use rack 2.2x headers implementation

lib/httpi/utils.rb

@@ -3,236 +3,93 @@
 # library for it. 
 module HTTPI
   module Utils
-    # HTTPI::Utils::Headers is a Hash subclass that downcases all keys.
+    # A case-insensitive Hash that preserves the original case of a
+    # header when set.
+    #
     class Headers < Hash
-      KNOWN_HEADERS = {}
-      %w(
-        Accept-CH
-        Accept-Patch
-        Accept-Ranges
-        Access-Control-Allow-Credentials
-        Access-Control-Allow-Headers
-        Access-Control-Allow-Methods
-        Access-Control-Allow-Origin
-        Access-Control-Expose-Headers
-        Access-Control-Max-Age
-        Age
-        Allow
-        Alt-Svc
-        Cache-Control
-        Connection
-        Content-Disposition
-        Content-Encoding
-        Content-Language
-        Content-Length
-        Content-Location
-        Content-MD5
-        Content-Range
-        Content-Security-Policy
-        Content-Security-Policy-Report-Only
-        Content-Type
-        Date
-        Delta-Base
-        ETag
-        Expect-CT
-        Expires
-        Feature-Policy
-        IM
-        Last-Modified
-        Link
-        Location
-        NEL
-        P3P
-        Permissions-Policy
-        Pragma
-        Preference-Applied
-        Proxy-Authenticate
-        Public-Key-Pins
-        Referrer-Policy
-        Refresh
-        Report-To
-        Retry-After
-        Server
-        Set-Cookie
-        Status
-        Strict-Transport-Security
-        Timing-Allow-Origin
-        Tk
-        Trailer
-        Transfer-Encoding
-        Upgrade
-        Vary
-        Via
-        WWW-Authenticate
-        Warning
-        X-Cascade
-        X-Content-Duration
-        X-Content-Security-Policy
-        X-Content-Type-Options
-        X-Correlation-ID
-        X-Correlation-Id
-        X-Download-Options
-        X-Frame-Options
-        X-Permitted-Cross-Domain-Policies
-        X-Powered-By
-        X-Redirect-By
-        X-Request-ID
-        X-Request-Id
-        X-Runtime
-        X-UA-Compatible
-        X-WebKit-CS
-        X-XSS-Protection
-      ).each do |str|
-        downcased = str.downcase.freeze
-        KNOWN_HEADERS[str] = KNOWN_HEADERS[downcased] = downcased
-      end
-
-      def self.[](*items)
-        if items.length % 2 != 0
-          if items.length == 1 && items.first.is_a?(Hash)
-            new.merge!(items.first)
-          else
-            raise ArgumentError, "odd number of arguments for Utils::Headers"
-          end
+      def self.[](headers)
+        if headers.is_a?(Headers) && !headers.frozen?
+          return headers
         else
-          hash = new
-          loop do
-            break if items.length == 0
-            key = items.shift
-            value = items.shift
-            hash[key] = value
-          end
-          hash
+          return self.new(headers)
         end
       end
 
-      def [](key)
-        super(downcase_key(key))
-      end
-
-      def []=(key, value)
-        super(KNOWN_HEADERS[key] || key.downcase.freeze, value)
-      end
-      alias store []=
-
-      def assoc(key)
-        super(downcase_key(key))
-      end
-
-      def compare_by_identity
-        raise TypeError, "Utils::Headers cannot compare by identity, use regular Hash"
-      end
-
-      def delete(key)
-        super(downcase_key(key))
-      end
-
-      def dig(key, *a)
-        super(downcase_key(key), *a)
+      def initialize(hash = {})
+        super()
+        @names = {}
+        hash.each { |k, v| self[k] = v }
       end
 
-      def fetch(key, *default, &block)
-        key = downcase_key(key)
+      # on dup/clone, we need to duplicate @names hash
+      def initialize_copy(other)
         super
+        @names = other.names.dup
       end
 
-      def fetch_values(*a)
-        super(*a.map!{|key| downcase_key(key)})
+      # on clear, we need to clear @names hash
+      def clear
+        super
+        @names.clear
       end
 
-      def has_key?(key)
-        super(downcase_key(key))
+      def each
+        super do |k, v|
+          yield(k, v.respond_to?(:to_ary) ? v.to_ary.join("\n") : v)
+        end
       end
-      alias include? has_key?
-      alias key? has_key?
-      alias member? has_key?
 
-      def invert
-        hash = self.class.new
-        each{|key, value| hash[value] = key}
+      def to_hash
+        hash = {}
+        each { |k, v| hash[k] = v }
         hash
       end
 
-      def merge(hash, &block)
-        dup.merge!(hash, &block)
+      def [](k)
+        super(k) || super(@names[k.downcase])
       end
 
-      def reject(&block)
-        hash = dup
-        hash.reject!(&block)
-        hash
+      def []=(k, v)
+        canonical = k.downcase.freeze
+        delete k if @names[canonical] && @names[canonical] != k # .delete is expensive, don't invoke it unless necessary
+        @names[canonical] = k
+        super k, v
       end
 
-      def replace(hash)
-        clear
-        update(hash)
+      def delete(k)
+        canonical = k.downcase
+        result = super @names.delete(canonical)
+        result
       end
 
-      def select(&block)
-        hash = dup
-        hash.select!(&block)
-        hash
+      def include?(k)
+        super || @names.include?(k.downcase)
       end
 
-      def to_proc
-        lambda{|x| self[x]}
-      end
+      alias_method :has_key?, :include?
+      alias_method :member?, :include?
+      alias_method :key?, :include?
 
-      def transform_values(&block)
-        dup.transform_values!(&block)
-      end
-
-      def update(hash, &block)
-        hash.each do |key, value|
-          self[key] = if block_given? && include?(key)
-            block.call(key, self[key], value)
-          else
-            value
-          end
-        end
+      def merge!(other)
+        other.each { |k, v| self[k] = v }
         self
       end
-      alias merge! update
 
-      def values_at(*keys)
-        keys.map{|key| self[key]}
+      def merge(other)
+        hash = dup
+        hash.merge! other
       end
 
-      # :nocov:
-      if RUBY_VERSION >= '2.5'
-      # :nocov:
-        def slice(*a)
-          h = self.class.new
-          a.each{|k| h[k] = self[k] if has_key?(k)}
-          h
-        end
-
-        def transform_keys(&block)
-          dup.transform_keys!(&block)
-        end
-
-        def transform_keys!
-          hash = self.class.new
-          each do |k, v|
-            hash[yield k] = v
-          end
-          replace(hash)
-        end
+      def replace(other)
+        clear
+        other.each { |k, v| self[k] = v }
+        self
       end
 
-      # :nocov:
-      if RUBY_VERSION >= '3.0'
-      # :nocov:
-        def except(*a)
-          super(*a.map!{|key| downcase_key(key)})
+      protected
+        def names
+          @names
         end
-      end
-
-      private
-
-      def downcase_key(key)
-        key.is_a?(String) ? KNOWN_HEADERS[key] || key.downcase : key
-      end
     end
   end
 end

spec/httpi/response_spec.rb

@@ -118,6 +118,10 @@
       it "returns the HTTP response headers" do
         expect(response.headers).to eq HTTPI::Utils::Headers.new.merge({ "Content-Type" => "application/dime" })
       end
+
+      it "preserves casing" do
+        expect(response.headers.keys).to eq ["Content-Type"]
+      end
     end
 
     describe "#body" do