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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 : sh002i 608 if ($courseEnv->{pg}->{options}->{catchWarnings}) {
48 : sh002i 612 warn "PG: about to install a warnings handler...\n"; # ***
49 : sh002i 608 local $SIG{__WARN__} = sub { $warnings .= shift };
50 :     }
51 : sh002i 414
52 :     # create a Translator
53 : sh002i 558 #warn "PG: creating a Translator\n";
54 : sh002i 414 my $translator = WeBWorK::PG::Translator->new;
55 :    
56 : sh002i 424 # set the directory hash
57 : sh002i 558 #warn "PG: setting the directory hash\n";
58 : sh002i 414 $translator->rh_directories({
59 :     courseScriptsDirectory => $courseEnv->{webworkDirs}->{macros},
60 :     macroDirectory => $courseEnv->{courseDirs}->{macros},
61 :     templateDirectory => $courseEnv->{courseDirs}->{templates},
62 :     tempDirectory => $courseEnv->{courseDirs}->{html_temp},
63 :     });
64 :    
65 : sh002i 424 # evaluate modules and "extra packages"
66 : sh002i 558 #warn "PG: evaluating modules and \"extra packages\"\n";
67 : sh002i 424 my @modules = @{ $courseEnv->{pg}->{modules} };
68 : sh002i 476 foreach my $module_packages_ref (@modules) {
69 :     my ($module, @extra_packages) = @$module_packages_ref;
70 :     # the first item is the main package
71 :     $translator->evaluate_modules($module);
72 : sh002i 424 # the remaining items are "extra" packages
73 : sh002i 476 $translator->load_extra_packages(@extra_packages);
74 : sh002i 414 }
75 :    
76 : sh002i 424 # set the environment (from defineProblemEnvir)
77 : sh002i 558 #warn "PG: setting the environment (from defineProblemEnvir)\n";
78 : sh002i 555 my $envir = defineProblemEnvir(
79 : sh002i 502 $courseEnv,
80 :     $user,
81 :     $key,
82 :     $set,
83 :     $problem,
84 :     $psvn,
85 :     $formFields,
86 :     $translationOptions,
87 : sh002i 555 );
88 :     $translator->environment($envir);
89 : sh002i 414
90 : sh002i 424 # initialize the Translator
91 : sh002i 558 #warn "PG: initializing the Translator\n";
92 : sh002i 414 $translator->initialize();
93 :    
94 : sh002i 612 # load IO.pl, PG.pl, and dangerousMacros.pl using unrestricted_load
95 : sh002i 425 # i'd like to change this at some point to have the same sort of interface to global.conf
96 :     # that the module loading does -- have a list of macros to load unrestrictedly.
97 : sh002i 612 #warn "PG: loading IO.pl, PG.pl, and dangerousMacros.pl using unrestricted_load\n";
98 :     foreach (qw(IO.pl PG.pl dangerousMacros.pl)) {
99 :     my $macroPath = $courseEnv->{webworkDirs}->{macros} . "/$_";
100 :     my $err = $translator->unrestricted_load($macroPath);
101 :     warn "Error while loading $macroPath: $err" if $err;
102 :     }
103 :     #my $pg_pl = $courseEnv->{webworkDirs}->{macros} . "/PG.pl";
104 :     #my $dangerousMacros_pl = $courseEnv->{webworkDirs}->{macros} . "/dangerousMacros.pl";
105 :     #my $io_pl = $courseEnv->{webworkDirs}->{macros} . "/IO.pl";
106 :     #my $err = $translator->unrestricted_load($pg_pl);
107 :     #warn "Error while loading $pg_pl: $err" if $err;
108 :     #$err = $translator->unrestricted_load($dangerousMacros_pl);
109 :     #warn "Error while loading $dangerousMacros_pl: $err" if $err;
110 :     #$err = $translator->unrestricted_load($io_pl);
111 :     #warn "Error while loading $io_pl: $err" if $err;
112 : sh002i 414
113 : sh002i 424 # set the opcode mask (using default values)
114 : sh002i 558 #warn "PG: setting the opcode mask (using default values)\n";
115 : sh002i 414 $translator->set_mask();
116 :    
117 : sh002i 424 # store the problem source
118 : sh002i 558 #warn "PG: storing the problem source\n";
119 : sh002i 492 my $sourceFile = $problem->source_file;
120 :     $sourceFile = $courseEnv->{courseDirs}->{templates}."/".$sourceFile
121 :     unless ($sourceFile =~ /^\//);
122 : sh002i 526 eval { $translator->source_string(readFile($sourceFile)) };
123 :     if ($@) {
124 :     # well, we couldn't get the problem source, for some reason.
