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1 : sh002i 440 ################################################################################
2 : sh002i 494 # WeBWorK mod_perl (c) 2000-2002 WeBWorK Project
3 : sh002i 440 # $Id$
4 :     ################################################################################
5 :    
6 : sh002i 424 package WeBWorK::PG;
7 : sh002i 414
8 : sh002i 455 =head1 NAME
9 :    
10 : sh002i 476 WeBWorK::PG - Wrap the action of the PG Translator in an easy-to-use API.
11 : sh002i 455
12 :     =cut
13 :    
14 : sh002i 414 use strict;
15 :     use warnings;
16 : sh002i 555 use File::Path qw(rmtree);
17 : sh002i 526 use File::Temp qw(tempdir);
18 : sh002i 414 use WeBWorK::DB::Classlist;
19 :     use WeBWorK::DB::WW;
20 :     use WeBWorK::PG::Translator;
21 : sh002i 492 use WeBWorK::Problem;
22 : sh002i 562 use WeBWorK::Utils qw(readFile formatDateTime writeTimingLogEntry);
23 : sh002i 414
24 : sh002i 424 sub new($$$$$$$$) {
25 : sh002i 415 my $invocant = shift;
26 :     my $class = ref($invocant) || $invocant;
27 : sh002i 424 my (
28 :     $courseEnv,
29 : sh002i 502 $user,
30 : sh002i 424 $key,
31 : sh002i 502 $set,
32 :     $problem,
33 :     $psvn,
34 :     $formFields, # in CGI::Vars format
35 : sh002i 424 $translationOptions, # hashref containing options for the
36 :     # translator, such as whether to show
37 :     # hints and the display mode to use
38 :     ) = @_;
39 : sh002i 415
40 : sh002i 562 # write timing log entry
41 :     writeTimingLogEntry($courseEnv, "WeBWorK::PG::new",
42 :     "user=".$user->id.",problem=".$courseEnv->{courseName}."/".$set->id."/".$problem->id.",mode=".$translationOptions->{displayMode},
43 :     "begin");
44 :    
45 : sh002i 558 # install a local warn handler to collect warnings
46 :     my $warnings = "";
47 :     local $SIG{__WARN__} = sub { $warnings .= shift };
48 : sh002i 414
49 :     # create a Translator
50 : sh002i 558 #warn "PG: creating a Translator\n";
51 : sh002i 414 my $translator = WeBWorK::PG::Translator->new;
52 :    
53 : sh002i 424 # set the directory hash
54 : sh002i 558 #warn "PG: setting the directory hash\n";
55 : sh002i 414 $translator->rh_directories({
56 :     courseScriptsDirectory => $courseEnv->{webworkDirs}->{macros},
57 :     macroDirectory => $courseEnv->{courseDirs}->{macros},
58 :     templateDirectory => $courseEnv->{courseDirs}->{templates},
59 :     tempDirectory => $courseEnv->{courseDirs}->{html_temp},
60 :     });
61 :    
62 : sh002i 424 # evaluate modules and "extra packages"
63 : sh002i 558 #warn "PG: evaluating modules and \"extra packages\"\n";
64 : sh002i 424 my @modules = @{ $courseEnv->{pg}->{modules} };
65 : sh002i 476 foreach my $module_packages_ref (@modules) {
66 :     my ($module, @extra_packages) = @$module_packages_ref;
67 :     # the first item is the main package
68 :     $translator->evaluate_modules($module);
69 : sh002i 424 # the remaining items are "extra" packages
70 : sh002i 476 $translator->load_extra_packages(@extra_packages);
71 : sh002i 414 }
72 :    
73 : sh002i 424 # set the environment (from defineProblemEnvir)
74 : sh002i 558 #warn "PG: setting the environment (from defineProblemEnvir)\n";
75 : sh002i 555 my $envir = defineProblemEnvir(
76 : sh002i 502 $courseEnv,
77 :     $user,
78 :     $key,
79 :     $set,
80 :     $problem,
81 :     $psvn,
82 :     $formFields,
83 :     $translationOptions,
84 : sh002i 555 );
85 :     $translator->environment($envir);
86 : sh002i 414
87 : sh002i 424 # initialize the Translator
88 : sh002i 558 #warn "PG: initializing the Translator\n";
89 : sh002i 414 $translator->initialize();
90 :    
91 : sh002i 424 # load PG.pl and dangerousMacros.pl using unrestricted_load
92 : sh002i 425 # i'd like to change this at some point to have the same sort of interface to global.conf
93 :     # that the module loading does -- have a list of macros to load unrestrictedly.
