This file is indexed.

/usr/share/perl5/HTML/Mason/Interp.pm is in libhtml-mason-perl 1:1.56-1.

This file is owned by root:root, with mode 0o644.

The actual contents of the file can be viewed below.

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

# Copyright (c) 1998-2005 by Jonathan Swartz. All rights reserved.
# This program is free software; you can redistribute it and/or modify it
# under the same terms as Perl itself.

package HTML::Mason::Interp;
$HTML::Mason::Interp::VERSION = '1.56';
use strict;
use warnings;

use File::Basename;
use File::Path;
use File::Spec;
use File::Temp;
use HTML::Mason;
use HTML::Mason::Escapes;
use HTML::Mason::Request;
use HTML::Mason::Resolver::File;
use HTML::Mason::Tools qw(read_file taint_is_on load_pkg);

use HTML::Mason::Exceptions( abbr => [qw(param_error system_error wrong_compiler_error compilation_error error)] );

use Params::Validate qw(:all);
Params::Validate::validation_options( on_fail => sub { param_error join '', @_  } );

use Class::Container;
use base qw(Class::Container);

BEGIN
{
    # Fields that can be set in new method, with defaults
    __PACKAGE__->valid_params
        (
         autohandler_name =>
         { parse => 'string',  default => 'autohandler', type => SCALAR,
           descr => "The filename to use for Mason's 'autohandler' capability" },

         buffer_preallocate_size =>
         { parse => 'string', default => 0, type => SCALAR,
           descr => "Number of bytes to preallocate in request buffer" },
         
         code_cache_max_size =>
         { parse => 'string',  default => 'unlimited', type => SCALAR,
           descr => "The maximum number of components in the code cache" },

         comp_root =>
         { parse => 'list',
           type => SCALAR|ARRAYREF,
           default => File::Spec->rel2abs( Cwd::cwd ),
           descr => "A string or array of arrays indicating the search path for component calls" },

         compiler =>
         { isa => 'HTML::Mason::Compiler',
           descr => "A Compiler object for compiling components" },

         data_dir =>
         { parse => 'string', optional => 1, type => SCALAR,
           descr => "A directory for storing cache files and other state information" },

         dynamic_comp_root =>
         { parse => 'boolean', default => 0, type => BOOLEAN,
           descr => "Indicates whether the comp_root may be changed between requests" },

         escape_flags =>
         { parse => 'hash_list', optional => 1, type => HASHREF,
           descr => "A list of escape flags to set (as if calling the set_escape() method" },

         object_file_extension =>
         { parse => 'string',  type => SCALAR, default => '.obj',
           descr => "Extension to add to the end of object files" },

         # OBJECT cause qr// returns an object
         ignore_warnings_expr =>
         { parse => 'string',  type => SCALAR|OBJECT, default => qr/Subroutine .* redefined/i,
           descr => "A regular expression describing Perl warning messages to ignore" },

         preloads =>
         { parse => 'list', optional => 1, type => ARRAYREF,
           descr => "A list of components to load immediately when creating the Interpreter" },

         resolver =>
         { isa => 'HTML::Mason::Resolver',
           descr => "A Resolver object for fetching components from storage" },

         static_source =>
         { parse => 'boolean', default => 0, type => BOOLEAN,
           descr => "When true, we only compile source files once" },

         static_source_touch_file =>
         { parse => 'string', optional => 1, type => SCALAR, 
           descr => "A file that, when touched, causes Mason to clear its component caches" },

         use_object_files =>
         { parse => 'boolean', default => 1, type => BOOLEAN,
           descr => "Whether to cache component objects on disk" },
        );

    __PACKAGE__->contained_objects
        (
         resolver => { class => 'HTML::Mason::Resolver::File',
                       descr => "This class is expected to return component information based on a component path" },
         compiler => { class => 'HTML::Mason::Compiler::ToObject',
                       descr => "This class is used to translate component source into code" },
         request  => { class => 'HTML::Mason::Request',
                       delayed => 1,
                       descr => "Objects returned by make_request are members of this class" },
        );
}

use HTML::Mason::MethodMaker
    ( read_only => [ qw( autohandler_name
                         buffer_preallocate_size
                         code_cache
                         code_cache_min_size
                         code_cache_max_size
                         compiler
                         data_dir
                         dynamic_comp_root
                         object_file_extension
                         preallocated_output_buffer
                         preloads
                         resolver
                         source_cache
                         static_source
                         static_source_touch_file
                         use_internal_component_caches
                         use_object_files
                        ) ],

      read_write => [ map { [ $_ => __PACKAGE__->validation_spec->{$_} ] }
                      qw( ignore_warnings_expr
                         )
                    ],

      read_write_contained => { request =>
                                [ [ autoflush => { type => BOOLEAN } ],
                                  [ data_cache_api => { type => SCALAR } ],
                                  [ data_cache_defaults => { type => HASHREF } ],
                                  [ dhandler_name => { type => SCALAR } ],
                                  [ error_format => { type => SCALAR } ],
                                  [ error_mode => { type => SCALAR } ],
                                  [ max_recurse => { type => SCALAR } ],
                                  [ out_method => { type => SCALARREF | CODEREF } ],
                                  [ plugins => { type => ARRAYREF } ],
                                ]
                              },
      );

sub new
{
    my $class = shift;
    my $self = $class->SUPER::new(@_);

    $self->_initialize;
    return $self;
}

sub _initialize
{
    my ($self) = shift;
    $self->{code_cache} = {};
    $self->{source_cache} = {};
    $self->{files_written} = [];
    $self->{static_source_touch_file_lastmod} = 0;

