camgunz / sst

A C Templating Engine

SST

SST is a simple template processor. This is what it looks like:

{{ include '/srv/http/templates/header.txt' }}

{{ if person.age >= 18 }}
    Don't forget to register to vote!
{{ else if person.age >= 14 }}
    If you'll be 18 before election day, register to vote!
{{ endif }}

{{ for person in people }}
    {{ person.name }} owes {{ person.income * tax_rate }} this year!
{{ endfor }}

{{ raw }}
    This is how you would use raw }} and {{ markers.
{{ endraw }}

{{ if upper(message) == 'OR PUT THEM IN STRINGS {{ }} }} {{' }}
    You guessed the magic message!
{{ endif }}

{{ for fib in [1, 1, 2, 3, 4, 5, 4 + 4, 13, 21, 34] }}
    {{ if fib == 4 }}
        {{ continue }}
    {{ endif }}
    Double {{ fib }}: {{ double(fib) }}
    (also {{ fibs[min(8, max(0, fib - 8))] }})
    {{ if fib >= 10 }}
        Whew fibs got too big: {{ fib }}
        {{ break }}
    {{ endif }}
{{ endfor }}

{{ include '/srv/http/templates/footer.txt' }}

Last little bit down here

SST is still in heavy development, but a few things differentiate SST from other template engines:

• Very simple
• Uses arbitrary-precision arithmetic behind the scenes
• Written in C (C99)
  • High throughput
  • Low latency
  • Low memory usage
• Does not use regular expressions

SST's parser is thread-aware: multiple parsers may be assigned on a 1:1 basis to multiple threads.

SST's templates are thread-safe: templates may be rendered by multiple threads simultaneously.

SST deals strictly in UTF-8.

A template engine in C? Are you out of your mind?

Maybe. Here's the plan to avoid disaster:

1. Use cbase, a small C data structures library with test coverage approaching 90% (what's left is error conditions)
2. Create a comprehensive test suite for SST itself
3. Fuzz SST with AFL
4. Use strict compiler flags
5. Use sanitizers during development

SST is written in what I would consider clear, readable, and safe C. It is also not very big: currently the line count is ~3,800 LOC and will probably stay under 5,000 LOC when fully implemented. It should be easy to understand and thus easy to audit.

Why not use template engine X?

I wanted an engine I could:

• Use from the command-line or as a library
• Avoid fatal bugs (PHP, bad regex, string interpolation injection, etc.)
• Not wait for a big runtime (Java, C#) to start up
• Not use copious amounts of RAM (Python, Ruby, JS)
• Use arbitrary-precision arithmetic

Basically there are no templating languages in C, C++, Go or Rust that use decimals and not regexes, so I wrote one.

What does SST stand for?

NOAA tracks sea surface temperature (SST), and since this project is a C templating engine...