Component Model C++

This repository contains a C++ ABI implementation of the WebAssembly Component Model.

Features

OS

• Ubuntu 24.04
• MacOS 13
• MacOS 14 (Arm)
• Windows 2019
• Windows 2022

Host Data Types

• Bool
• S8
• U8
• S16
• U16
• S32
• U32
• S64
• U64
• F32
• F64
• Char
• String
• utf8 String
• utf16 String
• latin1+utf16 String
• List
• Record
• Tuple
• Variant
• Enum
• Option
• Result
• Flags
• Own
• Borrow

Host Functions

• lower_flat_values
• lift_flat_values

Tests / Samples

• ABI
• WasmTime
• Wamr
• WasmEdge

Build Instructions

Prerequisites

• CMake 3.5 or higher (3.22+ recommended for presets)
• C++20 compatible compiler
• vcpkg for dependency management
• Rust toolchain with cargo (for additional tools)

Platform-specific requirements

Ubuntu/Linux:

sudo apt-get install -y autoconf autoconf-archive automake build-essential ninja-build

macOS:

brew install pkg-config autoconf autoconf-archive automake coreutils libtool cmake ninja

Windows:

• Visual Studio 2019 or 2022 with C++ support

Rust tools (required for samples and tests)

cargo install wasm-tools wit-bindgen-cli

Basic Build (Header-only)

For header-only usage without tests or samples:

git clone https://github.com/LexisNexis-GHCPE/component-model-cpp.git
cd component-model-cpp
git submodule update --init --recursive

mkdir build && cd build
cmake .. -DBUILD_TESTING=OFF -DBUILD_SAMPLES=OFF
cmake --build .

Build with Dependencies (Tests & Samples)

Using CMake presets with vcpkg:

Linux

git clone https://github.com/LexisNexis-GHCPE/component-model-cpp.git
cd component-model-cpp
git submodule update --init --recursive

# Configure and build
cmake --preset linux-ninja-Debug
cmake --build --preset linux-ninja-Debug

# Run tests
cd build && ctest -VV

Windows

git clone https://github.com/LexisNexis-GHCPE/component-model-cpp.git
cd component-model-cpp
git submodule update --init --recursive

# Configure and build
cmake --preset vcpkg-VS-17
cmake --build --preset VS-17-Debug

# Run tests
cd build && ctest -C Debug -VV

macOS

git clone https://github.com/LexisNexis-GHCPE/component-model-cpp.git
cd component-model-cpp
git submodule update --init --recursive

# Configure and build
cmake --preset linux-ninja-Debug
cmake --build --preset linux-ninja-Debug

# Run tests
cd build && ctest -VV

Manual Build without Presets

If you prefer not to use CMake presets:

mkdir build && cd build
cmake .. -DCMAKE_TOOLCHAIN_FILE=../vcpkg/scripts/buildsystems/vcpkg.cmake
cmake --build .
ctest -VV  # Run tests

Build Options

• -DBUILD_TESTING=ON/OFF - Enable/disable building tests (requires doctest, ICU)
• -DBUILD_SAMPLES=ON/OFF - Enable/disable building samples (requires wasi-sdk)
• -DCMAKE_BUILD_TYPE=Debug/Release/RelWithDebInfo/MinSizeRel - Build configuration

Usage

This library is a header only library. To use it in your project, you can:

• Copy the contents of the include directory to your project.
• Use vcpkg to install the library and its dependencies.

Related projects

• Component Model design and specification: Official Component Model specification.
• wit-bindgen c++ host: C++ host support for the WebAssembly Interface Types (WIT) Bindgen tool.

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