aboutsummaryrefslogtreecommitdiffstats
path: root/actionpack/lib/action_controller/routing.rb
blob: 333be93b6f52d2f7d2fbc4d32438db1cb838e06e (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
require 'cgi'
require 'uri'

class Object
  def to_param
    to_s
  end
end

class TrueClass
  def to_param
    self
  end
end

class FalseClass
  def to_param
    self
  end
end

class NilClass
  def to_param
    self
  end
end

class Regexp #:nodoc:
  def number_of_captures
    Regexp.new("|#{source}").match('').captures.length
  end
  
  class << self
    def optionalize(pattern)
      case unoptionalize(pattern)
        when /\A(.|\(.*\))\Z/ then "#{pattern}?"
        else "(?:#{pattern})?"
      end
    end
    
    def unoptionalize(pattern)
      [/\A\(\?:(.*)\)\?\Z/, /\A(.|\(.*\))\?\Z/].each do |regexp|
        return $1 if regexp =~ pattern
      end
      return pattern
    end
  end
end

module ActionController
  # == Routing 
  #
  # The routing module provides URL rewriting in native Ruby. It's a way to
  # redirect incoming requests to controllers and actions. This replaces
  # mod_rewrite rules. Best of all Rails' Routing works with any web server. 
  # Routes are defined in routes.rb in your RAILS_ROOT/config directory.
  #
  # Consider the following route, installed by Rails when you generate your 
  # application:
  #
  #   map.connect ':controller/:action/:id'
  #
  # This route states that it expects requests to consist of a 
  # :controller followed by an :action that in turns is fed by some :id 
  #
  # Suppose you get an incoming request for <tt>/blog/edit/22</tt>, you'll end up 
  # with:
  #
  #   params = { :controller => 'blog',
  #              :action     => 'edit' 
  #              :id         => '22'
  #           }
  #
  # Think of creating routes as drawing a map for your requests. The map tells 
  # them where to go based on some predefined pattern:
  #
  #  ActionController::Routing::Routes.draw do |map|
  #   Pattern 1 tells some request to go to one place
  #   Pattern 2 tell them to go to another
  #   ...
  #  end
  #
  # The following symbols are special:
  #
  #   :controller maps to your controller name
  #   :action     maps to an action with your controllers
  #   
  # Other names simply map to a parameter as in the case of +:id+.
  #    
  # == Route priority
  #
  # Not all routes are created equally. Routes have priority defined by the 
  # order of appearance of the routes in the routes.rb file. The priority goes
  # from top to bottom. The last route in that file is at the lowest priority
  # will be applied last. If no route matches, 404 is returned.
  #
  # Within blocks, the empty pattern goes first i.e. is at the highest priority.
  # In practice this works out nicely:
  #
  #  ActionController::Routing::Routes.draw do |map| 
  #    map.with_options :controller => 'blog' do |blog|
  #      blog.show    '',  :action => 'list'
  #    end
  #    map.connect ':controller/:action/:view 
  #  end
  #
  # In this case, invoking blog controller (with an URL like '/blog/') 
  # without parameters will activate the 'list' action by default.
  #
  # == Defaults routes and default parameters
  #
  # Setting a default route is straightforward in Rails because by appending a
  # Hash to the end of your mapping you can set default parameters.
  #
  # Example:
  #  ActionController::Routing:Routes.draw do |map|
  #    map.connect ':controller/:action/:id', :controller => 'blog'
  #  end
  #
  # This sets up  +blog+ as the default controller if no other is specified. 
  # This means visiting '/' would invoke the blog controller.
  #
  # More formally, you can define defaults in a route with the +:defaults+ key.
  #   
  #   map.connect ':controller/:id/:action', :action => 'show', :defaults => { :page => 'Dashboard' }
  #
  # == Named routes
  #
  # Routes can be named with the syntax <tt>map.name_of_route options</tt>,
  # allowing for easy reference within your source as +name_of_route_url+.
  #
  # Example:
  #   # In routes.rb
  #   map.login 'login', :controller => 'accounts', :action => 'login'
  #
  #   # With render, redirect_to, tests, etc.
  #   redirect_to login_url
  #
  # Arguments can be passed as well.
  #
  #   redirect_to show_item_url(:id => 25)
  #
  # When using +with_options+, the name goes after the item passed to the block.
  #
  #  ActionController::Routing::Routes.draw do |map| 
  #    map.with_options :controller => 'blog' do |blog|
  #      blog.show    '',            :action  => 'list'
  #      blog.delete  'delete/:id',  :action  => 'delete',
  #      blog.edit    'edit/:id',    :action  => 'edit'
  #    end
  #    map.connect ':controller/:action/:view 
  #  end
  #
  # You would then use the named routes in your views:
  #
  #   link_to @article.title, show_url(:id => @article.id) 
  #
  # == Pretty URL's
  #
  # Routes can generate pretty URLs. For example:
  #
  #  map.connect 'articles/:year/:month/:day',
  #   	         :controller => 'articles', 
  #              :action     => 'find_by_date',
  #              :year       => /\d{4}/,
  #              :month => /\d{1,2}/, 
  #              :day   => /\d{1,2}/
  #  
  #  # Using the route above, the url below maps to:
  #  # params = {:year => '2005', :month => '11', :day => '06'}
  #  # http://localhost:3000/articles/2005/11/06
  #
  # == Regular Expressions and parameters
  # You can specify a reqular expression to define a format for a parameter.
  #
  #  map.geocode 'geocode/:postalcode', :controller => 'geocode',
  #              :action => 'show', :postalcode => /\d{5}(-\d{4})?/
  #
  # or  more formally:
  #
  #   map.geocode 'geocode/:postalcode', :controller => 'geocode', 
  #                      :action => 'show', 
  #                      :requirements { :postalcode => /\d{5}(-\d{4})?/ }
  #
  # == Route globbing
  #
  # Specifying <tt>*[string]</tt> as part of a rule like :
  #
  #  map.connect '*path' , :controller => 'blog' , :action => 'unrecognized?'
  #
  # will glob all remaining parts of the route that were not recognized earlier. This idiom must appear at the end of the path. The globbed values are in <tt>params[:path]</tt> in this case.  
  #
  # == Reloading routes
  #
  # You can reload routes if you feel you must:
  #
  #  Action::Controller::Routes.reload
  #
  # This will clear all named routes and reload routes.rb
  #
  # == Testing Routes
  #
  # The two main methods for testing your routes:
  #
  # === +assert_routing+
  # 
  #  def test_movie_route_properly_splits
  #   opts = {:controller => "plugin", :action => "checkout", :id => "2"}
  #   assert_routing "plugin/checkout/2", opts
  #  end
  #  
  # +assert_routing+ lets you test whether or not the route properly resolves into options.
  #
  # === +assert_recognizes+
  #
  #  def test_route_has_options
  #   opts = {:controller => "plugin", :action => "show", :id => "12"}
  #   assert_recognizes opts, "/plugins/show/12" 
  #  end
  # 
  # Note the subtle difference between the two: +assert_routing+ tests that
  # an URL fits options while +assert_recognizes+ tests that an URL
  # breaks into parameters properly.
  #
  # In tests you can simply pass the URL or named route to +get+ or +post+.
  #
  #  def send_to_jail
  #    get '/jail'
  #    assert_response :success
  #    assert_template "jail/front"
  #  end
  #
  #  def goes_to_login
  #    get login_url
  #    #...
  #  end
  #
  module Routing
    SEPARATORS = %w( / ; . , ? )

