aboutsummaryrefslogtreecommitdiffstats
path: root/actionpack/lib/action_dispatch/routing/mapper.rb
blob: 9e59861e0145bc9a36d46753dd4ac0770490298b (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
require 'active_support/core_ext/hash/except'
require 'active_support/core_ext/object/blank'
require 'active_support/core_ext/object/inclusion'
require 'active_support/inflector'
require 'action_dispatch/routing/redirection'

module ActionDispatch
  module Routing
    class Mapper
      class Constraints #:nodoc:
        def self.new(app, constraints, request = Rack::Request)
          if constraints.any?
            super(app, constraints, request)
          else
            app
          end
        end

        attr_reader :app, :constraints

        def initialize(app, constraints, request)
          @app, @constraints, @request = app, constraints, request
        end

        def matches?(env)
          req = @request.new(env)

          @constraints.each { |constraint|
            if constraint.respond_to?(:matches?) && !constraint.matches?(req)
              return false
            elsif constraint.respond_to?(:call) && !constraint.call(*constraint_args(constraint, req))
              return false
            end
          }

          return true
        end

        def call(env)
          matches?(env) ? @app.call(env) : [ 404, {'X-Cascade' => 'pass'}, [] ]
        end

        private
          def constraint_args(constraint, request)
            constraint.arity == 1 ? [request] : [request.symbolized_path_parameters, request]
          end
      end

      class Mapping #:nodoc:
        IGNORE_OPTIONS = [:to, :as, :via, :on, :constraints, :defaults, :only, :except, :anchor, :shallow, :shallow_path, :shallow_prefix]
        ANCHOR_CHARACTERS_REGEX = %r{\A(\\A|\^)|(\\Z|\\z|\$)\Z}
        SHORTHAND_REGEX = %r{/[\w/]+$}
        WILDCARD_PATH = %r{\*([^/\)]+)\)?$}

        def initialize(set, scope, path, options)
          @set, @scope = set, scope
          @options = (@scope[:options] || {}).merge(options)
          @path = normalize_path(path)
          normalize_options!
        end

        def to_route
          [ app, conditions, requirements, defaults, @options[:as], @options[:anchor] ]
        end

        private

          def normalize_options!
            path_without_format = @path.sub(/\(\.:format\)$/, '')

            if using_match_shorthand?(path_without_format, @options)
              to_shorthand    = @options[:to].blank?
              @options[:to] ||= path_without_format.gsub(/\(.*\)/, "")[1..-1].sub(%r{/([^/]*)$}, '#\1')
            end

            @options.merge!(default_controller_and_action(to_shorthand))

            requirements.each do |name, requirement|
              # segment_keys.include?(k.to_s) || k == :controller
              next unless Regexp === requirement && !constraints[name]

              if requirement.source =~ ANCHOR_CHARACTERS_REGEX
                raise ArgumentError, "Regexp anchor characters are not allowed in routing requirements: #{requirement.inspect}"
              end
              if requirement.multiline?
                raise ArgumentError, "Regexp multiline option not allowed in routing requirements: #{requirement.inspect}"
              end
            end
          end

          # match "account/overview"
          def using_match_shorthand?(path, options)
            path && (options[:to] || options[:action]).nil? && path =~ SHORTHAND_REGEX
          end

          def normalize_path(path)
            raise ArgumentError, "path is required" if path.blank?
            path = Mapper.normalize_path(path)

            if path.match(':controller')
              raise ArgumentError, ":controller segment is not allowed within a namespace block" if @scope[:module]

              # Add a default constraint for :controller path segments that matches namespaced
              # controllers with default routes like :controller/:action/:id(.:format), e.g:
              # GET /admin/products/show/1
              # => { :controller => 'admin/products', :action => 'show', :id => '1' }
              @options[:controller] ||= /.+?/
            end

            # Add a constraint for wildcard route to make it non-greedy and match the
            # optional format part of the route by default
            if path.match(WILDCARD_PATH) && @options[:format] != false
              @options[$1.to_sym] ||= /.+?/
            end

            if @options[:format] == false
              @options.delete(:format)
              path
            elsif path.include?(":format") || path.end_with?('/')
              path
            elsif @options[:format] == true
              "#{path}.:format"
            else
              "#{path}(.:format)"
            end
          end

          def app
            Constraints.new(
              to.respond_to?(:call) ? to : Routing::RouteSet::Dispatcher.new(:defaults => defaults),
              blocks,
              @set.request_class
            )
          end

          def conditions
            { :path_info => @path }.merge(constraints).merge(request_method_condition)
          end

          def requirements
            @requirements ||= (@options[:constraints].is_a?(Hash) ? @options[:constraints] : {}).tap do |requirements|
              requirements.reverse_merge!(@scope[:constraints]) if @scope[:constraints]
              @options.each { |k, v| requirements[k] = v if v.is_a?(Regexp) }
            end
          end

          def defaults
            @defaults ||= (@options[:defaults] || {}).tap do |defaults|
              defaults.reverse_merge!(@scope[:defaults]) if @scope[:defaults]
              @options.each { |k, v| defaults[k] = v unless v.is_a?(Regexp) || IGNORE_OPTIONS.include?(k.to_sym) }
            end
          end

          def default_controller_and_action(to_shorthand=nil)
            if to.respond_to?(:call)
              { }
            else
              if to.is_a?(String)
                controller, action = to.split('#')
              elsif to.is_a?(Symbol)
                action = to.to_s
              end

