module Sprockets::Transformers

Constants

Transformer

Public Instance Methods

compose_transformers(transformers, types, preprocessors, postprocessors) click to toggle source

Internal: Compose multiple transformer steps into a single processor function.

transformers - Two level Hash of a source mime type to a target mime type types - Array of mime type steps

Returns Processor.

# File lib/sprockets/transformers.rb, line 115
def compose_transformers(transformers, types, preprocessors, postprocessors)
  if types.length < 2
    raise ArgumentError, "too few transform types: #{types.inspect}"
  end

  processors = types.each_cons(2).map { |src, dst|
    unless processor = transformers[src][dst]
      raise ArgumentError, "missing transformer for type: #{src} to #{dst}"
    end
    processor
  }

  compose_transformer_list processors, preprocessors, postprocessors
end
expand_transform_accepts(parsed_accepts) click to toggle source

Internal: Expand accept type list to include possible transformed types.

parsed_accepts - Array of accept q values

Examples

expand_transform_accepts([['application/javascript', 1.0]])
# => [['application/javascript', 1.0], ['text/coffeescript', 0.8]]

Returns an expanded Array of q values.

# File lib/sprockets/transformers.rb, line 97
def expand_transform_accepts(parsed_accepts)
  accepts = []
  parsed_accepts.each do |(type, q)|
    accepts.push([type, q])
    config[:inverted_transformers][type].each do |subtype|
      accepts.push([subtype, q * 0.8])
    end
  end
  accepts
end
register_transformer(from, to, proc) click to toggle source

Public: Register a transformer from and to a mime type.

from - String mime type to - String mime type proc - Callable block that accepts an input Hash.

Examples

register_transformer 'text/coffeescript', 'application/javascript',
  ConvertCoffeeScriptToJavaScript

register_transformer 'image/svg+xml', 'image/png', ConvertSvgToPng

Returns nothing.

# File lib/sprockets/transformers.rb, line 38
def register_transformer(from, to, proc)
  self.config = hash_reassoc(config, :registered_transformers) do |transformers|
    transformers << Transformer.new(from, to, proc)
  end
  compute_transformers!(self.config[:registered_transformers])
end
register_transformer_suffix(types, type_format, extname, processor) click to toggle source

Internal: Register transformer for existing type adding a suffix.

types - Array of existing mime type Strings type_format - String suffix formatting string extname - String extension to append processor - Callable block that accepts an input Hash.

Returns nothing.

# File lib/sprockets/transformers.rb, line 53
def register_transformer_suffix(types, type_format, extname, processor)
  Array(types).each do |type|
    extensions, charset = mime_types[type].values_at(:extensions, :charset)
    parts = type.split('/')
    suffix_type = type_format.sub('\1', parts[0]).sub('\2', parts[1])
    extensions = extensions.map { |ext| "#{ext}#{extname}" }

    register_mime_type(suffix_type, extensions: extensions, charset: charset)
    register_transformer(suffix_type, type, processor)
  end
end
resolve_transform_type(type, accept) click to toggle source

Internal: Resolve target mime type that the source type should be transformed to.

type - String from mime type accept - String accept type list (default: ‘/’)

Examples

resolve_transform_type('text/plain', 'text/plain')
# => 'text/plain'

resolve_transform_type('image/svg+xml', 'image/png, image/*')
# => 'image/png'

resolve_transform_type('text/css', 'image/png')
# => nil

Returns String mime type or nil is no type satisfied the accept value.

# File lib/sprockets/transformers.rb, line 83
def resolve_transform_type(type, accept)
  find_best_mime_type_match(accept || '*/*', [type].compact + config[:transformers][type].keys)
end
transformers() click to toggle source

Public: Two level mapping of a source mime type to a target mime type.

environment.transformers
# => { 'text/coffeescript' => {
         'application/javascript' => ConvertCoffeeScriptToJavaScript
       }
     }
# File lib/sprockets/transformers.rb, line 18
def transformers
  config[:transformers]
end

Private Instance Methods

compose_transformer_list(transformers, preprocessors, postprocessors) click to toggle source
# File lib/sprockets/transformers.rb, line 131
def compose_transformer_list(transformers, preprocessors, postprocessors)
  processors = []

  transformers.each do |processor|
    processors.concat postprocessors[processor.from]
    processors << processor.proc
    processors.concat preprocessors[processor.to]
  end

  if processors.size > 1
    compose_processors(*processors.reverse)
  elsif processors.size == 1
    processors.first
  end
end
compute_transformers!(registered_transformers) click to toggle source
# File lib/sprockets/transformers.rb, line 147
def compute_transformers!(registered_transformers)
  preprocessors         = self.config[:preprocessors]
  postprocessors        = self.config[:postprocessors]
  transformers          = Hash.new { {} }
  inverted_transformers = Hash.new { Set.new }
  incoming_edges        = registered_transformers.group_by(&:from)

  registered_transformers.each do |t|
    traversals = dfs_paths([t]) { |k| incoming_edges.fetch(k.to, []) }

    traversals.each do |nodes|
      src, dst = nodes.first.from, nodes.last.to
      processor = compose_transformer_list nodes, preprocessors, postprocessors

      transformers[src] = {} unless transformers.key?(src)
      transformers[src][dst] = processor

      inverted_transformers[dst] = Set.new unless inverted_transformers.key?(dst)
      inverted_transformers[dst] << src
    end
  end

  self.config = hash_reassoc(config, :transformers) { transformers }
  self.config = hash_reassoc(config, :inverted_transformers) { inverted_transformers }
end