Class: Nagoro::Pipe::Morph

Inherits:
Base
  • Object
show all
Defined in:
lib/nagoro/pipe/morph.rb

Overview

Morph is a search and replace system based on parameters of opening tags.

Available morphs are at the time of writing: each, filter, foreach, if, times, unless

Please take care not to use multiple morphable parameters in one tag, due to restrictions of the implementation of REXML and libxml there is no way to find out which one came first and so the order would get messed up, leading to unpredictable results. You can, however, use any number of other parameter together with morphs.

Example for each predefined morph:

<a if="@address" href="#@address">#@address</a>
# <?r if @address ?>
#   <a href="#@address">#@address</a>
# <?r end ?>

<a unless="logged_in?" href="/login">Login to your account</a>
# <?r unless logged_in? ?>
#   <a href="/login">Login to your account
# <?r end ?>

<div foreach="tag in @tags" class="tag">#{tag}</div>
# <?r for tag in @tags ?>
#  <div class="tag">#{tag}</div>
# <?r end ?>

<p filter="emoticonize">Hello there :)</p>
# <p>#{emoticonize(%<Hello there :)>)}</p>

<div times="10" class="shout">I am innocent!</div>
# <?r 10.times do |_t| ?>
#   <div class="shout">I am innocent!</div>
# <?r end ?>

<div each="@users">#{_e}</div>
# <?r @users.each do |_e| ?>
#   <div>#{_e}</div>
# <?r end ?>

How to add new morphs:

Nagoro::Pipe::Morph['until'] = [
  '<?r %morph %expression ?>', '<?r end ?>' ]

Constant Summary collapse

MORPHS = 
{
  'each'    => [ '<?r %expression.%morph do |_e| ?>', '<?r end ?>' ],
  'times'   => [ '<?r %expression.%morph do |_t| ?>', '<?r end ?>' ],
  'filter'  => [ '<?o %expression(%<', '>) ?>' ],
  'if'      => [ '<?r %morph %expression ?>', '<?r end ?>' ],
  'unless'  => [ '<?r %morph %expression ?>', '<?r end ?>' ],
  'foreach' => [ '<?r for %expression ?>', '<?r end ?>' ],
}

Constants inherited from Base

Base::EMPTY_TAG

Class Method Summary collapse

Instance Method Summary collapse

Methods inherited from Base

#append, #doctype, #initialize, #instruction, #result, #tag_with, #text

Constructor Details

This class inherits a constructor from Nagoro::Pipe::Base

Class Method Details

.[](key) ⇒ Object 



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# File 'lib/nagoro/pipe/morph.rb', line 89

def [](key)
  MORPHS[key]
end

.[]=(key, value) ⇒ Object 



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# File 'lib/nagoro/pipe/morph.rb', line 85

def []=(key, value)
  MORPHS[key] = value
end

Instance Method Details

#tag_end(tag) ⇒ Object 



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# File 'lib/nagoro/pipe/morph.rb', line 76

def tag_end(tag)
  super
  prev, morph = @stack.last
  return unless prev == tag
  append(MORPHS[morph][1])
  @stack.pop
end

#tag_start(tag, original_attrs, value_attrs) ⇒ Object 



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# File 'lib/nagoro/pipe/morph.rb', line 58

def tag_start(tag, original_attrs, value_attrs)
  morphs = value_attrs.keys & MORPHS.keys
  return super if morphs.empty?

  if morphs.size > 1
    raise "Cannot transform multiple morphs: #{value_attrs.inspect} in <#{tag}>"
  elsif morphs.size == 1
    morph = morphs.first
    value = value_attrs.delete(morph)
    original_attrs.delete(morph)
    open = MORPHS[morph][0]

    append open.gsub(/%morph/, morph).gsub(/%expression/, value)
    @stack << [tag, morph]
    super
  end
end