    # The root paths which may contain controller files
    mattr_accessor :controller_paths
    self.controller_paths = []

    class << self
      def with_controllers(names)
        prior_controllers = @possible_controllers
        use_controllers! names
        yield
      ensure
        use_controllers! prior_controllers
      end

      def normalize_paths(paths)
        # do the hokey-pokey of path normalization...
        paths = paths.collect do |path|
          path = path.
            gsub("//", "/").           # replace double / chars with a single
            gsub("\\\\", "\\").        # replace double \ chars with a single
            gsub(%r{(.)[\\/]$}, '\1')  # drop final / or \ if path ends with it

          # eliminate .. paths where possible
          re = %r{\w+[/\\]\.\.[/\\]}
          path.gsub!(%r{\w+[/\\]\.\.[/\\]}, "") while path.match(re)
          path
        end

        # start with longest path, first
        paths = paths.uniq.sort_by { |path| - path.length }
      end

      def possible_controllers
        unless @possible_controllers
          @possible_controllers = []
        
          paths = controller_paths.select { |path| File.directory?(path) && path != "." }

          seen_paths = Hash.new {|h, k| h[k] = true; false}
          normalize_paths(paths).each do |load_path|
            Dir["#{load_path}/**/*_controller.rb"].collect do |path|
              next if seen_paths[path.gsub(%r{^\.[/\\]}, "")]
              
              controller_name = path[(load_path.length + 1)..-1]
              
              controller_name.gsub!(/_controller\.rb\Z/, '')
              @possible_controllers << controller_name
            end
          end

          # remove duplicates
          @possible_controllers.uniq!
        end
        @possible_controllers
      end

      def use_controllers!(controller_names)
        @possible_controllers = controller_names
      end

      def controller_relative_to(controller, previous)
        if controller.nil?           then previous
        elsif controller[0] == ?/    then controller[1..-1]
        elsif %r{^(.*)/} =~ previous then "#{$1}/#{controller}"
        else controller
        end     
      end     
    end
  
    class Route #:nodoc:
      attr_accessor :segments, :requirements, :conditions
      
      def initialize
        @segments = []
        @requirements = {}
        @conditions = {}
      end
  
      # Write and compile a +generate+ method for this Route.
      def write_generation
        # Build the main body of the generation
        body = "expired = false\n#{generation_extraction}\n#{generation_structure}"
    
