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require 'sprockets/http_utils'
require 'sprockets/processor_utils'
require 'sprockets/utils'
module Sprockets
module Transformers
include HTTPUtils, ProcessorUtils, Utils
# Public: Two level mapping of a source mime type to a target mime type.
#
# environment.transformers
# # => { 'text/coffeescript' => {
# 'application/javascript' => ConvertCoffeeScriptToJavaScript
# }
# }
#
def transformers
config[:transformers]
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.
def register_transformer(from, to, proc)
self.config = hash_reassoc(config, :registered_transformers, from) do |transformers|
transformers.merge(to => proc)
end
compute_transformers!
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.
def resolve_transform_type(type, accept)
find_best_mime_type_match(accept || '*/*', [type].compact + config[:transformers][type].keys)
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.
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
# 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.
def compose_transformers(transformers, types)
if types.length < 2
raise ArgumentError, "too few transform types: #{types.inspect}"
end
i = 0
processors = []
loop do
src = types[i]
dst = types[i+1]
break unless src && dst
unless processor = transformers[src][dst]
raise ArgumentError, "missing transformer for type: #{src} to #{dst}"
end
processors.concat config[:postprocessors][src]
processors << processor
processors.concat config[:preprocessors][dst]
i += 1
end
if processors.size > 1
compose_processors(*processors.reverse)
elsif processors.size == 1
processors.first
end
end
private
def compute_transformers!
registered_transformers = self.config[:registered_transformers]
transformers = Hash.new { {} }
inverted_transformers = Hash.new { Set.new }
registered_transformers.keys.flat_map do |key|
dfs_paths([key]) { |k| registered_transformers[k].keys }
end.each do |types|
src, dst = types.first, types.last
processor = compose_transformers(registered_transformers, types)
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
self.config = hash_reassoc(config, :transformers) { transformers }
self.config = hash_reassoc(config, :inverted_transformers) { inverted_transformers }
end
end
end
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