Simple Iterators

This project aims at providing an iterator mechanism inspired by Java.

The iterators of the C++ standard library are rather complex and rely heavily on operator overloading. This library uses C++ 20 concepts to make anything iterable that has an iterator() member function returning an iterator. An iterator is anything providing the member functions has_next() and next().

Next to the two concepts Iterable and Iterator this library provides a bunch of algorithms that are compatible with any types implementing these concepts.

Usage

Including into Git and CMake based project

Add this library as a submodule and include it via add_subdirectory() into your CMake project. Then everything you need to do, is to link against the si target.

Example:

git submodule add https://github.com/Drako/simple_iterators

Then in your CMakeLists.txt do something like this:

add_subdirectory(simple_iterators)

add_executable(hello main.cxx)
target_link_libraries(hello PRIVATE si)

Defining custom iterables

/**
 * The minimum required functions are has_next() and next().
 * has_next() is supposed to return a bool.
 */
class IntRangeIterator final {
  int current;
  int last;

public:
  constexpr IntRangeIterator(int start, int last) noexcept
      :current{start}, last{last} { }
      
  [[nodiscard]] constexpr bool has_next() const noexcept
  {
    return current<=last;
  }

  // in case next() is called on an empty iterator, si::no_such_element_exception should be thrown.
  constexpr int next()
  {
    if (!has_next())
      throw si::no_such_element_exception{"Called next() on empty iterator."};
    return current++;
  }
};

/**
 * The minimum required function is iterator().
 */
class IntRange {
  int from;
  int to;

public:
  constexpr IntRange(int from, int to) noexcept
      :from{from}, to{to} { }

  [[nodiscard]] constexpr IntRangeIterator iterator() const noexcept
  {
    return IntRangeIterator{from, to};
  }
};

Compiler Support

As of this writing GCC 10 or Clang 10 are required. See C++ Compiler Support for further reference. Concepts must be supported.

Building & Testing

Other than the aforementioned compilers the project currently requires CMake version 3.17 or newer.

Assuming the project has not been cloned yet, this is the further process to get the tests running:

git clone --recursive https://github.com/Drako/simple_iterators
mkdir -p simple_iterators/build
cd simple_iterators/build
cmake -DCMAKE_BUILD_TYPE=Debug ..
cmake --build .
ctest -V .