125 :     return bless {
126 :     translator => $translator,
127 :     head_text => "",
128 :     body_text => <<EOF,
129 :     WeBWorK::Utils::readFile($sourceFile) says:
130 :     $@
131 :     EOF
132 :     answers => {},
133 :     result => {},
134 :     state => {},
135 :     errors => "Failed to read the problem source file.",
136 : sh002i 558 warnings => $warnings,
137 : sh002i 526 flags => {error_flag => 1},
138 :     }, $class;
139 :     }
140 : sh002i 414
141 :     # install a safety filter (&safetyFilter)
142 : sh002i 558 #warn "PG: installing a safety filter\n";
143 : sh002i 414 $translator->rf_safety_filter(\&safetyFilter);
144 :    
145 : sh002i 415 # translate the PG source into text
146 : sh002i 558 #warn "PG: translating the PG source into text\n";
147 : sh002i 415 $translator->translate();
148 :    
149 : sh002i 555 # after we're done translating, we may have to clean up after the translator.
150 :     # for example, 'images' mode uses a tempdir for dvipng's temp files. We have
151 :     # to remove it.
152 :     if ($translationOptions->{displayMode} eq 'images' && $envir->{dvipngTempDir}) {
153 : sh002i 558 rmtree($envir->{dvipngTempDir}, 0, 0);
154 : sh002i 555 }
155 :    
156 : sh002i 476 my ($result, $state); # we'll need these on the other side of the if block!
157 :     if ($translationOptions->{processAnswers}) {
158 :    
159 :     # process student answers
160 : sh002i 558 #warn "PG: processing student answers\n";
161 : sh002i 476 $translator->process_answers($formFields);
162 :    
163 :     # retrieve the problem state and give it to the translator
164 : sh002i 558 #warn "PG: retrieving the problem state and giving it to the translator\n";
165 : sh002i 476 $translator->rh_problem_state({
166 :     recorded_score => $problem->status,
167 :     num_of_correct_ans => $problem->num_correct,
168 :     num_of_incorrect_ans => $problem->num_incorrect,
169 :     });
170 :    
171 :     # determine an entry order -- the ANSWER_ENTRY_ORDER flag is built by
172 :     # the PG macro package (PG.pl)
173 : sh002i 558 #warn "PG: determining an entry order\n";
174 : sh002i 476 my @answerOrder =
175 :     $translator->rh_flags->{ANSWER_ENTRY_ORDER}
176 :     ? @{ $translator->rh_flags->{ANSWER_ENTRY_ORDER} }
177 :     : keys %{ $translator->rh_evaluated_answers };
178 :    
179 :     # install a grader -- use the one specified in the problem,
180 :     # or fall back on the default from the course environment.
181 :     # (two magic strings are accepted, to avoid having to
182 :     # reference code when it would be difficult.)
183 : sh002i 558 #warn "PG: installing a grader\n";
184 : sh002i 476 my $grader = $translator->rh_flags->{PROBLEM_GRADER_TO_USE}
185 :     || $courseEnv->{pg}->{options}->{grader};
186 :     $grader = $translator->rf_std_problem_grader
187 :     if $grader eq "std_problem_grader";
188 :     $grader = $translator->rf_avg_problem_grader
189 :     if $grader eq "avg_problem_grader";
190 :     die "Problem grader $grader is not a CODE reference."