        # If we have conditions that must be tested first, nest the body inside an if
        body = "if #{generation_requirements}\n#{body}\nend" if generation_requirements
        args = "options, hash, expire_on = {}"

        # Nest the body inside of a def block, and then compile it.
        raw_method = method_decl = "def generate_raw(#{args})\npath = begin\n#{body}\nend\n[path, hash]\nend"
        instance_eval method_decl, "generated code (#{__FILE__}:#{__LINE__})"

        # expire_on.keys == recall.keys; in other words, the keys in the expire_on hash
        # are the same as the keys that were recalled from the previous request. Thus,
        # we can use the expire_on.keys to determine which keys ought to be used to build
        # the query string. (Never use keys from the recalled request when building the
        # query string.)

        method_decl = "def generate(#{args})\npath, hash = generate_raw(options, hash, expire_on)\nappend_query_string(path, hash, extra_keys(options))\nend"
        instance_eval method_decl, "generated code (#{__FILE__}:#{__LINE__})"

        method_decl = "def generate_extras(#{args})\npath, hash = generate_raw(options, hash, expire_on)\n[path, extra_keys(options)]\nend"
        instance_eval method_decl, "generated code (#{__FILE__}:#{__LINE__})"
        raw_method
      end
  
      # Build several lines of code that extract values from the options hash. If any
      # of the values are missing or rejected then a return will be executed.
      def generation_extraction
        segments.collect do |segment|
          segment.extraction_code
        end.compact * "\n"
      end
  
      # Produce a condition expression that will check the requirements of this route
      # upon generation.
      def generation_requirements
        requirement_conditions = requirements.collect do |key, req|
          if req.is_a? Regexp
            value_regexp = Regexp.new "\\A#{req.source}\\Z"
            "hash[:#{key}] && #{value_regexp.inspect} =~ options[:#{key}]"
          else
            "hash[:#{key}] == #{req.inspect}"
          end
        end
        requirement_conditions * ' && ' unless requirement_conditions.empty?
      end
      def generation_structure
        segments.last.string_structure segments[0..-2]
      end
  
      # Write and compile a +recognize+ method for this Route.
      def write_recognition
        # Create an if structure to extract the params from a match if it occurs.
        body = "params = parameter_shell.dup\n#{recognition_extraction * "\n"}\nparams"
        body = "if #{recognition_conditions.join(" && ")}\n#{body}\nend"
    
        # Build the method declaration and compile it
        method_decl = "def recognize(path, env={})\n#{body}\nend"
        instance_eval method_decl, "generated code (#{__FILE__}:#{__LINE__})"
        method_decl
      end

      # Plugins may override this method to add other conditions, like checks on
      # host, subdomain, and so forth. Note that changes here only affect route
      # recognition, not generation.
      def recognition_conditions
        result = ["(match = #{Regexp.new(recognition_pattern).inspect}.match(path))"]
        result << "conditions[:method] === env[:method]" if conditions[:method]
        result
      end

      # Build the regular expression pattern that will match this route.
      def recognition_pattern(wrap = true)
        pattern = ''
        segments.reverse_each do |segment|
          pattern = segment.build_pattern pattern
        end
        wrap ? ("\\A" + pattern + "\\Z") : pattern
      end
      
      # Write the code to extract the parameters from a matched route.
      def recognition_extraction
        next_capture = 1
        extraction = segments.collect do |segment|
          x = segment.match_extraction next_capture
          next_capture += Regexp.new(segment.regexp_chunk).number_of_captures
          x
        end
        extraction.compact
      end
  
      # Write the real generation implementation and then resend the message.
      def generate(options, hash, expire_on = {})
        write_generation
        generate options, hash, expire_on
      end

      def generate_extras(options, hash, expire_on = {})
        write_generation
        generate_extras options, hash, expire_on
      end

      # Generate the query string with any extra keys in the hash and append
      # it to the given path, returning the new path.
      def append_query_string(path, hash, query_keys=nil)
        return nil unless path
        query_keys ||= extra_keys(hash)
        "#{path}#{build_query_string(hash, query_keys)}"
      end

      # Determine which keys in the given hash are "extra". Extra keys are
      # those that were not used to generate a particular route. The extra
      # keys also do not include those recalled from the prior request, nor
      # do they include any keys that were implied in the route (like a
      # :controller that is required, but not explicitly used in the text of
      # the route.)
      def extra_keys(hash, recall={})
        (hash || {}).keys.map { |k| k.to_sym } - (recall || {}).keys - significant_keys
      end

      # Build a query string from the keys of the given hash. If +only_keys+
      # is given (as an array), only the keys indicated will be used to build
      # the query string. The query string will correctly build array parameter
      # values.
      def build_query_string(hash, only_keys=nil)
        elements = []

        only_keys ||= hash.keys
        
        only_keys.each do |key|
          value = hash[key] or next
          key = CGI.escape key.to_s
          if value.class == Array
            key <<  '[]'
          else    
            value = [ value ] 
          end     
          value.each { |val| elements << "#{key}=#{CGI.escape(val.to_param.to_s)}" }
        end     
        
        query_string = "?#{elements.join("&")}" unless elements.empty?
        query_string || ""
      end
  
