https://github.com/bemanproject/any_view

A generalized type-erased view with customizable properties (P3411)

Science Score: 26.0%

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Low similarity (12.6%) to scientific vocabulary

Last synced: 6 months ago · JSON representation

Repository

A generalized type-erased view with customizable properties (P3411)

Basic Info

Host: GitHub
Owner: bemanproject
License: other
Language: C++
Default Branch: main
Homepage:
Size: 119 KB

Statistics

Stars: 6
Watchers: 10
Forks: 4
Open Issues: 5
Releases: 0

Created about 1 year ago · Last pushed 7 months ago

Metadata Files

Readme License Codeowners

beman.any_view: A generalized type-erased view with customizable properties

Library Status Standard Target

Implements: std::ranges::any_view proposed in any_view (P3411).

Status: Under development and not yet ready for production use.

Featured: C++Now 2025

Motivation

any_view equips library APIs with the ability to declare function parameters and return types as views, while de-coupling the interface from an implementation that can fully leverage the power of C++20 ranges. By using type-erased views, the library can be compiled separately.

As a return type, any_view grants a library author the freedom to change how the function is implemented to return the view without modifying its interface. As a parameter type, it allows users to call the library function with any range as an argument that can be consumed directly, rather than copying it into some bespoke, library-specific type.

Usage

```cpp

include

namespace bav = beman::anyview; using opt = bav::anyview_options;

template using proxyanyview = bav::any_view;

constexpr auto sum(proxyanyview> views) { auto result = 0;

for (auto view : views) {
    for (const auto value : view) {
        result += value;
    }
}

return result;

}

static_assert(10 == sum(std::vector{std::vector{1, 2}, std::vector{3, 4}}));

constexpr auto iota(int n) { return std::views::iota(1) | std::views::take(n); };

static_assert(35 == sum(iota(5) | std::views::transform(iota)));

static_assert(22 == sum(std::vector{iota(1), iota(3), iota(5)})); ```

Full code can be found in tests/beman/any_view/constexpr.test.cpp.

std::ranges::any_view is a class template that provides a type-erased interface for std::ranges::view. It may additionally model other concepts like std::ranges::contiguous_range, std::ranges::sized_range, std::ranges::borrowed_range, and std::copyable depending on the instantiation.

Integrate beman.any_view into your project

Use beman.any_view directly from CMake

For CMake based projects, you can include it as a dependency using the `FetchContent` module: ```cmake include(FetchContent) FetchContent_Declare( beman.any_view GIT_REPOSITORY https://github.com/bemanproject/any_view.git GIT_TAG main EXCLUDE_FROM_ALL ) FetchContent_MakeAvailable(beman.any_view) ``` You will also need to add `beman::any_view` to the link libraries of any targets that include `beman/any_view/*.hpp` in their source or header files: ```cmake target_link_libraries(yourlib PUBLIC beman::any_view) ```

Reference

Synopsis

```cpp namespace beman::any_view { // [range.any] enum class any_view_options { input = 0b00000001, forward = 0b00000011, bidirectional = 0b00000111, random_access = 0b00001111, contiguous = 0b00011111, sized = 0b00100000, borrowed = 0b01000000, copyable = 0b10000000, }; constexpr any_view_options operator|(any_view_options, any_view_options) noexcept; constexpr any_view_options operator&(any_view_options, any_view_options) noexcept; template struct /*rvalue-ref*/ { using type = T; }; template struct /*rvalue-ref*/ { using type = T&&; }; template using /*rvalue-ref-t*/ = /*rvalue-ref*/::type; template concept ext_any_compatible_viewable_range = /* ... */; template , class DiffT = std::ptrdiff_t> class any_view : public std::ranges::view_interface> { class iterator; // exposition-only class sentinel; // exposition-only public: // [range.any.ctor] template constexpr any_view(RangeT&& range); constexpr any_view(const any_view&); constexpr any_view(any_view&&) noexcept; constexpr any_view& operator=(const any_view&); constexpr any_view& operator=(any_view&&) noexcept; constexpr ~any_view(); // [range.any.access] constexpr iterator begin(); constexpr sentinel end(); constexpr std::make_unsigned_t size() const; // [range.any.swap] constexpr void swap(any_view&) noexcept; constexpr friend void swap(any_view&, any_view&) noexcept; }; } // namespace beman::any_view template inline constexpr bool std::ranges::enable_borrowed_range< beman::any_view::any_view> = bool(OptsV & beman::any_view::any_view_options::borrowed); ```

