protean is a library for representing hierarchical data in a uniform way across multiple platforms.

The library defines a variant object that can hold primitive data as well as collections (e.g. lists, dictionaries) with arbitrary depth. The variant can be inspected, enumerated, and/or serialised to XML/binary format.

Protean has implementations in C++, C# and Python.

Protean is known to build on:

• Windows with MS Visual Studio
• Mac with cmake and Apple clang
• CentOS Linux with cmake and GCC or clang

On Windows, the following method will work:

• Install Boost 1.69 or later
• Install Xerces 3.1 or later
• Copy projects/vc1x/vc1x-paths.props.template to projects/vc1x/vc1x-paths.props and edit the latter to set BOOST_VERSION, BOOST_ROOT, and XERCES_ROOT appropriately
• Open projects/vc1x-protean.sln in your chosen version of Visual Studio
• Choose a configuration, e.g. vc142 Release and x64, and Build Solution

On other platforms:

• Install boost, cmake and xerces dependencies, e.g. via yum or apt-get
• Build via mkdir build && cd build && cmake .. && make, or something like cmake -G Ninja && ninja to use a build tool besides the default of make
• Static linking of Boost can be forced via -DBOOST_STATIC_LINK_PATH=... if required

using variant = protean::variant;
variant root(variant::Dictionary);
variant books(variant::Dictionary);
variant book(variant::Dictionary);
variant book_attrs(variant::Dictionary);
book_attrs.insert("author", variant("XYZ"));
book_attrs.insert("year", variant(2013));
book.insert(protean::xml_attributes, book_attrs);
book.insert(protean::xml_text, variant("some text"));
books.insert("book", book);
root.insert("books", books);
std::stringstream contents;
protean::xml_writer writer(contents, xml_mode::Preserve | xml_mode::Indent);
writer << root;
std::cout << contents.str() << std::endl;

This will output:

<?xml version="1.0" encoding="utf-8"?>
<books>
  <book author="XYZ" year="2013">some text</book>
</books>

We welcome contributions and feedback. Please make use of GitHub's issue tracking and pull requests.