_type = ConditionExpression;
   using then_expression_type      = ThenExpression;
@@ -42,6 +33,10 @@ class if_then_else_expression
                                                        decltype(std::declval<ElseExpression>()())>;
   using subexpression_types       = std::tuple<ConditionExpression, ThenExpression, ElseExpression>;
 
+private:
+  [[no_unique_address]] subexpression_types m_expressions;
+
+public:
   /**
    * @brief Constructs an if_then_else_expression.
    * @tparam Condition Type of the condition expression.
@@ -60,7 +55,11 @@ class if_then_else_expression
                   std::forward<ElseEx>(else_))
   { }
 
-  constexpr result_type operator()() const
+  /**
+   * @brief Evaluates the conditional expression.
+   * @return The result of the conditional expression.
+   */
+  [[nodiscard]] constexpr result_type operator()() const
   {
     if (evaluate(std::get<0>(m_expressions)))
     {
@@ -72,7 +71,8 @@ class if_then_else_expression
     }
   }
 
-  constexpr result_type operator()()
+  /// @copydoc if_then_else_expression::operator()() const
+  [[nodiscard]] constexpr result_type operator()()
   {
     if (evaluate(std::get<0>(m_expressions)))
     {
@@ -116,7 +116,7 @@ class if_then_else_expression
  * @return An \ref if_then_else_expression that will perform the deferred evaluation.
  */
 template<typename ConditionExpression, typename ThenExpression, typename ElseExpression>
-constexpr auto
+[[nodiscard]] constexpr auto
 if_then_else(ConditionExpression&& condition, ThenExpression&& then_, ElseExpression&& else_)
 {
   using condition_expression = make_deferred_t<ConditionExpression>;

include/deferred/constant.hpp

@@ -1,11 +1,5 @@
-/** @file */
-/*
- * Copyright (c) 2019-2020 Yiannis Papadopoulos
- *
- * Distributed under the terms of the MIT License.
- *
- * (See accompanying file LICENSE or copy at http://opensource.org/licenses/MIT)
- */
+// SPDX-FileCopyrightText: 2019-2026 Yiannis Papadopoulos <giannis.papadopoulos@gmail.com>
+// SPDX-License-Identifier: MIT
 
 #ifndef DEFERRED_CONSTANT_HPP
 #define DEFERRED_CONSTANT_HPP
@@ -29,7 +23,7 @@ class constant_
   using subexpression_types = std::tuple<>;
 
 private:
-  T m_t;
+  [[no_unique_address]] T m_t;
 
 public:
   /**
@@ -48,13 +42,13 @@ class constant_
   constant_& operator=(constant_&&)      = delete;
 
   /// Returns the stored value.
-  constexpr T const& operator()() const& noexcept
+  [[nodiscard]] constexpr T const& operator()() const& noexcept
   {
     return m_t;
   }
 
   /// @copydoc operator()()
-  constexpr T operator()() && noexcept
+  [[nodiscard]] constexpr T operator()() && noexcept
   {
     return std::move(m_t);
   }
@@ -83,7 +77,7 @@ class constant_
  * @return A constant_ object containing the evaluated value.
  */
 template<typename T>
-constexpr auto constant(T&& t)
+[[nodiscard]] constexpr auto constant(T&& t)
 {
   using result_type = std::decay_t<decltype(recursive_evaluate(std::forward<T>(t)))>;
   return constant_<result_type>(recursive_evaluate(std::forward<T>(t)));

include/deferred/deferred.hpp

@@ -1,11 +1,5 @@
-/** @file */
-/*
- * Copyright (c) 2019-2020 Yiannis Papadopoulos
- *
- * Distributed under the terms of the MIT License.
- *
- * (See accompanying file LICENSE or copy at http://opensource.org/licenses/MIT)
- */
+// SPDX-FileCopyrightText: 2019-2026 Yiannis Papadopoulos <giannis.papadopoulos@gmail.com>
+// SPDX-License-Identifier: MIT
 