191 :     unless ref $grader eq "CODE";
192 :     $translator->rf_problem_grader($grader);
193 :    
194 :     # grade the problem
195 : sh002i 558 #warn "PG: grading the problem\n";
196 : sh002i 476 ($result, $state) = $translator->grade_problem(
197 :     answers_submitted => $translationOptions->{processAnswers},
198 :     ANSWER_ENTRY_ORDER => \@answerOrder,
199 :     );
200 :    
201 :     }
202 : sh002i 415
203 : sh002i 562 # write timing log entry
204 :     writeTimingLogEntry($courseEnv, "WeBWorK::PG::new", "", "end");
205 :    
206 : sh002i 424 # return an object which contains the translator and the results of
207 :     # the translation process. this is DIFFERENT from the "format expected
208 :     # by Webwork.pm (and I believe processProblem8, but check.)"
209 :     return bless {
210 :     translator => $translator,
211 :     head_text => ${ $translator->r_header },
212 :     body_text => ${ $translator->r_text },
213 :     answers => $translator->rh_evaluated_answers,
214 :     result => $result,
215 :     state => $state,
216 : sh002i 558 errors => $translator->errors,
217 :     warnings => $warnings,
218 : sh002i 424 flags => $translator->rh_flags,
219 :     }, $class;
220 : sh002i 414 }
221 :    
222 :     # -----
223 :    
224 : sh002i 424 sub defineProblemEnvir($$$$$$$) {
225 :     my (
226 :     $courseEnv,
227 :     $user,
228 :     $key,
229 :     $set,
230 :     $problem,
231 :     $psvn,
232 :     $formFields,
233 :     $options,
234 :     ) = @_;
235 : sh002i 414
236 :     my %envir;
237 :    
238 :     # PG environment variables
239 :     # from docs/pglanguage/pgreference/environmentvariables as of 06/25/2002
240 :     # any changes are noted by "ADDED:" or "REMOVED:"
241 :    
242 :     # Vital state information
243 : sh002i 612 # ADDED: displayHintsQ, displaySolutionsQ, refreshMath2img,
244 :     # texDisposition
245 : sh002i 414
246 :     $envir{psvn} = $psvn;
247 :     $envir{psvnNumber} = $envir{psvn};
248 :     $envir{probNum} = $problem->id;
249 :     $envir{questionNumber} = $envir{probNum};
250 :     $envir{fileName} = $problem->source_file;
251 :     $envir{probFileName} = $envir{fileName};
252 :     $envir{problemSeed} = $problem->problem_seed;
253 : sh002i 424 $envir{displayMode} = translateDisplayModeNames($options->{displayMode});
254 : sh002i 414 $envir{languageMode} = $envir{displayMode};
255 :     $envir{outputMode} = $envir{displayMode};
256 : sh002i 424 $envir{displayHintsQ} = $options->{hints};
257 :     $envir{displaySolutionsQ} = $options->{solutions};
258 : sh002i 434 $envir{refreshMath2img} = $options->{refreshMath2img};
259 : sh002i 612 $envir{texDisposition} = "pdf"; # in webwork-modperl, we use pdflatex
260 : sh002i 414
261 :     # Problem Information
262 :     # ADDED: courseName
263 :    
264 :     $envir{openDate} = $set->open_date;
265 : sh002i 424 $envir{formattedOpenDate} = formatDateTime($envir{openDate});
266 : sh002i 414 $envir{dueDate} = $set->due_date;
267 : sh002i 424 $envir{formattedDueDate} = formatDateTime($envir{dueDate});
268 : sh002i 414 $envir{answerDate} = $set->answer_date;