Building

There are workflows available in CMake presets such as gcc-debug:

bash cmake --workflow --preset gcc-debug

Alternatively you can manually configure, build, and test with CMake and CTest:

bash cmake -B build cmake --build build ctest --test-dir build

Possible output

```text Executing workflow step 1 of 3: configure preset "gcc-debug" Preset CMake variables: BEMAN_BUILDSYS_SANITIZER="MaxSan" CMAKE_BUILD_TYPE="Debug" CMAKE_EXPORT_COMPILE_COMMANDS:BOOL="TRUE" CMAKE_TOOLCHAIN_FILE="cmake/gnu-toolchain.cmake" -- The CXX compiler identification is GNU 15.0.0 -- Detecting CXX compiler ABI info -- Detecting CXX compiler ABI info - done -- Check for working CXX compiler: /usr/bin/g++ - skipped -- Detecting CXX compile features -- Detecting CXX compile features - done -- The C compiler identification is GNU 15.0.0 -- Detecting C compiler ABI info -- Detecting C compiler ABI info - done -- Check for working C compiler: /usr/bin/gcc - skipped -- Detecting C compile features -- Detecting C compile features - done -- Found Python3: /usr/bin/python3.12 (found version "3.12.7") found components: Interpreter -- Performing Test CMAKE_HAVE_LIBC_PTHREAD -- Performing Test CMAKE_HAVE_LIBC_PTHREAD - Success -- Found Threads: TRUE -- Configuring done (2.7s) -- Generating done (0.0s) -- Build files have been written to: /home/patrick/projects/any_view/build/gcc-debug Executing workflow step 2 of 3: build preset "gcc-debug" [12/12] Linking CXX executable tests/beman/any_view/beman.any_view.tests.constexpr Executing workflow step 3 of 3: test preset "gcc-debug" Test project /home/patrick/projects/any_view/build/gcc-debug Start 1: ConceptsTest.iterator_concept 1/21 Test #1: ConceptsTest.iterator_concept ................... Passed 0.01 sec Start 2: ConceptsTest.sized_concept 2/21 Test #2: ConceptsTest.sized_concept ...................... Passed 0.01 sec Start 3: ConceptsTest.borrowed_concept 3/21 Test #3: ConceptsTest.borrowed_concept ................... Passed 0.01 sec Start 4: ConceptsTest.copyable_concept 4/21 Test #4: ConceptsTest.copyable_concept ................... Passed 0.01 sec Start 5: ConstexprTest.sum_vector_of_vector 5/21 Test #5: ConstexprTest.sum_vector_of_vector .............. Passed 0.01 sec Start 6: ConstexprTest.sum_transform_view_of_iota_view 6/21 Test #6: ConstexprTest.sum_transform_view_of_iota_view ... Passed 0.01 sec Start 7: ConstexprTest.sum_vector_of_iota_view 7/21 Test #7: ConstexprTest.sum_vector_of_iota_view ........... Passed 0.01 sec Start 8: ConstexprTest.sort_vector 8/21 Test #8: ConstexprTest.sort_vector ....................... Passed 0.01 sec Start 9: SfinaeTest.istream_view 9/21 Test #9: SfinaeTest.istream_view ......................... Passed 0.01 sec Start 10: SfinaeTest.forward_list 10/21 Test #10: SfinaeTest.forward_list ......................... Passed 0.01 sec Start 11: SfinaeTest.list 11/21 Test #11: SfinaeTest.list ................................. Passed 0.01 sec Start 12: SfinaeTest.deque 12/21 Test #12: SfinaeTest.deque ................................ Passed 0.01 sec Start 13: SfinaeTest.vector 13/21 Test #13: SfinaeTest.vector ............................... Passed 0.01 sec Start 14: SfinaeTest.vector_of_bool 14/21 Test #14: SfinaeTest.vector_of_bool ....................... Passed 0.01 sec Start 15: SfinaeTest.span 15/21 Test #15: SfinaeTest.span ................................. Passed 0.01 sec Start 16: TypeTraitsTest.value_type 16/21 Test #16: TypeTraitsTest.value_type ....................... Passed 0.01 sec Start 17: TypeTraitsTest.reference_type 17/21 Test #17: TypeTraitsTest.reference_type ................... Passed 0.01 sec Start 18: TypeTraitsTest.rvalue_reference_type 18/21 Test #18: TypeTraitsTest.rvalue_reference_type ............ Passed 0.01 sec Start 19: TypeTraitsTest.difference_type 19/21 Test #19: TypeTraitsTest.difference_type .................. Passed 0.01 sec Start 20: TypeTraitsTest.size_type 20/21 Test #20: TypeTraitsTest.size_type ........................ Passed 0.01 sec Start 21: TypeTraitsTest.borrowed_iterator_type 21/21 Test #21: TypeTraitsTest.borrowed_iterator_type ........... Passed 0.01 sec 100% tests passed, 0 tests failed out of 21 Total Test time (real) = 0.15 sec ```

Performance

Various benchmarks are available to build and run using the CMake target beman.any_view.benchmarks.

Example output comparing reserved to fused for beman.any_view.benchmarks.all

