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-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,
  
  # Custom headers:
  "connection" => Header::Connection,
  "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-charset" => Header::AcceptCharset,
  "accept-encoding" => Header::AcceptEncoding,
  "accept-language" => Header::AcceptLanguage,
  
  # Performance headers:
  "server-timing" => Header::ServerTiming,
  
  # Content integrity headers:
  "digest" => Header::Digest,
}.tap{|hash| hash.default = Split}

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 73

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 131

attr :fields

#fields ⇒ Object (readonly)

Returns the value of attribute fields.



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# File 'lib/protocol/http/headers.rb', line 131

def fields
  @fields
end

#policy ⇒ Object

Returns the value of attribute policy.



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# File 'lib/protocol/http/headers.rb', line 86

def policy
  @policy
end

#tail ⇒ Object (readonly)

Returns the value of attribute tail.



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# File 'lib/protocol/http/headers.rb', line 134

def tail
  @tail
end

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



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# File 'lib/protocol/http/headers.rb', line 134

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 47

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 465

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 281

def [] key
  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 255

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) ⇒ Object

Add the specified header key value pair.



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

def add(key, value)
  value = value.to_s
  
  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 109

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 372

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 193

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

#empty? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/protocol/http/headers.rb', line 184

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 212

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 126

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 116

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 171

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 198

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 101

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 458

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

#keys ⇒ Object 



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# File 'lib/protocol/http/headers.rb', line 205

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 295

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 286

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 244

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 86

attr :policy

#to_a ⇒ Object 



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# File 'lib/protocol/http/headers.rb', line 137

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.



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# File 'lib/protocol/http/headers.rb', line 439

def to_h
  unless @indexed
    @indexed = {}
    
    @fields.each_with_index do |(key, value), index|
      trailer = (@tail && index >= @tail)
      
      merge_into(@indexed, key.downcase, value, trailer)
    end
  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 162

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 155

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 142

def trailer?
  @tail != nil
end