              controller ||= default_controller
              action     ||= default_action

              unless controller.is_a?(Regexp) || to_shorthand
                controller = [@scope[:module], controller].compact.join("/").presence
              end

              if controller.is_a?(String) && controller =~ %r{\A/}
                raise ArgumentError, "controller name should not start with a slash"
              end

              controller = controller.to_s unless controller.is_a?(Regexp)
              action     = action.to_s     unless action.is_a?(Regexp)

              if controller.blank? && segment_keys.exclude?("controller")
                raise ArgumentError, "missing :controller"
              end

              if action.blank? && segment_keys.exclude?("action")
                raise ArgumentError, "missing :action"
              end

              hash = {}
              hash[:controller] = controller unless controller.blank?
              hash[:action]     = action unless action.blank?
              hash
            end
          end

          def blocks
            constraints = @options[:constraints]
            if constraints.present? && !constraints.is_a?(Hash)
              [constraints]
            else
              @scope[:blocks] || []
            end
          end

          def constraints
            @constraints ||= requirements.reject { |k, v| segment_keys.include?(k.to_s) || k == :controller }
          end

          def request_method_condition
            if via = @options[:via]
              list = Array(via).map { |m| m.to_s.dasherize.upcase }
              { :request_method => list }
            else
              { }
            end
          end

          def segment_keys
            @segment_keys ||= Journey::Path::Pattern.new(
              Journey::Router::Strexp.compile(@path, requirements, SEPARATORS)
            ).names
          end

          def to
            @options[:to]
          end

          def default_controller
            @options[:controller] || @scope[:controller]
          end

          def default_action
            @options[:action] || @scope[:action]
          end
      end

      # Invokes Rack::Mount::Utils.normalize path and ensure that
      # (:locale) becomes (/:locale) instead of /(:locale). Except
      # for root cases, where the latter is the correct one.
      def self.normalize_path(path)
        path = Journey::Router::Utils.normalize_path(path)
        path.gsub!(%r{/(\(+)/?}, '\1/') unless path =~ %r{^/\(+[^/]+\)$}
        path
      end

      def self.normalize_name(name)
        normalize_path(name)[1..-1].gsub("/", "_")
      end

      module Base
        # You can specify what Rails should route "/" to with the root method:
        #
        #   root :to => 'pages#main'
        #
        # For options, see +match+, as +root+ uses it internally.
        #
        # You should put the root route at the top of <tt>config/routes.rb</tt>,
        # because this means it will be matched first. As this is the most popular route
        # of most Rails applications, this is beneficial.
        def root(options = {})
          match '/', { :as => :root }.merge(options)
        end

        # Matches a url pattern to one or more routes. Any symbols in a pattern
        # are interpreted as url query parameters and thus available as +params+
        # in an action:
        #
        #   # sets :controller, :action and :id in params
        #   match ':controller/:action/:id'
        #
        # Two of these symbols are special, +:controller+ maps to the controller
        # and +:action+ to the controller's action. A pattern can also map
        # wildcard segments (globs) to params:
        #
        #   match 'songs/*category/:title' => 'songs#show'
        #
        #   # 'songs/rock/classic/stairway-to-heaven' sets
        #   #  params[:category] = 'rock/classic'
        #   #  params[:title] = 'stairway-to-heaven'
        #
        # When a pattern points to an internal route, the route's +:action+ and
        # +:controller+ should be set in options or hash shorthand. Examples:
        #
        #   match 'photos/:id' => 'photos#show'
        #   match 'photos/:id', :to => 'photos#show'
        #   match 'photos/:id', :controller => 'photos', :action => 'show'
        #
        # A pattern can also point to a +Rack+ endpoint i.e. anything that
        # responds to +call+:
        #
        #   match 'photos/:id' => lambda {|hash| [200, {}, "Coming soon"] }
        #   match 'photos/:id' => PhotoRackApp
        #   # Yes, controller actions are just rack endpoints
        #   match 'photos/:id' => PhotosController.action(:show)
        #
        # === Options
        #
        # Any options not seen here are passed on as params with the url.
        #
        # [:controller]
        #   The route's controller.
        #
        # [:action]
        #   The route's action.
        #
        # [:path]
        #   The path prefix for the routes.
        #
        # [:module]
        #   The namespace for :controller.
        #
        #     match 'path' => 'c#a', :module => 'sekret', :controller => 'posts'
        #     #=> Sekret::PostsController
        #
        #   See <tt>Scoping#namespace</tt> for its scope equivalent.
        #
        # [:as]
        #   The name used to generate routing helpers.
        #
        # [:via]
        #   Allowed HTTP verb(s) for route.
        #
        #      match 'path' => 'c#a', :via => :get
        #      match 'path' => 'c#a', :via => [:get, :post]
        #
        # [:to]
        #   Points to a +Rack+ endpoint. Can be an object that responds to
        #   +call+ or a string representing a controller's action.
        #
        #      match 'path', :to => 'controller#action'
        #      match 'path', :to => lambda { [200, {}, "Success!"] }
        #      match 'path', :to => RackApp
        #
        # [:on]
        #   Shorthand for wrapping routes in a specific RESTful context. Valid
        #   values are +:member+, +:collection+, and +:new+. Only use within
        #   <tt>resource(s)</tt> block. For example:
        #
        #      resource :bar do
        #        match 'foo' => 'c#a', :on => :member, :via => [:get, :post]
        #      end
        #
        #   Is equivalent to:
        #
        #      resource :bar do
        #        member do
        #          match 'foo' => 'c#a', :via => [:get, :post]
        #        end
        #      end
        #
        # [:constraints]
        #   Constrains parameters with a hash of regular expressions or an
        #   object that responds to <tt>matches?</tt>
        #
        #     match 'path/:id', :constraints => { :id => /[A-Z]\d{5}/ }
        #
        #     class Blacklist
        #       def matches?(request) request.remote_ip == '1.2.3.4' end
        #     end
        #     match 'path' => 'c#a', :constraints => Blacklist.new
        #
        #   See <tt>Scoping#constraints</tt> for more examples with its scope
        #   equivalent.
        #
        # [:defaults]
        #   Sets defaults for parameters
        #
        #     # Sets params[:format] to 'jpg' by default
        #     match 'path' => 'c#a', :defaults => { :format => 'jpg' }
        #
        #   See <tt>Scoping#defaults</tt> for its scope equivalent.
        #
        # [:anchor]
        #   Boolean to anchor a <tt>match</tt> pattern. Default is true. When set to
        #   false, the pattern matches any request prefixed with the given path.
        #
        #     # Matches any request starting with 'path'
        #     match 'path' => 'c#a', :anchor => false
        def match(path, options=nil)
        end

