https://github.com/andreysolovyev381/zip_in_cpp

REAL zip iterator, that will be considered as an Iterator by other C++ code.
https://github.com/andreysolovyev381/zip_in_cpp

concepts cplusplus cpp cpp17 cpp20 header-only header-only-library headeronly iter iterator metaprogramming zip

Last synced: about 2 months ago
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REAL zip iterator, that will be considered as an Iterator by other C++ code.

• Host: GitHub
• URL: https://github.com/andreysolovyev381/zip_in_cpp
• Owner: andreysolovyev381
• License: mit
• Created: 2023-03-01T00:16:40.000Z (almost 2 years ago)
• Default Branch: master
• Last Pushed: 2023-04-09T08:55:26.000Z (over 1 year ago)
• Last Synced: 2023-08-31T03:41:10.245Z (over 1 year ago)
• Topics: concepts, cplusplus, cpp, cpp17, cpp20, header-only, header-only-library, headeronly, iter, iterator, metaprogramming, zip
• Language: C++
• Homepage:
• Size: 107 KB
• Stars: 2
• Watchers: 1
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: readme.md
  • License: license.md

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README

        
## Zip in C++

### Reasoning and Some info

I like small useful snippets, like this one. Let myself have an entertaining night while coding this exercise.

- Standard and Compilers: works like a charm in 17 and 20 (in case you are not yet in 23, but when you are there, you should take a look at [respective page at cppref](https://en.cppreference.com/w/cpp/ranges/zip_view)). Anyway, this impl compiles ok by gcc and clang on Linux - see GH Actions for this repo. Dependencies: header only, STL only.

- Iterator's big five is properly defined in the class: value_type, reference, difference_type, pointer, iterator_category. So other C++ code will consider this zip_iterator as an iterator as well.

- Lots of concept (C++20) and SFINAE (C++17) guards will fail the attempts of enlightened user to get an iterator from type void. Compile with WRONG_ITERATOR_COMPILE_FAILURE to see compile-time errors generated by the tests, or simply uncomment this #define in the test file.

- UI is simple - call 'zip' using either arbitrary number of containers or arbitrary number of iterators as the arguments. **If there are containers, then 'zip' provides A PAIR of iterators for each container, begin() and end() respectively.**

- It is tested - see the file.

- Problems - move_iterators work by copying r_value_references :see_no_evil: Maybe will fix it later :nerd_face:

### Usage

Pretty much straightforward, see the test file. Here is the most vivid example:

```c++

	std::vector v{ 1,2,3,4,5 };

	std::map m { {1, "one"s}, {2, "two"s}, {3, "three"s}, };

	std::string s { "abcdefghhlk" };

	

	/// Here it is, see the for loop expr

	for (auto const& [i, pair, ch] : itertools::zip(v, m, s)) {

		std::cout << i << ' ' << pair.first << ' ' << pair.second << ' ' << ch << '\n';

	}

```

Another example, if zipping iterators instead of containers:

```c++

	struct TestStruct {

		std::map m { {1, "one"s}, {2, "two"s}, {3, "three"s}, };

		auto begin() const { return m.begin(); }

		auto end() const { return m.end(); }

	};

	TestStruct test_struct;

	std::vector v{ 1,2,3,4,5 };

	std::string s { "abcdefghlk" };

	/// Here it is, zipping different input iterators - normal, constant and reverse

	auto begin = itertools::zip(v.cbegin(), s.crbegin(), test_struct.begin());

	auto end = itertools::zip(v.cend(), s.crend(), test_struct.end());

	for (auto itb = begin; itb != end; ++itb ) {

		auto const &[normal, const_reverse, const_normal] = itb;

		auto const &[i, c] = const_normal;

		std::cout << normal << ' ' << const_reverse << ' ' << i << ' ' << c << '\n';

	}

```

### Disclaimer 

Feel free to use it for your needs at your own risk. No guarantees of any kind is given :)

### License

MIT License