      # Write the real recognition implementation and then resend the message.
      def recognize(path, environment={})
        write_recognition
        recognize path, environment
      end
  
      # A route's parameter shell contains parameter values that are not in the
      # route's path, but should be placed in the recognized hash.
      # 
      # For example, +{:controller => 'pages', :action => 'show'} is the shell for the route:
      # 
      #   map.connect '/page/:id', :controller => 'pages', :action => 'show', :id => /\d+/
      # 
      def parameter_shell
        @parameter_shell ||= returning({}) do |shell|
          requirements.each do |key, requirement|
            shell[key] = requirement unless requirement.is_a? Regexp
          end
        end
      end
  
      # Return an array containing all the keys that are used in this route. This
      # includes keys that appear inside the path, and keys that have requirements
      # placed upon them.
      def significant_keys
        @significant_keys ||= returning [] do |sk|
          segments.each { |segment| sk << segment.key if segment.respond_to? :key }
          sk.concat requirements.keys
          sk.uniq!
        end
      end

      # Return a hash of key/value pairs representing the keys in the route that
      # have defaults, or which are specified by non-regexp requirements.
      def defaults
        @defaults ||= returning({}) do |hash|
          segments.each do |segment|
            next unless segment.respond_to? :default
            hash[segment.key] = segment.default unless segment.default.nil?
          end
          requirements.each do |key,req|
            next if Regexp === req || req.nil?
            hash[key] = req
          end
        end
      end

      def matches_controller_and_action?(controller, action)
        unless defined? @matching_prepared
          @controller_requirement = requirement_for(:controller)
          @action_requirement = requirement_for(:action)
          @matching_prepared = true
        end

        (@controller_requirement.nil? || @controller_requirement === controller) &&
        (@action_requirement.nil? || @action_requirement === action)
      end

      def to_s
        @to_s ||= begin
          segs = segments.inject("") { |str,s| str << s.to_s }
          "%-6s %-40s %s" % [(conditions[:method] || :any).to_s.upcase, segs, requirements.inspect]
        end
      end
  
    protected
      def requirement_for(key)
        return requirements[key] if requirements.key? key
        segments.each do |segment|
          return segment.regexp if segment.respond_to?(:key) && segment.key == key
        end
        nil
      end
  
    end

    class Segment #:nodoc:
      attr_accessor :is_optional
      alias_method :optional?, :is_optional

      def initialize
        self.is_optional = false
      end

      def extraction_code
        nil
      end
  
      # Continue generating string for the prior segments.
      def continue_string_structure(prior_segments)
        if prior_segments.empty?
          interpolation_statement(prior_segments)
        else
          new_priors = prior_segments[0..-2]
          prior_segments.last.string_structure(new_priors)
        end
      end
  
      # Return a string interpolation statement for this segment and those before it.
      def interpolation_statement(prior_segments)
        chunks = prior_segments.collect { |s| s.interpolation_chunk }
        chunks << interpolation_chunk
        "\"#{chunks * ''}\"#{all_optionals_available_condition(prior_segments)}"
      end
  
      def string_structure(prior_segments)
        optional? ? continue_string_structure(prior_segments) : interpolation_statement(prior_segments)
      end
  
      # Return an if condition that is true if all the prior segments can be generated.
      # If there are no optional segments before this one, then nil is returned.
      def all_optionals_available_condition(prior_segments)
        optional_locals = prior_segments.collect { |s| s.local_name if s.optional? && s.respond_to?(:local_name) }.compact
        optional_locals.empty? ? nil : " if #{optional_locals * ' && '}"
      end
  
      # Recognition
  
      def match_extraction(next_capture)
        nil
      end
  
      # Warning
  
      # Returns true if this segment is optional? because of a default. If so, then
      # no warning will be emitted regarding this segment.
      def optionality_implied?
        false
      end
    end

    class StaticSegment < Segment #:nodoc:
      attr_accessor :value, :raw
      alias_method :raw?, :raw
  
      def initialize(value = nil)
        super()
        self.value = value
      end
  
      def interpolation_chunk
        raw? ? value : URI.escape(value)
      end
  
      def regexp_chunk
        chunk = Regexp.escape value
        optional? ? Regexp.optionalize(chunk) : chunk
      end
  
      def build_pattern(pattern)
        escaped = Regexp.escape(value)
        if optional? && ! pattern.empty?
          "(?:#{Regexp.optionalize escaped}\\Z|#{escaped}#{Regexp.unoptionalize pattern})"
        elsif optional?
          Regexp.optionalize escaped
        else
          escaped + pattern
        end
      end
  
      def to_s
        value
      end
    end

    class DividerSegment < StaticSegment #:nodoc:
      def initialize(value = nil)
        super(value)
        self.raw = true
        self.is_optional = true
      end
  
      def optionality_implied?
        true
      end
    end

    class DynamicSegment < Segment #:nodoc:
      attr_accessor :key, :default, :regexp
  