        # Mount a Rack-based application to be used within the application.
        #
        #   mount SomeRackApp, :at => "some_route"
        #
        # Alternatively:
        #
        #   mount(SomeRackApp => "some_route")
        #
        # For options, see +match+, as +mount+ uses it internally.
        #
        # All mounted applications come with routing helpers to access them.
        # These are named after the class specified, so for the above example
        # the helper is either +some_rack_app_path+ or +some_rack_app_url+.
        # To customize this helper's name, use the +:as+ option:
        #
        #   mount(SomeRackApp => "some_route", :as => "exciting")
        #
        # This will generate the +exciting_path+ and +exciting_url+ helpers
        # which can be used to navigate to this mounted app.
        def mount(app, options = nil)
          if options
            path = options.delete(:at)
          else
            options = app
            app, path = options.find { |k, v| k.respond_to?(:call) }
            options.delete(app) if app
          end

          raise "A rack application must be specified" unless path

          options[:as] ||= app_name(app)

          match(path, options.merge(:to => app, :anchor => false, :format => false))

          define_generate_prefix(app, options[:as])
          self
        end

        def default_url_options=(options)
          @set.default_url_options = options
        end
        alias_method :default_url_options, :default_url_options=

        def with_default_scope(scope, &block)
          scope(scope) do
            instance_exec(&block)
          end
        end

        private
          def app_name(app)
            return unless app.respond_to?(:routes)

            if app.respond_to?(:railtie_name)
              app.railtie_name
            else
              class_name = app.class.is_a?(Class) ? app.name : app.class.name
              ActiveSupport::Inflector.underscore(class_name).gsub("/", "_")
            end
          end

          def define_generate_prefix(app, name)
            return unless app.respond_to?(:routes) && app.routes.respond_to?(:define_mounted_helper)

            _route = @set.named_routes.routes[name.to_sym]
            _routes = @set
            app.routes.define_mounted_helper(name)
            app.routes.class_eval do
              define_method :_generate_prefix do |options|
                prefix_options = options.slice(*_route.segment_keys)
                # we must actually delete prefix segment keys to avoid passing them to next url_for
                _route.segment_keys.each { |k| options.delete(k) }
                prefix = _routes.url_helpers.send("#{name}_path", prefix_options)
                prefix = '' if prefix == '/'
                prefix
              end
            end
          end
      end

      module HttpHelpers
        # Define a route that only recognizes HTTP GET.
        # For supported arguments, see <tt>Base#match</tt>.
        #
        # Example:
        #
        # get 'bacon', :to => 'food#bacon'
        def get(*args, &block)
          map_method(:get, *args, &block)
        end

        # Define a route that only recognizes HTTP POST.
        # For supported arguments, see <tt>Base#match</tt>.
        #
        # Example:
        #
        # post 'bacon', :to => 'food#bacon'
        def post(*args, &block)
          map_method(:post, *args, &block)
        end

        # Define a route that only recognizes HTTP PUT.
        # For supported arguments, see <tt>Base#match</tt>.
        #
        # Example:
        #
        # put 'bacon', :to => 'food#bacon'
        def put(*args, &block)
          map_method(:put, *args, &block)
        end

        # Define a route that only recognizes HTTP PUT.
        # For supported arguments, see <tt>Base#match</tt>.
        #
        # Example:
        #
        # delete 'broccoli', :to => 'food#broccoli'
        def delete(*args, &block)
          map_method(:delete, *args, &block)
        end

        private
          def map_method(method, *args, &block)
            options = args.extract_options!
            options[:via] = method
            args.push(options)
            match(*args, &block)
            self
          end
      end

