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
-------------------------------------------------------------------------------
--- This module contains functions that compare the behavior of two versions of
--- a package.
---
--- For this purpose, copies of these packages and a main "comparison"
--- module (with name "Compare") are generated in the temporary
--- directory `/tmp/CPM/bdiff` and then CurryCheck is executed on `Compare`.
--------------------------------------------------------------------------------

module CPM.Diff.Behavior
  ( ComparisonInfo (..)
  , getBaseTemp
  , genCurryCheckProgram
  , diffBehavior
  , preparePackageDirs
  , preparePackageAndDir
  , preparePackages
  , findFunctionsToCompare
  ) where

import System.Directory   ( createDirectory, doesDirectoryExist, getTemporaryDirectory )
import System.FilePath    ( (</>), joinPath )
import System.Environment ( getEnv, setEnv, unsetEnv )
import Data.Char          ( isAlphaNum )
import Data.List          ( intercalate, intersect, nub, splitOn, isPrefixOf
                          , isInfixOf, find, delete, (\\), nubBy )
import Data.Maybe         ( isJust, fromJust, fromMaybe, listToMaybe )
import Control.Monad

import AbstractCurry.Build
import AbstractCurry.Pretty ( defaultOptions, ppCTypeExpr, showCProg )
import AbstractCurry.Select ( publicFuncNames, funcName, functions, funcArity
                            , funcType, argTypes, typeName, types, tconsOfType
                            , tconsArgsOfType, resultType, isIOType
                            , typeOfQualType )
import AbstractCurry.Transform (updCFuncDecl)
import AbstractCurry.Types ( CurryProg (..), CFuncDecl (..), CVisibility (..)
                           , CTypeExpr (..), CPattern (..), CExpr (..)
                           , CTypeDecl (..), CConsDecl (..), CFieldDecl (..)
                           , CVarIName, QName)
import Analysis.Types       ( Analysis )
import Analysis.ProgInfo    ( ProgInfo, emptyProgInfo, combineProgInfo
                            , lookupProgInfo)
import Analysis.Termination ( productivityAnalysis, Productivity(..) )
import Analysis.TypeUsage   ( typesInValuesAnalysis )
import CASS.Server          ( analyzeGeneric )
import System.CurryPath     ( lookupModuleSource )
import Text.Pretty          ( pPrint, text, indent, vcat, (<+>), (<$$>) )

import CPM.AbstractCurry ( readAbstractCurryFromDeps, loadPathForPackage )
import CPM.Config        ( Config (curryExec) )
import CPM.Diff.API as APIDiff
import CPM.Diff.CurryComments (readComments, getFuncComment)
import CPM.Diff.Rename (prefixPackageAndDeps)
import CPM.ErrorLogger
import CPM.FileUtil ( copyDirectory, recreateDirectory, inDirectory
                    , joinSearchPath, tempDir )
import CPM.Package ( Package, Version, name, version, showVersion, packageId
                   , exportedModules, loadPackageSpec)
import CPM.PackageCache.Global as GC
import CPM.PackageCopy (resolveAndCopyDependencies)
import CPM.Repository (Repository)

-- What this module does (and how)
-- ===============================
--
-- This module compares two package versions using CurryCheck/EasyCheck. Each
-- function that can be tested (the criteria for what makes a function testable
-- are listed below), is compared using a EasyCheck property test equating both
-- versions of the function. A function is considered testable, if
--
-- - it is present in both versions of the module AND
-- - its type is unchanged between both versions of the module AND
-- - it is public AND
-- - its argument types are either all types from the Curry standard library or
--   they are the same in both versions of the module (including types in
--   package dependencies) AND
-- - the function is not marked with a do-not-checked pragma
--
-- To test a function, we have to generate a new Curry program containing a test
-- that calls both versions of the function (from the old and from the new
-- version of the package) and compares the results. Since we have to use both
-- versions of the package from within the same Curry program, we have to rename
-- their modules to be able to import both into the same program. Renaming the
-- modules also means renaming all references to the modules. And since the
-- package's dependencies can also change between different versions, we have to
-- rename all modules in all transitive dependencies as well. When renaming the
-- modules, we simply prefix them with the version of the original package (i.e.
-- the transitive dependencies get the same prefix as the original package). If
-- we have package versions 1.0.0 and 1.1.0 and our module is called
-- `Test.Functions`, then we will rename the from version 1.0.0 to
-- `V_1_0_0_Test.Functions` and the one from version 1.1.0 to
-- `V_1_1_0_Test.Functions`.
--
-- We can now import both module versions and call functions from both versions
-- in the same Curry program. We still have a problem with property tests that
-- are parameterized over a data type present in one of the packages or one of
-- its dependencies:
--
-- ```
-- test_sayHello :: SayHello.MyType -> Test.Prop.Prop
-- test_sayHello x0 = V_1_0_0_SayHello.sayHello x0 <~> V_1_1_0_SayHello.sayHello x0
-- ```
--
-- In this scenario, the parameter type cannot remain `SayHello.MyType`, since
-- we renamed both versions of the module and they each have their own version
-- of the type, `V_1_0_0_SayHello.MyType` and `V_1_1_0_SayHello.MyType`. If we
-- choose one of the renamed types, we cannot give it to the function from the
-- other version of the module as-is. So we generate translator functions that
-- can translate one version of the data type into the other, using
-- `genTranslatorFunction`.
--
-- The comments in this module refer to version A and version B of the module
-- and/or package. Which version is which (e.g. whether A is the smaller
-- version) is irrelevant.

--- Contains information from the package preparation (moving to temp directory
--- and renaming).
data ComparisonInfo = ComparisonInfo
  { infPackageA :: Package  --- A version of package
  , infPackageB :: Package  --- B version of package
  , infDirA :: String       --- Directory where renamed A version is stored
  , infDirB :: String       --- Directory where renamed B version is stored
  , infSourceDirA :: String --- Directory where original A version is stored
  , infSourceDirB :: String --- Directory where original B version is stored
  , infPrefixA :: String    --- Prefix for modules in A version
  , infPrefixB :: String    --- Prefix for modules in B version
  , infModMapA :: [(String, String)] --- Map from old to new module names, ver A
  , infModMapB :: [(String, String)] --- Map from old to new module names, ver B
  }

--- Create temporary directory for the behavior diff.
createBaseTemp :: IO String
createBaseTemp = do
  tmpDir <- getTemporaryDirectory
  let tmp = tmpDir </> "CPM" </> "bdiff"
  recreateDirectory tmp
  return tmp

--- Get temporary directory for the behavior diff.
getBaseTemp :: IO String
getBaseTemp = do
  tmpDir <- getTemporaryDirectory
  return $ tmpDir </> "CPM" </> "bdiff"

--- This message is printed before CurryCheck is executed.
infoText :: String
infoText = unlines
  [ "Running behavior diff where the raw output of CurryCheck is shown."
  , "The test operations are named after the operations they compare."
  , "If a test fails, their implementations semantically differ." ]

--- Compare the behavior of two package versions using CurryCheck.
---
--- @param cfg - the CPM configuration
--- @param repo - the central package index
--- @param gc - the global package cache
--- @param info - the comparison info obtained from preparePackageDirs
--- @param groundequiv - test ground equivalence only?
--- @param useanalysis - use program analysis to filter non-term. operations?
--- @param mods - a list of modules to compare
diffBehavior :: Config
             -> Repository
             -> GC.GlobalCache
             -> ComparisonInfo
             -> Bool
             -> Bool
             -> Maybe [String]
             -> ErrorLogger ()
diffBehavior cfg repo gc info groundequiv useanalysis cmods = do
  baseTmp <- liftIOEL getBaseTemp
  (acyCache, loadpath, funcs, removed) <-
    findFunctionsToCompare cfg repo gc (infSourceDirA info) (infSourceDirB info)
                          useanalysis cmods
  let filteredFuncs =
        maybe funcs
              (\mods -> filter ((`elem` mods) . fst . funcName . snd) funcs)
              cmods
      filteredNames = map snd filteredFuncs
  logDebug ("Filtered operations to be checked: " ++
                  showFuncNames filteredNames)
  case funcs of
    [] -> liftIOEL (printRemoved removed >> return ())
    _  -> do
      liftIOEL $ do
         putStrLn infoText
         printRemoved removed
         putStrLn $
           "Comparing operations " ++ showFuncNames filteredNames ++ "\n"
      genCurryCheckProgram cfg repo gc filteredFuncs info groundequiv
                            acyCache loadpath
      callCurryCheck cfg info baseTmp
 where
   printRemoved removed =
     if null removed then return ()
                     else putStrLn (renderRemoved removed) >> putStrLn ""