    $self->_assign_comp_root($self->{comp_root});
    $self->_check_data_dir();
    $self->_create_data_subdirs();
    $self->_initialize_escapes();

    #
    # Create preallocated buffer for requests.
    #
    $self->{preallocated_output_buffer} = ' ' x $self->buffer_preallocate_size;

    $self->_set_code_cache_attributes();

    #
    # If static_source=1, unlimited_code_cache=1, and
    # dynamic_comp_root=0, we can safely cache component objects keyed
    # on path throughout the framework (e.g. within other component
    # objects). These internal caches can be cleared in
    # $interp->flush_code_cache (the only legimiate place for a
    # component to be eliminated from the cache), eliminating any
    # chance for leaked objects.
    #
    # static_source has to be on or else we might keep around
    # old versions of components that have changed.
    #
    # unlimited_code_cache has to be on or else we might leak
    # components when we discard.
    #
    # dynamic_comp_root has to be 0 because the cache would not be
    # valid for different combinations of component root across
    # different requests.
    #
    $self->{use_internal_component_caches} =
        ($self->{static_source} &&
         $self->{unlimited_code_cache} &&
         !$self->{dynamic_comp_root});

    $self->_preload_components();
}

sub _check_data_dir
{
    my $self = shift;

    return unless $self->{data_dir};

    $self->{data_dir} = File::Spec->canonpath( $self->{data_dir} );
    param_error "data_dir '$self->{data_dir}' must be an absolute directory"
        unless File::Spec->file_name_is_absolute( $self->{data_dir} );
}

sub _create_data_subdirs
{
    my $self = shift;

    if ($self->data_dir) {
        $self->_make_object_dir;
        $self->_make_cache_dir;
    } else {
        $self->{use_object_files} = 0;
    }
}

sub _initialize_escapes
{
    my $self = shift;

    #
    # Add the escape flags (including defaults)
    #
    foreach ( [ h => \&HTML::Mason::Escapes::html_entities_escape ],
              [ u => \&HTML::Mason::Escapes::url_escape ],
            )
    {
        $self->set_escape(@$_);
    }

    if ( my $e = delete $self->{escape_flags} )
    {
        while ( my ($flag, $code) = each %$e )
        {
            $self->set_escape( $flag => $code );
        }
    }
}

sub _set_code_cache_attributes
{
    my $self = shift;

    $self->{unlimited_code_cache} = ($self->{code_cache_max_size} eq 'unlimited');
    unless ($self->{unlimited_code_cache}) {
        $self->{code_cache_min_size} = $self->{code_cache_max_size} * 0.75;
    }
}

sub _preload_components
{
    my $self = shift;

    return unless $self->preloads;

    foreach my $pattern (@{$self->preloads}) {
        error "preload pattern '$pattern' must be an absolute path"
            unless File::Spec->file_name_is_absolute($pattern);
        my %path_hash;
        foreach my $pair ($self->comp_root_array) {
            my $root = $pair->[1];
            foreach my $path ($self->resolver->glob_path($pattern, $root)) {
                $path_hash{$path}++;
            }
        }
        my @paths = keys(%path_hash);
        warn "Didn't find any components for preload pattern '$pattern'"
            unless @paths;
        foreach (@paths)
        {
            $self->load($_)
                or error "Cannot load component $_, found via pattern $pattern";
        }
    }
}

#
# Functions for retrieving and creating data subdirectories.
#
sub object_dir { my $self = shift; return $self->data_dir ? File::Spec->catdir( $self->data_dir, 'obj' ) : ''; }
sub object_create_marker_file { my $self = shift; return $self->object_dir ? File::Spec->catfile($self->object_dir, '.__obj_create_marker') : ''; }
sub cache_dir  { my $self = shift; return $self->data_dir ? File::Spec->catdir( $self->data_dir, 'cache' ) : ''; }

sub _make_data_subdir
{
    my ($self, $dir) = @_;

    unless (-d $dir) {
        my @newdirs = eval { mkpath( $dir, 0, 0775 ) };
        if ($@) {
            my $user  = getpwuid($<);
            my $group = getgrgid($();
            my $data_dir = $self->data_dir;
            error "Cannot create directory '$dir' ($@) for user '$user', group '$group'. " .
                "Perhaps you need to create or set permissions on your data_dir ('$data_dir'). ";
        }
        $self->push_files_written(@newdirs);
    }
}

sub _make_object_dir
{
    my ($self) = @_;

    my $object_dir = $self->object_dir;
    $self->_make_data_subdir($object_dir);
    my $object_create_marker_file = $self->object_create_marker_file;
    unless (-f $object_create_marker_file) {
        open my $fh, ">$object_create_marker_file"
            or system_error "Could not create '$object_create_marker_file': $!";
        $self->push_files_written($object_create_marker_file);
    }
}

sub _make_cache_dir
{
    my ($self) = @_;

    my $cache_dir = $self->cache_dir;
    $self->_make_data_subdir($cache_dir);
}

#
# exec is the initial entry point for executing a component
# in a new request.
#
sub exec {
    my $self = shift;
    my $comp = shift;
    $self->make_request(comp=>$comp, args=>\@_)->exec;
}

sub make_request {
    my $self = shift;

    return $self->create_delayed_object( 'request', interp => $self, @_ );
}

sub comp_exists {
    my ($self, $path) = @_;
    return $self->resolve_comp_path_to_source($path);
}

