Implements: transform_view (P3117)
Status: Under development and not yet ready for production use.
This library contains only beman::transform_view::transform_view and its
associated view adaptor beman::transform_view::transform. These work
exactly like std::ranges::transform_view and std::ranges::transform,
except that the beman transform_view is a borrowable_range if its
adapted view V is borrowable, and if detail::tidy_func<F> is true for the
callable F. detail::tidy_func is defined like this:
template <class F>
constexpr bool tidy_func =
std::is_empty_v<F> && std::is_trivially_default_constructible_v<F> &&
std::is_trivially_destructible_v<F>;If a transform_view is borrowable, its iterator re-creates F each time
it uses F, rather than going back to the parent transform_view.
beman.transform_view is licensed under the Apache License v2.0 with LLVM Exceptions.
#include <beman/transform_view/transform_view.hpp>
#include <iostream>
namespace tv26 = beman::transform_view;
int main() {
auto to_lower = [](char c) { return char(c + 0x20); };
const std::string upper_str = "LOWER";
std::cout << (upper_str | tv26::views::transform(to_lower) |
std::ranges::to<std::string>())
<< '\n';
return 0;
}See online documentation at https://tzlaine.github.io/transform_view .
This project requires at least the following to build:
- A C++ compiler that conforms to the C++23 standard or greater
- CMake 3.28 or later
- (Test Only) GoogleTest
You can disable building tests by setting CMake option
BEMAN_TRANSFORM_VIEW_BUILD_TESTS to OFF
when configuring the project.
This project officially supports:
- GCC versions 14–15
- LLVM Clang++ (with libstdc++ or libc++) versions 18–21
- AppleClang version 17.0.0 (i.e., the latest version on GitHub-hosted macOS runners)
- MSVC version 19.44.35215.0 (i.e., the latest version on GitHub-hosted Windows runners)
Note
Versions outside of this range would likely work as well, especially if you're using a version above the given range (e.g. HEAD/ nightly). These development environments are verified using our CI configuration.
This project supports GitHub Codespace via Development Containers, which allows rapid development and instant hacking in your browser. We recommend using GitHub codespace to explore this project as it requires minimal setup.
Click the following badge to create a codespace:
For more documentation on GitHub codespaces, please see this doc.
Note
The codespace container may take up to 5 minutes to build and spin-up; this is normal.
For Linux
Beman libraries require recent versions of CMake, we recommend downloading CMake directly from CMake's website or installing it with the Kitware apt library.
A supported compiler should be available from your package manager.
For MacOS
Beman libraries require recent versions of CMake.
Use Homebrew to install the latest version of CMake.
brew install cmakeA supported compiler is also available from brew.
For example, you can install the latest major release of Clang as:
brew install llvmFor Windows
To build Beman libraries, you will need the MSVC compiler. MSVC can be obtained by installing Visual Studio; the free Visual Studio 2022 Community Edition can be downloaded from Microsoft.
After Visual Studio has been installed, you can launch "Developer PowerShell for VS 2022" by typing it into Windows search bar. This shell environment will provide CMake, Ninja, and MSVC, allowing you to build the library and run the tests.
Note that you will need to use FetchContent to build GoogleTest. To do so, please see the instructions in the "Build GoogleTest dependency from github.com" dropdown in the Project specific configure arguments section.
This project recommends using CMake Presets
to configure, build and test the project.
Appropriate presets for major compilers have been included by default.
You can use cmake --list-presets to see all available presets.
Here is an example to invoke the gcc-debug preset.
cmake --workflow --preset gcc-debugGenerally, there are two kinds of presets, debug and release.
The debug presets are designed to aid development, so it has debugging
instrumentation enabled and many sanitizers enabled.
Note
The sanitizers that are enabled vary from compiler to compiler.
See the toolchain files under (cmake) to determine the exact configuration used for each preset.
The release presets are designed for production use, and
consequently have the highest optimization turned on (e.g. O3).
If the presets are not suitable for your use-case, a traditional CMake invocation will provide more configurability.
To configure, build and test the project with extra arguments, you can run this set of commands.
cmake \
-B build \
-S . \
-DCMAKE_CXX_STANDARD=20 \
-DCMAKE_PREFIX_PATH=$PWD/infra/cmake \
# Your extra arguments here.
cmake --build build
ctest --test-dir buildImportant
Beman projects are
passive projects,
therefore,
you will need to specify the C++ version via CMAKE_CXX_STANDARD
when manually configuring the project.
If you do not have GoogleTest installed on your development system, you may optionally configure this project to download a known-compatible release of GoogleTest from source and build it as well.
Example commands:
cmake -B build -S . \
-DCMAKE_PROJECT_TOP_LEVEL_INCLUDES=./infra/cmake/use-fetch-content.cmake \
-DCMAKE_CXX_STANDARD=20
cmake --build build --target all
cmake --build build --target testThe precise version of GoogleTest that will be used is maintained in
./lockfile.json.
Project-specific options are prefixed with BEMAN_TRANSFORM_VIEW.
You can see the list of available options with:
cmake -LH -S . -B build | grep "BEMAN_TRANSFORM_VIEW" -C 2Details of CMake arguments.
Enable building tests and test infrastructure. Default: ON.
Values: { ON, OFF }.
You can configure the project to have this option turned off via:
cmake -B build -S . -DCMAKE_CXX_STANDARD=20 -DBEMAN_TRANSFORM_VIEW_BUILD_TESTS=OFF[!TIP] Because this project requires GoogleTest for running tests, disabling
BEMAN_TRANSFORM_VIEW_BUILD_TESTSavoids the project from cloning GoogleTest from GitHub.
Enable building examples. Default: ON. Values: { ON, OFF }.
Enable installing the CMake config file package. Default: ON. Values: { ON, OFF }.
This is required so that users of beman.transform_view can use
find_package(beman.transform_view) to locate the library.
To use beman.transform_view in your C++ project,
include an appropriate beman.transform_view header from your source code.
#include <beman/transform_view/transform_view.hpp>Note
beman.transform_view headers are to be included with the beman/transform_view/ prefix.
Altering include search paths to spell the include target another way (e.g.
#include <transform_view.hpp>) is unsupported.
The process for incorporating beman.transform_view into your project depends on the
build system being used. Instructions for CMake are provided in following sections.
For CMake based projects,
you will need to use the beman.transform_view CMake module
to define the beman::transform_view CMake target:
find_package(beman.transform_view REQUIRED)You will also need to add beman::transform_view to the link libraries of
any libraries or executables that include beman.transform_view headers.
target_link_libraries(yourlib PUBLIC beman::transform_view)You can produce transform_view's interface library locally by:
cmake --workflow --preset gcc-release
cmake --install build/gcc-release --prefix /opt/bemanThis will generate the following directory structure at /opt/beman.
/opt/beman
├── include
│ └── beman
│ └── transform_view
│ └── transform_view.hpp
└── lib
└── cmake
└── beman.transform_view
├── beman.transform_view-config-version.cmake
├── beman.transform_view-config.cmake
└── beman.transform_view-targets.cmake