--- Renders the list of functions that were excluded from the comparison along
--- with reasons for their exclusion.
renderRemoved :: [(CFuncDecl, FilterReason)] -> String
renderRemoved rs =
  pPrint $ text "The following operations are not compared:" <$$>
  vcat (map renderReason rs)
 where
  renderReason (f, r) = indent 4 $ (text $ showQName (funcName f)) <+>
                                   text "-" <+> reasonText r
  reasonText NoReason = text "Unknown reason"
  reasonText Diffing = text "Different function types or function missing"
  reasonText NonMatchingTypes = text "Some types inside the function type differ"
  reasonText HighArity = text "Arity too high"
  reasonText IOAction  = text "IO action"
  reasonText NoCompare = text "Marked NOCOMPARE"
  reasonText FuncArg   = text "Takes functions as arguments"
  reasonText NonTerm   = text "Possibly non-terminating"

--- Runs CurryCheck on the generated program.
callCurryCheck :: Config -> ComparisonInfo -> String -> ErrorLogger ()
callCurryCheck cfg info baseTmp = do
  oldPath <- liftIOEL $ getEnv "CURRYPATH"
  let currybin  = curryExec cfg
  let currypath = infDirA info ++ ":" ++ infDirB info
  liftIOEL $ setEnv "CURRYPATH" currypath
  logDebug $ "Run `curry check Compare' in `" ++ baseTmp ++ "' with"
  logDebug $ "CURRYPATH=" ++ currypath
  ecode <- inDirectoryEL baseTmp $ showExecCmd (currybin ++ " check Compare")
  liftIOEL $ setEnv "CURRYPATH" oldPath
  logDebug "CurryCheck finished"
  if ecode==0
    then return ()
    else logError "CurryCheck detected behavior error!"

--- Generates a program containing CurryCheck tests that will compare the
--- behavior of the given functions. The program will be written to the
--- `Compare.curry` file in the behavior diff temp directory.
genCurryCheckProgram :: Config
                     -> Repository
                     -> GC.GlobalCache
                     -> [(Bool,CFuncDecl)]
                     -> ComparisonInfo
                     -> Bool
                     -> ACYCache -> [String]
                     -> ErrorLogger ()
genCurryCheckProgram cfg repo gc prodfuncs info groundequiv acyCache loadpath = do
  baseTmp <- liftIOEL $ getBaseTemp
  let translatorGenerator = uncurry $ genTranslatorFunction cfg repo gc info
  (_, transMap) <- foldM translatorGenerator (acyCache, emptyTrans)
                     translateTypes
  let (limittypes,testFunctions) =
         unzip (map (genTestFunction info groundequiv transMap) prodfuncs)
  let transFunctions = transFuncs transMap
  let limittconss    = nub (concatMap tconsOfType (concat limittypes))
  let limittcmods    = nub (map fst limittconss)
  -- get the declarations of all types which require limit functions:
  (_, limittdecls) <- foldM addLimitType (acyCache,[]) limittconss
  typeinfos <- analyzeModules "recursive type" typesInValuesAnalysis loadpath
                              limittcmods
  let limitFunctions = concatMap (genLimitFunction typeinfos) limittdecls
      prog = simpleCurryProg "Compare" imports []
               (concat testFunctions ++ transFunctions ++
                (if groundequiv then limitFunctions else []))
               []
  let prodops = map snd (filter fst prodfuncs)
  liftIOEL $ unless (null prodops) $ putStrLn $
    "Productive operations (currently not fully supported for all types):\n" ++
    showFuncNames prodops ++ "\n"
  liftIOEL $ writeFile (baseTmp </> "Compare.curry")
            (progcmts ++ "\n" ++ showCProg prog ++ "\n")
  return ()
 where
  addLimitType (acy,tdecls) qn =
    findTypeInModules cfg repo gc info acy qn >>= \ (acy',tdecl) ->
    return (acy', tdecl:tdecls)

  progcmts = unlines $ map ("-- "++)
    [ "This file contains properties to compare packages"
    , packageId (infPackageA info) ++
      " and " ++ packageId (infPackageB info) ++ "."
    , ""
    , "It should be processed by 'curry check Compare' with setting"
    , "export CURRYPATH=" ++ infDirA info ++ ":" ++ infDirB info
    ]

  allReferencedTypes =
    nub ((concat $ map (argTypes . typeOfQualType . funcType . snd) prodfuncs)
         ++ map (resultType . typeOfQualType . funcType . snd) prodfuncs)
  translateTypes = filter (needToTranslatePart info) allReferencedTypes

  mods = map (fst . funcName . snd) prodfuncs
  modsA = map (\mod -> (infPrefixA info) ++ "_" ++ mod) mods
  modsB = map (\mod -> (infPrefixB info) ++ "_" ++ mod) mods
  imports = modsA ++ modsB ++ ["Test.Prop"]

--- Generates functions to limit the result depth of values of
--- the given data type.
genLimitFunction :: ProgInfo [QName] -> CTypeDecl -> [CFuncDecl]
genLimitFunction typeinfos tdecl = case tdecl of
  CType tc _ tvs consdecls _ ->
    [stCmtFunc ("Limit operation for type " ++ tcname)
      (transCTCon2Limit tc) (length tvs + 2) Private
      (foldr (~>) (limitFunType (applyTC tc (map CTVar tvs)))
             (map (limitFunType . CTVar) tvs))
      (cdecls2rules tc tvs consdecls)]
  _ -> error $ "Cannot generate limit function for type " ++ tcname
 where
  tcname = showQName (typeName tdecl)

  limitFunType texp = baseType ("Nat","Nat") ~> texp ~> texp

  var2limitfun (i,ti) = (i,"lf"++ti)

  cdecls2rules tc tvs cdecls =
    if null cdecls
      then [simpleRule [CPVar (0,"_"), CPVar (1,"x")] (CVar (1,"x"))]
      else concatMap (cdecl2rules tvs (nullaryConsOf cdecls)) cdecls
   where
    nullaryConsOf [] = error $ "Cannot generate limit operation for types " ++
                               "without nullary constructors: " ++ showQName tc
    nullaryConsOf (CCons qc _ []   : _ ) = qc
    nullaryConsOf (CCons _ _ (_:_) : cs) = nullaryConsOf cs
    nullaryConsOf (CRecord _ _ _   : cs) = nullaryConsOf cs

  cdecl2rules tvs tnull (CCons qc _ texps) =
    let lfunargs = map (CPVar . var2limitfun) tvs
        argvars  = map (\i -> (i,"x"++show i)) [0 .. length texps - 1]
        isRecursive t = t `elem` fromMaybe [] (lookupProgInfo t typeinfos)
        isRecursiveCons = any isRecursive (concatMap tconsOfType texps)
    in
    (if isRecursiveCons
     then [simpleRule (lfunargs ++ [CPComb ("Nat","Z") [],
                                    CPComb qc (map CPVar argvars)])
                      (applyF tnull [])]
     else []) ++
    [simpleRule
      (lfunargs ++ [if isRecursiveCons then CPComb ("Nat","S") [CPVar (0,"n")]
                                       else CPVar (0,"n"),
                    CPComb qc (map CPVar argvars)])
      (applyF qc (map (\ (te,v) -> applyE (type2LimOp te)
                                 [CVar (0,"n"), CVar v]) (zip texps argvars)))]
  cdecl2rules _ _ (CRecord qc _ _) =
    error $ "Cannot generate limit operation for record field " ++ showQName qc

  type2LimOp texp = case texp of
    CTVar tv -> CVar (var2limitfun tv)
    CFuncType _ _ ->
      error "type2LimOp: cannot generate limit operation for function type"
    _ -> maybe (error "type2LimOp: cannot generate limit operation for type application")
               (\ (tc,ts) -> applyF (transCTCon2Limit tc) (map type2LimOp ts))
               (tconsArgsOfType texp)


