Update EasyIterator to work with C++20 (#13)

* Update EasyIterator to work with C++20

* Make changes compatible with C++17 and earlier

* update GitHub workflows to run on PRs

* run clang-format

* lock version of clang-format

* use ubuntu-latest for style workflow, which should allow global installation of python dependencies

---------

Co-authored-by: Lars Melchior <[email protected]>

.github/workflows/benchmark.yml

@@ -1,6 +1,14 @@
 name: Benchmark
 
-on: [push]
+on:
+  push:
+    branches:
+      - master
+      - main
+  pull_request:
+    branches:
+      - master
+      - main
 
 jobs:
   build:

.github/workflows/install.yml

@@ -1,6 +1,14 @@
 name: Install
 
-on: [push]
+on:
+  push:
+    branches:
+      - master
+      - main
+  pull_request:
+    branches:
+      - master
+      - main
 
 env:
   CTEST_OUTPUT_ON_FAILURE: 1

.github/workflows/macos.yml

@@ -1,6 +1,14 @@
 name: MacOS
 
-on: [push]
+on:
+  push:
+    branches:
+      - master
+      - main
+  pull_request:
+    branches:
+      - master
+      - main
 
 env:
   CTEST_OUTPUT_ON_FAILURE: 1

.github/workflows/style.yml

@@ -1,20 +1,28 @@
 name: Style
 
-on: [push]
+on:
+  push:
+    branches:
+      - master
+      - main
+  pull_request:
+    branches:
+      - master
+      - main
 
 jobs:
   build:
 
-    runs-on: macos-latest
+    runs-on: ubuntu-latest
 
     steps:
     - uses: actions/checkout@v1
 
-    - name: Install clang-format
-      run: brew install clang-format
+    - name: Install format dependencies
+      run: pip3 install clang-format==14.0.6
 
     - name: configure
-      run: cmake -Htest -Bbuild
+      run: cmake -Stest -Bbuild
 
     - name: check style
       run: cmake --build build --target check-format

.github/workflows/ubuntu.yml

@@ -1,6 +1,14 @@
 name: Ubuntu
 
-on: [push]
+on:
+  push:
+    branches:
+      - master
+      - main
+  pull_request:
+    branches:
+      - master
+      - main
 
 env:
   CTEST_OUTPUT_ON_FAILURE: 1

.github/workflows/windows.yml

@@ -1,6 +1,14 @@
 name: Windows
 
-on: [push]
+on:
+  push:
+    branches:
+      - master
+      - main
+  pull_request:
+    branches:
+      - master
+      - main
 
 env:
   CTEST_OUTPUT_ON_FAILURE: 1

.gitignore

@@ -1,3 +1,4 @@
 .DS_Store
 .vscode
+.venv
 /build*

CMakeLists.txt

@@ -27,9 +27,9 @@ CPMAddPackage(
 
 # ---- Header target ----
 
-FILE(GLOB_RECURSE headers CONFIGURE_DEPENDS "${CMAKE_CURRENT_SOURCE_DIR}/include/*.h")
+file(GLOB_RECURSE headers CONFIGURE_DEPENDS "${CMAKE_CURRENT_SOURCE_DIR}/include/*.h")
 add_library(EasyIterator-headers EXCLUDE_FROM_ALL ${headers})
-SET_TARGET_PROPERTIES(EasyIterator-headers PROPERTIES LINKER_LANGUAGE CXX)
+set_target_properties(EasyIterator-headers PROPERTIES LINKER_LANGUAGE CXX)
 
 # ---- Create library ----
 

include/easy_iterator.h

@@ -123,8 +123,8 @@ namespace easy_iterator {
   /**
    * Base class for simple iterators. Takes several template parameters.
    * Implementations must define `operator++()` to update the value of `value`.
-   * @param `T` - The data type held by the iterator
-   * @param `D` - A functional that dereferences the data. Determines the value type of the
+   * @param `T` - The data type held by the iterator.
+   * @param `D` - A function that dereferences the data. Determines the value type of the
    * iterator.
    * @param `C` - A function that compares two values of type `T`. Used to determine if two
    * iterators are equal.
@@ -155,21 +155,35 @@ namespace easy_iterator {
           value(std::forward<F>(first)) {}
 
