Class: Protocol::HTTP::Headers

Inherits:
Object
  • Object
show all
Defined in:
lib/protocol/http/headers.rb

Overview

Headers are an array of key-value pairs. Some header keys represent multiple values.

Defined Under Namespace

Classes: Merged

Constant Summary collapse

Split = 
Header::Split
Multiple = 
Header::Multiple
TRAILER = 
"trailer"
POLICY =

The policy for various headers, including how they are merged and normalized.

{
	# Headers which may only be specified once:
	"content-type" => false,
	"content-disposition" => false,
	"content-length" => false,
	"user-agent" => false,
	"referer" => false,
	"host" => false,
	"from" => false,
	"location" => false,
	"max-forwards" => false,
	"retry-after" => false,
	
	# Custom headers:
	"connection" => Header::Connection,
	"cache-control" => Header::CacheControl,
	"vary" => Header::Vary,
	"priority" => Header::Priority,
	
	# Headers specifically for proxies:
	"via" => Split,
	"x-forwarded-for" => Split,
	
	# Authorization headers:
	"authorization" => Header::Authorization,
	"proxy-authorization" => Header::Authorization,
	
	# Cache validations:
	"etag" => Header::ETag,
	"if-match" => Header::ETags,
	"if-none-match" => Header::ETags,
	
	# Headers which may be specified multiple times, but which can't be concatenated:
	"www-authenticate" => Multiple,
	"proxy-authenticate" => Multiple,
	
	# Custom headers:
	"set-cookie" => Header::SetCookie,
	"cookie" => Header::Cookie,
	
	# Date headers:
	# These headers include a comma as part of the formatting so they can't be concatenated.
	"date" => Header::Date,
	"expires" => Header::Date,
	"last-modified" => Header::Date,
	"if-modified-since" => Header::Date,
	"if-unmodified-since" => Header::Date,
	
	# Accept headers:
	"accept" => Header::Accept,
	"accept-charset" => Header::AcceptCharset,
	"accept-encoding" => Header::AcceptEncoding,
	"accept-language" => Header::AcceptLanguage,
}.tap{|hash| hash.default = Split}

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(fields = [], indexed = nil) ⇒ Headers

Initialize the headers with the specified fields.



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# File 'lib/protocol/http/headers.rb', line 66

def initialize(fields = [], indexed = nil)
	@fields = fields
	@indexed = indexed
	
	# Marks where trailer start in the @fields array.
	@tail = nil
end

Instance Attribute Details

#An array of `[key, value]` pairs.(arrayof`[key, value]`pairs.) ⇒ Object (readonly) 



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# File 'lib/protocol/http/headers.rb', line 107

attr :fields

#fields ⇒ Object (readonly)

Returns the value of attribute fields.



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# File 'lib/protocol/http/headers.rb', line 107

def fields
  @fields
end

Class Method Details

.[](headers) ⇒ Headers

Construct an instance from a headers Array or Hash. No-op if already an instance of ‘Headers`. If the underlying array is frozen, it will be duped.

Returns:

  • (Headers) —

    an instance of headers.



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# File 'lib/protocol/http/headers.rb', line 40

def self.[] headers
	if headers.nil?
		return self.new
	end
	
	if headers.is_a?(self)
		if headers.frozen?
			return headers.dup
		else
			return headers
		end
	end
	
	fields = headers.to_a
	
	if fields.frozen?
		fields = fields.dup
	end
	
	return self.new(fields)
end

Instance Method Details

#==(other) ⇒ Object

Compare this object to another object. May depend on the order of the fields.



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# File 'lib/protocol/http/headers.rb', line 371

def == other
	case other
	when Hash
		to_h == other
	when Headers
		@fields == other.fields
	else
		@fields == other
	end
end

#[](key) ⇒ Object

Get the value of the specified header key.



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# File 'lib/protocol/http/headers.rb', line 344

def [] key
	to_h[key]
end

#[]=(key, value) ⇒ Object

Append the value to the given key. Some values can be appended multiple times, others can only be set once.



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# File 'lib/protocol/http/headers.rb', line 230

def []= key, value
	if @indexed
		merge_into(@indexed, key.downcase, value)
	end
	
	@fields << [key, value]
end

#add(key, value) ⇒ Object

Add the specified header key value pair.



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# File 'lib/protocol/http/headers.rb', line 198

def add(key, value)
	self[key] = value
end

#clear ⇒ Object

Clear all headers.



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# File 'lib/protocol/http/headers.rb', line 85

def clear
	@fields.clear
	@indexed = nil
	@tail = nil
end

#delete(key) ⇒ Object

Delete all header values for the given key, and return the merged value.