269 : sh002i 424 $envir{formattedAnswerDate} = formatDateTime($envir{answerDate});
270 : sh002i 607 $envir{numOfAttempts} = ($problem->num_correct || 0) + ($problem->num_incorrect || 0);
271 : sh002i 414 $envir{problemValue} = $problem->value;
272 : sh002i 424 $envir{sessionKey} = $key;
273 : sh002i 414 $envir{courseName} = $courseEnv->{courseName};
274 :    
275 :     # Student Information
276 :     # ADDED: studentID
277 :    
278 :     $envir{sectionName} = $user->section;
279 :     $envir{sectionNumber} = $envir{sectionName};
280 :     $envir{recitationName} = $user->recitation;
281 :     $envir{recitationNumber} = $envir{recitationName};
282 :     $envir{setNumber} = $set->id;
283 :     $envir{studentLogin} = $user->id;
284 :     $envir{studentName} = $user->first_name . " " . $user->last_name;
285 : sh002i 424 $envir{studentID} = $user->student_id;
286 : sh002i 414
287 :     # Answer Information
288 : sh002i 434 # REMOVED: refSubmittedAnswers
289 : sh002i 414
290 : sh002i 434 $envir{inputs_ref} = $formFields;
291 : sh002i 414
292 : sh002i 433 # External Programs
293 : sh002i 562 # ADDED: externalLaTeXPath, externalDvipngPath,
294 :     # externalGif2EpsPath, externalPng2EpsPath
295 : sh002i 434
296 : sh002i 433 $envir{externalTTHPath} = $courseEnv->{externalPrograms}->{tth};
297 : sh002i 526 $envir{externalLaTeXPath} = $courseEnv->{externalPrograms}->{latex};
298 :     $envir{externalDvipngPath} = $courseEnv->{externalPrograms}->{dvipng};
299 : sh002i 562 $envir{externalGif2EpsPath} = $courseEnv->{externalPrograms}->{gif2eps};
300 :     $envir{externalPng2EpsPath} = $courseEnv->{externalPrograms}->{png2eps};
301 : sh002i 612 $envir{externalGif2PngPath} = $courseEnv->{externalPrograms}->{gif2png};
302 : sh002i 414
303 :     # Directories and URLs
304 :     # REMOVED: courseName
305 : sh002i 526 # ADDED: dvipngTempDir
306 : sh002i 414
307 :     $envir{cgiDirectory} = undef;
308 :     $envir{cgiURL} = undef;
309 :     $envir{classDirectory} = undef;
310 : sh002i 424 $envir{courseScriptsDirectory} = $courseEnv->{webworkDirs}->{macros}."/";
311 :     $envir{htmlDirectory} = $courseEnv->{courseDirs}->{html}."/";
312 : sh002i 562 $envir{htmlURL} = $courseEnv->{courseURLs}->{html}."/";
313 : sh002i 424 $envir{macroDirectory} = $courseEnv->{courseDirs}->{macros}."/";
314 :     $envir{templateDirectory} = $courseEnv->{courseDirs}->{templates}."/";
315 :     $envir{tempDirectory} = $courseEnv->{courseDirs}->{html_temp}."/";
316 : sh002i 562 $envir{tempURL} = $courseEnv->{courseURLs}->{html_temp}."/";
317 : sh002i 414 $envir{scriptDirectory} = undef;
318 : sh002i 562 $envir{webworkDocsURL} = $courseEnv->{webworkURLs}->{docs}."/";
319 : sh002i 555 $envir{dvipngTempDir} = $options->{displayMode} eq 'images'
320 : sh002i 558 ? tempdir("webwork-dvipng-XXXXXXXX", DIR => $envir{tempDirectory})
321 : sh002i 555 : undef;
322 : sh002i 414
323 : sh002i 433 # Default values for evaluating answers
324 : sh002i 425
325 : sh002i 433 my $ansEvalDefaults = $courseEnv->{pg}->{ansEvalDefaults};
326 :     $envir{$_} = $ansEvalDefaults->{$_} foreach (keys %$ansEvalDefaults);
327 :    
328 :     # Other things...