      def initialize(key = nil, options = {})
        super()
        self.key = key
        self.default = options[:default] if options.key? :default
        self.is_optional = true if options[:optional] || options.key?(:default)
      end
  
      def to_s
        ":#{key}"
      end
  
      # The local variable name that the value of this segment will be extracted to.
      def local_name
        "#{key}_value"
      end
  
      def extract_value
        "#{local_name} = hash[:#{key}] #{"|| #{default.inspect}" if default}"
      end
      def value_check
        if default # Then we know it won't be nil
          "#{value_regexp.inspect} =~ #{local_name}" if regexp
        elsif optional?
          # If we have a regexp check that the value is not given, or that it matches.
          # If we have no regexp, return nil since we do not require a condition.
          "#{local_name}.nil? || #{value_regexp.inspect} =~ #{local_name}" if regexp
        else # Then it must be present, and if we have a regexp, it must match too.
          "#{local_name} #{"&& #{value_regexp.inspect} =~ #{local_name}" if regexp}"
        end
      end
      def expiry_statement
        "expired, hash = true, options if !expired && expire_on[:#{key}]"
      end
  
      def extraction_code
        s = extract_value
        vc = value_check
        s << "\nreturn [nil,nil] unless #{vc}" if vc
        s << "\n#{expiry_statement}"
      end
  
      def interpolation_chunk
        "\#{URI.escape(#{local_name}.to_s)}"
      end
  
      def string_structure(prior_segments)
        if optional? # We have a conditional to do...
          # If we should not appear in the url, just write the code for the prior
          # segments. This occurs if our value is the default value, or, if we are
          # optional, if we have nil as our value.
          "if #{local_name} == #{default.inspect}\n" + 
            continue_string_structure(prior_segments) + 
          "\nelse\n" + # Otherwise, write the code up to here
            "#{interpolation_statement(prior_segments)}\nend"
        else
          interpolation_statement(prior_segments)
        end
      end
  
      def value_regexp
        Regexp.new "\\A#{regexp.source}\\Z" if regexp
      end
      def regexp_chunk
        regexp ? "(#{regexp.source})" : "([^#{Routing::SEPARATORS.join}]+)"
      end
  
      def build_pattern(pattern)
        chunk = regexp_chunk
        chunk = "(#{chunk})" if Regexp.new(chunk).number_of_captures == 0
        pattern = "#{chunk}#{pattern}"
        optional? ? Regexp.optionalize(pattern) : pattern
      end
      def match_extraction(next_capture)
        hangon = (default ? "|| #{default.inspect}" : "if match[#{next_capture}]")
        
        # All non code-related keys (such as :id, :slug) have to be unescaped as other CGI params
        "params[:#{key}] = match[#{next_capture}] #{hangon}"
      end
  
      def optionality_implied?
        [:action, :id].include? key
      end
  
    end

    class ControllerSegment < DynamicSegment #:nodoc:
      def regexp_chunk
        possible_names = Routing.possible_controllers.collect { |name| Regexp.escape name }
        "(?i-:(#{(regexp || Regexp.union(*possible_names)).source}))"
      end

      # Don't URI.escape the controller name, since it may have slashes in it,
      # like admin/foo.
      def interpolation_chunk
        "\#{#{local_name}.to_s}"
      end

      # Make sure controller names like Admin/Content are correctly normalized to
      # admin/content
      def extract_value
        "#{local_name} = (hash[:#{key}] #{"|| #{default.inspect}" if default}).downcase"
      end

      def match_extraction(next_capture)
        if default
          "params[:#{key}] = match[#{next_capture}] ? match[#{next_capture}].downcase : '#{default}'"
        else
          "params[:#{key}] = match[#{next_capture}].downcase if match[#{next_capture}]"
        end
      end
    end

    class PathSegment < DynamicSegment #:nodoc:
      EscapedSlash = URI.escape("/")
      def interpolation_chunk
        "\#{URI.escape(#{local_name}.to_s).gsub(#{EscapedSlash.inspect}, '/')}"
      end

      def default
        ''
      end

      def default=(path)
        raise RoutingError, "paths cannot have non-empty default values" unless path.blank?
      end

      def match_extraction(next_capture)
        "params[:#{key}] = PathSegment::Result.new_escaped((match[#{next_capture}]#{" || " + default.inspect if default}).split('/'))#{" if match[" + next_capture + "]" if !default}"
      end

      def regexp_chunk
        regexp || "(.*)"
      end

      class Result < ::Array #:nodoc:
        def to_s() join '/' end 
        def self.new_escaped(strings)
          new strings.collect {|str| URI.unescape str}
        end     
      end     
    end

    class RouteBuilder #:nodoc:
      attr_accessor :separators, :optional_separators
  
      def initialize
        self.separators = Routing::SEPARATORS
        self.optional_separators = %w( / )
      end
  
      def separator_pattern(inverted = false)
        "[#{'^' if inverted}#{Regexp.escape(separators.join)}]"
      end
  
      def interval_regexp
        Regexp.new "(.*?)(#{separators.source}|$)"
      end
  
      # Accepts a "route path" (a string defining a route), and returns the array
      # of segments that corresponds to it. Note that the segment array is only
      # partially initialized--the defaults and requirements, for instance, need
      # to be set separately, via the #assign_route_options method, and the
      # #optional? method for each segment will not be reliable until after
      # #assign_route_options is called, as well.
      def segments_for_route_path(path)
        rest, segments = path, []
    
        until rest.empty?
          segment, rest = segment_for rest
          segments << segment
        end
        segments
      end