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# File 'lib/protocol/http/headers.rb', line 298

def delete(key)
	deleted, @fields = @fields.partition do |field|
		field.first.downcase == key
	end
	
	if deleted.empty?
		return nil
	end
	
	if @indexed
		return @indexed.delete(key)
	elsif policy = POLICY[key]
		(key, value), *tail = deleted
		merged = policy.new(value)
		
		tail.each{|k,v| merged << v}
		
		return merged
	else
		key, value = deleted.last
		return value
	end
end

#each(&block) ⇒ Object

Enumerate all header keys and values.



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# File 'lib/protocol/http/headers.rb', line 161

def each(&block)
	@fields.each(&block)
end

#empty? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/protocol/http/headers.rb', line 152

def empty?
	@fields.empty?
end

#extract(keys) ⇒ Object

Extract the specified keys from the headers.



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# File 'lib/protocol/http/headers.rb', line 180

def extract(keys)
	deleted, @fields = @fields.partition do |field|
		keys.include?(field.first.downcase)
	end
	
	if @indexed
		keys.each do |key|
			@indexed.delete(key)
		end
	end
	
	return deleted
end

#flatten ⇒ Object

Flatten trailer into the headers, returning a new instance of Protocol::HTTP::Headers.



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# File 'lib/protocol/http/headers.rb', line 102

def flatten
	self.dup.flatten!
end

#flatten! ⇒ Object

Flatten trailer into the headers, in-place.



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# File 'lib/protocol/http/headers.rb', line 92

def flatten!
	if @tail
		self.delete(TRAILER)
		@tail = nil
	end
	
	return self
end

#freeze ⇒ Object

Freeze the headers, and ensure the indexed hash is generated.



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# File 'lib/protocol/http/headers.rb', line 139

def freeze
	return if frozen?
	
	# Ensure @indexed is generated:
	self.to_h
	
	@fields.freeze
	@indexed.freeze
	
	super
end

#include?(key) ⇒ Boolean Also known as: key?

Returns:

  • (Boolean) 


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# File 'lib/protocol/http/headers.rb', line 166

def include? key
	self[key] != nil
end

#initialize_dup(other) ⇒ Object

Initialize a copy of the headers.



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# File 'lib/protocol/http/headers.rb', line 77

def initialize_dup(other)
	super
	
	@fields = @fields.dup
	@indexed = @indexed.dup
end

#inspect ⇒ Object

Inspect the headers.



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# File 'lib/protocol/http/headers.rb', line 364

def inspect
	"#<#{self.class} #{@fields.inspect}>"
end

#keys ⇒ Object 



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# File 'lib/protocol/http/headers.rb', line 173

def keys
	self.to_h.keys
end

#merge(headers) ⇒ Object

Merge the headers into a new instance of Protocol::HTTP::Headers.



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# File 'lib/protocol/http/headers.rb', line 222

def merge(headers)
	self.dup.merge!(headers)
end

#merge!(headers) ⇒ Object

Merge the headers into this instance.



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# File 'lib/protocol/http/headers.rb', line 213

def merge!(headers)
	headers.each do |key, value|
		self[key] = value
	end
	
	return self
end

#set(key, value) ⇒ Object

Set the specified header key to the specified value, replacing any existing header keys with the same name.



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# File 'lib/protocol/http/headers.rb', line 206

def set(key, value)
	# TODO This could be a bit more efficient:
	self.delete(key)
	self.add(key, value)
end

#to_h ⇒ Object Also known as: as_json

Compute a hash table of headers, where the keys are normalized to lower case and the values are normalized according to the policy for that header.



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# File 'lib/protocol/http/headers.rb', line 351

def to_h
	@indexed ||= @fields.inject({}) do |hash, (key, value)|
		merge_into(hash, key.downcase, value)
		
		hash
	end
end

#trailer(&block) ⇒ Object

Enumerate all headers in the trailer, if there are any.



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# File 'lib/protocol/http/headers.rb', line 130

def trailer(&block)
	return to_enum(:trailer) unless block_given?
	
	if @tail
		@fields.drop(@tail).each(&block)
	end
end

#trailer!(&block) ⇒ Object

Record the current headers, and prepare to add trailers.

This method is typically used after headers are sent to capture any additional headers which should then be sent as trailers.

A sender that intends to generate one or more trailer fields in a message should generate a trailer header field in the header section of that message to indicate which fields might be present in the trailers.



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# File 'lib/protocol/http/headers.rb', line 123

def trailer!(&block)
	@tail ||= @fields.size
	
	return trailer(&block)
end

#trailer? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/protocol/http/headers.rb', line 110

def trailer?
	@tail != nil
end