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.

A policy may be ‘false` to indicate that the header may only be specified once and is a simple string.

Otherwise, the policy is a class which implements the header normalization logic, including ‘parse` and `coerce` class methods.

{
  # Headers which may only be specified once:
  "content-disposition" => false,
  "content-length" => false,
  "content-type" => false,
  "expect" => false,
  "from" => false,
  "host" => false,
  "location" => false,
  "max-forwards" => false,
  "range" => false,
  "referer" => false,
  "retry-after" => false,
  "server" => false,
  "transfer-encoding" => Header::TransferEncoding,
  "user-agent" => false,
  "trailer" => Header::Trailer,
  
  # Connection handling:
  "connection" => Header::Connection,
  "upgrade" => Header::Split,
  
  # Cache handling:
  "cache-control" => Header::CacheControl,
  "te" => Header::TE,
  "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,
  "if-range" => false,
  
  # 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-ranges" => Header::Split,
  "accept-charset" => Header::AcceptCharset,
  "accept-encoding" => Header::AcceptEncoding,
  "accept-language" => Header::AcceptLanguage,
  
  # Content negotiation headers:
  "content-encoding" => Header::Split,
  "content-range" => false,
  
  # Performance headers:
  "server-timing" => Header::ServerTiming,
  
  # Content integrity headers:
  "digest" => Header::Digest,
}.tap{|hash| hash.default = Header::Generic}

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(fields = [], tail = nil, indexed: nil, policy: POLICY) ⇒ Headers

Initialize the headers with the specified fields.



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# File 'lib/protocol/http/headers.rb', line 74

def initialize(fields = [], tail = nil, indexed: nil, policy: POLICY)
  @fields = fields
  
  # Marks where trailer start in the @fields array:
  @tail = tail
  
  # The cached index of headers:
  @indexed = nil
  
  @policy = policy
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 132

attr :fields

#fields ⇒ Object (readonly)

Returns the value of attribute fields.



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# File 'lib/protocol/http/headers.rb', line 132

def fields
  @fields
end

#policy ⇒ Object

Returns the value of attribute policy.



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# File 'lib/protocol/http/headers.rb', line 87

def policy
  @policy
end

#tail ⇒ Object (readonly)

Returns the value of attribute tail.



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# File 'lib/protocol/http/headers.rb', line 135

def tail
  @tail
end

#The index where trailers begin.(indexwheretrailers) ⇒ Object (readonly) 



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# File 'lib/protocol/http/headers.rb', line 135

attr :tail

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 48

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 495

def == other
  case other
  when Hash
    self.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 310

def [] key
  self.to_h[key]
end

#[]=(key, value) ⇒ Object

Set the specified header key to the specified value, replacing any existing values.

The value can be a String or a coercable value.



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# File 'lib/protocol/http/headers.rb', line 284

def []=(key, value)
  key = key.downcase
  
  # Delete existing value if any:
  self.delete(key)
  
  if policy = @policy[key]
    unless value.is_a?(policy)
      value = policy.coerce(value)
    end
  else
    value = value.to_s
  end
  
  # Clear the indexed cache so it will be rebuilt with parsed values when accessed:
  if @indexed
    @indexed[key] = value
  end
  
  @fields << [key, value.to_s]
end

#add(key, value, trailer: self.trailer?) ⇒ Object

Add the specified header key value pair.



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# File 'lib/protocol/http/headers.rb', line 251

def add(key, value, trailer: self.trailer?)
  value = value.to_s
  
  if trailer
    policy = @policy[key.downcase]
    
    if !policy or !policy.trailer?
      raise InvalidTrailerError, key
    end
  end
  
  if @indexed
    merge_into(@indexed, key.downcase, value)
  end
  
  @fields << [key, value]
end

#clear ⇒ Object

Clear all headers.



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

def clear
  @fields.clear
  @tail = nil
  @indexed = 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 413

def delete(key)
  # If we've indexed the headers, we can bail out early if the key is not present:
  if @indexed && !@indexed.key?(key.downcase)
    return nil
  end
  
  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.parse(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 213

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

#empty? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/protocol/http/headers.rb', line 204

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 232

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 127

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 117

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 191

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

#header(&block) ⇒ Object

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



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# File 'lib/protocol/http/headers.rb', line 167

def header(&block)
  return to_enum(:header) unless block_given?
  
  if @tail and @tail < @fields.size
    @fields.first(@tail).each(&block)
  else
    @fields.each(&block)
  end
end

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

Returns:

  • (Boolean) 


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# File 'lib/protocol/http/headers.rb', line 218

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 102

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 488

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

#keys ⇒ Object 



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# File 'lib/protocol/http/headers.rb', line 225

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 324

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 315

def merge!(headers)
  headers.each do |key, value|
    self.add(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 273

def set(key, value)
  self.delete(key)
  self.add(key, value)
end

#The policy for the headers.=(policy) ⇒ Object 



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# File 'lib/protocol/http/headers.rb', line 87

attr :policy

#to_a ⇒ Object 



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# File 'lib/protocol/http/headers.rb', line 138

def to_a
  @fields
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.

This will enforce policy rules, such as merging multiple headers into arrays, or raising errors for duplicate headers.



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# File 'lib/protocol/http/headers.rb', line 468

def to_h
  unless @indexed
    indexed = {}
    
    @fields.each do |key, value|
      merge_into(indexed, key.downcase, value)
    end
    
    # Deferred assignment so that exceptions in `merge_into` don't leave us in an inconsistent state:
    @indexed = indexed
  end
  
  return @indexed
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 182

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 156

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 143

def trailer?
  @tail != nil
end