--- Generates a test function to compare two versions of the given function.
--- If the argument and result types must be transformed between types
--- of the two different version, also auxiliary operations are generated
--- for the equivalence test.
--- If the function is productive, we also return the result type of
--- the function in order to generate "limit" functions for this type.
genTestFunction :: ComparisonInfo -> Bool -> TransMap -> (Bool, CFuncDecl)
                -> ([CTypeExpr], [CFuncDecl])
genTestFunction info groundequiv tm (isprod,f) =
 (if isprod && groundequiv then [newResultTypeA] else [],
  if groundequiv
    then
      [stCmtFunc ("Check ground equivalence of operation " ++ fmod ++ "." ++
                  fname ++ if isprod then " up to a depth limit" else "")
        (modName, testName ++ "_GroundEquiv") (realArity f) Private newType
        [if isprod
           then let limitvar = (100,"limit") in
                simpleRule (if isprod then CPVar limitvar : vars else vars)
                  (applyF (easyCheckMod "<~>")
                    [applyE (type2LimitFunc newResultTypeA)
                            [CVar limitvar, callA],
                     applyE (type2LimitFunc newResultTypeA)
                            [CVar limitvar, callB]])
           else simpleRule vars (applyF (easyCheckMod "<~>") [callA, callB])]
      ]
    else
      [stFunc testName1 (realArity f) Private
              (replaceResultType newType newResultTypeB)
              [simpleRule vars callA]
      ,stFunc testName2 (realArity f) Private
              (replaceResultType newType newResultTypeB)
              [simpleRule vars callB]
      ,stCmtFunc ("Check equivalence of operation " ++ fmod ++ "." ++ fname)
        (modName, testName ++ "_Equivalent") 0 Private
        (baseType (easyCheckMod "Prop"))
        [simpleRule [] (applyF (easyCheckMod "<=>")
                                  [constF testName1, constF testName2])]]
 )
 where
  (fmod,fname) = funcName f
  modName = "Compare"
  both fun (a, b) = (fun a, fun b)
  testName = "test_" ++
       combineTuple (both (replace' '.' '_') $ (fmod, encodeCurryId fname)) "_"
  testName1 = (modName, testName++"_1")
  testName2 = (modName, testName++"_2")
  vars = pVars (realArity f)
  modA = infPrefixA info ++ "_" ++ fmod
  modB = infPrefixB info ++ "_" ++ fmod
  instantiatedFunc = instantiateBool $ typeOfQualType $ funcType f

  newResultTypeA = mapTypes (infModMapA info)
                    (instantiateBool (resultType (typeOfQualType (funcType f))))

  newResultTypeB = mapTypes (infModMapB info)
                    (instantiateBool (resultType (typeOfQualType (funcType f))))

  newType = let ftype = mapTypes (infModMapA info) $ genTestFuncType f
            in if isprod then baseType ("Nat","Nat") ~> ftype
                         else ftype

  returnTransform = case findTrans tm (resultType $ instantiatedFunc) of
    Nothing -> id
    Just tr -> \t -> applyF (modName, tr) [t]

  -- Since we use the data types from the A version in type of the generated
  -- test function, we transform the parameters in the call of the B version of
  -- the tested function using the translator functions from the TransMap. As we
  -- already have translator functions from data type version A to B, we will
  -- translate the result of the A function using these functions. The
  -- comparison of function results will thus be done on the B version of the
  -- types, while the parameter generation will be done on the A version.
  callA = returnTransform $ applyF (modA, fname)
                                   $ map (\(CPVar v) -> CVar v) vars
  callB = applyF (modB, fname) $ map transformedVar
                               $ zip (argTypes $ instantiatedFunc) vars

  transformedVar (texp,exp) = case (texp,exp) of
    (CTVar _, CPVar v) -> CVar v
    (CFuncType _ _, CPVar v) -> CVar v
    (_, CPVar v) ->
      maybe (CVar v)
            (\_ -> case findTrans tm texp of
                     Just  n -> applyF (modName, n) [CVar v]
                     Nothing -> CVar v)
            (tconsArgsOfType texp)
    _ -> error "CPM.Diff.Behavior.transformedVar: This case should be impossible to reach"

-- encode a Curry identifier into an alphanum form:
encodeCurryId :: String -> String
encodeCurryId [] = []
encodeCurryId (c:cs)
  | isAlphaNum c || c == '_' = c : encodeCurryId cs
  | otherwise =  let oc = ord c
    in int2hex (oc `div` 16) : int2hex (oc `mod` 16) : encodeCurryId cs
 where
   int2hex i = if i<10 then chr (ord '0' + i)
                       else chr (ord 'A' + i - 10)

--- Checks if any part of the given type needs to be translated using a
--- translator function.
needToTranslatePart :: ComparisonInfo -> CTypeExpr -> Bool
needToTranslatePart _    (CTVar _) = False
needToTranslatePart info (CFuncType e1 e2) =
  needToTranslatePart info e1 || needToTranslatePart info e2
needToTranslatePart info (CTApply e1 e2) =
  needToTranslatePart info e1 || needToTranslatePart info e2
needToTranslatePart info (CTCons n) =
  isMappedType info n

--- Checks if the module of the given type is one of the mapped modules, i.e.
--- one that is present in two versions.
isMappedType :: ComparisonInfo -> (String, String) -> Bool
isMappedType info (mod, _) = isJust $ lookup mod (infModMapA info)

--- The TransMap contains a map of type expressions to translator function
--- names, as well as the next translator function number and a list of the
--- translator functions themselves.
data TransMap = TransMap [(CTypeExpr, String)] Int [CFuncDecl]

--- An empty TransMap.
emptyTrans :: TransMap
emptyTrans = TransMap [] 0 []

--- Adds an entry to the TransMap. Note that this does not add the
--- function itself. Use `addFunc` to add the function.
addEntry :: TransMap -> CTypeExpr -> (TransMap, String)
addEntry (TransMap m n fs) e =
  (TransMap ((e, "tt_" ++ show n) : m) (n + 1) fs, "tt_" ++ show n)

--- Adds a translator function to the list of functions in the TransMap.
addFunc :: TransMap -> CFuncDecl -> TransMap
addFunc (TransMap m n fs) f = TransMap m n (f:fs)

--- Finds the name of the translator function for a type expression, if it
--- exists.
findTrans :: TransMap -> CTypeExpr -> Maybe String
findTrans (TransMap m _ _) e = lookup e m

--- Gets all translator functions from a TransMap.
transFuncs :: TransMap -> [CFuncDecl]
transFuncs (TransMap _ _ fs) = fs

--- Get type declarations for some types that are namespaced to the Prelude
--- module, but whose type declarations are not actually contained in the
--- Prelude module.
predefinedType :: (String, String) -> Maybe CTypeDecl
predefinedType x = case x of
  ("Prelude", "[]") -> Just $ CType ("Prelude", "[]") Public [(0, "a")] [
      simpleCCons ("Prelude", "[]") Public []
    , simpleCCons ("Prelude", ":") Public
                  [CTVar (0, "a"), listType (CTVar (0, "a"))]] []
  ("Prelude", "(,)") -> Just $ CType ("Prelude", "(,)") Public [(0, "a"), (1, "b")] [
    simpleCCons ("Prelude", "(,)") Public [CTVar (0, "a"), CTVar (1, "b")]] []
  ("Prelude", "(,,)") -> Just $ CType ("Prelude", "(,,)") Public [(0, "a"), (1, "b"), (2, "c")] [
    simpleCCons ("Prelude", "(,,)") Public [CTVar (0, "a"), CTVar (1, "b"), CTVar (2, "c")]] []
  ("Prelude", "(,,,)") -> Just $ CType ("Prelude", "(,,,)") Public [(0, "a"), (1, "b"), (2, "c"), (3, "d")] [
    simpleCCons ("Prelude", "(,,,)") Public [CTVar (0, "a"), CTVar (1, "b"), CTVar (2, "c"), CTVar (3, "d")]] []
  _ -> Nothing

--- The ACYCache caches the AbstractCurry representations of Curry modules,
--- specific to the directory it is stored in (to support multiple versions of a
--- module).
data ACYCache = ACYCache [(String, [(String, CurryProg)])]

--- An empty ACYCache.
emptyACYCache :: ACYCache
emptyACYCache = ACYCache []

--- Finds a module inside an ACYCache, regardless of its directory.
findModule :: String -> ACYCache -> Maybe CurryProg
findModule mod (ACYCache ps) = case lookup mod ps of
  Nothing -> Nothing
  Just ms -> listToMaybe $ map snd ms

