herb

Minimal template engine with default escaping.

Description

Herb is a fork of Mote that uses a ERB-like style syntax and auto-escape HTML special characters by default.

Installation

Add this line to your application's Gemfile:

gem "herb"

And then execute:

$ bundle

Or install it yourself as:

$ gem install herb

Basic Usage

This is a basic example:

require "herb"

template = Herb.parse("your template goes here!")
template.call
# => "your template goes here!"

Herb recognizes two tags to evaluate Ruby code: <% %>, and <%= %>. The difference between them is that while the <% %> tags only evaluate the code, the <%= %> tags also prints the result to the template.

Imagine that your template looks like this:

<% # single line code %>
<% gems = ["rack", "cuba", "herb"] %>

<%
  # multi-line code
  sorted = gems.sort
%>

<ul>
<% sorted.each do |name| %>
  <li><%= name %></li>
<% end %>
</ul>

The generated result will be like:

<ul>
  <li>cuba</li>
  <li>herb</li>
  <li>rack</li>
</ul>

Parameters

The values passed to the template are available as local variables:

template = Herb.parse("Hello {{ name }}", [:name])
template.call(name: "Ruby")
# => Hello Ruby

You can also use the params local variable to access the given parameters:

template = Herb.parse("Hello {{ params[:name] }}")
template.call(name: "Ruby")
# => Hello Ruby

Auto-escaping

By default, Herb escapes HTML special characters to prevent XSS attacks. You can start the expression with an exclamation mark to disable escaping for that expression:

template = Herb.parse("Hello {{ name }}", [:name])
template.call(name: "<b>World</b>")
# => Hello &lt;b&gt;World&lt;b&gt;

template = Herb.parse("Hello {{! name }}", [:name])
template.call(name: "<b>World</b>")
# => Hello <b>World</b>

Herb::Helpers

There's a helper available in the Herb::Helpers module, and you are free to include it in your code. To do it, just type:

include Herb::Helpers

Using the herb helper

The herb helper receives a file name and a hash and returns the rendered version of its content. The compiled template is cached for subsequent calls.

herb("test/basic.erb", n: 3)
# => "***\n"

Template caching

When the herb helper is first called with a template name, the file is read and parsed, and a proc is created and stored in the current thread. The parameters passed are defined as local variables in the template. If you want to provide more parameters once the template was cached, you won't be able to access the values as local variables, but you can always access the params hash.

For example:

# First call
herb("foo.erb", a: 1, b: 2)

Contributing

Fork the project with:

$ git clone git@github.com:frodsan/herb.git

To install dependencies, use:

$ bundle install

To run the test suite, do:

$ rake test

For bug reports and pull requests use GitHub.

License

Herb is released under the MIT License.