      # You may wish to organize groups of controllers under a namespace.
      # Most commonly, you might group a number of administrative controllers
      # under an +admin+ namespace. You would place these controllers under
      # the <tt>app/controllers/admin</tt> directory, and you can group them
      # together in your router:
      #
      #   namespace "admin" do
      #     resources :posts, :comments
      #   end
      #
      # This will create a number of routes for each of the posts and comments
      # controller. For <tt>Admin::PostsController</tt>, Rails will create:
      #
      #   GET	    /admin/posts
      #   GET	    /admin/posts/new
      #   POST	  /admin/posts
      #   GET	    /admin/posts/1
      #   GET	    /admin/posts/1/edit
      #   PUT	    /admin/posts/1
      #   DELETE  /admin/posts/1
      #
      # If you want to route /posts (without the prefix /admin) to
      # <tt>Admin::PostsController</tt>, you could use
      #
      #   scope :module => "admin" do
      #     resources :posts
      #   end
      #
      # or, for a single case
      #
      #   resources :posts, :module => "admin"
      #
      # If you want to route /admin/posts to +PostsController+
      # (without the Admin:: module prefix), you could use
      #
      #   scope "/admin" do
      #     resources :posts
      #   end
      #
      # or, for a single case
      #
      #   resources :posts, :path => "/admin/posts"
      #
      # In each of these cases, the named routes remain the same as if you did
      # not use scope. In the last case, the following paths map to
      # +PostsController+:
      #
      #   GET	    /admin/posts
      #   GET	    /admin/posts/new
      #   POST	  /admin/posts
      #   GET	    /admin/posts/1
      #   GET	    /admin/posts/1/edit
      #   PUT	    /admin/posts/1
      #   DELETE  /admin/posts/1
      module Scoping
        # Scopes a set of routes to the given default options.
        #
        # Take the following route definition as an example:
        #
        #   scope :path => ":account_id", :as => "account" do
        #     resources :projects
        #   end
        #
        # This generates helpers such as +account_projects_path+, just like +resources+ does.
        # The difference here being that the routes generated are like /:account_id/projects,
        # rather than /accounts/:account_id/projects.
        #
        # === Options
        #
        # Takes same options as <tt>Base#match</tt> and <tt>Resources#resources</tt>.
        #
        # === Examples
        #
        #   # route /posts (without the prefix /admin) to <tt>Admin::PostsController</tt>
        #   scope :module => "admin" do
        #     resources :posts
        #   end
        #
        #   # prefix the posts resource's requests with '/admin'
        #   scope :path => "/admin" do
        #     resources :posts
        #   end
        #
        #   # prefix the routing helper name: +sekret_posts_path+ instead of +posts_path+
        #   scope :as => "sekret" do
        #     resources :posts
        #   end
        def scope(*args)
          options = args.extract_options!
          options = options.dup

          options[:path] = args.first if args.first.is_a?(String)
          recover = {}

          options[:constraints] ||= {}
          unless options[:constraints].is_a?(Hash)
            block, options[:constraints] = options[:constraints], {}
          end

          scope_options.each do |option|
            if value = options.delete(option)
              recover[option] = @scope[option]
              @scope[option]  = send("merge_#{option}_scope", @scope[option], value)
            end
          end

          recover[:block] = @scope[:blocks]
          @scope[:blocks] = merge_blocks_scope(@scope[:blocks], block)

          recover[:options] = @scope[:options]
          @scope[:options]  = merge_options_scope(@scope[:options], options)

          yield
          self
        ensure
          scope_options.each do |option|
            @scope[option] = recover[option] if recover.has_key?(option)
          end

          @scope[:options] = recover[:options]
          @scope[:blocks]  = recover[:block]
        end

        # Scopes routes to a specific controller
        #
        # Example:
        #   controller "food" do
        #     match "bacon", :action => "bacon"
        #   end
        def controller(controller, options={})
          options[:controller] = controller
          scope(options) { yield }
        end

        # Scopes routes to a specific namespace. For example:
        #
        #   namespace :admin do
        #     resources :posts
        #   end
        #
        # This generates the following routes:
        #
        #       admin_posts GET    /admin/posts(.:format)          admin/posts#index
        #       admin_posts POST   /admin/posts(.:format)          admin/posts#create
        #    new_admin_post GET    /admin/posts/new(.:format)      admin/posts#new
        #   edit_admin_post GET    /admin/posts/:id/edit(.:format) admin/posts#edit
        #        admin_post GET    /admin/posts/:id(.:format)      admin/posts#show
        #        admin_post PUT    /admin/posts/:id(.:format)      admin/posts#update
        #        admin_post DELETE /admin/posts/:id(.:format)      admin/posts#destroy
        #
        # === Options
        #
        # The +:path+, +:as+, +:module+, +:shallow_path+ and +:shallow_prefix+
        # options all default to the name of the namespace.
        #
        # For options, see <tt>Base#match</tt>. For +:shallow_path+ option, see
        # <tt>Resources#resources</tt>.
        #
        # === Examples
        #
        #   # accessible through /sekret/posts rather than /admin/posts
        #   namespace :admin, :path => "sekret" do
        #     resources :posts
        #   end
        #
        #   # maps to <tt>Sekret::PostsController</tt> rather than <tt>Admin::PostsController</tt>
        #   namespace :admin, :module => "sekret" do
        #     resources :posts
        #   end
        #
        #   # generates +sekret_posts_path+ rather than +admin_posts_path+
        #   namespace :admin, :as => "sekret" do
        #     resources :posts
        #   end
        def namespace(path, options = {})
          path = path.to_s
          options = { :path => path, :as => path, :module => path,
                      :shallow_path => path, :shallow_prefix => path }.merge!(options)
          scope(options) { yield }
        end