      # A factory method that returns a new segment instance appropriate for the
      # format of the given string.
      def segment_for(string)
        segment = case string
          when /\A:(\w+)/
            key = $1.to_sym
            case key
              when :controller then ControllerSegment.new(key)
              else DynamicSegment.new key
            end
          when /\A\*(\w+)/ then PathSegment.new($1.to_sym, :optional => true)
          when /\A\?(.*?)\?/
            returning segment = StaticSegment.new($1) do
              segment.is_optional = true
            end
          when /\A(#{separator_pattern(:inverted)}+)/ then StaticSegment.new($1)
          when Regexp.new(separator_pattern) then
            returning segment = DividerSegment.new($&) do
              segment.is_optional = (optional_separators.include? $&)
            end
        end
        [segment, $~.post_match]
      end
  
      # Split the given hash of options into requirement and default hashes. The
      # segments are passed alongside in order to distinguish between default values
      # and requirements.
      def divide_route_options(segments, options)
        options = options.dup
        requirements = (options.delete(:requirements) || {}).dup
        defaults     = (options.delete(:defaults)     || {}).dup
        conditions   = (options.delete(:conditions)   || {}).dup

        path_keys = segments.collect { |segment| segment.key if segment.respond_to?(:key) }.compact
        options.each do |key, value|
          hash = (path_keys.include?(key) && ! value.is_a?(Regexp)) ? defaults : requirements
          hash[key] = value
        end
    
        [defaults, requirements, conditions]
      end
      
      # Takes a hash of defaults and a hash of requirements, and assigns them to
      # the segments. Any unused requirements (which do not correspond to a segment)
      # are returned as a hash.
      def assign_route_options(segments, defaults, requirements)
        route_requirements = {} # Requirements that do not belong to a segment
        
        segment_named = Proc.new do |key|
          segments.detect { |segment| segment.key == key if segment.respond_to?(:key) }
        end
        
        requirements.each do |key, requirement|
          segment = segment_named[key]
          if segment
            raise TypeError, "#{key}: requirements on a path segment must be regular expressions" unless requirement.is_a?(Regexp)
            if requirement.source =~ %r{\A(\\A|\^)|(\\Z|\\z|\$)\Z}
              raise ArgumentError, "Regexp anchor characters are not allowed in routing requirements: #{requirement.inspect}"
            end
            segment.regexp = requirement
          else
            route_requirements[key] = requirement
          end
        end
        
        defaults.each do |key, default|
          segment = segment_named[key]
          raise ArgumentError, "#{key}: No matching segment exists; cannot assign default" unless segment
          segment.is_optional = true
          segment.default = default.to_param if default
        end
        
        assign_default_route_options(segments)
        ensure_required_segments(segments)
        route_requirements
      end
      
      # Assign default options, such as 'index' as a default for :action. This
      # method must be run *after* user supplied requirements and defaults have
      # been applied to the segments.
      def assign_default_route_options(segments)
        segments.each do |segment|
          next unless segment.is_a? DynamicSegment
          case segment.key
            when :action
              if segment.regexp.nil? || segment.regexp.match('index').to_s == 'index'
                segment.default ||= 'index'
                segment.is_optional = true
              end
            when :id
              if segment.default.nil? && segment.regexp.nil? || segment.regexp =~ ''
                segment.is_optional = true
              end
          end
        end
      end
      
      # Makes sure that there are no optional segments that precede a required
      # segment. If any are found that precede a required segment, they are
      # made required.
      def ensure_required_segments(segments)
        allow_optional = true
        segments.reverse_each do |segment|
          allow_optional &&= segment.optional?
          if !allow_optional && segment.optional?
            unless segment.optionality_implied?
              warn "Route segment \"#{segment.to_s}\" cannot be optional because it precedes a required segment. This segment will be required."
            end
            segment.is_optional = false
          elsif allow_optional & segment.respond_to?(:default) && segment.default
            # if a segment has a default, then it is optional
            segment.is_optional = true
          end
        end
      end
      
