Lazily evaluate block

Author: tylerhunt

CHANGELOG.md

@@ -1,5 +1,9 @@
 # Changelog
 
+## Unreleased
+
+  * Lazily evaluate block ([Robert Keresnyei][yenshirak])
+
 ## 1.3.0 (2024-03-15)
 
   * Respond to invalid request URL with 400 ([Gareth Jones][G-Rath])
@@ -100,3 +104,4 @@
 [olleolleolle]: https://github.com/olleolleolle
 [vinnydiehl]: https://github.com/vinnydiehl
 [G-Rath]: https://github.com/G-Rath
+[yenshirak]: https://github.com/yenshirak

lib/rack/canonical_host.rb

@@ -17,8 +17,7 @@ def call(env)
 
       return request.bad_request_response unless request.valid?
 
-      host = evaluate_host(env)
-      redirect = Redirect.new(env, host, options)
+      redirect = Redirect.new(env, host, options, &block)
 
       if redirect.canonical?
         app.call(env)
@@ -33,11 +32,5 @@ def call(env)
     attr_accessor :host
     attr_accessor :options
     attr_accessor :block
-
-  private
-
-    def evaluate_host(env)
-      block and block.call(env) or host
-    end
   end
 end

lib/rack/canonical_host/redirect.rb

@@ -15,9 +15,10 @@ class Redirect
         </html>
       HTML
 
-      def initialize(env, host, options={})
+      def initialize(env, host=nil, options={}, &block)
         self.env = env
-        self.host = host
+        self.default_host = host
+        self.block = block
         self.ignore = Array(options[:ignore])
         self.conditions = Array(options[:if])
         self.cache_control = options[:cache_control]
@@ -35,7 +36,8 @@ def response
     protected
 
       attr_accessor :env
-      attr_accessor :host
+      attr_accessor :default_host
+      attr_accessor :block
       attr_accessor :ignore
       attr_accessor :conditions
       attr_accessor :cache_control
@@ -53,6 +55,12 @@ def any_match?(patterns, request_uri)
         }
       end
 
+      def enabled?
+        return true if conditions.empty?
+
+        any_match?(conditions, request_uri)
+      end
+
       def headers
         {
           'cache-control' => cache_control,
@@ -61,10 +69,9 @@ def headers
         }.reject { |_, value| !value }
       end
 
-      def enabled?
-        return true if conditions.empty?
-
-        any_match?(conditions, request_uri)
+      def host
+        return @host if defined?(@host)
+        @host = block && block.call(env) || default_host
       end
 
       def ignored?

spec/rack/canonical_host_spec.rb

@@ -298,6 +298,18 @@ def call_app
           let(:url) { 'http://www.example.com/full/path' }
         end
       end
+
+      context 'with :if option that rejects the request' do
+        let(:url) { 'http://api.example.com/full/path' }
+
+        let(:app) {
+          build_app(nil, if: ->(uri) { uri.host == 'example.com' }) { raise }
+        }
+
+        it 'does not evaluate the block' do
+          expect { call_app }.to_not raise_error
+        end
+      end
     end
   end
 end