        # === Parameter Restriction
        # Allows you to constrain the nested routes based on a set of rules.
        # For instance, in order to change the routes to allow for a dot character in the +id+ parameter:
        #
        #   constraints(:id => /\d+\.\d+/) do
        #     resources :posts
        #   end
        #
        # Now routes such as +/posts/1+ will no longer be valid, but +/posts/1.1+ will be.
        # The +id+ parameter must match the constraint passed in for this example.
        #
        # You may use this to also restrict other parameters:
        #
        #   resources :posts do
        #     constraints(:post_id => /\d+\.\d+/) do
        #       resources :comments
        #     end
        #   end
        #
        # === Restricting based on IP
        #
        # Routes can also be constrained to an IP or a certain range of IP addresses:
        #
        #   constraints(:ip => /192.168.\d+.\d+/) do
        #     resources :posts
        #   end
        #
        # Any user connecting from the 192.168.* range will be able to see this resource,
        # where as any user connecting outside of this range will be told there is no such route.
        #
        # === Dynamic request matching
        #
        # Requests to routes can be constrained based on specific criteria:
        #
        #    constraints(lambda { |req| req.env["HTTP_USER_AGENT"] =~ /iPhone/ }) do
        #      resources :iphones
        #    end
        #
        # You are able to move this logic out into a class if it is too complex for routes.
        # This class must have a +matches?+ method defined on it which either returns +true+
        # if the user should be given access to that route, or +false+ if the user should not.
        #
        #    class Iphone
        #      def self.matches?(request)
        #        request.env["HTTP_USER_AGENT"] =~ /iPhone/
        #      end
        #    end
        #
        # An expected place for this code would be +lib/constraints+.
        #
        # This class is then used like this:
        #
        #    constraints(Iphone) do
        #      resources :iphones
        #    end
        def constraints(constraints = {})
          scope(:constraints => constraints) { yield }
        end

        # Allows you to set default parameters for a route, such as this:
        #   defaults :id => 'home' do
        #     match 'scoped_pages/(:id)', :to => 'pages#show'
        #   end
        # Using this, the +:id+ parameter here will default to 'home'.
        def defaults(defaults = {})
          scope(:defaults => defaults) { yield }
        end

        private
          def scope_options #:nodoc:
            @scope_options ||= private_methods.grep(/^merge_(.+)_scope$/) { $1.to_sym }
          end

          def merge_path_scope(parent, child) #:nodoc:
            Mapper.normalize_path("#{parent}/#{child}")
          end

          def merge_shallow_path_scope(parent, child) #:nodoc:
            Mapper.normalize_path("#{parent}/#{child}")
          end

          def merge_as_scope(parent, child) #:nodoc:
            parent ? "#{parent}_#{child}" : child
          end

          def merge_shallow_prefix_scope(parent, child) #:nodoc:
            parent ? "#{parent}_#{child}" : child
          end

          def merge_module_scope(parent, child) #:nodoc:
            parent ? "#{parent}/#{child}" : child
          end

          def merge_controller_scope(parent, child) #:nodoc:
            child
          end

          def merge_path_names_scope(parent, child) #:nodoc:
            merge_options_scope(parent, child)
          end

          def merge_constraints_scope(parent, child) #:nodoc:
            merge_options_scope(parent, child)
          end

          def merge_defaults_scope(parent, child) #:nodoc:
            merge_options_scope(parent, child)
          end

          def merge_blocks_scope(parent, child) #:nodoc:
            merged = parent ? parent.dup : []
            merged << child if child
            merged
          end

          def merge_options_scope(parent, child) #:nodoc:
            (parent || {}).except(*override_keys(child)).merge(child)
          end

          def merge_shallow_scope(parent, child) #:nodoc:
            child ? true : false
          end

          def override_keys(child) #:nodoc:
            child.key?(:only) || child.key?(:except) ? [:only, :except] : []
          end
      end

      # Resource routing allows you to quickly declare all of the common routes
      # for a given resourceful controller. Instead of declaring separate routes
      # for your +index+, +show+, +new+, +edit+, +create+, +update+ and +destroy+
      # actions, a resourceful route declares them in a single line of code:
      #
      #  resources :photos
      #
      # Sometimes, you have a resource that clients always look up without
      # referencing an ID. A common example, /profile always shows the profile of
      # the currently logged in user. In this case, you can use a singular resource
      # to map /profile (rather than /profile/:id) to the show action.
      #
      #  resource :profile
      #
      # It's common to have resources that are logically children of other
      # resources:
      #
      #   resources :magazines do
      #     resources :ads
      #   end
      #
      # You may wish to organize groups of controllers under a namespace. Most
      # commonly, you might group a number of administrative controllers under
      # an +admin+ namespace. You would place these controllers under the
      # <tt>app/controllers/admin</tt> directory, and you can group them together
      # in your router:
      #
      #   namespace "admin" do
      #     resources :posts, :comments
      #   end
      #
      # By default the +:id+ parameter doesn't accept dots. If you need to
      # use dots as part of the +:id+ parameter add a constraint which
      # overrides this restriction, e.g:
      #
      #   resources :articles, :id => /[^\/]+/
      #
      # This allows any character other than a slash as part of your +:id+.
      #
      module Resources
        # CANONICAL_ACTIONS holds all actions that does not need a prefix or
        # a path appended since they fit properly in their scope level.
        VALID_ON_OPTIONS  = [:new, :collection, :member]
        RESOURCE_OPTIONS  = [:as, :controller, :path, :only, :except]
        CANONICAL_ACTIONS = %w(index create new show update destroy)

        class Resource #:nodoc:
          attr_reader :controller, :path, :options

          def initialize(entities, options = {})
            @name       = entities.to_s
            @path       = (options[:path] || @name).to_s
            @controller = (options[:controller] || @name).to_s
            @as         = options[:as]
            @options    = options
          end

