[boost] New Boost library proposal, Mustache

30 Dec 2022

      I'm looking for endorsements and a review manager volunteer for
a new library, Boost.Mustache. It's an implementation of Mustache
templates (http://mustache.github.io/) in C++11 and at the moment
supports the mandatory portions of the Mustache spec
(https://github.com/mustache/spec).

The repository is https://github.com/pdimov/mustache.

Mustache is a simple templating language in which tags of the form
{{something}} are replaced with the value of the entity `something`, which
typically means with the member "something" of the JSON object passed
when rendering the template.

Boost.Mustache can take a Boost.JSON object as the context against which
data references are resolved, but it can also take arbitrary values that can
be converted to boost::json::value by using boost::json::value_from.

This allows, for instance, described classes (structs and classes annotated
with Boost.Describe) to be passed as the data context, such that references
to e.g. {{title}} in the template are resolved to the corresponding `title`
member of the class.

A simple usage example demonstrating the above is:

```
#include <boost/mustache.hpp>
#include <boost/describe.hpp>
#include <iostream>

struct item
{
    std::string title;
    std::string author;
    std::string link;
};

BOOST_DESCRIBE_STRUCT(item, (), (title, author, link))

struct reference
{
    std::string heading;
    std::vector<item> items;
};

BOOST_DESCRIBE_STRUCT(reference, (), (heading, items))

int main()
{
    reference ref =
    {
        "Reference",
        {
            {
                "Better Bit Mixing - Improving on MurmurHash3's 64-bit Finalizer",
                "David Stafford",
                "https://zimbry.blogspot.com/2011/09/better-bit-mixing-improving-on.html"
            },
            {
                "Stronger, better, morer, Moremur; a better Murmur3-type mixer",
                "Pelle Evensen",
                "https://mostlymangling.blogspot.com/2019/12/stronger-better-morer-moremur-be..."
            },
            {
                "Improved mx3 and the RRC test",
                "Jon Maiga",
                "http://jonkagstrom.com/mx3/mx3_rev2.html"
            }
        }
    };

    std::string tmpl =
R"(<html>
<body>
<h1>{{heading}}</h1>
<ul>
{{#items}}
<li>
  <strong>{{title}}</strong><br>
  <em>{{author}}</em><br>
  <a href="{{link}}">{{link}}</a>
{{/items}}
</ul>
</body>
</html>)";

    boost::mustache::render( tmpl, std::cout, ref, {} );
}
```

The resulting output is

<html>
<body>
<h1>Reference</h1>
<ul>
<li>
  <strong>Better Bit Mixing - Improving on MurmurHash3's 64-bit Finalizer</strong><br>
  <em>David Stafford</em><br>
  <a href="https://zimbry.blogspot.com/2011/09/better-bit-mixing-improving-on.html">https://zimbry.blogspot.com/2011/09/better-bit-mixing-improving-on.html</a>
<li>
  <strong>Stronger, better, morer, Moremur; a better Murmur3-type mixer</strong><br>
  <em>Pelle Evensen</em><br>
  <a href="https://mostlymangling.blogspot.com/2019/12/stronger-better-morer-moremur-better.html">https://mostlymangling.blogspot.com/2019/12/stronger-better-morer-moremur-better.html</a>
<li>
  <strong>Improved mx3 and the RRC test</strong><br>
  <em>Jon Maiga</em><br>
  <a href="http://jonkagstrom.com/mx3/mx3_rev2.html">http://jonkagstrom.com/mx3/mx3_rev2.html</a>
</ul>
</body>
</html>

[boost] New Boost library proposal, Mustache

Peter Dimov