94 : sh002i 558 #warn "PG: loading PG.pl and dangerousMacros.pl using unrestricted_load\n";
95 : sh002i 414 my $pg_pl = $courseEnv->{webworkDirs}->{macros} . "/PG.pl";
96 : sh002i 424 my $dangerousMacros_pl = $courseEnv->{webworkDirs}->{macros} . "/dangerousMacros.pl";
97 : sh002i 562 my $io_pl = $courseEnv->{webworkDirs}->{macros} . "/IO.pl";
98 : sh002i 414 my $err = $translator->unrestricted_load($pg_pl);
99 :     warn "Error while loading $pg_pl: $err" if $err;
100 :     $err = $translator->unrestricted_load($dangerousMacros_pl);
101 :     warn "Error while loading $dangerousMacros_pl: $err" if $err;
102 : sh002i 562 $err = $translator->unrestricted_load($io_pl);
103 :     warn "Error while loading $io_pl: $err" if $err;
104 : sh002i 414
105 : sh002i 424 # set the opcode mask (using default values)
106 : sh002i 558 #warn "PG: setting the opcode mask (using default values)\n";
107 : sh002i 414 $translator->set_mask();
108 :    
109 : sh002i 424 # store the problem source
110 : sh002i 558 #warn "PG: storing the problem source\n";
111 : sh002i 492 my $sourceFile = $problem->source_file;
112 :     $sourceFile = $courseEnv->{courseDirs}->{templates}."/".$sourceFile
113 :     unless ($sourceFile =~ /^\//);
114 : sh002i 526 eval { $translator->source_string(readFile($sourceFile)) };
115 :     if ($@) {
116 :     # well, we couldn't get the problem source, for some reason.
117 :     return bless {
118 :     translator => $translator,
119 :     head_text => "",
120 :     body_text => <<EOF,
121 :     WeBWorK::Utils::readFile($sourceFile) says:
122 :     $@
123 :     EOF
124 :     answers => {},
125 :     result => {},
126 :     state => {},
127 :     errors => "Failed to read the problem source file.",
128 : sh002i 558 warnings => $warnings,
129 : sh002i 526 flags => {error_flag => 1},
130 :     }, $class;
131 :     }
132 : sh002i 414
133 :     # install a safety filter (&safetyFilter)
134 : sh002i 558 #warn "PG: installing a safety filter\n";
135 : sh002i 414 $translator->rf_safety_filter(\&safetyFilter);
136 :    
137 : sh002i 415 # translate the PG source into text
138 : sh002i 558 #warn "PG: translating the PG source into text\n";
139 : sh002i 415 $translator->translate();
140 :    
141 : sh002i 555 # after we're done translating, we may have to clean up after the translator.
142 :     # for example, 'images' mode uses a tempdir for dvipng's temp files. We have
143 :     # to remove it.
144 :     if ($translationOptions->{displayMode} eq 'images' && $envir->{dvipngTempDir}) {
145 : sh002i 558 rmtree($envir->{dvipngTempDir}, 0, 0);
146 : sh002i 555 }
147 :    
148 : sh002i 476 my ($result, $state); # we'll need these on the other side of the if block!