          def default_actions
            [:index, :create, :new, :show, :update, :destroy, :edit]
          end

          def actions
            if only = @options[:only]
              Array(only).map(&:to_sym)
            elsif except = @options[:except]
              default_actions - Array(except).map(&:to_sym)
            else
              default_actions
            end
          end

          def name
            @as || @name
          end

          def plural
            @plural ||= name.to_s
          end

          def singular
            @singular ||= name.to_s.singularize
          end

          alias :member_name :singular

          # Checks for uncountable plurals, and appends "_index" if the plural
          # and singular form are the same.
          def collection_name
            singular == plural ? "#{plural}_index" : plural
          end

          def resource_scope
            { :controller => controller }
          end

          alias :collection_scope :path

          def member_scope
            "#{path}/:id"
          end

          def new_scope(new_path)
            "#{path}/#{new_path}"
          end

          def nested_scope
            "#{path}/:#{singular}_id"
          end

        end

        class SingletonResource < Resource #:nodoc:
          def initialize(entities, options)
            super
            @as         = nil
            @controller = (options[:controller] || plural).to_s
            @as         = options[:as]
          end

          def default_actions
            [:show, :create, :update, :destroy, :new, :edit]
          end

          def plural
            @plural ||= name.to_s.pluralize
          end

          def singular
            @singular ||= name.to_s
          end

          alias :member_name :singular
          alias :collection_name :singular

          alias :member_scope :path
          alias :nested_scope :path
        end

        def resources_path_names(options)
          @scope[:path_names].merge!(options)
        end

        # Sometimes, you have a resource that clients always look up without
        # referencing an ID. A common example, /profile always shows the
        # profile of the currently logged in user. In this case, you can use
        # a singular resource to map /profile (rather than /profile/:id) to
        # the show action:
        #
        #   resource :geocoder
        #
        # creates six different routes in your application, all mapping to
        # the +GeoCoders+ controller (note that the controller is named after
        # the plural):
        #
        #   GET     /geocoder/new
        #   POST    /geocoder
        #   GET     /geocoder
        #   GET     /geocoder/edit
        #   PUT     /geocoder
        #   DELETE  /geocoder
        #
        # === Options
        # Takes same options as +resources+.
        def resource(*resources, &block)
          options = resources.extract_options!

          if apply_common_behavior_for(:resource, resources, options, &block)
            return self
          end

          resource_scope(:resource, SingletonResource.new(resources.pop, options)) do
            yield if block_given?

            collection do
              post :create
            end if parent_resource.actions.include?(:create)

            new do
              get :new
            end if parent_resource.actions.include?(:new)

            member do
              get    :edit if parent_resource.actions.include?(:edit)
              get    :show if parent_resource.actions.include?(:show)
              put    :update if parent_resource.actions.include?(:update)
              delete :destroy if parent_resource.actions.include?(:destroy)
            end
          end

          self
        end

        # In Rails, a resourceful route provides a mapping between HTTP verbs
        # and URLs and controller actions. By convention, each action also maps
        # to particular CRUD operations in a database. A single entry in the
        # routing file, such as
        #
        #   resources :photos
        #
        # creates seven different routes in your application, all mapping to
        # the +Photos+ controller:
        #
        #   GET     /photos
        #   GET     /photos/new
        #   POST    /photos
        #   GET     /photos/:id
        #   GET     /photos/:id/edit
        #   PUT     /photos/:id
        #   DELETE  /photos/:id
        #
        # Resources can also be nested infinitely by using this block syntax:
        #
        #   resources :photos do
        #     resources :comments
        #   end
        #
        # This generates the following comments routes:
        #
        #   GET     /photos/:photo_id/comments
        #   GET     /photos/:photo_id/comments/new
        #   POST    /photos/:photo_id/comments
        #   GET     /photos/:photo_id/comments/:id
        #   GET     /photos/:photo_id/comments/:id/edit
        #   PUT     /photos/:photo_id/comments/:id
        #   DELETE  /photos/:photo_id/comments/:id
        #
        # === Options
        # Takes same options as <tt>Base#match</tt> as well as:
        #
        # [:path_names]
        #   Allows you to change the segment component of the +edit+ and +new+ actions.
        #   Actions not specified are not changed.
        #
        #     resources :posts, :path_names => { :new => "brand_new" }
        #
        #   The above example will now change /posts/new to /posts/brand_new
        #
        # [:path]
        #   Allows you to change the path prefix for the resource.
        #
        #     resources :posts, :path => 'postings'
        #
        #   The resource and all segments will now route to /postings instead of /posts
        #
        # [:only]
        #   Only generate routes for the given actions.
        #
        #     resources :cows, :only => :show
        #     resources :cows, :only => [:show, :index]
        #
        # [:except]
        #   Generate all routes except for the given actions.
        #
        #     resources :cows, :except => :show
        #     resources :cows, :except => [:show, :index]
        #
        # [:shallow]
        #   Generates shallow routes for nested resource(s). When placed on a parent resource,
        #   generates shallow routes for all nested resources.
        #
        #     resources :posts, :shallow => true do
        #       resources :comments
        #     end
        #
        #   Is the same as:
        #
        #     resources :posts do
        #       resources :comments, :except => [:show, :edit, :update, :destroy]
        #     end
        #     resources :comments, :only => [:show, :edit, :update, :destroy]
        #
        #   This allows URLs for resources that otherwise would be deeply nested such
        #   as a comment on a blog post like <tt>/posts/a-long-permalink/comments/1234</tt>
        #   to be shortened to just <tt>/comments/1234</tt>.
        #
        # [:shallow_path]
        #   Prefixes nested shallow routes with the specified path.
        #
        #     scope :shallow_path => "sekret" do
        #       resources :posts do
        #         resources :comments, :shallow => true
        #       end
        #     end
        #
        #   The +comments+ resource here will have the following routes generated for it:
        #
        #     post_comments    GET    /posts/:post_id/comments(.:format)
        #     post_comments    POST   /posts/:post_id/comments(.:format)
        #     new_post_comment GET    /posts/:post_id/comments/new(.:format)
        #     edit_comment     GET    /sekret/comments/:id/edit(.:format)
        #     comment          GET    /sekret/comments/:id(.:format)
        #     comment          PUT    /sekret/comments/:id(.:format)
        #     comment          DELETE /sekret/comments/:id(.:format)
        #
        # === Examples
        #
        #   # routes call <tt>Admin::PostsController</tt>
        #   resources :posts, :module => "admin"
        #
        #   # resource actions are at /admin/posts.
        #   resources :posts, :path => "admin/posts"
        def resources(*resources, &block)
          options = resources.extract_options!