--- Finds a module inside the ACYCache that was read from a specific directory.
findModuleDir :: String -> String -> ACYCache -> Maybe CurryProg
findModuleDir dir mod (ACYCache ps) = case lookup mod ps of
  Nothing -> Nothing
  Just ms -> lookup dir ms

--- Adds a module to the ACYCache without a directory.
addModule :: String -> CurryProg -> ACYCache -> ACYCache
addModule mod p (ACYCache ps) = case lookup mod ps of
  Just  _ -> ACYCache ps
  Nothing -> ACYCache $ (mod, [("", p)]):ps

--- Adds a module to the ACYCache with a directory.
addModuleDir :: String -> String -> CurryProg -> ACYCache -> ACYCache
addModuleDir dir mod p (ACYCache ps) = case lookup mod ps of
  Just ms -> case lookup dir ms of
    Just  _ -> ACYCache ps
    Nothing -> ACYCache $ (mod, (dir, p):ms):(delete (mod, ms) ps)
  Nothing -> ACYCache $ (mod, [(dir, p)]):ps

--- Generate a translator function for a type expression. Expects a CTCons.
---
--- @param cfg current CPM configuration
--- @param repo package repository
--- @param gc the global package cache
--- @param info information about the current comparison
--- @param tm the map of translator functions
--- @param e the type expression to generate a translator for
genTranslatorFunction :: Config
                      -> Repository
                      -> GC.GlobalCache
                      -> ComparisonInfo
                      -> ACYCache
                      -> TransMap
                      -> CTypeExpr
                      -> ErrorLogger (ACYCache, TransMap)
genTranslatorFunction cfg repo gc info acy tm texp =
-- TODO: generate also translation functions for functional types.
-- This requires type translator in both directions but currently
-- we generate only one direction.
-- For instance, to translate a function A->B into A'->B':
-- (A->B)2(A'->B') f = \x -> B2B' (f (A'2A x))
 let (mod, n) = maybe
        (error $ "CPM.Diff.Behavior.genTranslatorFunction: " ++
                 "cannot generate type translation function for type:\n" ++
                 pPrint (ppCTypeExpr defaultOptions texp))
        fst
        (tconsArgsOfType texp)
 in
  -- Don't generate another translator if there already is one for the current
  -- type.
  if isJust $ findTrans tm t'
    then return (acy, tm)
    else findTypeInModules cfg repo gc info acy (mod,n) >>=
  -- We want to work on the constructors with all type variables instantiated
  -- with the types from the type that we're supposed to build a translator for.
  \(acy', typeDecl) -> (return $ instantiate typeDecl t') >>=
  -- Add the entry at this point to make sure that it's available when we
  -- generate the other translators and if we need to call it recursively later
  -- on.
  \instTypeDecl -> (return $ addEntry tm t') >>=
  \(tm', name) -> foldM (uncurry $ genTranslatorFunction cfg repo gc info)
                         (acy', tm') (transExprs instTypeDecl) >>=
  \(acy'', tm'') ->
    let
      aType = prefixMappedTypes (infPrefixA info) t'
      bType = prefixMappedTypes (infPrefixB info) t'
      fType = CFuncType aType bType
      fName = ("Compare", name)
      mapIfNeeded modMap m =
        if isMappedType info (m, "") then fromJust $ lookup m modMap
                                     else m
      mapIfNeededA = mapIfNeeded (infModMapA info)
      mapIfNeededB = mapIfNeeded (infModMapB info)

      transformer (i,te) = case te of
        CTVar _ -> CVar (i, "x" ++ show i)
        CFuncType _ _ -> CVar (i, "x" ++ show i)
        _ -> case findTrans tm'' te of
               Nothing -> CVar (i, "x" ++ show i)
               Just tn -> applyF ("Compare", tn) [CVar (i, "x" ++ show i)]

      ruleForCons (CCons (m, cn) _ es) = simpleRule [pattern] call
       where
        pattern = CPComb (mapIfNeededA m, cn) (pVars (length es))
        -- Apply constructor from B, calling translator functions if neccessary.
        call = applyF (mapIfNeededB m, cn) $ map transformer
                                           $ zip (take (length es) [0..]) es
      ruleForCons (CRecord (m, cn) _ fs) = simpleRule [pattern] call
       where
        pattern = CPComb (mapIfNeededA m, cn) (pVars (length fs))
        call = applyF (mapIfNeededB m, cn) $ map transformer
               $ zip (take (length fs) [0..]) (map (\(CField _ _ es) -> es) fs)

      synRule e = simpleRule [CPVar (0, "x0")] call
       where
        call = transformer (0, e)
    in case instTypeDecl of
      CType _ _ _ cs _ -> return $
        (acy'', addFunc tm'' (stFunc fName 1 Public fType (map ruleForCons cs)))
      CTypeSyn _ _ _ e -> return $
        (acy'', addFunc tm'' (stFunc fName 1 Public fType [synRule e]))
      CNewType _ _ _ c _ -> return $
        (acy'', addFunc tm'' (stFunc fName 1 Public fType [ruleForCons c]))
 where
  -- Since our test functions always use polymorphic types instantiated to Bool,
  -- we generate our translator functions for Bool-instantiated types as well.
  t' = instantiateBool texp

  -- Finds all type expressions in the instantiated constructors that contain
  -- types that need to be translated.
  transExprs cs = filter (needToTranslatePart info) $ nub $ extractExprs cs
  extractExprs (CType _ _ _ es _) = concat $ map extractExprsCons es
  extractExprs (CTypeSyn _ _ _ e) = [e]
  extractExprs (CNewType _ _ _ c _) = extractExprsCons c
  extractExprsCons (CCons _ _ es) = es
  extractExprsCons (CRecord _ _ fs) = map (\(CField _ _ es) -> es) fs

  -- Recursively prefixes those types which are present in two versions.
  prefixMappedTypes pre (CTCons (mod', n')) =
    if isMappedType info (mod', n')
      then CTCons (pre ++ "_" ++ mod', n')
      else CTCons (mod', n')
  prefixMappedTypes _   (CTVar v) = CTVar v
  prefixMappedTypes pre (CFuncType e1 e2) =
    CFuncType (prefixMappedTypes pre e1) (prefixMappedTypes pre e2)
  prefixMappedTypes pre (CTApply e1 e2) =
    CTApply (prefixMappedTypes pre e1) (prefixMappedTypes pre e2)

-- Finds the type declaration for a given qualified type constructor.
-- If the module is not in the ACYCache, it is read and added to the cache.
findTypeInModules :: Config -> Repository -> GC.GlobalCache -> ComparisonInfo
                  -> ACYCache -> QName -> ErrorLogger (ACYCache, CTypeDecl)
findTypeInModules cfg repo gc info acy (mod,n) =
  case predefinedType (mod, n) of
    Just ty -> return (acy, ty)
    Nothing ->
     (case findModule mod acy of
       Just  p -> return $ p
       Nothing -> resolveAndCopyDependencies cfg repo gc
                                          (infSourceDirA info) >>= \deps ->
                  readAbstractCurryFromDeps (infSourceDirA info) deps mod >>=
                                                       return) >>= \prog ->
                  case filter ((== n) . snd . typeName) (types prog) of
                    [] -> fail $ "No type defined '" ++ n ++ "' in module '"
                                   ++ mod ++ "'"
                    (x:_) -> return (addModule mod prog acy, x)

--- Replaces type variables with their expression in the map if there is one,
--- leaves them alone otherwise.
maybeReplaceVar :: [(CVarIName, CTypeExpr)] -> CTypeExpr -> CTypeExpr
maybeReplaceVar vm (CTVar v) = case lookup v vm of
  Nothing -> CTVar v
  Just e' -> e'
maybeReplaceVar _  (CTCons n) = CTCons n
maybeReplaceVar vm (CFuncType e1 e2) =
  CFuncType (maybeReplaceVar vm e1) (maybeReplaceVar vm e2)
maybeReplaceVar vm (CTApply e1 e2) =
  CTApply (maybeReplaceVar vm e1) (maybeReplaceVar vm e2)