#
# Load <$path> into a component, possibly parsing the source and/or
# caching the code. Returns a component object or undef if the
# component was not found.
#
sub load {
    my ($self, $path) = @_;
    my ($maxfilemod, $objfile, $objfilemod);
    my $code_cache = $self->{code_cache};
    my $resolver = $self->{resolver};

    #
    # Path must be absolute.
    #
    unless (substr($path, 0, 1) eq '/') {
        error "Component path given to Interp->load must be absolute (was given $path)";
    }

    #
    # Get source info from resolver.
    #
    my $source = $self->resolve_comp_path_to_source($path);

    # No component matches this path.
    return unless defined $source;

    # comp_id is the unique name for the component, used for cache key
    # and object file name.
    my $comp_id = $source->comp_id;

    #
    # Get last modified time of source.
    #
    my $srcmod = $source->last_modified;

    #
    # If code cache contains an up to date entry for this path, use
    # the cached comp.  Always use the cached comp in static_source
    # mode.
    #
    if ( exists $code_cache->{$comp_id} &&
         ( $self->static_source || $code_cache->{$comp_id}->{lastmod} >= $srcmod )
       ) {
        return $code_cache->{$comp_id}->{comp};
    }

    if ($self->{use_object_files}) {
        $objfile = $self->comp_id_to_objfile($comp_id);

        my @stat = stat $objfile;
        if ( @stat && ! -f _ ) {
            error "The object file '$objfile' exists but it is not a file!";
        }

        if ($self->static_source) {
            # No entry in the code cache so if the object file exists,
            # we will use it, otherwise we must create it.  These
            # values make that happen.
            $objfilemod = @stat ? $srcmod : 0;
        } else {
            # If the object file exists, get its modification time.
            # Otherwise (it doesn't exist or it is a directory) we
            # must create it.
            $objfilemod = @stat ? $stat[9] : 0;
        }
    }

    my $comp;
    if ($objfile) {
        #
        # We are using object files.  Update object file if necessary
        # and load component from there.
        #
        # If loading the object file generates an error, or results in
        # a non-component object, try regenerating the object file
        # once before giving up and reporting an error. This can be
        # handy in the rare case of an empty or corrupted object file.
        # (But add an exception for "Compilation failed in require" errors, since
        # the bad module will be added to %INC and the error will not occur
        # the second time - RT #39803).
        #
        if ($objfilemod < $srcmod) {
            $self->compiler->compile_to_file( file => $objfile, source => $source);
        }
        $comp = eval { $self->eval_object_code( object_file => $objfile ) };

        if (!UNIVERSAL::isa($comp, 'HTML::Mason::Component')) {
            if (!defined($@) || $@ !~ /failed in require/) {
                $self->compiler->compile_to_file( file => $objfile, source => $source);
                $comp = eval { $self->eval_object_code( object_file => $objfile ) };
            }

            if (!UNIVERSAL::isa($comp, 'HTML::Mason::Component')) {
                my $error = $@ ? $@ : "Could not get HTML::Mason::Component object from object file '$objfile'";
                $self->_compilation_error( $source->friendly_name, $error );
            }
        }
    } else {
        #
        # Not using object files. Load component directly into memory.
        #
        my $object_code = $source->object_code( compiler => $self->compiler );
        $comp = eval { $self->eval_object_code( object_code => $object_code ) };
        $self->_compilation_error( $source->friendly_name, $@ ) if $@;
    }
    $comp->assign_runtime_properties($self, $source);

    #
    # Delete any stale cached version of this component, then
    # cache it.
    #
    $self->delete_from_code_cache($comp_id);
    $code_cache->{$comp_id} = { lastmod => $srcmod, comp => $comp };

    return $comp;
}

sub delete_from_code_cache {
    my ($self, $comp_id) = @_;
    return unless defined $self->{code_cache}{$comp_id}{comp};

    delete $self->{code_cache}{$comp_id};
    return;
}

sub comp_id_to_objfile {
    my ($self, $comp_id) = @_;

    return File::Spec->catfile
               ( $self->object_dir,
                 $self->compiler->object_id,
                 ( split /\//, $comp_id ),
               ) . $self->object_file_extension;
}

#
# Empty in-memory code cache.
#
sub flush_code_cache {
    my $self = shift;

    # Necessary for preventing memory leaks
    if ($self->use_internal_component_caches) {
        foreach my $entry (values %{$self->{code_cache}}) {
            my $comp = $entry->{comp};
            $comp->flush_internal_caches;
        }
    }
    $self->{code_cache} = {};
    $self->{source_cache} = {};
}

#
# If code cache has exceeded maximum, remove least frequently used
# elements from cache until size falls below minimum.
#
sub purge_code_cache {
    my ($self) = @_;

    return if $self->{unlimited_code_cache};
    my $current_size = scalar(keys(%{$self->{code_cache}}));
    if ($current_size > $self->code_cache_max_size) {
        my $code_cache = $self->{code_cache};
        my $min_size = $self->code_cache_min_size;
        my $decay_factor = 0.75;

        my @elems;
        while (my ($path,$href) = each(%{$code_cache})) {
            push(@elems,[$path,$href->{comp}->mfu_count,$href->{comp}]);
        }
        @elems = sort { $a->[1] <=> $b->[1] } @elems;
        while (($current_size > $min_size) and @elems) {
            $self->delete_from_code_cache(shift(@elems)->[0]);
            $current_size--;
        }