          if apply_common_behavior_for(:resources, resources, options, &block)
            return self
          end

          resource_scope(:resources, Resource.new(resources.pop, options)) do
            yield if block_given?

            collection do
              get  :index if parent_resource.actions.include?(:index)
              post :create if parent_resource.actions.include?(:create)
            end

            new do
              get :new
            end if parent_resource.actions.include?(:new)

            member do
              get    :edit if parent_resource.actions.include?(:edit)
              get    :show if parent_resource.actions.include?(:show)
              put    :update if parent_resource.actions.include?(:update)
              delete :destroy if parent_resource.actions.include?(:destroy)
            end
          end

          self
        end

        # To add a route to the collection:
        #
        #   resources :photos do
        #     collection do
        #       get 'search'
        #     end
        #   end
        #
        # This will enable Rails to recognize paths such as <tt>/photos/search</tt>
        # with GET, and route to the search action of +PhotosController+. It will also
        # create the <tt>search_photos_url</tt> and <tt>search_photos_path</tt>
        # route helpers.
        def collection
          unless resource_scope?
            raise ArgumentError, "can't use collection outside resource(s) scope"
          end

          with_scope_level(:collection) do
            scope(parent_resource.collection_scope) do
              yield
            end
          end
        end

        # To add a member route, add a member block into the resource block:
        #
        #   resources :photos do
        #     member do
        #       get 'preview'
        #     end
        #   end
        #
        # This will recognize <tt>/photos/1/preview</tt> with GET, and route to the
        # preview action of +PhotosController+. It will also create the
        # <tt>preview_photo_url</tt> and <tt>preview_photo_path</tt> helpers.
        def member
          unless resource_scope?
            raise ArgumentError, "can't use member outside resource(s) scope"
          end

          with_scope_level(:member) do
            scope(parent_resource.member_scope) do
              yield
            end
          end
        end

        def new
          unless resource_scope?
            raise ArgumentError, "can't use new outside resource(s) scope"
          end

          with_scope_level(:new) do
            scope(parent_resource.new_scope(action_path(:new))) do
              yield
            end
          end
        end

        def nested
          unless resource_scope?
            raise ArgumentError, "can't use nested outside resource(s) scope"
          end

          with_scope_level(:nested) do
            if shallow?
              with_exclusive_scope do
                if @scope[:shallow_path].blank?
                  scope(parent_resource.nested_scope, nested_options) { yield }
                else
                  scope(@scope[:shallow_path], :as => @scope[:shallow_prefix]) do
                    scope(parent_resource.nested_scope, nested_options) { yield }
                  end
                end
              end
            else
              scope(parent_resource.nested_scope, nested_options) { yield }
            end
          end
        end

        # See ActionDispatch::Routing::Mapper::Scoping#namespace
        def namespace(path, options = {})
          if resource_scope?
            nested { super }
          else
            super
          end
        end

        def shallow
          scope(:shallow => true, :shallow_path => @scope[:path]) do
            yield
          end
        end

        def shallow?
          parent_resource.instance_of?(Resource) && @scope[:shallow]
        end

        def match(path, *rest)
          if rest.empty? && Hash === path
            options  = path
            path, to = options.find { |name, value| name.is_a?(String) }
            options[:to] = to
            options.delete(path)
            paths = [path]
          else
            options = rest.pop || {}
            paths = [path] + rest
          end

          options[:anchor] = true unless options.key?(:anchor)

          if options[:on] && !VALID_ON_OPTIONS.include?(options[:on])
            raise ArgumentError, "Unknown scope #{on.inspect} given to :on"
          end

          paths.each { |_path| decomposed_match(_path, options.dup) }
          self
        end

        def decomposed_match(path, options) # :nodoc:
          if on = options.delete(:on)
            send(on) { decomposed_match(path, options) }
          else
            case @scope[:scope_level]
            when :resources
              nested { decomposed_match(path, options) }
            when :resource
              member { decomposed_match(path, options) }
            else
              add_route(path, options)
            end
          end
        end

        def add_route(action, options) # :nodoc:
          path = path_for_action(action, options.delete(:path))

          if action.to_s =~ /^[\w\/]+$/
            options[:action] ||= action unless action.to_s.include?("/")
          else
            action = nil
          end

          if !options.fetch(:as, true)
            options.delete(:as)
          else
            options[:as] = name_for_action(options[:as], action)
          end