     DereferencedType operator*() { return dereferencer(value); }
-    auto *operator-> () const { return &**this; }
-    template <typename... Args> bool operator==(const IteratorPrototype<Args...> &other) const {
-      return compare(value, other.value);
-    }
-    template <typename... Args> bool operator!=(const IteratorPrototype<Args...> &other) const {
-      return !operator==(other);
-    }
+    auto *operator->() const { return &**this; }
+
+    template <typename... LArgs, typename... RArgs>
+    friend bool operator==(const IteratorPrototype<LArgs...> &lhs,
+                           const IteratorPrototype<RArgs...> &rhs);
+
+    // required for C++17 or earlier
+    template <typename... LArgs, typename... RArgs>
+    friend bool operator!=(const IteratorPrototype<LArgs...> &lhs,
+                           const IteratorPrototype<RArgs...> &rhs);
   };
 
-  template <class T> IteratorPrototype(const T &)->IteratorPrototype<T>;
+  template <typename... LArgs, typename... RArgs>
+  bool operator==(const IteratorPrototype<LArgs...> &lhs, const IteratorPrototype<RArgs...> &rhs) {
+    return lhs.compare(lhs.value, rhs.value);
+  }
+
+  // required for C++17 or earlier
+  template <typename... LArgs, typename... RArgs>
+  bool operator!=(const IteratorPrototype<LArgs...> &lhs, const IteratorPrototype<RArgs...> &rhs) {
+    return !(lhs == rhs);
+  }
+
+  template <class T> IteratorPrototype(const T &) -> IteratorPrototype<T>;
 
-  template <class T, typename D> IteratorPrototype(const T &, const D &)->IteratorPrototype<T, D>;
+  template <class T, typename D> IteratorPrototype(const T &, const D &) -> IteratorPrototype<T, D>;
 
-  template <class T, typename D, typename C>
-  IteratorPrototype(const T &, const D &, const C &)->IteratorPrototype<T, D, C>;
+  template <class T, typename D, typename C> IteratorPrototype(const T &, const D &, const C &)
+      -> IteratorPrototype<T, D, C>;
 
   namespace iterator_detail {
     struct WithState {
@@ -185,7 +199,7 @@ namespace easy_iterator {
   }  // namespace iterator_detail
 
   /**
-   * IteratorPrototype where advance is defined by the functional held by `F`.
+   * IteratorPrototype where advance is defined by the function held by `F`.
    */
   template <class T, typename F = increment::ByValue<1>, typename D = dereference::ByValueReference,
             typename C = compare::ByValue>
@@ -222,16 +236,13 @@ namespace easy_iterator {
       }
       return Base::dereferencer(Base::value);
     }
-    using Base::operator==;
-    using Base::operator!=;
-    bool operator==(const IterationEnd &other) const { return !operator!=(other); }
-    bool operator!=(const IterationEnd &) const {
-      if constexpr (Iterator::hasState) {
-        return Iterator::state;
-      } else {
-        return true;
-      }
-    }
+
+    template <typename... Args>
+    friend bool operator==(const Iterator<Args...> &lhs, const IterationEnd &);
+    // required for C++17 or earlier
+    template <typename... Args>
+    friend bool operator!=(const Iterator<Args...> &lhs, const IterationEnd &);
+
     explicit operator bool() const {
       if constexpr (Iterator::hasState) {
         return Iterator::state;
@@ -241,15 +252,25 @@ namespace easy_iterator {
     }
   };
 
-  template <class T> Iterator(const T &)->Iterator<T>;
+  template <typename... Args> bool operator==(const Iterator<Args...> &lhs, const IterationEnd &) {
+    return !static_cast<bool>(lhs);
+  }
+
+  // required for C++17 or earlier
+  template <typename... Args>
+  bool operator!=(const Iterator<Args...> &lhs, const IterationEnd &rhs) {
+    return !(lhs == rhs);
+  }
+
+  template <class T> Iterator(const T &) -> Iterator<T>;
 
-  template <class T, typename F> Iterator(const T &, const F &)->Iterator<T, F>;
+  template <class T, typename F> Iterator(const T &, const F &) -> Iterator<T, F>;
 
