Erubi
Erubi is a ERB template engine for ruby. It is a simplified fork of Erubis, using the same basic algorithm, with the following differences:
-
Handles postfix conditionals when using escaping (e.g.
<%= foo if bar %>
) -
Supports frozen_string_literal: true in templates via :freeze option
-
Works with ruby’s
--enable-frozen-string-literal
option -
Automatically freezes strings for template text when ruby optimizes it (on ruby 2.1+)
-
Escapes
'
(apostrophe) when escaping for better XSS protection -
Has 6x faster escaping on ruby 2.3+ by using cgi/escape
-
Has 81% smaller memory footprint (calculated using
ObjectSpace.memsize_of_all
) -
Does no monkey patching (Erubis adds a method to Kernel)
-
Uses an immutable design (all options passed to the constructor, which returns a frozen object)
-
Has simpler internals (1 file, <150 lines of code)
-
Is not dead (Erubis hasn’t been updated since 2011)
It is not designed with Erubis API compatibility in mind, though most Erubis ERB syntax works, with the following exceptions:
-
No support for
<%===
for debug output
Installation
gem install erubi
Source Code
Source code is available on GitHub at github.com/jeremyevans/erubi
Usage
Erubi only has built in support for retrieving the generated source for a file:
require 'erubi'
eval(Erubi::Engine.new(File.read('filename.erb')).src)
Most users will probably use Erubi via Rails or Tilt. Erubi is the default erb template handler in Tilt 2.0.6+ and Rails 5.1+.
Capturing
Erubi does not support capturing block output into the template by default. However, it comes with an erubi/capture_end
file that supports capturing via <%|=
and <%|==
tags which are closed with a <%|
tag:
<%|= form do %>
<input>
<%| end %>
This offers similar functionality to that offered by Rails’ <%=
tags, but without the corner cases with that approach (which are due to attempting to parse ruby code via a regexp). Similar to the <%=
and <%==
tags, <%|=
captures by default and <%|==
captures and escapes by default, but this can be reversed via the :escape_capture
or :escape
options.
To use the capture_end support with tilt:
require 'tilt'
require 'erubi/capture_end'
Tilt.new("filename.erb", :engine_class=>Erubi::CaptureEndEngine).render
When using the capture_end support, any methods (such as form
in the example above) should return the (potentially modified) buffer. Since the buffer variable is a local variable and not an instance variable by default, you’ll probably want to set the :bufvar
variable when using the capture_end support to an instance variable, and have any methods used access that instance variable. Example:
def form
@_buf << "<form>"
yield
@_buf << "</form>"
@_buf
end
puts eval(Erubi::CaptureEndEngine.new(<<-END, :bufvar=>:@_buf).src)
before
<%|= form do %>
inside
<%| end %>
after
END
# Output:
# before
# <form>
# inside
# </form>
# after
Alternatively, passing the option :yield_returns_buffer => true
will return the buffer captured by the block instead of the last expression in the block.
Reporting Bugs
The bug tracker is located at github.com/jeremyevans/erubi/issues
License
MIT
Authors
Jeremy Evans <[email protected]> kuwata-lab.com