149 :     if ($translationOptions->{processAnswers}) {
150 :    
151 :     # process student answers
152 : sh002i 558 #warn "PG: processing student answers\n";
153 : sh002i 476 $translator->process_answers($formFields);
154 :    
155 :     # retrieve the problem state and give it to the translator
156 : sh002i 558 #warn "PG: retrieving the problem state and giving it to the translator\n";
157 : sh002i 476 $translator->rh_problem_state({
158 :     recorded_score => $problem->status,
159 :     num_of_correct_ans => $problem->num_correct,
160 :     num_of_incorrect_ans => $problem->num_incorrect,
161 :     });
162 :    
163 :     # determine an entry order -- the ANSWER_ENTRY_ORDER flag is built by
164 :     # the PG macro package (PG.pl)
165 : sh002i 558 #warn "PG: determining an entry order\n";
166 : sh002i 476 my @answerOrder =
167 :     $translator->rh_flags->{ANSWER_ENTRY_ORDER}
168 :     ? @{ $translator->rh_flags->{ANSWER_ENTRY_ORDER} }
169 :     : keys %{ $translator->rh_evaluated_answers };
170 :    
171 :     # install a grader -- use the one specified in the problem,
172 :     # or fall back on the default from the course environment.
173 :     # (two magic strings are accepted, to avoid having to
174 :     # reference code when it would be difficult.)
175 : sh002i 558 #warn "PG: installing a grader\n";
176 : sh002i 476 my $grader = $translator->rh_flags->{PROBLEM_GRADER_TO_USE}
177 :     || $courseEnv->{pg}->{options}->{grader};
178 :     $grader = $translator->rf_std_problem_grader
179 :     if $grader eq "std_problem_grader";
180 :     $grader = $translator->rf_avg_problem_grader
181 :     if $grader eq "avg_problem_grader";
182 :     die "Problem grader $grader is not a CODE reference."
183 :     unless ref $grader eq "CODE";
184 :     $translator->rf_problem_grader($grader);
185 :    
186 :     # grade the problem
187 : sh002i 558 #warn "PG: grading the problem\n";
188 : sh002i 476 ($result, $state) = $translator->grade_problem(
189 :     answers_submitted => $translationOptions->{processAnswers},
190 :     ANSWER_ENTRY_ORDER => \@answerOrder,
191 :     );
192 :    
193 :     }
194 : sh002i 415
195 : sh002i 562 # write timing log entry
196 :     writeTimingLogEntry($courseEnv, "WeBWorK::PG::new", "", "end");
197 :    
198 : sh002i 424 # return an object which contains the translator and the results of
199 :     # the translation process. this is DIFFERENT from the "format expected
200 :     # by Webwork.pm (and I believe processProblem8, but check.)"
201 :     return bless {
202 :     translator => $translator,
203 :     head_text => ${ $translator->r_header },
204 :     body_text => ${ $translator->r_text },
205 :     answers => $translator->rh_evaluated_answers,
206 :     result => $result,
207 :     state => $state,
208 : sh002i 558 errors => $translator->errors,
209 :     warnings => $warnings,
210 : sh002i 424 flags => $translator->rh_flags,
211 :     }, $class;
212 : sh002i 414 }
213 :    
214 :     # -----
215 :    
216 : sh002i 424 sub defineProblemEnvir($$$$$$$) {
217 :     my (
218 :     $courseEnv,
219 :     $user,
220 :     $key,
221 :     $set,
222 :     $problem,
223 :     $psvn,
224 :     $formFields,
225 :     $options,
226 :     ) = @_;
227 : sh002i 414
228 :     my %envir;
229 :    
230 :     # PG environment variables