--- Instantiates all constructors of a type declaration with the types from a
--- constructor type expression. Type variables that are not used in the
--- constructor referenced by the type expression remain as they are.
instantiate :: CTypeDecl -> CTypeExpr -> CTypeDecl
instantiate tdecl texp = case texp of
  CTVar _ -> error "CPM.Diff.Behavior.instantiate: Cannot instantiate CTVar"
  CFuncType _ _ -> error "CPM.Diff.Behavior.instantiate: Cannot instantiate CFuncType"
  _ -> maybe (error "CPM.Diff.Behavior.instantiate: Cannot instantiate CTApply")
             (\ (_,texps) -> instantiate' tdecl texps)
             (tconsArgsOfType texp)
 where
  instantiate' (CType n v vs cs d) es = CType n v vs (map cons cs) d
   where
    varMap = zip vs es
    cons (CCons n' v' es') =
          CCons n' v' $ map (maybeReplaceVar varMap) es'
    cons (CRecord n' v' fs') =
          CRecord n' v' $ map maybeReplaceField fs'
    maybeReplaceField (CField n'' v'' e) =
      CField n'' v'' $ maybeReplaceVar varMap e
  instantiate' (CTypeSyn n v vs e) es =
      CTypeSyn n v vs $ maybeReplaceVar varMap e
   where
    varMap = zip vs es
  instantiate' (CNewType n v vs c d) es = CNewType n v vs (cons c) d
   where
    varMap = zip vs es
    cons (CCons n' v' es') =
          CCons n' v' $ map (maybeReplaceVar varMap) es'
    cons (CRecord n' v' fs') =
          CRecord n' v' $ map maybeReplaceField fs'
    maybeReplaceField (CField n'' v'' e) =
      CField n'' v'' $ maybeReplaceVar varMap e


--- Recursively transforms the module names of all type constructors in a
--- type expression into new module names according to a mapping of
--- module names.
mapTypes :: [(String,String)] -> CTypeExpr -> CTypeExpr
mapTypes mmap (CFuncType a b) = CFuncType (mapTypes mmap a) (mapTypes mmap b)
mapTypes mmap (CTApply a b)   = CTApply (mapTypes mmap a) (mapTypes mmap b)
mapTypes _    v@(CTVar _)     = v
mapTypes mmap (CTCons (m, n)) =
  case lookup m mmap of
    Nothing -> CTCons (m, n)
    Just m' -> CTCons (m', n)

realArity :: CFuncDecl -> Int
realArity (CFunc _ _ _ t _) = arityOfType (typeOfQualType t)
realArity (CmtFunc _ _ _ _ t _) = arityOfType (typeOfQualType t)

arityOfType :: CTypeExpr -> Int
arityOfType (CFuncType _ b) = 1 + arityOfType b
arityOfType (CTVar _) = 0
arityOfType (CTCons _) = 0
arityOfType (CTApply _ _) = 0

-- Wrap an expression of a given type with a call to a corresponding
-- depth-limit function:
type2LimitFunc :: CTypeExpr -> CExpr
type2LimitFunc texp = case texp of
  CTVar _ ->
    error "type2LimitFunc: cannot generate limit operation for type variable"
  CFuncType _ _ ->
    error "type2LimitFunc: cannot generate limit operation for function type"
  _ -> maybe
        (error
        "type2LimitFunc: cannot generate limit operation for type application")
        (\ (tc,ts) -> applyF (transCTCon2Limit tc) (map type2LimitFunc ts))
        (tconsArgsOfType texp)

-- Translate a type constructor name to the name of the corresponding limit
-- operation:
transCTCon2Limit :: QName -> QName
transCTCon2Limit (_,tcn) = ("Compare", "limit" ++ trans tcn)
 where
  trans n | n=="[]"             = "List"
          | n=="()"             = "Unit"
          | "(," `isPrefixOf` n = "Tuple" ++ show (length n - 1)
          | otherwise           = n

--- Qualify a name by `Test.Prop` module:
easyCheckMod :: String -> QName
easyCheckMod n = ("Test.Prop", n)

--- Generates a function type for the test function by replacing the result
--- type with `Test.Prop.Prop`. Also instantiates polymorphic types to
--- Bool.
genTestFuncType :: CFuncDecl -> CTypeExpr
genTestFuncType f = replaceResultType t (baseType (easyCheckMod "Prop"))
  where t = instantiateBool $ typeOfQualType $ funcType f

--- Instantiates all type variables in a type expression to `Prelude.Bool`.
instantiateBool :: CTypeExpr -> CTypeExpr
instantiateBool (CTVar _) = boolType
instantiateBool (CTCons n) = CTCons n
instantiateBool (CTApply a b) = CTApply (instantiateBool a) (instantiateBool b)
instantiateBool (CFuncType a b) =
  CFuncType (instantiateBool a) (instantiateBool b)

--- Replaces the result type of a function type.
replaceResultType :: CTypeExpr -> CTypeExpr -> CTypeExpr
replaceResultType (CFuncType a (CTVar _)) z = CFuncType a z
replaceResultType (CFuncType a (CTCons _)) z = CFuncType a z
replaceResultType (CFuncType a (CTApply _ _)) z = CFuncType a z
replaceResultType (CFuncType a b@(CFuncType _ _)) z =
  CFuncType a (replaceResultType b z)
replaceResultType (CTVar _) z = z
replaceResultType (CTCons _) z = z
replaceResultType (CTApply _ _) z = z

combineTuple :: (String, String) -> String -> String
combineTuple (a, b) s = a ++ s ++ b

showQName :: QName -> String
showQName qn = combineTuple qn "."

showFuncNames :: [CFuncDecl] -> String
showFuncNames = intercalate ", " . map (showQName . funcName)

replace' :: Eq a => a -> a -> [a] -> [a]
replace' _ _ [] = []
replace' o n (x:xs) | x == o = n : replace' o n xs
                    | otherwise = x : replace' o n xs

------------------------------------------------------------------------------
--- Finds a list of functions that can be compared. At the moment, this uses the
--- functionality from `CPM.Diff.API` to compare the public interfaces of both
--- module versions and find the functions that have not changed between
--- versions.
---
--- @param cfg the CPM configuration
--- @param repo the current repository
--- @param gc the global package cache
--- @param dirA the directory of the A version of the package
--- @param dirB the directory of the B version of the package
--- @param useanalysis - use program analysis to filter non-term. operations?
--- @param mods - the modules to compare (if Nothing, compare exported modules)
--- @return a tuple consisting of an ACYCache, a list of functions to
---         be compared (with a flag which is true if they are productive,
---         might be non-terminating but can be compared level-wise),
---         and a list of non-comparable functions with a reason
findFunctionsToCompare :: Config
                       -> Repository
                       -> GC.GlobalCache
                       -> String
                       -> String
                       -> Bool
                       -> Maybe [String]
                       -> ErrorLogger (ACYCache, [String],
                              [(Bool,CFuncDecl)], [(CFuncDecl, FilterReason)])
findFunctionsToCompare cfg repo gc dirA dirB useanalysis onlymods = do
  pkgA <- loadPackageSpec dirA
  pkgB <- loadPackageSpec dirB
  depsA <- resolveAndCopyDependencies cfg repo gc dirA
  let cmods = intersect (exportedModules pkgA) (exportedModules pkgB)
  let mods = maybe cmods (intersect cmods) onlymods
  if null mods
   then logInfo "No exported modules to compare" >>
        return (emptyACYCache,[],[],[])
   else do
    logInfo ("Comparing modules: "++ intercalate " " mods)
    diffs <- APIDiff.compareModulesInDirs cfg repo gc dirA dirB (Just mods)
    (acy, allFuncs) <- findAllFunctions dirA dirB pkgA depsA emptyACYCache mods
    logDebug ("All public functions: " ++ showFuncNames allFuncs)
    let areDiffThenFilter        = thenFilter allFuncs Diffing
    let areHighArityThenFilter   = thenFilter allFuncs HighArity
    let areIOActionThenFilter    = thenFilter allFuncs IOAction
    let areNoCompareThenFilter   = thenFilter allFuncs NoCompare
    let areNonMatchingThenFilter = thenFilter allFuncs NonMatchingTypes
    let haveFuncArgThenFilter    = thenFilter allFuncs FuncArg
    (emptyFilter ((liftFilter $ filterDiffingFunctions diffs) acy allFuncs)
                            `areDiffThenFilter`
        liftFilter filterHighArity `areHighArityThenFilter`
        liftFilter filterIOAction  `areIOActionThenFilter`
        filterNoCompare        dirA dirB depsA `areNoCompareThenFilter`
        filterNonMatchingTypes dirA dirB depsA `areNonMatchingThenFilter`
        filterFuncArg          dirA dirB depsA `haveFuncArgThenFilter`
        liftFilter id ) >>= terminationFilter pkgA dirA depsA useanalysis

