jsonld-cpp

JSON-LD Implementation for C++

This is a C++ implementation of JSON-LD (http://json-ld.org)

Development is still in progress--currently it only supports the expand() and toRdf() functions.

jsonld-cpp uses http-link-header-cpp and includes it as a submodule. When cloning, use git clone --recursive to include the submodule. See repo documentation for dependencies.

Implementation Notes

Some parts of the JSON-LD API spec make note of using Promises to return API results. This C++ does not support any Promise-like capability.

The RemoteDocument implementation currently only supports local files, not documents from arbitrary URLs.

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Building jsonld-cpp

To build jsonld-cpp, you will need:

• cmake
• g++, clang or Visual Studio (community edition)

jsonld-cpp uses a pretty standard cmake build system:

mkdir build
cd build
cmake ..
make

You may run into permission issues during the build when the dependencies are being installed during the build step. To install them in the project directory instead run cmake with the following command:

cmake .. "-DCMAKE_INSTALL_PREFIX=$(pwd)/install"

You can also run all the tests:

make test

Installing prerequisites

If the above doesn't work, you probably need to install some prerequisites. For example, on a fresh Debian Bullseye system:

$ sudo apt-get install make cmake gcc g++ libssl-dev

Now you can again try to build jsonld-cpp.

Examples

You can find in the examples directory a simple application showing how to interface with the library called jsonld2rdf. It can convert a json-ld document into normalized RDF data in NQuads format. There are also two example files showing how the normalized RDF could be hashed to show that the two documents are equivalent:

$ ./build/debug/jsonld-cpp-examples-prefix/src/jsonld-cpp-examples-build/jsonld2rdf examples/ex01a.jsonld | shasum -a 256
cb92d57d8b7abf09e4642338049bd9ee91a0ee0fe327e0a6061a8bbc2f4314bf  -
$ ./build/debug/jsonld-cpp-examples-prefix/src/jsonld-cpp-examples-build/jsonld2rdf examples/ex01b.jsonld | shasum -a 256
cb92d57d8b7abf09e4642338049bd9ee91a0ee0fe327e0a6061a8bbc2f4314bf  -

Debugging

To include debugging symbols for gdb and compile_commands.json file, run cmake with the following arguments:

cmake .. -DCMAKE_BUILD_TYPE=Debug -DCMAKE_EXPORT_COMPILE_COMMANDS=1