module Sprockets::Transformers
Constants
- Transformer
Public Instance Methods
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
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
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
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
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
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
# 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
# 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