          mapping = Mapping.new(@set, @scope, path, options)
          app, conditions, requirements, defaults, as, anchor = mapping.to_route
          @set.add_route(app, conditions, requirements, defaults, as, anchor)
        end

        def root(options={})
          if @scope[:scope_level] == :resources
            with_scope_level(:root) do
              scope(parent_resource.path) do
                super(options)
              end
            end
          else
            super(options)
          end
        end

        protected

          def parent_resource #:nodoc:
            @scope[:scope_level_resource]
          end

          def apply_common_behavior_for(method, resources, options, &block) #:nodoc:
            if resources.length > 1
              resources.each { |r| send(method, r, options, &block) }
              return true
            end

            if resource_scope?
              nested { send(method, resources.pop, options, &block) }
              return true
            end

            options.keys.each do |k|
              (options[:constraints] ||= {})[k] = options.delete(k) if options[k].is_a?(Regexp)
            end

            scope_options = options.slice!(*RESOURCE_OPTIONS)
            unless scope_options.empty?
              scope(scope_options) do
                send(method, resources.pop, options, &block)
              end
              return true
            end

            unless action_options?(options)
              options.merge!(scope_action_options) if scope_action_options?
            end

            false
          end

          def action_options?(options) #:nodoc:
            options[:only] || options[:except]
          end

          def scope_action_options? #:nodoc:
            @scope[:options] && (@scope[:options][:only] || @scope[:options][:except])
          end

          def scope_action_options #:nodoc:
            @scope[:options].slice(:only, :except)
          end

          def resource_scope? #:nodoc:
            [:resource, :resources].include? @scope[:scope_level]
          end

          def resource_method_scope? #:nodoc:
            [:collection, :member, :new].include? @scope[:scope_level]
          end

          def with_exclusive_scope
            begin
              old_name_prefix, old_path = @scope[:as], @scope[:path]
              @scope[:as], @scope[:path] = nil, nil

              with_scope_level(:exclusive) do
                yield
              end
            ensure
              @scope[:as], @scope[:path] = old_name_prefix, old_path
            end
          end

          def with_scope_level(kind, resource = parent_resource)
            old, @scope[:scope_level] = @scope[:scope_level], kind
            old_resource, @scope[:scope_level_resource] = @scope[:scope_level_resource], resource
            yield
          ensure
            @scope[:scope_level] = old
            @scope[:scope_level_resource] = old_resource
          end

          def resource_scope(kind, resource) #:nodoc:
            with_scope_level(kind, resource) do
              scope(parent_resource.resource_scope) do
                yield
              end
            end
          end

          def nested_options #:nodoc:
            options = { :as => parent_resource.member_name }
            options[:constraints] = {
              :"#{parent_resource.singular}_id" => id_constraint
            } if id_constraint?

            options
          end

          def id_constraint? #:nodoc:
            @scope[:constraints] && @scope[:constraints][:id].is_a?(Regexp)
          end

          def id_constraint #:nodoc:
            @scope[:constraints][:id]
          end

          def canonical_action?(action, flag) #:nodoc:
            flag && resource_method_scope? && CANONICAL_ACTIONS.include?(action.to_s)
          end

          def shallow_scoping? #:nodoc:
            shallow? && @scope[:scope_level] == :member
          end

          def path_for_action(action, path) #:nodoc:
            prefix = shallow_scoping? ?
              "#{@scope[:shallow_path]}/#{parent_resource.path}/:id" : @scope[:path]

            path = if canonical_action?(action, path.blank?)
              prefix.to_s
            else
              "#{prefix}/#{action_path(action, path)}"
            end
          end

          def action_path(name, path = nil) #:nodoc:
            # Ruby 1.8 can't transform empty strings to symbols
            name = name.to_sym if name.is_a?(String) && !name.empty?
            path || @scope[:path_names][name] || name.to_s
          end

          def prefix_name_for_action(as, action) #:nodoc:
            if as
              as.to_s
            elsif !canonical_action?(action, @scope[:scope_level])
              action.to_s
            end
          end

          def name_for_action(as, action) #:nodoc:
            prefix = prefix_name_for_action(as, action)
            prefix = Mapper.normalize_name(prefix) if prefix
            name_prefix = @scope[:as]

            if parent_resource
              return nil unless as || action

              collection_name = parent_resource.collection_name
              member_name = parent_resource.member_name
            end

            name = case @scope[:scope_level]
            when :nested
              [name_prefix, prefix]
            when :collection
              [prefix, name_prefix, collection_name]
            when :new
              [prefix, :new, name_prefix, member_name]
            when :member
              [prefix, shallow_scoping? ? @scope[:shallow_prefix] : name_prefix, member_name]
            when :root
              [name_prefix, collection_name, prefix]
            else
              [name_prefix, member_name, prefix]
            end

            if candidate = name.select(&:present?).join("_").presence
              # If a name was not explicitly given, we check if it is valid
              # and return nil in case it isn't. Otherwise, we pass the invalid name
              # forward so the underlying router engine treats it and raises an exception.
              if as.nil?
                candidate unless @set.routes.find { |r| r.name == candidate } || candidate !~ /\A[_a-z]/i
              else
                candidate
              end
            end
          end
      end

      def initialize(set) #:nodoc:
        @set = set
        @scope = { :path_names => @set.resources_path_names }
      end

      include Base
      include HttpHelpers
      include Redirection
      include Scoping
      include Resources
    end
  end
end