        #
        # Multiply each remaining cache item's count by a decay factor,
        # to gradually reduce impact of old information.
        #
        foreach my $elem (@elems) {
            $elem->[2]->mfu_count( $elem->[2]->mfu_count * $decay_factor );
        }
    }
}

#
# Clear the object directory of all current files and subdirectories.
# Do this by renaming the object directory to a temporary name,
# immediately recreating an empty object directory, then removing
# the empty object directory. If another process tries to write
# the object file in between these steps, it'll create the top
# object directory instead.
#
# Would be nice to fork off a separate process to do the removing so
# that it doesn't affect a request's response time, but difficult to
# do this in an environment-generic way.
#
sub remove_object_files
{
    my $self = shift;

    my $object_dir = $self->object_dir;
    if (-d $object_dir) {
        my $temp_dir = File::Temp::tempdir(DIR => $self->data_dir);
        rename($object_dir, File::Spec->catdir( $temp_dir, 'target' ) )
            or die "could not rename '$object_dir' to '$temp_dir': $@";
        $self->_make_object_dir();
        rmtree($temp_dir);
    } else {
        $self->_make_object_dir();
    }
}

#
# Check the static_source_touch_file, if one exists, to see if it has
# changed since we last checked. If it has, clear the code cache and
# object files if appropriate.
#
sub check_static_source_touch_file
{
    my $self = shift;

    if (my $touch_file = $self->static_source_touch_file) {
        return unless -f $touch_file;
        my $touch_file_lastmod = (stat($touch_file))[9];
        if ($touch_file_lastmod > $self->{static_source_touch_file_lastmod}) {

            # File has been touched since we last checked.  First,
            # clear the object file directory if the last mod of
            # its ._object_create_marker is earlier than the touch file,
            # or if the marker doesn't exist.
            #
            if ($self->use_object_files) {
                my $object_create_marker_file = $self->object_create_marker_file;
                if (!-e $object_create_marker_file ||
                    (stat($object_create_marker_file))[9] < $touch_file_lastmod) {
                    $self->remove_object_files;
                }
            }

            # Next, clear the in-memory component cache.
            #
            $self->flush_code_cache;

            # Reset lastmod value.
            #
            $self->{static_source_touch_file_lastmod} = $touch_file_lastmod;
        }
    }
}

#
# Construct a component on the fly.  Virtual if 'path' parameter is
# given, otherwise anonymous.
#
sub make_component {
    my $self = shift;

    my %p = validate(@_, { comp_source => { type => SCALAR, optional => 1 },
                           comp_file   => { type => SCALAR, optional => 1 },
                           name        => { type => SCALAR, optional => 1 } });

    $p{comp_source} = read_file(delete $p{comp_file}) if exists $p{comp_file};
    param_error "Must specify either 'comp_source' or 'comp_file' parameter to 'make_component()'"
        unless defined $p{comp_source};

    $p{name} ||= '<anonymous component>';

    my $source = HTML::Mason::ComponentSource->new( friendly_name => $p{name},
                                                    comp_path => $p{name},
                                                    comp_id => undef,
                                                    last_modified => time,
                                                    comp_class => 'HTML::Mason::Component',
                                                    source_callback => sub { $p{comp_source} },
                                                  );

    my $object_code = $source->object_code( compiler => $self->compiler);

    my $comp = eval { $self->eval_object_code( object_code => $object_code ) };
    $self->_compilation_error( $p{name}, $@ ) if $@;

    $comp->assign_runtime_properties($self, $source);

    return $comp;
}

sub set_global
{
    my ($self, $decl, @values) = @_;
    param_error "Interp->set_global: expects a variable name and one or more values"
        unless @values;
    my ($prefix, $name) = ($decl =~ s/^([\$@%])//) ? ($1, $decl) : ('$', $decl);

    my $varname = sprintf("%s::%s",$self->compiler->in_package,$name);
    no strict 'refs';
    no warnings 'once';
    if ($prefix eq '$') {
        $$varname = $values[0];
    } elsif ($prefix eq '@') {
        @$varname = @values;
    } else {
        %$varname = @values;
    }
}

sub comp_root
{
    my $self = shift;
    
    if (my $new_comp_root = shift) {
        die "cannot assign new comp_root unless dynamic_comp_root parameter is set"
          unless $self->dynamic_comp_root;
        $self->_assign_comp_root($new_comp_root);
    }
    if (@{$self->{comp_root}} == 1 and $self->{comp_root}[0][0] eq 'MAIN') {
        return $self->{comp_root}[0][1];
    } else {
        return $self->{comp_root};
    }
}

sub comp_root_array
{
    return @{ $_[0]->{comp_root} };
}

sub _assign_comp_root
{
    my ($self, $new_comp_root) = @_;

    # Force into lol format.
    if (!ref($new_comp_root)) {
        $new_comp_root = [[ MAIN => $new_comp_root ]];
    } elsif (ref($new_comp_root) ne 'ARRAY') {
        die "Component root $new_comp_root must be a scalar or array reference";
    }