--- Filters out functions which are possibly non-terminating and
--- non-productive, and mark productive functions so that they are
--- tested not by standard equality.
terminationFilter :: Package -> String -> [Package] -> Bool
                  -> (ACYCache, [CFuncDecl], [(CFuncDecl, FilterReason)])
                  -> ErrorLogger (ACYCache, [String], [(Bool,CFuncDecl)],
                                  [(CFuncDecl, FilterReason)])
terminationFilter _ _ _ False (a,fs,rm) =
  return (a, [], map (\f->(False,f)) fs, rm)
terminationFilter pkgA dirA depsA True (acy, funcs, rm) = do
  let currypath = loadPathForPackage pkgA dirA depsA
      mods = nub (map (fst . funcName) funcs)
  ainfo <- analyzeModules "productivity" productivityAnalysis currypath mods
  -- compute functions which should be definitely compared (due to TERMINATE
  -- or PRODUCTIVE pragmas):
  modscmts <- liftIOEL $ mapM (getCompare currypath) mods
  let termfuns = concatMap (\md -> md ("TERMINATE"  `isInfixOf`)) modscmts
      prodfuns = concatMap (\md -> md ("PRODUCTIVE" `isInfixOf`)) modscmts
  logDebug ("Functions marked with TERMINATE: " ++ showFuncNames termfuns)
    >> return ()
  logDebug ("Functions marked with PRODUCTIVE: " ++ showFuncNames prodfuns)
    >> return ()
  let infoOf f = fromMaybe Looping (lookupProgInfo (funcName f) ainfo)
      ntfuncs  = filter (\f -> infoOf f == Looping  &&
                               f `notElem` termfuns && f `notElem` prodfuns)
                        funcs
  return (acy, currypath,
             map (\f -> (not (infoOf f == Terminating || f `elem` termfuns), f))
                 (funcs \\ ntfuncs),
             rm ++ map (\f -> (f,NonTerm)) ntfuncs)
 where
  --- Get functions in a module satisfying a given predicate on pragma comments
  getCompare currypath modname = do
    src <- lookupModuleSource currypath modname
    (_,comments) <- case src of
      Nothing        -> error $ "Module not found: " ++ modname
      Just (_, file) -> readComments file
    return (\p -> filter (\f -> let (mn,fn) = funcName f
                          in mn == modname &&
                             p (getFuncComment fn comments))
                         funcs)

-- Analyze a list of modules with some static program analysis in a given
-- load path. Returns the combined analysis information.
-- Raises an error if something goes wrong.
analyzeModules :: (Read a, Show a)
               => String -> Analysis a -> [String] -> [String]
               -> ErrorLogger (ProgInfo a)
analyzeModules ananame analysis currypath mods = do
  logDebug ("Running " ++ ananame ++ " analysis on modules: " ++
             intercalate ", " mods)
  logDebug ("CURRYPATH=" ++ joinSearchPath currypath)
  anainfos <- liftIOEL $ mapM (analyzeModule analysis currypath) mods
  logDebug "Analysis finished"
  return $ foldr combineProgInfo emptyProgInfo anainfos

-- Analyze a module with some static program analysis in a given
-- load path. Raises an error if something goes wrong.
analyzeModule :: (Read a, Show a)
              => Analysis a -> [String] -> String -> IO (ProgInfo a)
analyzeModule analysis currypath mod = do
  setEnv "CURRYPATH" (joinSearchPath currypath)
  aresult <- analyzeGeneric analysis mod
  unsetEnv "CURRYPATH"
  either return
         (\e -> do putStrLn "WARNING: error occurred during analysis:"
                   putStrLn e
                   putStrLn "Ignoring analysis information"
                   return emptyProgInfo)
         aresult


emptyFilter :: ErrorLogger (ACYCache, [CFuncDecl])
      -> ErrorLogger (ACYCache, [CFuncDecl], [(CFuncDecl, FilterReason)])
emptyFilter st = st >>= \(a, fs) -> return (a, fs, [])

--- Reasons why a function can be excluded from the list of functions to be
--- compared.
data FilterReason = NoReason
                  | HighArity
                  | IOAction
                  | NoCompare
                  | NonMatchingTypes
                  | Diffing
                  | FuncArg
                  | NonTerm

--- Chain filter functions and mark the ones removed by the previous filter
--- with a given reason.
thenFilter :: [CFuncDecl]
       -> FilterReason
       -> ErrorLogger (ACYCache, [CFuncDecl], [(CFuncDecl, FilterReason)])
       -> (ACYCache -> [CFuncDecl] -> ErrorLogger (ACYCache, [CFuncDecl]))
       -> ErrorLogger (ACYCache, [CFuncDecl], [(CFuncDecl, FilterReason)])
thenFilter allFuncs r st f =
  st >>=
  \(a, fs, rm) -> f a fs >>=
  \(a', fs') -> return (a', fs', rm ++ zip (findMissing rm fs) (repeat r))
 where
  findMissing rm fs = (allFuncs \\ (map fst rm)) \\ fs

--- Lifts a simple filter to a filter that executes inside the IO monad and
--- takes an ACYCache.
liftFilter :: ([CFuncDecl] -> [CFuncDecl])
       -> (ACYCache -> [CFuncDecl] -> ErrorLogger (ACYCache, [CFuncDecl]))
liftFilter f = \a fs -> return (a, f fs)

--- Excludes those functions which take a functional argument, either directly
--- or via a nested type.
filterFuncArg :: String -> String -> [Package] -> ACYCache -> [CFuncDecl]
              -> ErrorLogger (ACYCache, [CFuncDecl])
filterFuncArg = filterFuncsDeep checkFunc
 where
  checkFunc (CFuncType _ _) = True
  checkFunc (CTVar _)       = False
  checkFunc (CTCons _)      = False
  checkFunc (CTApply _ _)   = False

--- Filters functions via a predicate on their argument types. Checks the
--- predicates on nested types as well.
filterFuncsDeep :: (CTypeExpr -> Bool) -> String -> String -> [Package]
                -> ACYCache -> [CFuncDecl]
                -> ErrorLogger (ACYCache, [CFuncDecl])
filterFuncsDeep tpred dirA _ deps acy allFuncs =
  foldM checkFunc (acy, [], []) allFuncs >>=
  \(acy', _, fns) -> return (acy', fns)
 where
  findType n m = case predefinedType n of
    Nothing -> find ((== n) . typeName) $ filter isTypePublic $ types m
    Just ty -> Just ty

  checkFunc (a, c, fs) f =
    (foldM checkTypeExpr (a, c, False) $ argTypes $ typeOfQualType $ funcType f) >>=
    \(a', c', r) -> if r then return (a', c', fs)
                         else return (a', c', f:fs)

  checkTypeExpr (a, c, r) t@(CFuncType e1 e2) =
    if t `elem` c
      then return (a, c, r)
      else if tpred t
             then return (a, c, True)
             else checkTypeExpr (a, c, r) e1 >>=
                  \ (a', c', r') -> checkTypeExpr (a', e1:c', r') e2 >>=
                  \ (a'', c'', r'') -> return (a'', e2:c'', r || r' || r'')
  checkTypeExpr (a, c, r) t@(CTApply e1 e2) =
    if t `elem` c
      then return (a, c, r)
      else if tpred t
             then return (a, c, True)
             else checkTypeExpr (a, c, r) e1 >>=
                  \ (a', c', r') -> checkTypeExpr (a', e1:c', r') e2 >>=
                  \ (a'', c'', r'') -> return (a'', e2:c'', r || r' || r'')
  checkTypeExpr (a, c, r) (CTVar _) = return (a, c, r)
  checkTypeExpr (a, c, r) t@(CTCons n@(mod, _)) =
    if t `elem` c
      then return (a, c, r)
      else if tpred t
             then return (a, c, True)
             else return (a, c, r) >>=
                  \(a', c', _) -> readCached dirA deps a' mod >>=
                  \(a'', prog) -> case findType n prog of
                    Nothing -> fail $ "Type '" ++ show n ++ "' not found."
                    Just t' -> checkType a'' (t:c') t' >>=
                           \(a''', c'', r'') -> return (a''', c'', r || r'')

  checkType a ts (CType _ _ _ cs _)   = foldM checkCons (a, ts, False) cs
  checkType a ts (CTypeSyn _ _ _ e)   = checkTypeExpr (a, ts, False) e
  checkType a ts (CNewType _ _ _ c _) = checkCons (a, ts, False) c

  checkCons (a, ts, r) (CCons _ _ es) = foldM checkTypeExpr (a, ts, r) es
  checkCons (a, ts, r) (CRecord _ _ fs) =
    let es = map (\(CField _ _ e) -> e) fs
    in foldM checkTypeExpr (a, ts, r) es