231 :     # from docs/pglanguage/pgreference/environmentvariables as of 06/25/2002
232 :     # any changes are noted by "ADDED:" or "REMOVED:"
233 :    
234 :     # Vital state information
235 : sh002i 476 # ADDED: displayHintsQ, displaySolutionsQ, refreshMath2img
236 : sh002i 414
237 :     $envir{psvn} = $psvn;
238 :     $envir{psvnNumber} = $envir{psvn};
239 :     $envir{probNum} = $problem->id;
240 :     $envir{questionNumber} = $envir{probNum};
241 :     $envir{fileName} = $problem->source_file;
242 :     $envir{probFileName} = $envir{fileName};
243 :     $envir{problemSeed} = $problem->problem_seed;
244 : sh002i 424 $envir{displayMode} = translateDisplayModeNames($options->{displayMode});
245 : sh002i 414 $envir{languageMode} = $envir{displayMode};
246 :     $envir{outputMode} = $envir{displayMode};
247 : sh002i 424 $envir{displayHintsQ} = $options->{hints};
248 :     $envir{displaySolutionsQ} = $options->{solutions};
249 : sh002i 434 $envir{refreshMath2img} = $options->{refreshMath2img};
250 : sh002i 414
251 :     # Problem Information
252 :     # ADDED: courseName
253 :    
254 :     $envir{openDate} = $set->open_date;
255 : sh002i 424 $envir{formattedOpenDate} = formatDateTime($envir{openDate});
256 : sh002i 414 $envir{dueDate} = $set->due_date;
257 : sh002i 424 $envir{formattedDueDate} = formatDateTime($envir{dueDate});
258 : sh002i 414 $envir{answerDate} = $set->answer_date;
259 : sh002i 424 $envir{formattedAnswerDate} = formatDateTime($envir{answerDate});
260 : sh002i 414 $envir{numOfAttempts} = $problem->num_correct + $problem->num_incorrect;
261 :     $envir{problemValue} = $problem->value;
262 : sh002i 424 $envir{sessionKey} = $key;
263 : sh002i 414 $envir{courseName} = $courseEnv->{courseName};
264 :    
265 :     # Student Information
266 :     # ADDED: studentID
267 :    
268 :     $envir{sectionName} = $user->section;
269 :     $envir{sectionNumber} = $envir{sectionName};
270 :     $envir{recitationName} = $user->recitation;
271 :     $envir{recitationNumber} = $envir{recitationName};
272 :     $envir{setNumber} = $set->id;
273 :     $envir{studentLogin} = $user->id;
274 :     $envir{studentName} = $user->first_name . " " . $user->last_name;
275 : sh002i 424 $envir{studentID} = $user->student_id;
276 : sh002i 414
277 :     # Answer Information
278 : sh002i 434 # REMOVED: refSubmittedAnswers
279 : sh002i 414
280 : sh002i 434 $envir{inputs_ref} = $formFields;
281 : sh002i 414
282 : sh002i 433 # External Programs
283 : sh002i 562 # ADDED: externalLaTeXPath, externalDvipngPath,
284 :     # externalGif2EpsPath, externalPng2EpsPath
285 : sh002i 434
286 : sh002i 433 $envir{externalTTHPath} = $courseEnv->{externalPrograms}->{tth};
287 : sh002i 526 $envir{externalLaTeXPath} = $courseEnv->{externalPrograms}->{latex};
288 :     $envir{externalDvipngPath} = $courseEnv->{externalPrograms}->{dvipng};
289 : sh002i 562 $envir{externalGif2EpsPath} = $courseEnv->{externalPrograms}->{gif2eps};
290 :     $envir{externalPng2EpsPath} = $courseEnv->{externalPrograms}->{png2eps};
291 : sh002i 414
292 :     # Directories and URLs
293 :     # REMOVED: courseName
294 : sh002i 526 # ADDED: dvipngTempDir
295 : sh002i 414
296 : sh002i 526
297 : sh002i 414 $envir{cgiDirectory} = undef;
298 :     $envir{cgiURL} = undef;
299 :     $envir{classDirectory} = undef;
300 : sh002i 424 $envir{courseScriptsDirectory} = $courseEnv->{webworkDirs}->{macros}."/";