      # Construct and return a route with the given path and options.
      def build(path, options)
        # Wrap the path with slashes
        path = "/#{path}" unless path[0] == ?/
        path = "#{path}/" unless path[-1] == ?/
    
        segments = segments_for_route_path(path)
        defaults, requirements, conditions = divide_route_options(segments, options)
        requirements = assign_route_options(segments, defaults, requirements)

        route = Route.new
        route.segments = segments
        route.requirements = requirements
        route.conditions = conditions

        if !route.significant_keys.include?(:action) && !route.requirements[:action]
          route.requirements[:action] = "index"
          route.significant_keys << :action
        end

        if !route.significant_keys.include?(:controller)
          raise ArgumentError, "Illegal route: the :controller must be specified!"
        end

        route
      end
    end

    class RouteSet #:nodoc:
      # Mapper instances are used to build routes. The object passed to the draw
      # block in config/routes.rb is a Mapper instance.
      # 
      # Mapper instances have relatively few instance methods, in order to avoid
      # clashes with named routes.
      class Mapper #:nodoc:
        def initialize(set)
          @set = set
        end
    
        # Create an unnamed route with the provided +path+ and +options+. See 
        # SomeHelpfulUrl for an introduction to routes.
        def connect(path, options = {})
          @set.add_route(path, options)
        end

        # Creates a named route called "root" for matching the root level request.
        def root(options = {})
          named_route("root", '', options)
        end

        def named_route(name, path, options = {})
          @set.add_named_route(name, path, options)
        end

        def method_missing(route_name, *args, &proc)
          super unless args.length >= 1 && proc.nil?
          @set.add_named_route(route_name, *args)
        end
      end

      # A NamedRouteCollection instance is a collection of named routes, and also
      # maintains an anonymous module that can be used to install helpers for the
      # named routes.
      class NamedRouteCollection #:nodoc:
        include Enumerable

        attr_reader :routes, :helpers

        def initialize
          clear!
        end

        def clear!
          @routes = {}
          @helpers = []
          
          @module ||= Module.new
          @module.instance_methods.each do |selector|
            @module.send :remove_method, selector
          end
        end

        def add(name, route)
          routes[name.to_sym] = route
          define_named_route_methods(name, route)
        end

        def get(name)
          routes[name.to_sym]
        end

        alias []=   add
        alias []    get
        alias clear clear!

        def each
          routes.each { |name, route| yield name, route }
          self
        end

        def names
          routes.keys
        end

        def length
          routes.length
        end

        def install(destinations = [ActionController::Base, ActionView::Base])
          Array(destinations).each { |dest| dest.send :include, @module }
        end

        private
          def url_helper_name(name, kind = :url)
            :"#{name}_#{kind}"
          end

          def hash_access_name(name, kind = :url)
            :"hash_for_#{name}_#{kind}"
          end

          def define_named_route_methods(name, route)
            {:url => {:only_path => false}, :path => {:only_path => true}}.each do |kind, opts|
              hash = route.defaults.merge(:use_route => name).merge(opts)
              define_hash_access route, name, kind, hash
              define_url_helper route, name, kind, hash
            end
          end
          
          def define_hash_access(route, name, kind, options)
            selector = hash_access_name(name, kind)
            @module.send :module_eval, <<-end_eval # We use module_eval to avoid leaks
              def #{selector}(options = nil)
                options ? #{options.inspect}.merge(options) : #{options.inspect}
              end
            end_eval
            @module.send(:protected, selector)
            helpers << selector
          end
          
          def define_url_helper(route, name, kind, options)
            selector = url_helper_name(name, kind)
            
            # The segment keys used for positional paramters
            segment_keys = route.segments.collect do |segment|
              segment.key if segment.respond_to? :key
            end.compact
            hash_access_method = hash_access_name(name, kind)
            
            @module.send :module_eval, <<-end_eval # We use module_eval to avoid leaks
              def #{selector}(*args)
                opts = if args.empty? || Hash === args.first
                  args.first || {}
                else
                  # allow ordered parameters to be associated with corresponding
                  # dynamic segments, so you can do
                  #
                  #   foo_url(bar, baz, bang)
                  #
                  # instead of
                  #
                  #   foo_url(:bar => bar, :baz => baz, :bang => bang)
                  args.zip(#{segment_keys.inspect}).inject({}) do |h, (v, k)|
                    h[k] = v
                    h
                  end
                end
                
                url_for(#{hash_access_method}(opts))
              end
            end_eval
            @module.send(:protected, selector)
            helpers << selector
          end
          
      end
  
      attr_accessor :routes, :named_routes
  
      def initialize
        self.routes = []
        self.named_routes = NamedRouteCollection.new
      end

      # Subclasses and plugins may override this method to specify a different
      # RouteBuilder instance, so that other route DSL's can be created.
      def builder
        @builder ||= RouteBuilder.new
      end

      def draw
        clear!
        yield Mapper.new(self)
        named_routes.install
      end
  
      def clear!
        routes.clear
        named_routes.clear
        @combined_regexp = nil
        @routes_by_controller = nil
      end

      def empty?
        routes.empty?
      end
  
      def load!
        Routing.use_controllers! nil # Clear the controller cache so we may discover new ones
        clear!
        load_routes!
        named_routes.install
      end

      alias reload load!

