Class: Less::Engine

Inherits:
String
  • Object
show all
Defined in:
lib/less/engine.rb

Constant Summary collapse

REGEXP = 
{
  :path => /([#.][->#.\w]+)?( ?> ?)?@([\w\-]+)/, # #header > .title > @var
  :selector => /[-\w #.>*_:]/,                   # .cow .milk > a
  :values => /[-\w @>\/*+#%.,'"]/,               # 10px solid #fff
  :variable => /^@([\w\-]+)/                     # @milk-white
}

Instance Method Summary collapse

Constructor Details

#initialize(s) ⇒ Engine

Returns a new instance of Engine.



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# File 'lib/less/engine.rb', line 10

def initialize s
  super
  @tree = Tree.new self.hashify
end

Instance Method Details

#compile ⇒ Object Also known as: render 



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# File 'lib/less/engine.rb', line 15

def compile     
  #
  # Parse the variables and mixins
  #
  # We use symbolic keys, such as :mixins, to store LESS-only data,
  # each branch has its own :mixins => [], and :variables => {}
  # Once a declaration has been recognised as LESS-specific, it is copied 
  # in the appropriate data structure in that branch. The declaration itself
  # can then be deleted.
  #
  @tree = @tree.traverse :leaf do |key, value, path, node|
    matched = if match = key.match( REGEXP[:variable] )
      node[:variables] ||= {}
      node[:variables][ match.captures.first ] = value
    elsif value == :mixin
      node[:mixins] ||= []          
      node[:mixins] << key
    end
    node.delete key if matched # Delete the property if it's LESS-specific
  end
  
  #
  # Evaluate mixins
  #
  @tree = @tree.traverse :branch do |path, node|
    if node.include? :mixins
      node[:mixins].each do |m|
        @tree.find( :mixin, m.delete(' ').split('>') ).each {|k, v| node[ k ] = v }
      end
    end
  end
  
  #
  # Evaluate the variables
  #
  @tree = @tree.traverse :leaf do |key, value, path, node|
    convert = lambda do |key, value, node| # We declare this as a lambda, for re-use
      if value.is_a?(String) && value.include?('@') # There's a var to evaluate        
        
        # Find its value
        var = value.delete(' ').match( REGEXP[:path] ).captures.join  
        var = unless var.include? '>'
          node.var( var ) || @tree.var( var ) # Try local first, then global
        else
          @tree.find :var, var.split('>')           # Try finding it in a specific namespace
        end
      
        if var
          node[ key ] = value.gsub REGEXP[:path], var # substitute variable with value
        else
          node.delete key # discard the declaration if the variable wasn't found
        end
      end
    end
    
    # Call `convert` on css properties, such as 'font-size: @big'
    convert.call key, value, node
    
    # Call `convert` on variables, such as '@dark: @light / 2'
    if node.vars? 
      node.vars.each do |key, value|
        convert.call key, value, node
      end
    end
  end            
end

#evaluate(s) ⇒ Object 



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# File 'lib/less/engine.rb', line 87

def evaluate s
  eval( s )
end

#hashify ⇒ Object 



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# File 'lib/less/engine.rb', line 91

def hashify
#
# Parse the LESS structure into a hash
#
###
  #   less:     color: black;
  #   hashify: "color" => "black"
  #
  hash = self.gsub(/"/, "'").                                                         # ""
              gsub(/([@a-z\-]+):[ \t]*(#{ REGEXP[:values] }+);/, '"\\1" => "\\2",').  # Properties
              gsub(/\}/, "},").                                                       # Closing }
              gsub(/([ \t]*)(#{ REGEXP[:selector] }+?)[ \t\n]*\{/m, '\\1"\\2" => {'). # Selectors
              gsub(/([.#][->\w .#]+);/, '"\\1" => :mixin,').                          # Mixins
              gsub("\n\n", "\n").                                                     # New-lines
              gsub(/\/\/.*\n/, '')                                                    # Comments
  eval "{" + hash + "}"                                                               # Return {hash}
end

#to_css ⇒ Object 



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# File 'lib/less/engine.rb', line 83

def to_css
  self.compile.to_css
end