    # Validate key/path pairs, and check to see if any of them
    # conflict with old pairs.
    my $comp_root_key_map = $self->{comp_root_key_map} ||= {};
    foreach my $pair (@$new_comp_root) {
        param_error "Multiple-path component root must consist of a list of two-element lists"
          if ref($pair) ne 'ARRAY';
        param_error "Component root key '$pair->[0]' cannot contain slash"
          if $pair->[0] =~ /\//;
        $pair->[1] = File::Spec->canonpath( $pair->[1] );
        param_error "comp_root path '$pair->[1]' is not an absolute directory"
          unless File::Spec->file_name_is_absolute( $pair->[1] );
            
        my ($key, $path) = @$pair;
        if (my $orig_path = $comp_root_key_map->{$key}) {
            if ($path ne $orig_path) {
                die "comp_root key '$key' was originally associated with '$path', cannot change to '$orig_path'";
            }
        } else {
            $comp_root_key_map->{$key} = $path;
        }
    }
    $self->{comp_root} = $new_comp_root;
}

sub resolve_comp_path_to_source
{
    my ($self, $path) = @_;
    
    my $source;
    if ($self->{static_source}) {
        # Maintain a separate source_cache for each component root,
        # because the set of active component roots can change
        # from request to request.
        #
        my $source_cache = $self->{source_cache};
        foreach my $pair (@{$self->{comp_root}}) {
            my $source_cache_for_root = $source_cache->{$pair->[0]} ||= {};
            unless (exists($source_cache_for_root->{$path})) {
                $source_cache_for_root->{$path}
                  = $self->{resolver}->get_info($path, @$pair);
            }
            last if $source = $source_cache_for_root->{$path};
        }
    } else {
        my $resolver = $self->{resolver};
        foreach my $pair ($self->comp_root_array) {
            last if $source = $resolver->get_info($path, @$pair);
        }
    }
    return $source;
}

sub files_written
{
    my $self = shift;
    return @{$self->{files_written}};
}

#
# Push onto list of written files.
#
sub push_files_written
{
    my $self = shift;
    my $fref = $self->{'files_written'};
    push(@$fref,@_);
}

#
# Look for component <$name> starting in <$startpath> and moving upwards
# to the root. Return component object or undef.
#
sub find_comp_upwards
{
    my ($self, $startpath, $name) = @_;
    $startpath =~ s{/+$}{};

    # Don't use File::Spec here, this is a URL path.
    do {
      my $comp = $self->load("$startpath/$name");
      return $comp if $comp;
    } while $startpath =~ s{/+[^/]*$}{};

    return;  # Nothing found
}

###################################################################
# The eval_object_code & write_object_file methods used to be in
# Parser.pm.  This is a temporary home only.  They need to be moved
# again at some point in the future (during some sort of interp
# re-architecting).
###################################################################

#
# eval_object_code
#   (object_code, object_file, error)
# Evaluate an object file or object text.  Return a component object
# or undef if error.
#
# I think this belongs in the resolver (or comp loader) - Dave
#
sub eval_object_code
{
    my ($self, %p) = @_;

    #
    # Evaluate object file or text with warnings on, unless
    # ignore_warnings_expr is '.'.
    #
    my $ignore_expr = $self->ignore_warnings_expr;
    my ($comp, $err);
    my $warnstr = '';

    {
        local $^W = $ignore_expr eq '.' ? 0 : 1;
        local $SIG{__WARN__} =
            ( $ignore_expr ?
              ( $ignore_expr eq '.' ?
                sub { } :
                sub { $warnstr .= $_[0] if $_[0] !~ /$ignore_expr/ }
              ) :
              sub { $warnstr .= $_[0] } );
        
        $comp = $self->_do_or_eval(\%p);
    }

    $err = $warnstr . $@;

    #
    # Return component or error
    #
    if ($err) {
        # attempt to stem very long eval errors
        $err =~ s/has too many errors\..+/has too many errors./s;
        compilation_error $err;
    } else {
        return $comp;
    }
}

sub _do_or_eval
{
    my ($self, $p) = @_;

    if ($p->{object_file}) {
        return do $p->{object_file};
    } else {
        # If in taint mode, untaint the object text
        (${$p->{object_code}}) = ${$p->{object_code}} =~ /^(.*)/s if taint_is_on;

        return eval ${$p->{object_code}};
    }
}

sub _compilation_error {
    my ($self, $filename, $err) = @_;

    HTML::Mason::Exception::Compilation->throw(error=>$err, filename=>$filename);
}


sub object_file {
    my ($self, $comp) = @_;
    return $comp->persistent ?
        $self->comp_id_to_objfile($comp->comp_id) :
        undef;
}

sub use_autohandlers
{
    my $self = shift;
    return (defined $self->{autohandler_name} and length $self->{autohandler_name});
}

# Generate HTML that describes Interp's current status.
# This is used in things like Apache::Status reports.  Currently shows:
# -- Interp properties
# -- loaded (cached) components
sub status_as_html {
    my ($self, %p) = @_;

    # Should I be scared about this?  =)

    my $comp_source = <<'EOF';
<h3>Interpreter properties:</h3>
<blockquote>
 <h4>Startup options:</h4>
 <tt>
<table width="100%">
<%perl>
foreach my $property (sort keys %$interp) {
    my $val = $interp->{$property};

    my $default = ( defined $val && defined $valid{$property}{default} && $val eq $valid{$property}{default} ) || ( ! defined $val && exists $valid{$property}{default} && ! defined $valid{$property}{default} );

    my $display = $val;
    if (ref $val) {
        $display = '<font color="darkred">';
        # only object can ->can, others die
        my $is_object = eval { $val->can('anything'); 1 };
        if ($is_object) {
            $display .= ref $val . ' object';
        } else {
            if (UNIVERSAL::isa($val, 'ARRAY')) {
                $display .= 'ARRAY reference - [ ';
                $display .= join ', ', @$val;
                $display .= '] ';
            } elsif (UNIVERSAL::isa($val, 'HASH')) {
                $display .= 'HASH reference - { ';
                my @pairs;
                while (my ($k, $v) = each %$val) {
                   push @pairs, "$k => $v";
                }
                $display .= join ', ', @pairs;
                $display .= ' }';
            } else {
                $display = ref $val . ' reference';
            }
        }
        $display .= '</font>';
    }

