Tang

Tang is a new template language library written in C++ as part of a YouTube series.

Syntax

The Tang syntax is a mixture of C++, PHP, and Python, with an emphasis on seamlessly supporting Unicode characters in Utf-8 encodings, as well as HTML encoding and percent encodings where applicable.

How to use Tang

Depending on your perspective, you are either wanting to know how to use Tang as part of a C++ project, or you want to know how to use Tang as a template code editor.

Using Tang: As a C++ library

Warning!! - The language example represents the aspiration of what Tang will become. It's not there yet, though!

This project compiles Tang into a shared library (libtang.so) so that it can be included into your project as a library. The tang.hpp header will contain all necessary class information. A simple use case might be:

#include <iostream>
#include "tang.hpp"

int main() {
  auto program = Tang::TangBase::make_shared().compileScript(R"(
    // Compute the nth number of the fibonacci sequence, where 1 is the first
    // number.  Use a very inefficient recursive solution, just to prove that
    // it works.  Also, this is only meant to be called for positive numbers.
    // It's just an example, after all!
    function fib(n) {
      if (n < 2)
        return n;
      return fib(n - 2) + fib(n - 1);
    }
    print(fib(10));
  )");
  std::cout << program.execute().out << std::endl;
  return 0;
}

The output of the above program should be:

55

For more sophisticated use cases, check the Documentation (when it's finished).

Using Tang: As a template designer.

Tang templates allow you to intersperse code into your templates using code tags <% and %>. There is also a shorthand code <%= to print the value supplied without explicitly calling a print function.

Warning!! - The following examples are the intended ideal, and are not yet implemented.

Example 1

Suppose a variable named user exists, and it is a string containg "Alice".

If this is your template:

Welcome, <%= user %>!

Then this will be your output:

Welcome, Alice!

Example 2

Suppose a variable named users exists, and it is a list of names: "Alice", "Bob", "Carol", and "Frank".

If this is your template:

<ul>
<%
for (name : names) {
  print!("  <li>");
  print(name);
  print!("</li>\n");
}
</ul>

Then this will be your output:

<ul>
  <li>Alice</li>
  <li>Bob</li>
  <li>Carol</li>
  <li>Frank</li>
</ul>

Alternatively, the following code could have been used as well, although it will include a few additional line breaks:

<ul>
<% for (name : names) { %>
  <li><%= name %></li>
<% } %>
</ul>

Compiling Tang from source

The following instructions were written for Ubuntu 22.04.

Install packages

First, the necessary packages must be installed.

sudo apt install g++ make bison flex build-essential pkgconf libgtest-dev googletest

Additional packages must be installed in order to create documentation and enhance the build experience.

sudo apt install doxygen graphviz texlive-latex-base texlive-latex-extra cloc inotify-tools valgrind gdb

If you're working in the WSL, you can install the wslu package, so that you can view files (such as the documentation) using a cli command.

sudo apt install wslu

Example use:

wslview ./docs/html/index.html

Compile source code

make

For additional commands, run:

make help