 #ifndef DEFERRED_DEFERRED_HPP
 #define DEFERRED_DEFERRED_HPP

include/deferred/evaluate.hpp

@@ -1,11 +1,5 @@
-/** @file */
-/*
- * Copyright (c) 2019-2020 Yiannis Papadopoulos
- *
- * Distributed under the terms of the MIT License.
- *
- * (See accompanying file LICENSE or copy at http://opensource.org/licenses/MIT)
- */
+// SPDX-FileCopyrightText: 2019-2026 Yiannis Papadopoulos <giannis.papadopoulos@gmail.com>
+// SPDX-License-Identifier: MIT
 
 #ifndef DEFERRED_EVALUATE_HPP
 #define DEFERRED_EVALUATE_HPP
@@ -24,7 +18,7 @@ namespace deferred {
  * @return The result of evaluating the expression.
  */
 template<typename T>
-constexpr decltype(auto) evaluate(T&& t)
+constexpr auto evaluate(T&& t)
 {
   if constexpr (Deferred<T>)
   {
@@ -34,8 +28,7 @@ constexpr decltype(auto) evaluate(T&& t)
     }
     else
     {
-      auto v = evaluate(std::forward<T>(t)());
-      return v;
+      return evaluate(std::forward<T>(t)());
     }
   }
   else
@@ -46,17 +39,14 @@ constexpr decltype(auto) evaluate(T&& t)
 
 /**
  * @brief Recursively evaluates @p t until a non-callable is returned.
- * @tparam T The type of the expression to recursively evaluate.
- * @param t The expression to recursively evaluate.
- * @return The result of the recursive evaluation.
+ * @copydoc evaluate(T&&)
  */
 template<typename T>
-constexpr decltype(auto) recursive_evaluate(T&& t)
+constexpr auto recursive_evaluate(T&& t)
 {
   if constexpr (std::is_invocable_v<T>)
   {
-    auto v = recursive_evaluate(std::forward<T>(t)());
-    return v;
+    return recursive_evaluate(std::forward<T>(t)());
   }
   else
   {

include/deferred/expression.hpp

@@ -1,11 +1,5 @@
-/** @file */
-/*
- * Copyright (c) 2019-2020 Yiannis Papadopoulos
- *
- * Distributed under the terms of the MIT License.
- *
- * (See accompanying file LICENSE or copy at http://opensource.org/licenses/MIT)
- */
+// SPDX-FileCopyrightText: 2019-2026 Yiannis Papadopoulos <giannis.papadopoulos@gmail.com>
+// SPDX-License-Identifier: MIT
 
 #ifndef DEFERRED_EXPRESSION_HPP
 #define DEFERRED_EXPRESSION_HPP
@@ -31,14 +25,16 @@ namespace deferred {
 template<typename Operator, typename... Expressions>
 class expression_
 {
-  [[no_unique_address]] Operator m_op;
-  [[no_unique_address]] std::tuple<Expressions...> m_expressions;
-
 public:
   using operator_type       = Operator;
   using expression_types    = std::tuple<Expressions...>;
   using subexpression_types = std::tuple<Operator, Expressions...>;
 
+private:
+  [[no_unique_address]] operator_type m_op;
+  [[no_unique_address]] expression_types m_expressions;
+
+public:
   /**
    * @brief Constructs an expression.
    * @tparam Op The type of the operator.
@@ -60,22 +56,23 @@ class expression_
   expression_& operator=(expression_ const&) = delete;
   expression_& operator=(expression_&&)      = delete;
 
-  constexpr decltype(auto) operator()() const
+  [[nodiscard]] constexpr decltype(auto) operator()() const
   {
     return deferred::apply(m_op, m_expressions);
   }
 
-  constexpr decltype(auto) operator()()
+  /// @copydoc operator()() const
+  [[nodiscard]] constexpr decltype(auto) operator()()
   {
     return deferred::apply(m_op, m_expressions);
   }
 
-  constexpr operator_type const& operator_() const noexcept
+  [[nodiscard]] constexpr operator_type const& operator_() const noexcept
   {
     return m_op;
   }
 
-  constexpr expression_types const& subexpressions() const noexcept
+  [[nodiscard]] constexpr expression_types const& subexpressions() const noexcept
   {
     return m_expressions;
   }