    defined $display && $display =~ s,([\x00-\x1F]),'<font color="purple">control-' . chr( ord('A') + ord($1) - 1 ) . '</font>',eg; # does this work for non-ASCII?
</%perl>
 <tr valign="top" cellspacing="10">
  <td>
    <% $property | h %>
  </td>
  <td>
   <% defined $display ? $display : '<i>undef</i>' %>
   <% $default ? '<font color=green>(default)</font>' : '' %>
  </td>
 </tr>
% }
</table>
  </tt>

 <h4>Components in memory cache:</h4>
 <tt>
% my $cache;
% if ($cache = $interp->code_cache and %$cache) {
%   foreach my $key (sort keys %$cache) {
      <% $key |h%> (modified <% scalar localtime $cache->{$key}->{lastmod} %>)
      <br>
%   }
% } else {
    <I>None</I>
% }
  </tt>
</blockquote>

<%args>
 $interp   # The interpreter we'll elucidate
 %valid    # Default values for interp member data
</%args>
EOF

    my $comp = $self->make_component(comp_source => $comp_source);
    my $out;

    my $args = [interp => $self, valid => $self->validation_spec];
    $self->make_request(comp=>$comp, args=>$args, out_method=>\$out, %p)->exec;

    return $out;
}

sub set_escape
{
    my $self = shift;
    my %p = @_;

    while ( my ($name, $sub) = each %p )
    {
        my $flag_regex = $self->compiler->lexer->escape_flag_regex;

        param_error "Invalid escape name ($name)"
            if $name !~ /^$flag_regex$/ || $name =~ /^n$/;

        my $coderef;
        if ( ref $sub )
        {
            $coderef = $sub;
        }
        else
        {
            if ( $sub =~ /^\w+$/ )
            {
                no strict 'refs';
                unless ( defined &{"HTML::Mason::Escapes::$sub"} )
                {
                    param_error "Invalid escape: $sub (no matching subroutine in HTML::Mason::Escapes";
                }

                $coderef = \&{"HTML::Mason::Escapes::$sub"};
            }
            else
            {
                $coderef = eval $sub;
                param_error "Invalid escape: $sub ($@)" if $@;
            }
        }

        $self->{escapes}{$name} = $coderef;
    }
}

sub remove_escape
{
    my $self = shift;

    delete $self->{escapes}{ shift() };
}

sub apply_escapes
{
    my $self = shift;
    my $text = shift;

    foreach my $flag (@_)
    {
        param_error "Invalid escape flag: $flag"
            unless exists $self->{escapes}{$flag};

        $self->{escapes}{$flag}->(\$text);
    }

    return $text;
}

1;

__END__

=head1 NAME

HTML::Mason::Interp - Mason Component Interpreter

=head1 SYNOPSIS

    my $i = HTML::Mason::Interp->new (data_dir=>'/usr/local/mason',
                                      comp_root=>'/usr/local/www/htdocs/',
                                      ...other params...);

=head1 DESCRIPTION

Interp is the Mason workhorse, executing components and routing their
output and errors to all the right places. In a mod_perl environment,
Interp objects are handed off immediately to an ApacheHandler object
which internally calls the Interp implementation methods. In that case
the only user method is the new() constructor.

=head1 PARAMETERS TO THE new() CONSTRUCTOR

=over

=item autohandler_name

File name used for
L<autohandlers|HTML::Mason::Devel/autohandlers>. Default is
"autohandler".  If this is set to an empty string ("") then
autohandlers are turned off entirely.

=item buffer_preallocate_size

=for html <a name="item_buffer_preallocate_size"></a>

Number of bytes to preallocate in the output buffer for each request.
Defaults to 0. Setting this to, say, your maximum page size (or close
to it) can reduce the number of reallocations Perl performs as
components add to the output buffer.

=item code_cache_max_size

=for html <a name="item_code_cache_max_size"></a>

Specifies the maximum number of components that should be held in the
in-memory code cache. The default is 'unlimited', meaning no
components will ever be discarded; Mason can perform certain
optimizations in this mode. Setting this to zero disables the code
cache entirely. See the L<code cache|HTML::Mason::Admin/code cache>
section of the administrator's manual for further details.

=item comp_root

=for html <a name="item_comp_root"></a>

The component root marks the top of your component hierarchy and
defines how component paths are translated into real file paths. For
example, if your component root is F</usr/local/httpd/docs>, a component
path of F</products/index.html> translates to the file
F</usr/local/httpd/docs/products/index.html>.

Under L<Apache|HTML::Mason::ApacheHandler> and
L<CGI|HTML::Mason::CGIHandler>, comp_root defaults to the server's
document root. In standalone mode comp_root defaults to the current
working directory.

This parameter may be either a scalar or an array reference.  If it is
a scalar, it should be a filesystem path indicating the component
root. If it is an array reference, it should be of the following form:

 [ [ foo => '/usr/local/foo' ],
   [ bar => '/usr/local/bar' ] ]

This is an array of two-element array references, not a hash.  The
"keys" for each path must be unique and their "values" must be
filesystem paths.  These paths will be searched in the provided order
whenever a component path is resolved. For example, given the above
component roots and a component path of F</products/index.html>, Mason
would search first for F</usr/local/foo/products/index.html>, then for
F</usr/local/bar/products/index.html>.