301 :     $envir{htmlDirectory} = $courseEnv->{courseDirs}->{html}."/";
302 : sh002i 562 $envir{htmlURL} = $courseEnv->{courseURLs}->{html}."/";
303 : sh002i 424 $envir{macroDirectory} = $courseEnv->{courseDirs}->{macros}."/";
304 :     $envir{templateDirectory} = $courseEnv->{courseDirs}->{templates}."/";
305 :     $envir{tempDirectory} = $courseEnv->{courseDirs}->{html_temp}."/";
306 : sh002i 562 $envir{tempURL} = $courseEnv->{courseURLs}->{html_temp}."/";
307 : sh002i 414 $envir{scriptDirectory} = undef;
308 : sh002i 562 $envir{webworkDocsURL} = $courseEnv->{webworkURLs}->{docs}."/";
309 : sh002i 555 $envir{dvipngTempDir} = $options->{displayMode} eq 'images'
310 : sh002i 558 ? tempdir("webwork-dvipng-XXXXXXXX", DIR => $envir{tempDirectory})
311 : sh002i 555 : undef;
312 : sh002i 414
313 : sh002i 433 # Default values for evaluating answers
314 : sh002i 425
315 : sh002i 433 my $ansEvalDefaults = $courseEnv->{pg}->{ansEvalDefaults};
316 :     $envir{$_} = $ansEvalDefaults->{$_} foreach (keys %$ansEvalDefaults);
317 :    
318 :     # Other things...
319 :    
320 : sh002i 425 $envir{PROBLEM_GRADER_TO_USE} = $courseEnv->{pg}->{options}->{grader};
321 :    
322 : sh002i 414 return \%envir;
323 :     }
324 :    
325 : sh002i 424 sub translateDisplayModeNames($) {
326 :     my $name = shift;
327 :     return {
328 : sh002i 476 tex => "TeX",
329 : sh002i 424 plainText => "HTML",
330 :     formattedText => "HTML_tth",
331 : sh002i 433 images => "HTML_img"
332 : sh002i 424 }->{$name};
333 :     }
334 :    
335 : sh002i 414 sub safetyFilter {
336 : sh002i 415 my $answer = shift; # accepts one answer and checks it
337 : sh002i 414 my $submittedAnswer = $answer;
338 :     $answer = '' unless defined $answer;
339 :     my ($errorno);
340 :     $answer =~ tr/\000-\037/ /;
341 :     # Return if answer field is empty
342 :     unless ($answer =~ /\S/) {
343 :     #$errorno = "<BR>No answer was submitted.";
344 :     $errorno = 0; ## don't report blank answer as error
345 :     return ($answer,$errorno);
346 :     }
347 :     # replace ^ with ** (for exponentiation)
348 :     # $answer =~ s/\^/**/g;
349 :     # Return if forbidden characters are found
350 :     unless ($answer =~ /^[a-zA-Z0-9_\-\+ \t\/@%\*\.\n^\(\)]+$/ ) {
351 :     $answer =~ tr/a-zA-Z0-9_\-\+ \t\/@%\*\.\n^\(\)/#/c;
352 :     $errorno = "<BR>There are forbidden characters in your answer: $submittedAnswer<BR>";
353 :     return ($answer,$errorno);
354 :     }
355 :     $errorno = 0;
356 :     return($answer, $errorno);
357 :     }
358 :    
359 :     1;
360 : sh002i 440
361 :     __END__
362 :    
363 :     =head1 SYNOPSIS
364 :    
365 :     $pg = WeBWorK::PG->new(
366 : sh002i 502 $courseEnv, # a WeBWorK::CourseEnvironment object
367 :     $user, # a WeBWorK::User object
368 : sh002i 440 $sessionKey,
369 : sh002i 502 $set, # a WeBWorK::Set object
370 :     $problem, # a WeBWorK::Problem object
371 :     $psvn,
372 :     $formFields # in &WeBWorK::Form::Vars format
373 : sh002i 440 { # translation options
374 :     displayMode => "images", # (plainText|formattedText|images)
375 :     showHints => 1, # (0|1)
376 :     showSolutions => 0, # (0|1)
377 :     refreshMath2img => 0, # (0|1)
378 :     processAnswers => 1, # (0|1)
379 :     },
380 :     );
381 :    
382 :     $translator = $pg->{translator}; # WeBWorK::PG::Translator