--- Filters out functions marked with the NOCOMPARE pragma.
filterNoCompare :: String -> String -> [Package] -> ACYCache -> [CFuncDecl]
                -> ErrorLogger (ACYCache, [CFuncDecl])
filterNoCompare dirA dirB _ a fs = liftIOEL $ do
  allCommentsA <- mapM (readComments . modPath dirA) modules
  allCommentsB <- mapM (readComments . modPath dirB) modules
  let commentsA = funcsWithComments $ zip modules allCommentsA
  let commentsB = funcsWithComments $ zip modules allCommentsB
  return (a, filter (not . noCompare commentsA commentsB) fs)
 where
  modules = nub $ map (fst . funcName) fs
  modPath dir mod = dir </> "src" </> joinPath (splitOn "." mod) ++ ".curry"
  -- Zip up all functions with their respective comments.
  funcsWithComments cmts = zip fs (map (getFuncComment' cmts) fs)
  getFuncComment' cmts f =
    let
      mname = fst $ funcName f
      lname = snd $ funcName f
    in case lookup mname cmts of
      Nothing -> ""
      Just cs -> getFuncComment lname $ snd cs
  noCompare cmtsA cmtsB f = noCompare' cmtsA f || noCompare' cmtsB f
  -- Check if NOCOMPARE is mentioned in the comments
  noCompare' cmts f = case lookup f cmts of
    Nothing -> False
    Just  c -> "NOCOMPARE" `isInfixOf` c


--- Removes all functions that have more than five arguments (currently the
--- maximum number of parameters that CurryCheck supports in property tests).
filterHighArity :: [CFuncDecl] -> [CFuncDecl]
filterHighArity = filter ((<= 5) . length . argTypes . typeOfQualType . funcType)

--- Removes all IO actions since they cannot be compared as
--- properties in CurryCheck.
filterIOAction :: [CFuncDecl] -> [CFuncDecl]
filterIOAction = filter (not . isIOType . resultType . typeOfQualType . funcType)

--- Removes all functions that have a diff associated with their name from the
--- given list of functions.
---
--- @param fs the functions to filter
--- @param ds a list of pairs of module names and diffs
filterDiffingFunctions :: [(String, Differences)] -> [CFuncDecl] -> [CFuncDecl]
filterDiffingFunctions diffs allFuncs = nub $ concatMap filterModule modules
 where
  modules = nub $ map (fst . funcName) allFuncs
  diffsForModule mod = case lookup mod diffs of
    Nothing -> []
    Just (_, funcDiffs, _, _) -> map funcDiffName funcDiffs
  funcDiffName (Addition f) = funcName f
  funcDiffName (Removal  f) = funcName f
  funcDiffName (Change _ f) = funcName f
  filterModule mod = filter (not . (`elem` (diffsForModule mod)) . funcName)
                            (funcsForModule mod)
  funcsForModule mod = filter ((== mod) . fst . funcName) allFuncs

--- Excludes those functions whose types do not match in both versions. Checks
--- nested types.
filterNonMatchingTypes :: String -> String -> [Package] -> ACYCache
                      -> [CFuncDecl] -> ErrorLogger (ACYCache, [CFuncDecl])
filterNonMatchingTypes dirA dirB deps acyCache allFuncs =
  foldM funcTypesCompatible (acyCache, [], []) allFuncs >>=
  \(acy, _, fns) -> return (acy, fns)
 where
  allTypes f = let ft = typeOfQualType (funcType f)
               in (resultType ft) : (argTypes ft)
  onlyCons = filter isConsType
  funcTypesCompatible (a, seen, fs) f =
    (foldM typesCompatible (a, seen, True) $ onlyCons $ allTypes f) >>=
    \(a', seen', c) -> if c
      then return (a', seen', f:fs)
      else return (a', seen', fs)
  typesCompatible (a, seen, r) t = case lookup t seen of
    Just b  -> return (a, seen, b && r)
    Nothing -> typesEqual t dirA dirB deps a [] >>=
      \(a', r') -> return (a', ((t, r'):seen), r' && r)

--- Compares the declarations of types mentioned in a type expression
--- recursively. Returns False if the types are different.
typesEqual :: CTypeExpr -> String -> String -> [Package] -> ACYCache
           -> [CTypeExpr] -> ErrorLogger (ACYCache, Bool)
typesEqual texp dirA dirB deps acyCache checked =
  maybe (fail $ "typesEqual not called on type constructor: " ++ show texp)
        (return . fst)
        (tconsArgsOfType texp) >>= \n -> let (mod,_) = n in
  if texp `elem` checked
    then return (acyCache, True)
    else readCached dirA deps acyCache mod >>= \(acy',modA) ->
         readCached dirB deps acy' mod >>= \(acy'', modB) ->
         let typeA = findType n modA
             typeB = findType n modB
         in typesEqual' typeA typeB acy''
 where
  findType n m = case predefinedType n of
    Nothing -> find ((== n) . typeName) $ filter isTypePublic $ types m
    Just ty -> Just ty

  typesEqual' :: Maybe CTypeDecl -> Maybe CTypeDecl -> ACYCache
              -> ErrorLogger (ACYCache, Bool)
  typesEqual' (Just (CType n1 v1 tvs1 cs1 _)) (Just (CType n2 v2 tvs2 cs2 _))
              acy =
    if n1 == n2 && v1 == v2 && tvs1 == tvs2 && cs1 == cs2
      then foldM (\(a, r) (c1, c2) -> consEqual a c1 c2 >>= \(a', r') ->
           return (a', r && r')) (acy, True) (zip cs1 cs2)
      else return (acy, False)
  typesEqual' (Just (CTypeSyn n1 v1 tvs1 e1))
              (Just (CTypeSyn n2 v2 tvs2 e2)) acy =
    if n1 == n2 && v1 == v2 && tvs1 == tvs2 && e1 == e2
      then if isConsType e1
        then typesEqual e1 dirA dirB deps acy (texp:checked)
        else return (acy, True)
      else return (acy, False)
  typesEqual' (Just (CNewType n1 v1 tvs1 c1 _))
              (Just (CNewType n2 v2 tvs2 c2 _)) acy =
    if n1 == n2 && v1 == v2 && tvs1 == tvs2 && c1 == c2
      then consEqual acy c1 c2
      else return (acy, False)
  typesEqual' (Just (CType _ _ _ _ _)) (Just (CTypeSyn _ _ _ _)) acy =
    return (acy, False)
  typesEqual' (Just (CType _ _ _ _ _)) (Just (CNewType _ _ _ _ _)) acy =
    return (acy, False)
  typesEqual' (Just (CTypeSyn _ _ _ _)) (Just (CType _ _ _ _ _)) acy =
    return (acy, False)
  typesEqual' (Just (CTypeSyn _ _ _ _)) (Just (CNewType _ _ _ _ _)) acy =
    return (acy, False)
  typesEqual' (Just (CNewType _ _ _ _ _)) (Just (CType _ _ _ _ _)) acy =
    return (acy, False)
  typesEqual' (Just (CNewType _ _ _ _ _)) (Just (CTypeSyn _ _ _ _)) acy =
    return (acy, False)
  typesEqual' Nothing (Just _) acy = return (acy, False)
  typesEqual' (Just _) Nothing acy = return (acy, False)
  typesEqual' Nothing  Nothing acy = return (acy, False)

  consEqual :: ACYCache -> CConsDecl -> CConsDecl
            -> ErrorLogger (ACYCache, Bool)
  consEqual acy (CCons _ _ es1) (CCons _ _ es2) =
    foldM esEqual (acy, True) (zip es1 es2)
   where
    esEqual (a, r) (e1, e2) = if e1 == e2
      then if isConsType e1
        then typesEqual e1 dirA dirB deps a (texp:checked)
        else return (acy, r)
      else return (acy, False)
  consEqual acy (CRecord _ _ fs1) (CRecord _ _ fs2) =
    foldM fEqual (acy, True) (zip fs1 fs2)
   where
    fEqual (a, r) (f1@(CField _ _ e1), f2@(CField _ _ _)) = if f1 == f2
      then if isConsType e1
        then typesEqual e1 dirA dirB deps a (texp:checked)
        else return (acy, r)
      else return (acy, False)
  consEqual acy (CCons _ _ _) (CRecord _ _ _) = return (acy, False)
  consEqual acy (CRecord _ _ _) (CCons _ _ _) = return (acy, False)

isTypePublic :: CTypeDecl -> Bool
isTypePublic (CType _ v _ _ _)    = v == Public
isTypePublic (CTypeSyn _ v _ _)   = v == Public
isTypePublic (CNewType _ v _ _ _) = v == Public

isConsType :: CTypeExpr -> Bool
isConsType (CTCons _) = True
isConsType (CTVar _) = False
isConsType (CFuncType _ _) = False
isConsType (CTApply t _) = isConsType t

