CarrotA templating engine for Java

Template language

Carrot's template language is actually pretty simple. At the top level, there's three main kinds of tags you can use. They are:

{# comment #}
{{ echo }}
{% tag %}

Comments

{# comment #}

The first type of tag is the simplest, a comment. Comments are stripped from the output and otherwise ignored. Useful also for commenting out bits of other template, since you can just put a # between the { and the % or {.

At this point, I should also just note that you can escape a tag with a backslash, like so:

You can output a literal {% like so: {\%

Same, of course, with the other types of tags.

Echo

{{ <expr> }}

The next type of tag, the "echo" tag is actually just a shortcut for {% echo <expr> %}. It simple echos the evaluation of the expression inside the tag.

See the Expressions section for more details about how expression are evaluated.

Tags

{% echo <expr> %}
{% if <expr> %}...{% end %}
{% for identifier in <expr> %}...{% end %}
{% extends <expr> %}...{% end %}
{% include <expr> %}
{% block <expr> %}...{% end %}

Tags are where most of the interesting work happens in your template. See the following pages for details, but basically there are two types of tags: block tags and inline tags. Inline tags, like the echo tag don't tag children and just output directly into the stream. Block tags like if, for, etc have children and can optionally output their children.

You can register your own classes as tags like so:

  CarrotEngine engine = new CarrotEngine(
      new Configuration.Builder()
          .setTagRegistry(
              new TagRegistry.Builder().add("tagName", MyTag.class))
      .build());

Your tag class must inherit from Tag. More details, and an example, can be found in the custom tags section.