383 :     $body = $pg->{body_text}; # text string
384 :     $header = $pg->{head_text}; # text string
385 :     $answerHash = $pg->{answers}; # WeBWorK::PG::AnswerHash
386 :     $result = $pg->{result}; # hash reference
387 :     $state = $pg->{state}; # hash reference
388 :     $errors = $pg->{errors}; # text string
389 :     $warnings = $pg->{warnings}; # text string
390 :     $flags = $pg->{flags}; # hash reference
391 :    
392 :     =head1 DESCRIPTION
393 :    
394 :     WeBWorK::PG encapsulates the PG translation process, making multiple calls to
395 :     WeBWorK::PG::Translator. Much of the flexibility of the Translator is hidden,
396 :     instead making choices that are appropriate for the webwork-modperl system.
397 :    
398 :     =head1 CONSTRUCTION
399 :    
400 :     =over
401 :    
402 : sh002i 502 =item new (ENVIRONMENT, USER, KEY, SET, PROBLEM, PSVN, FIELDS, OPTIONS)
403 : sh002i 440
404 :     The C<new> method creates a translator, initializes it using the parameters
405 :     specified, translates a PG file, and processes answers. It returns a reference
406 :     to a blessed hash containing the results of the translation process.
407 :    
408 :     =back
409 :    
410 :     =head2 Parameters
411 :    
412 :     =over
413 :    
414 :     =item ENVIRONMENT
415 :    
416 :     a WeBWorK::CourseEnvironment object
417 :    
418 :     =item USER
419 :    
420 : sh002i 502 a WeBWorK::User object
421 : sh002i 440
422 :     =item KEY
423 :    
424 :     the session key of the current session
425 :    
426 :     =item SET
427 :    
428 : sh002i 502 a WeBWorK::Set object
429 : sh002i 440
430 :     =item PROBLEM
431 :    
432 : sh002i 526 a WeBWorK::Problem object. The contents of the source_file field can specify a
433 :     PG file either by absolute path or path relative to the "templates" directory.
434 :     I<The caller should remove taint from this value before passing!>
435 : sh002i 440
436 : sh002i 502 =item PSVN
437 :    
438 :     the problem set version number
439 :    
440 :     =item FIELDS
441 :    
442 :     a reference to a hash (as returned by &WeBWorK::Form::Vars) containing form
443 :     fields submitted by a problem processor. The translator will look for fields
444 :     like "AnSwEr[0-9]" containing submitted student answers.
445 :    
446 : sh002i 440 =item OPTIONS
447 :    
448 :     a reference to a hash containing the following data:
449 :    
450 :     =over
451 :    
452 :     =item displayMode
453 :    
454 :     one of "plainText", "formattedText", or "images"
455 :    
456 :     =item showHints
457 :    
458 :     boolean, render hints
459 :    
460 :     =item showSolutions
461 :    
462 :     boolean, render solutions
463 :    
464 :     =item refreshMath2img
465 :    
466 :     boolean, force images created by math2img (in "images" mode) to be recreated,
467 :     even if the PG source has not been updated.
468 :    
469 :     =item processAnswers
470 :    
471 :     boolean, call answer evaluators and graders
472 :    
473 :     =back
474 :    
475 :     =back
476 :    
477 :     =head2 RETURN VALUE
478 :    
479 :     The C<new> method returns a blessed hash reference containing the following
480 :     fields. More information can be found in the documentation for
481 :     WeBWorK::PG::Translator.