------------------------------------------------------------------------------
--- Reads a module in AbstractCurry form.
readCached :: String -> [Package] -> ACYCache -> String
           -> ErrorLogger (ACYCache, CurryProg)
readCached dir deps acyCache mod = case findModuleDir dir mod acyCache of
  Just  p -> return (acyCache, p)
  Nothing -> do prog <- readAbstractCurryFromDeps dir deps mod
                return (addModuleDir dir mod prog acyCache, prog)

--- Reads all modules of the given package and finds all public functions
--- in all of those modules.
---
--- @param dirA the directory where copy A of the package is stored
--- @param dirB the directory where copy B of the package is stored
--- @param pkg the package
--- @param deps a list of package dependencies
--- @param mods the list of modules to search for public functions
findAllFunctions :: String -> String -> Package -> [Package] -> ACYCache
                 -> [String] -> ErrorLogger (ACYCache, [CFuncDecl])
findAllFunctions dirA dirB _ deps acyCache mods =
  logDebug ("Finding public functions of modules: " ++ intercalate "," mods) >>
  logDebug ("in package directories " ++ dirA ++ " and " ++ dirB) >>
  foldM findForMod (acyCache, []) mods >>=
  \(a, fs) -> return (a, nub fs)
 where
  findForMod (acy,fdecls) mod =
    readCached dirA deps acy mod >>= \(_, progA) ->
    readCached dirB deps acy mod >>= \(acy'', progB) ->
    let funcsA = filter isPublic $ functions progA
        funcsB = filter isPublic $ functions progB
    in return (acy'', fdecls ++ nubBy (\a b -> funcName a == funcName b)
                                         (funcsA ++ funcsB))

--- Checks whether a function is public.
isPublic :: CFuncDecl -> Bool
isPublic (CFunc _ _ Public _ _) = True
isPublic (CFunc _ _ Private _ _) = False
isPublic (CmtFunc _ _ _ Public _ _) = True
isPublic (CmtFunc _ _ _ Private _ _) = False

--- Prepares two packages from the global package cache in two versions for
--- comparison by copying them to the temporary directory and building renamed
--- versions.
---
--- @param cfg the CPM configuration
--- @param repo the package repository
--- @param gc the global package cache
--- @param nameA the name of the first package
--- @param verA the version of the first package
--- @param nameB the name of the second package
--- @param verB the version of the second package
preparePackages :: Config
                -> Repository
                -> GC.GlobalCache
                -> String
                -> Version
                -> String
                -> Version
                -> ErrorLogger ComparisonInfo
preparePackages cfg repo gc nameA verA nameB verB =
  GC.tryFindPackage gc nameA verA >>= \pkgA ->
  findPackageDir cfg pkgA >>= \dirA ->
  GC.tryFindPackage gc nameB verB >>= \pkgB ->
  findPackageDir cfg pkgB >>= \dirB ->
  preparePackageDirs cfg repo gc dirA dirB

--- Prepares two package, one from a directory and one from the global package
--- cache. Copies them to a temporary directory and builds renamed versions of
--- the packages and all dependencies.
---
--- @param cfg the CPM configuration
--- @param repo the package repository
--- @param gc the global package cache
--- @param dirA the directory for the first package
--- @param nameB the name of the second package
--- @param verB the version of the second package
preparePackageAndDir :: Config
                     -> Repository
                     -> GC.GlobalCache
                     -> String
                     -> String
                     -> Version
                     -> ErrorLogger ComparisonInfo
preparePackageAndDir cfg repo gc dirA nameB verB =
  GC.tryFindPackage gc nameB verB >>= \pkgB ->
  findPackageDir cfg pkgB >>= \dirB ->
  preparePackageDirs cfg repo gc dirA dirB

--- Prepares two packages from two directories for comparison. Copies the 
--- package files to a temporary directory and creates renamed version of the
--- packages and their dependencies.
---
--- @param cfg the CPM configuration
--- @param repo the package repository
--- @param gc the global package cache
--- @param dirA the directory containing the first package
--- @param dirB the directory containing the second package
preparePackageDirs :: Config
                   -> Repository
                   -> GC.GlobalCache
                   -> String
                   -> String
                   -> ErrorLogger ComparisonInfo
preparePackageDirs cfg repo gc dirA dirB = do
  baseTmp <- liftIOEL $ createBaseTemp
  specA <- loadPackageSpec dirA
  specB <- loadPackageSpec dirB
  let versionPrefixA = versionPrefix specA
  let versionPrefixB = versionPrefix specB
  let copyDirA       = baseTmp </> ("src_" ++ versionPrefixA)
  let copyDirB       = baseTmp </> ("src_" ++ versionPrefixB)
  let destDirA       = baseTmp </> ("dest_" ++ versionPrefixA)
  let destDirB       = baseTmp </> ("dest_" ++ versionPrefixB)
  logDebug ("Copying " ++ packageId specA ++
             " from " ++ dirA ++ " into " ++ copyDirA)
  logDebug ("and transforming it into " ++ destDirA)
  logDebug ("Copying " ++ packageId specB ++
             " from " ++ dirB ++ " into " ++ copyDirB)
  logDebug ("and transforming it into " ++ destDirB)
  modMapA <- copyAndPrefixPackage cfg repo gc dirA versionPrefixA
                                        copyDirA destDirA
  modMapB <- copyAndPrefixPackage cfg repo gc dirB versionPrefixB
                                        copyDirB destDirB
  return $ ComparisonInfo
    { infPackageA   = specA
    , infPackageB   = specB
    , infDirA       = destDirA
    , infDirB       = destDirB
    , infSourceDirA = copyDirA
    , infSourceDirB = copyDirB
    , infPrefixA    = versionPrefixA
    , infPrefixB    = versionPrefixB
    , infModMapA    = modMapA
    , infModMapB    = modMapB }

versionPrefix :: Package -> String
versionPrefix pkg = "V_" ++ (showVersion' $ version pkg)

--- Copies a package from a directory to the temporary directory and creates
--- another copy of the package with all its modules and the modules of its
--- dependencies prefixed with the given string.
---
--- @param cfg the CPM configuration
--- @param repo the package repository
--- @param gc the global package cache
--- @param pkgDir the package directory to copy from
--- @param prefix the prefix for the modules
--- @param tmpDir the temporary directory to copy the files to
--- @param srcDir the temporary directory where the source package is copied
--- @param destDir the temporary directory where the prefixed copy is written
copyAndPrefixPackage :: Config
                     -> Repository
                     -> GC.GlobalCache
                     -> String
                     -> String
                     -> String
                     -> String
                     -> ErrorLogger [(String, String)]
copyAndPrefixPackage cfg repo gc pkgDir prefix srcDir destDir = do
  liftIOEL $ copyDirectory pkgDir srcDir
  liftIOEL $ createDirectory destDir
  prefixPackageAndDeps cfg repo gc srcDir (prefix ++ "_") destDir

showVersion' :: Version -> String
showVersion' (maj, min, pat, Nothing) =
  intercalate "_" [show maj, show min, show pat]
showVersion' (maj, min, pat, Just pre) =
  intercalate "_" [show maj, show min, show pat, pre]

--- Tries to find the package directory in the global package cache.
findPackageDir :: Config -> Package -> ErrorLogger String
findPackageDir cfg pkg = do
  exists <- liftIOEL $ doesDirectoryExist srcDir
  if not exists
    then fail $ "Package " ++ (packageId pkg) ++ " not installed"
    else return srcDir
 where
  srcDir = GC.installedPackageDir cfg pkg