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# frozen_string_literal: true
# Released under the MIT License.
# Copyright, 2025, by Samuel Williams.
# Copyright, 2025, by William T. Nelson.
require_relative "split"
require_relative "../quoted_string"
require_relative "../error"
module Protocol
module HTTP
module Header
# The `accept-content-type` header represents a list of content-types that the client can accept.
class Accept < Array
# Regular expression used to split values on commas, with optional surrounding whitespace, taking into account quoted strings.
SEPARATOR = /
(?: # Start non-capturing group
"[^"\\]*" # Match quoted strings (no escaping of quotes within)
| # OR
[^,"]+ # Match non-quoted strings until a comma or quote
)+
(?=,|\z) # Match until a comma or end of string
/x
ParseError = Class.new(Error)
MEDIA_RANGE = /\A(?<type>#{TOKEN})\/(?<subtype>#{TOKEN})(?<parameters>.*)\z/
PARAMETER = /\s*;\s*(?<key>#{TOKEN})=((?<value>#{TOKEN})|(?<quoted_value>#{QUOTED_STRING}))/
# A single entry in the Accept: header, which includes a mime type and associated parameters. A media range can include wild cards, but a media type is a specific type and subtype.
MediaRange = Struct.new(:type, :subtype, :parameters) do
# Create a new media range.
#
# @parameter type [String] the type of the media range.
# @parameter subtype [String] the subtype of the media range.
# @parameter parameters [Hash] the parameters associated with the media range.
def initialize(type, subtype = "*", parameters = {})
super(type, subtype, parameters)
end
# Compare the media range with another media range or a string, based on the quality factor.
def <=> other
other.quality_factor <=> self.quality_factor
end
private def parameters_string
return "" if parameters == nil or parameters.empty?
parameters.collect do |key, value|
";#{key.to_s}=#{QuotedString.quote(value.to_s)}"
end.join
end
# The string representation of the media range, including the type, subtype, and any parameters.
def to_s
"#{type}/#{subtype}#{parameters_string}"
end
alias to_str to_s
# The quality factor associated with the media range, which is used to determine the order of preference.
#
# @returns [Float] the quality factor, which defaults to 1.0 if not specified.
def quality_factor
parameters.fetch("q", 1.0).to_f
end
end
# Parse the `accept` header value into a list of content types.
#
# @parameter value [String] the value of the header.
def initialize(value = nil)
if value
super(value.scan(SEPARATOR).map(&:strip))
end
end
# Adds one or more comma-separated values to the header.
#
# The input string is split into distinct entries and appended to the array.
#
# @parameter value [String] the value or values to add, separated by commas.
def << value
self.concat(value.scan(SEPARATOR).map(&:strip))
end
# Serializes the stored values into a comma-separated string.
#
# @returns [String] the serialized representation of the header values.
def to_s
join(",")
end
# Whether this header is acceptable in HTTP trailers.
# @returns [Boolean] `false`, as Accept headers are used for response content negotiation.
def self.trailer?
false
end
# Parse the `accept` header.
#
# @returns [Array(Charset)] the list of content types and their associated parameters.
def media_ranges
self.map do |value|
self.parse_media_range(value)
end
end
private
def parse_media_range(value)
if match = value.match(MEDIA_RANGE)
type = match[:type]
subtype = match[:subtype]
parameters = {}
match[:parameters].scan(PARAMETER) do |key, value, quoted_value|
if quoted_value
value = QuotedString.unquote(quoted_value)
end
parameters[key] = value
end
return MediaRange.new(type, subtype, parameters)
else
raise ParseError, "Invalid media type: #{value.inspect}"
end
end
end
end
end
end
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