      def load_routes!
        if defined?(RAILS_ROOT) && defined?(::ActionController::Routing::Routes) && self == ::ActionController::Routing::Routes
          load File.join("#{RAILS_ROOT}/config/routes.rb")
        else
          add_route ":controller/:action/:id"
        end
      end
  
      def add_route(path, options = {})
        route = builder.build(path, options)
        routes << route
        route
      end
  
      def add_named_route(name, path, options = {})
        named_routes[name] = add_route(path, options)
      end
  
      def options_as_params(options)
        # If an explicit :controller was given, always make :action explicit
        # too, so that action expiry works as expected for things like
        #
        #   generate({:controller => 'content'}, {:controller => 'content', :action => 'show'})
        #
        # (the above is from the unit tests). In the above case, because the
        # controller was explicitly given, but no action, the action is implied to
        # be "index", not the recalled action of "show".
        #
        # great fun, eh?

        options_as_params = options[:controller] ? { :action => "index" } : {}
        options.each do |k, value|
          options_as_params[k] = value.to_param
        end
        options_as_params
      end
  
      def build_expiry(options, recall)
        recall.inject({}) do |expiry, (key, recalled_value)|
          expiry[key] = (options.key?(key) && options[key] != recalled_value)
          expiry
        end
      end

      # Generate the path indicated by the arguments, and return an array of
      # the keys that were not used to generate it.
      def extra_keys(options, recall={})
        generate_extras(options, recall).last
      end

      def generate_extras(options, recall={})
        generate(options, recall, :generate_extras)
      end

      def generate(options, recall = {}, method=:generate)
        named_route_name = options.delete(:use_route)
        if named_route_name
          named_route = named_routes[named_route_name]
          options = named_route.parameter_shell.merge(options)
        end

        options = options_as_params(options)
        expire_on = build_expiry(options, recall)

        # if the controller has changed, make sure it changes relative to the
        # current controller module, if any. In other words, if we're currently
        # on admin/get, and the new controller is 'set', the new controller
        # should really be admin/set.
        if !named_route && expire_on[:controller] && options[:controller] && options[:controller][0] != ?/
          old_parts = recall[:controller].split('/')
          new_parts = options[:controller].split('/')
          parts = old_parts[0..-(new_parts.length + 1)] + new_parts
          options[:controller] = parts.join('/')
        end

        # drop the leading '/' on the controller name
        options[:controller] = options[:controller][1..-1] if options[:controller] && options[:controller][0] == ?/
        merged = recall.merge(options)

        if named_route
          path = named_route.generate(options, merged, expire_on)
          raise RoutingError, "#{named_route_name}_url failed to generate from #{options.inspect}, expected: #{named_route.requirements.inspect}, diff: #{named_route.requirements.diff(options).inspect}" if path.nil?
          return path
        else
          merged[:action] ||= 'index'
          options[:action] ||= 'index'
  
          controller = merged[:controller]
          action = merged[:action]

          raise RoutingError, "Need controller and action!" unless controller && action
          # don't use the recalled keys when determining which routes to check
          routes = routes_by_controller[controller][action][options.keys.sort_by { |x| x.object_id }]

          routes.each do |route|
            results = route.send(method, options, merged, expire_on)
            return results if results && (!results.is_a?(Array) || results.first)
          end
        end
    
        raise RoutingError, "No route matches #{options.inspect}"
      end
  
      def recognize(request)
        params = recognize_path(request.path, extract_request_environment(request))
        request.path_parameters = params.with_indifferent_access
        "#{params[:controller].camelize}Controller".constantize
      end
  
      def recognize_path(path, environment={})
        path = URI.unescape(path)
        routes.each do |route|
          result = route.recognize(path, environment) and return result
        end
        raise RoutingError, "no route found to match #{path.inspect} with #{environment.inspect}"
      end
  
      def routes_by_controller
        @routes_by_controller ||= Hash.new do |controller_hash, controller|
          controller_hash[controller] = Hash.new do |action_hash, action|
            action_hash[action] = Hash.new do |key_hash, keys|
              key_hash[keys] = routes_for_controller_and_action_and_keys(controller, action, keys)
            end
          end
        end
      end
  
      def routes_for(options, merged, expire_on)
        raise "Need controller and action!" unless controller && action
        controller = merged[:controller]
        merged = options if expire_on[:controller]
        action = merged[:action] || 'index'
    
        routes_by_controller[controller][action][merged.keys]
      end
  
      def routes_for_controller_and_action(controller, action)
        selected = routes.select do |route|
          route.matches_controller_and_action? controller, action
        end
        (selected.length == routes.length) ? routes : selected
      end
  
      def routes_for_controller_and_action_and_keys(controller, action, keys)
        selected = routes.select do |route|
          route.matches_controller_and_action? controller, action
        end
        selected.sort_by do |route|
          (keys - route.significant_keys).length
        end
      end

      # Subclasses and plugins may override this method to extract further attributes
      # from the request, for use by route conditions and such.
      def extract_request_environment(request)
        { :method => request.method }
      end
    end

    Routes = RouteSet.new
  end
end