482 :    
483 :     =over
484 :    
485 :     =item translator
486 :    
487 :     The WeBWorK::PG::Translator object used to render the problem.
488 :    
489 :     =item head_text
490 :    
491 :     HTML code for the E<lt>headE<gt> block of an resulting web page. Used for
492 :     JavaScript features.
493 :    
494 :     =item body_text
495 :    
496 :     HTML code for the E<lt>bodyE<gt> block of an resulting web page.
497 :    
498 :     =item answers
499 :    
500 :     An C<AnswerHash> object containing submitted answers, and results of answer
501 :     evaluation.
502 :    
503 :     =item result
504 :    
505 :     A hash containing the results of grading the problem.
506 :    
507 :     =item state
508 :    
509 :     A hash containing the new problem state.
510 :    
511 :     =item errors
512 :    
513 :     A string containing any errors encountered while rendering the problem.
514 :    
515 :     =item warnings
516 :    
517 :     A string containing any warnings encountered while rendering the problem.
518 :    
519 :     =item flags
520 :    
521 :     A hash containing PG_flags (see the Translator docs).
522 :    
523 :     =back
524 :    
525 :     =head1 OPERATION
526 :    
527 :     WeBWorK::PG goes through the following operations when constructed:
528 :    
529 :     =over
530 :    
531 :     =item Get database information
532 :    
533 :     Retrieve information about the current user, set, and problem from the
534 :     database.
535 :    
536 :     =item Create a translator
537 :    
538 :     Instantiate a WeBWorK::PG::Translator object.
539 :    
540 :     =item Set the directory hash
541 :    
542 :     Set the translator's directory hash (courseScripts, macros, templates, and temp
543 :     directories) from the course environment.
544 :    
545 :     =item Evaluate PG modules
546 :    
547 :     Using the module list from the course environment (pg->modules), perform a
548 :     "use"-like operation to evaluate modules at runtime.
549 :    
550 :     =item Set the problem environment
551 :    
552 :     Use data from the user, set, and problem, as well as the course environemnt and
553 :     translation options, to set the problem environment.
554 :    
555 :     =item Initialize the translator
556 :    
557 :     Call &WeBWorK::PG::Translator::initialize. What more do you want?
558 :    
559 :     =item Load PG.pl and dangerousMacros.pl
560 :    
561 :     These macros must be loaded without opcode masking, so they are loaded here.
562 :    
563 :     =item Set the opcode mask
564 :    
565 :     Set the opcode mask to the default specified by WeBWorK::PG::Translator.
566 :    
567 :     =item Load the problem source
568 :    
569 :     Give the problem source to the translator.
570 :    
571 :     =item Install a safety filter
572 :    
573 :     The safety filter is used to preprocess student input before evaluation. The
574 :     default safety filter, &WeBWorK::PG::safetyFilter, is used.
575 :    
576 :     =item Translate the problem source
577 :    
578 :     Call &WeBWorK::PG::Translator::translate to render the problem source into the
579 :     format given by the display mode.
580 :    
581 :     =item Process student answers
582 :    
583 :     Use form field inputs to evaluate student answers.
584 :    
585 :     =item Load the problem state
586 :    
587 :     Use values from the database to initialize the problem state, so that the
588 :     grader will have a point of reference.
589 :    
590 :     =item Determine an entry order
591 :    
592 :     Use the ANSWER_ENTRY_ORDER flag to determine the order of answers in the
593 :     problem. This is important for problems with dependancies among parts.
594 :    
595 :     =item Install a grader
596 :    
597 :     Use the PROBLEM_GRADER_TO_USE flag, or a default from the course environment,
598 :     to install a grader.
599 :    
600 :     =item Grade the problem
601 :    
602 :     Use the selected grader to grade the problem.
603 :    
604 :     =back
605 :    
606 :     =head1 AUTHOR
607 :    
608 :     Written by Sam Hathaway, sh002i (at) math.rochester.edu.
609 :    
610 :     =cut

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