```text + cmake --build build --config Release --target beman.any_view.benchmarks.all [27/27] Linking CXX executable tests/beman/any_view/beman.any_view.benchmarks.all + build/_deps/benchmark-src/tools/compare.py benchmarksfiltered build/tests/beman/any_view/beman.any_view.benchmarks.all reserved build/tests/beman/any_view/beman.any_view.benchmarks.all fused RUNNING: build/tests/beman/any_view/beman.any_view.benchmarks.all --benchmark_filter=reserved Run on (32 X 2419.2 MHz CPU s) CPU Caches: L1 Data 48 KiB (x16) L1 Instruction 32 KiB (x16) L2 Unified 2048 KiB (x16) L3 Unified 36864 KiB (x1) Load Average: 0.25, 0.17, 0.11 ----------------------------------------------------------------- Benchmark Time CPU Iterations ----------------------------------------------------------------- BM_all_reserved/1024 1783 ns 1783 ns 389936 BM_all_reserved/2048 3839 ns 3839 ns 191729 BM_all_reserved/4096 7067 ns 7067 ns 89826 BM_all_reserved/8192 14756 ns 14756 ns 48245 BM_all_reserved/16384 30317 ns 30317 ns 23191 BM_all_reserved/32768 73651 ns 73650 ns 9626 BM_all_reserved/65536 215342 ns 215341 ns 3413 BM_all_reserved/131072 424794 ns 424793 ns 1654 BM_all_reserved/262144 887833 ns 887828 ns 789 RUNNING: build/tests/beman/any_view/beman.any_view.benchmarks.all --benchmark_filter=fused Run on (32 X 2419.2 MHz CPU s) CPU Caches: L1 Data 48 KiB (x16) L1 Instruction 32 KiB (x16) L2 Unified 2048 KiB (x16) L3 Unified 36864 KiB (x1) Load Average: 0.31, 0.19, 0.11 -------------------------------------------------------------- Benchmark Time CPU Iterations -------------------------------------------------------------- BM_all_fused/1024 1660 ns 1660 ns 437469 BM_all_fused/2048 3219 ns 3219 ns 210096 BM_all_fused/4096 7100 ns 7100 ns 100823 BM_all_fused/8192 15088 ns 15088 ns 45117 BM_all_fused/16384 33719 ns 33719 ns 21827 BM_all_fused/32768 72098 ns 72097 ns 9582 BM_all_fused/65536 150699 ns 150698 ns 4629 BM_all_fused/131072 316431 ns 316430 ns 2234 BM_all_fused/262144 583499 ns 583500 ns 1091 Comparing reserved (from build/tests/beman/any_view/beman.any_view.benchmarks.all) to fused (from build/tests/beman/any_view/beman.any_view.benchmarks.all) Benchmark Time CPU Time Old Time New CPU Old CPU New --------------------------------------------------------------------------------------------------------------------------------- BM_all_[reserved vs. fused]/1024 -0.0689 -0.0689 1783 1660 1783 1660 BM_all_[reserved vs. fused]/2048 -0.1615 -0.1615 3839 3219 3839 3219 BM_all_[reserved vs. fused]/4096 +0.0047 +0.0047 7067 7100 7067 7100 BM_all_[reserved vs. fused]/8192 +0.0225 +0.0225 14756 15088 14756 15088 BM_all_[reserved vs. fused]/16384 +0.1122 +0.1122 30317 33719 30317 33719 BM_all_[reserved vs. fused]/32768 -0.0211 -0.0211 73651 72098 73650 72097 BM_all_[reserved vs. fused]/65536 -0.3002 -0.3002 215342 150699 215341 150698 BM_all_[reserved vs. fused]/131072 -0.2551 -0.2551 424794 316431 424793 316430 BM_all_[reserved vs. fused]/262144 -0.3428 -0.3428 887833 583499 887828 583500 OVERALL_GEOMEAN -0.1255 -0.1255 ```

Contributing

Please do! Issues and pull requests are appreciated.

Owner

Name: The Beman Project
Login: bemanproject
Kind: organization

Website: bemanproject.org
Twitter: bemanproject
Repositories: 3
Profile: https://github.com/bemanproject

Supporting the efficient design and adoption of the highest quality C++ standard libraries

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Open Source Science

https://github.com/bemanproject/any_view

Science Score: 26.0%

Repository

Basic Info

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Metadata Files

README.md

beman.any_view: A generalized type-erased view with customizable properties

Motivation

Usage

include

include

include

Integrate beman.any_view into your project

Reference

Building

Performance

Contributing

Owner

GitHub Events

Total

Last Year

Issues and Pull Requests

All Time

Past Year

Top Authors

Issue Authors

Pull Request Authors

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