-  template <class T, typename F, typename D>
-  Iterator(const T &, const F &, const D &)->Iterator<T, F, D>;
+  template <class T, typename F, typename D> Iterator(const T &, const F &, const D &)
+      -> Iterator<T, F, D>;
 
   template <class T, typename F, typename D, typename C>
-  Iterator(const T &, const F &, const D &, const C &)->Iterator<T, F, D, C>;
+  Iterator(const T &, const F &, const D &, const C &) -> Iterator<T, F, D, C>;
 
   template <class T, typename F = increment::ByValue<1>, typename D = dereference::ByValueReference,
             typename C = compare::ByValue>
@@ -310,25 +331,25 @@ namespace easy_iterator {
   }
 
   /**
-   * Returns an iterator that increases it's value from `begin` to `end` by `1` for each step.
+   * Returns an iterator that increases its value from `begin` to `end` by `1` for each step.
    */
   template <class T> auto range(T begin, T end) { return range<T>(begin, end, 1); }
 
   /**
-   * Returns an iterator that increases it's value from `0` to `end` by `1` for each step.
+   * Returns an iterator that increases its value from `0` to `end` by `1` for each step.
    */
   template <class T> auto range(T end) { return range<T>(0, end); }
 
   /**
-   * Wrappes the `rbegin` and `rend` iterators.
+   * Wraps the `rbegin` and `rend` iterators.
    */
   template <class T> auto reverse(T &v) { return wrap(v.rbegin(), v.rend()); }
 
   /**
    * Returns an iterable object where all argument iterators are traversed simultaneously.
    * Behaviour is undefined if the iterators do not have the same length.
    */
-  template <typename... Args> auto zip(Args &&... args) {
+  template <typename... Args> auto zip(Args &&...args) {
     auto begin = Iterator(std::make_tuple(args.begin()...), increment::ByTupleIncrement(),
                           dereference::ByTupleDereference(), compare::ByLastTupleElementMatch());
     auto end = Iterator(std::make_tuple(args.end()...), increment::ByTupleIncrement(),
@@ -344,7 +365,7 @@ namespace easy_iterator {
   }
 
   /**
-   * When used as a base class for a iterator type, `MakeIterable` will call the `bool init()`
+   * When used as a base class for an iterator type, `MakeIterable` will call the `bool init()`
    * member before iteration. If `init()` returns false, the iterator is empty.
    */
   struct InitializedIterable {};
@@ -368,7 +389,7 @@ namespace easy_iterator {
     auto end() const { return IterationEnd(); }
 
     explicit MakeIterable(T &&value) : start(std::move(value)) {}
-    template <typename... Args> explicit MakeIterable(Args &&... args)
+    template <typename... Args> explicit MakeIterable(Args &&...args)
         : start(T(std::forward<Args>(args)...)) {}
   };
 
@@ -380,7 +401,7 @@ namespace easy_iterator {
   }
 
   /**
-   * copy-assigns the given value to every element in a container
+   * Copy-assigns the given value to every element in a container
    */
   template <class T, class A> void fill(A &arr, const T &value) {
     for (auto &v : arr) {
@@ -389,7 +410,7 @@ namespace easy_iterator {
   }
 
   /**
-   * copies values from one container to another.
+   * Copies values from one container to another.
    * @param `a` - the container with values to be copies.
    * @param `b` - the target container.
    * @param `f` (optional) - a function to transform values before copying.

test/CMakeLists.txt

@@ -16,7 +16,7 @@ include(../cmake/CPM.cmake)
 CPMAddPackage(
   NAME doctest
   GITHUB_REPOSITORY onqtam/doctest
-  GIT_TAG 2.3.7
+  GIT_TAG v2.4.11
 )
 
 if (TEST_INSTALLED_VERSION)
@@ -53,11 +53,11 @@ endif()
 
 # ---- Add EasyIteratorTests ----
 
-ENABLE_TESTING() 
+enable_testing() 
 
 # Note: doctest and similar testing frameworks can automatically configure CMake tests
 # For other testing frameworks add the tests target instead:
-# ADD_TEST(EasyIteratorTests EasyIteratorTests)
+# add_test(EasyIteratorTests EasyIteratorTests)
 
 include(${doctest_SOURCE_DIR}/scripts/cmake/doctest.cmake)
 doctest_discover_tests(EasyIteratorTests)