The keys are used in several ways. They help to distinguish component
caches and object files between different component roots, and they
appear in the C<title()> of a component.

When you specify a single path for a component root, this is actually
translated into

  [ [ MAIN => path ] ]

If you have turned on L<dynamic_comp_root|HTML::Mason::Params/dynamic_comp_root>, you may modify the
component root(s) of an interpreter between requests by calling
C<$interp-E<gt>comp_root> with a value. However, the path associated
with any given key may not change between requests. For example,
if the initial component root is

 [ [ foo => '/usr/local/foo' ],
   [ bar => '/usr/local/bar' ], ]

then it may not be changed to

 [ [ foo => '/usr/local/bar' ],
   [ bar => '/usr/local/baz' ],

but it may be changed to

 [ [ foo   => '/usr/local/foo' ],
   [ blarg => '/usr/local/blarg' ] ]

In other words, you may add or remove key/path pairs but not modify an
already-used key/path pair. The reason for this restriction is that
the interpreter maintains a component cache per key that would become
invalid if the associated paths were to change.

=item compiler

The Compiler object to associate with this Interpreter.  By default a
new object of class L<compiler_class|HTML::Mason::Params/compiler_class> will be created.

=item compiler_class

The class to use when creating a compiler. Defaults to
L<HTML::Mason::Compiler|HTML::Mason::Compiler>.

=item data_dir

The data directory is a writable directory that Mason uses for various
features and optimizations: for example, component object files and
data cache files. Mason will create the directory on startup, if necessary, and set its
permissions according to the web server User/Group.

Under L<Apache|HTML::Mason::ApacheHandler>, data_dir defaults to a
directory called "mason" under the Apache server root. You will
need to change this on certain systems that assign a high-level
server root such as F</usr>!

In non-Apache environments, data_dir has no default. If it is left
unspecified, Mason will not use L<object files|HTML::Mason::Admin/object files>, and the default
L<data cache class|HTML::Mason::Request/item_cache> will be
C<MemoryCache> instead of C<FileCache>.

=item dynamic_comp_root

True or false, defaults to false. Indicates whether the L<comp_root|HTML::Mason::Params/comp_root>
can be modified on this interpreter between requests. Mason can
perform a few optimizations with a fixed component root, so you
should only set this to true if you actually need it.

=item escape_flags

A hash reference of escape flags to set for this object.  See the
section on the L<set_escape
method|HTML::Mason::Interp/item_set_escape> for more details.

=item ignore_warnings_expr

Regular expression indicating which warnings to ignore when loading
components. Any warning that is not ignored will prevent the
component from being loaded and executed. For example:

    ignore_warnings_expr =>
        'Global symbol.*requires explicit package'

If set to undef, all warnings are heeded. If set to '.', warnings
are turned off completely as a specially optimized case.

By default, this is set to 'Subroutine .* redefined'.  This allows you
to declare global subroutines inside <%once> sections and not receive
an error when the component is reloaded.

=item object_file_extension

Extension to add to the end of object files. Default is ".obj".

=item preloads

A list of component paths, optionally with glob wildcards, to load
when the interpreter initializes. e.g.

    preloads => ['/foo/index.html','/bar/*.pl']

Default is the empty list.  For maximum performance, this should only
be used for components that are frequently viewed and rarely updated.
See the L<preloading components|HTML::Mason::Admin/preloading components> section of the administrator's manual for further details.

As mentioned in the developer's manual, a component's C<< <%once> >>
section is executed when it is loaded.  For preloaded components, this
means that this section will be executed before a Mason or Apache
request exist, so preloading a component that uses C<$m> or C<$r> in a
C<< <%once> >> section will fail.

=item request_class

The class to use when creating requests. Defaults to
L<HTML::Mason::Request|HTML::Mason::Request>.

=item resolver

The Resolver object to associate with this Compiler. By default a new
object of class L<resolver_class|HTML::Mason::Params/resolver_class> will be created.

=item resolver_class

The class to use when creating a resolver. Defaults to
L<HTML::Mason::Resolver::File|HTML::Mason::Resolver::File>.

=item static_source

True or false, default is false. When false, Mason checks the
timestamp of the component source file each time the component is used
to see if it has changed. This provides the instant feedback for
source changes that is expected for development.  However it does
entail a file stat for each component executed.

When true, Mason assumes that the component source tree is unchanging:
it will not check component source files to determine if the memory
cache or object file has expired.  This can save many file stats per
request. However, in order to get Mason to recognize a component
source change, you must flush the memory cache and remove object files.
See L<static_source_touch_file|HTML::Mason::Params/static_source_touch_file> for one easy way to arrange this.

We recommend turning this mode on in your production sites if
possible, if performance is of any concern.

=item static_source_touch_file

Specifies a filename that Mason will check once at the beginning of
of every request. When the file timestamp changes, Mason will (1) clear
its in-memory component cache, and (2) remove object files if
they have not already been deleted by another process.

This provides a convenient way to implement L<static_source|HTML::Mason::Params/static_source> mode.
All you need to do is make sure that a single file gets touched
whenever components change. For Mason's part, checking a single
file at the beginning of a request is much cheaper than checking
every component file when static_source=0.

=item use_object_files

True or false, default is true.  Specifies whether Mason creates
object files to save the results of component parsing. You may want to
turn off object files for disk space reasons, but otherwise this
should be left alone.

