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# frozen_string_literal: true
# Released under the MIT License.
# Copyright, 2024-2026, by Samuel Williams.
require_relative "split"
module Protocol
module HTTP
module Header
# Represents the `priority` header, used to indicate the relative importance of an HTTP request.
#
# The `priority` header allows clients to express their preference for how resources should be prioritized by the server. It supports directives like `u=` to specify the urgency level of a request, and `i` to indicate whether a response can be delivered incrementally. The urgency levels range from 0 (highest priority) to 7 (lowest priority), while the `i` directive is a boolean flag.
class Priority < Split
# Parses a raw header value.
#
# @parameter value [String] a raw header value containing comma-separated directives.
# @returns [Priority] a new instance with normalized (lowercase) directives.
def self.parse(value)
self.new(value.downcase.split(COMMA))
end
# Coerces a value into a parsed header object.
#
# @parameter value [String | Array] the value to coerce.
# @returns [Priority] a parsed header object with normalized values.
def self.coerce(value)
case value
when Array
self.new(value.map(&:downcase))
else
self.parse(value.to_s)
end
end
# Add a value to the priority header.
#
# @parameter value [String] a raw header value containing directives to add to the header.
def << value
super(value.downcase)
end
# The default urgency level if not specified.
DEFAULT_URGENCY = 3
# The urgency level, if specified using `u=`. 0 is the highest priority, and 7 is the lowest.
#
# Note that when duplicate Dictionary keys are encountered, all but the last instance are ignored.
#
# @returns [Integer | Nil] the urgency level if specified, or `nil` if not present.
def urgency(default = DEFAULT_URGENCY)
if value = self.reverse_find{|value| value.start_with?("u=")}
_, level = value.split("=", 2)
return Integer(level)
end
return default
end
# Checks if the response should be delivered incrementally.
#
# The `i` directive, when present, indicates that the response can be delivered incrementally as data becomes available.
#
# @returns [Boolean] whether the request should be delivered incrementally.
def incremental?
self.include?("i")
end
end
end
end
end
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