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|
# encoding: utf-8
# frozen_string_literal: true
module Mail
module Encodings
class TransferEncoding
NAME = ''
PRIORITY = -1
# And encoding's superclass can always transport it since the
# class hierarchy is arranged e.g. Base64 < 7bit < 8bit < Binary.
def self.can_transport?(enc)
enc && enc <= self
end
# Override in subclasses to indicate that they can encode text
# that couldn't be directly transported, e.g. Base64 has 7bit output,
# but it can encode binary.
def self.can_encode?(enc)
can_transport? enc
end
def self.cost(str)
raise "Unimplemented"
end
def self.compatible_input?(str)
true
end
def self.to_s
self::NAME
end
def self.negotiate(message_encoding, source_encoding, str, allowed_encodings = nil)
message_encoding = Encodings.get_encoding(message_encoding) || Encodings.get_encoding('8bit')
source_encoding = Encodings.get_encoding(source_encoding)
if message_encoding && source_encoding && message_encoding.can_transport?(source_encoding) && source_encoding.compatible_input?(str)
source_encoding
else
renegotiate(message_encoding, source_encoding, str, allowed_encodings)
end
end
def self.renegotiate(message_encoding, source_encoding, str, allowed_encodings = nil)
encodings = Encodings.get_all.select do |enc|
(allowed_encodings.nil? || allowed_encodings.include?(enc)) &&
message_encoding.can_transport?(enc) &&
enc.can_encode?(source_encoding)
end
lowest_cost(str, encodings)
end
def self.lowest_cost(str, encodings)
best = nil
best_cost = nil
encodings.each do |enc|
# If the current choice cannot be transported safely, give priority
# to other choices but allow it to be used as a fallback.
this_cost = enc.cost(str) if enc.compatible_input?(str)
if !best_cost || (this_cost && this_cost < best_cost)
best_cost = this_cost
best = enc
elsif this_cost == best_cost
best = enc if enc::PRIORITY < best::PRIORITY
end
end
best
end
end
end
end
|