=back

=head1 ACCESSOR METHODS

All of the above properties have standard accessor methods of the same
name. Only comp_root and ignore_warnings_expr can be modified in an
existing interpreter; the rest are read-only.

=head1 ESCAPE FLAG METHODS

=over

=item apply_escapes ($text, $flags, [more flags...])

=for html <a name="item_apply_escapes"></a>

This method applies a one or more escapes to a piece of text.  The
escapes are specified by giving their flag.  Each escape is applied to
the text in turn, after which the now-modified text is returned.

=item remove_escape ($name)

=for html <a name="item_remove_escape"></a>

Given an escape name, this removes that escape from the interpreter's
known escapes.  If the name is not recognized, it is simply ignored.

=item set_escape ($name => see below])

=for html <a name="item_set_escape"></a>

This method is called to add an escape flag to the list of known
escapes for the interpreter.  The flag may only consist of the
characters matching C<\w> and the dash (-).  It must start with an
alpha character or an underscore (_).

The right hand side may be one of several things.  It can be a
subroutine reference.  It can also be a string match C</^\w+$/>, in
which case it is assumed to be the name of a subroutine in the
C<HTML::Mason::Escapes> module.  Finally, if it is a string that does
not match the above regex, then it is assumed to be C<eval>able code,
which will return a subroutine reference.

When setting these with C<PerlSetVar> directives in an Apache
configuration file, you can set them like this:

  PerlSetVar  MasonEscapeFlags  "h => \&HTML::Mason::Escapes::basic_html_escape"
  PerlSetVar  MasonEscapeFlags  "flag  => \&subroutine"
  PerlSetVar  MasonEscapeFlags  "uc    => sub { ${$_[0]} = uc ${$_[0]}; }"
  PerlAddVar  MasonEscapeFlags  "thing => other_thing"

=back

=head1 OTHER METHODS

=over

=item comp_exists (path)

=for html <a name="item_comp_exists"></a>

Given an I<absolute> component path, this method returns a boolean
value indicating whether or not a component exists for that path.

=item exec (comp, args...)

=for html <a name="item_exec"></a>

Creates a new HTML::Mason::Request object for the given I<comp> and
I<args>, and executes it. The return value is the return value of
I<comp>, if any.

This is useful for running Mason outside of a web environment.
See L<HTML::Mason::Admin/using Mason from a standalone script>
for examples.

This method isn't generally useful in a mod_perl environment; see
L<subrequests|HTML::Mason::Devel/Subrequests> instead.

=item flush_code_cache

=for html <a name="flush_code_cache"></a>

Empties the component cache. When using Perl 5.00503 or earlier, you
should call this when finished with an interpreter, in order to remove
circular references that would prevent the interpreter from being
destroyed.

=item load (path)

=for html <a name="item_load"></a>

Returns the component object corresponding to an absolute component
C<path>, or undef if none exists. Dies with an error if the component
fails to load because of a syntax error.

=item make_component (comp_source => ... )

=item make_component (comp_file => ... )

=for html <a name="item_make_component"></a>

This method compiles Mason component source code and returns a
Component object.  The source may be passed in as a string in C<comp_source>,
or as a filename in C<comp_file>.  When using C<comp_file>, the
filename is specified as a path on the file system, not as a path
relative to Mason's component root (see 
L<$m-E<gt>fetch_comp|HTML::Mason::Request/item_fetch_comp> for that).

If Mason encounters an error during processing, an exception will be thrown.

Example of usage:

    # Make an anonymous component
    my $anon_comp =
      eval { $interp->make_component
               ( comp_source => '<%perl>my $name = "World";</%perl>Hello <% $name %>!' ) };
    die $@ if $@;

    $m->comp($anon_comp);

=item make_request (@request_params)

=for html <a name="item_make_request"></a>

This method creates a Mason request object. The arguments to be passed
are the same as those for the C<< HTML::Mason::Request->new >>
constructor or its relevant subclass. This method will likely only be
of interest to those attempting to write new handlers or to subclass
C<HTML::Mason::Interp>.  If you want to create a I<subrequest>, see
L<subrequests|HTML::Mason::Devel/Subrequests> instead.

=item purge_code_cache ()

=for html <a name="purge_code_cache"></a>

Called during request execution in order to clear out the code
cache. Mainly useful to subclasses that may want to take some custom
action upon clearing the cache.

=item set_global ($varname, [values...])

=for html <a name="item_set_global"></a>

This method sets a global to be used in components. C<varname> is a
variable name, optionally preceded with a prefix (C<$>, C<@>, or
C<%>); if the prefix is omitted then C<$> is assumed. C<varname> is
followed by a value, in the case of a scalar, or by one or more values
in the case of a list or hash.  For example:

    # Set a global variable $dbh containing the database handle
    $interp->set_global(dbh => DBI->connect(...));

    # Set a global hash %session from a local hash
    $interp->set_global('%session', %s);

The global is set in the package that components run in: usually
C<HTML::Mason::Commands>, although this can be overridden via the
L<in_package|HTML::Mason::Params/in_package> parameter.
The lines above, for example, are equivalent to:

    $HTML::Mason::Commands::dbh = DBI->connect(...);
    %HTML::Mason::Commands::session = %s;

assuming that L<in_package|HTML::Mason::Params/in_package> has not been changed.

Any global that you set should also be registered with the
L<allow_globals|HTML::Mason::Params/allow_globals> parameter; otherwise you'll get warnings from
C<strict>.

=back

=cut