329 :    
330 : sh002i 425 $envir{PROBLEM_GRADER_TO_USE} = $courseEnv->{pg}->{options}->{grader};
331 :    
332 : sh002i 414 return \%envir;
333 :     }
334 :    
335 : sh002i 424 sub translateDisplayModeNames($) {
336 :     my $name = shift;
337 :     return {
338 : sh002i 476 tex => "TeX",
339 : sh002i 424 plainText => "HTML",
340 :     formattedText => "HTML_tth",
341 : sh002i 433 images => "HTML_img"
342 : sh002i 424 }->{$name};
343 :     }
344 :    
345 : sh002i 414 sub safetyFilter {
346 : sh002i 415 my $answer = shift; # accepts one answer and checks it
347 : sh002i 414 my $submittedAnswer = $answer;
348 :     $answer = '' unless defined $answer;
349 :     my ($errorno);
350 :     $answer =~ tr/\000-\037/ /;
351 :     # Return if answer field is empty
352 :     unless ($answer =~ /\S/) {
353 :     #$errorno = "<BR>No answer was submitted.";
354 :     $errorno = 0; ## don't report blank answer as error
355 :     return ($answer,$errorno);
356 :     }
357 :     # replace ^ with ** (for exponentiation)
358 :     # $answer =~ s/\^/**/g;
359 :     # Return if forbidden characters are found
360 :     unless ($answer =~ /^[a-zA-Z0-9_\-\+ \t\/@%\*\.\n^\(\)]+$/ ) {
361 :     $answer =~ tr/a-zA-Z0-9_\-\+ \t\/@%\*\.\n^\(\)/#/c;
362 :     $errorno = "<BR>There are forbidden characters in your answer: $submittedAnswer<BR>";
363 :     return ($answer,$errorno);
364 :     }
365 :     $errorno = 0;
366 :     return($answer, $errorno);
367 :     }
368 :    
369 :     1;
370 : sh002i 440
371 :     __END__
372 :    
373 :     =head1 SYNOPSIS
374 :    
375 :     $pg = WeBWorK::PG->new(
376 : sh002i 502 $courseEnv, # a WeBWorK::CourseEnvironment object
377 :     $user, # a WeBWorK::User object
378 : sh002i 440 $sessionKey,
379 : sh002i 502 $set, # a WeBWorK::Set object
380 :     $problem, # a WeBWorK::Problem object
381 :     $psvn,
382 :     $formFields # in &WeBWorK::Form::Vars format
383 : sh002i 440 { # translation options
384 :     displayMode => "images", # (plainText|formattedText|images)
385 :     showHints => 1, # (0|1)
386 :     showSolutions => 0, # (0|1)
387 :     refreshMath2img => 0, # (0|1)
388 :     processAnswers => 1, # (0|1)
389 :     },
390 :     );
391 :    
392 :     $translator = $pg->{translator}; # WeBWorK::PG::Translator
393 :     $body = $pg->{body_text}; # text string
394 :     $header = $pg->{head_text}; # text string
395 :     $answerHash = $pg->{answers}; # WeBWorK::PG::AnswerHash
396 :     $result = $pg->{result}; # hash reference
397 :     $state = $pg->{state}; # hash reference
398 :     $errors = $pg->{errors}; # text string
399 :     $warnings = $pg->{warnings}; # text string
400 :     $flags = $pg->{flags}; # hash reference
401 :    
402 :     =head1 DESCRIPTION
403 :    
404 :     WeBWorK::PG encapsulates the PG translation process, making multiple calls to
405 :     WeBWorK::PG::Translator. Much of the flexibility of the Translator is hidden,
406 :     instead making choices that are appropriate for the webwork-modperl system.
407 :    
408 :     =head1 CONSTRUCTION
409 :    
410 :     =over
411 :    
412 : sh002i 502 =item new (ENVIRONMENT, USER, KEY, SET, PROBLEM, PSVN, FIELDS, OPTIONS)
413 : sh002i 440
414 :     The C<new> method creates a translator, initializes it using the parameters
415 :     specified, translates a PG file, and processes answers. It returns a reference
416 :     to a blessed hash containing the results of the translation process.
417 :    
418 :     =back
419 :    
420 :     =head2 Parameters
421 :    
422 :     =over
423 :    
424 :     =item ENVIRONMENT
425 :    
426 :     a WeBWorK::CourseEnvironment object
427 :    
428 :     =item USER
429 :    
430 : sh002i 502 a WeBWorK::User object
431 : sh002i 440
432 :     =item KEY
433 :    
434 :     the session key of the current session
435 :    
436 :     =item SET
437 :    
438 : sh002i 502 a WeBWorK::Set object
439 : sh002i 440
440 :     =item PROBLEM
441 :    
442 : sh002i 526 a WeBWorK::Problem object. The contents of the source_file field can specify a
443 :     PG file either by absolute path or path relative to the "templates" directory.
444 :     I<The caller should remove taint from this value before passing!>
445 : sh002i 440
446 : sh002i 502 =item PSVN
447 :    
448 :     the problem set version number
449 :    
450 :     =item FIELDS
451 :    
452 :     a reference to a hash (as returned by &WeBWorK::Form::Vars) containing form
453 :     fields submitted by a problem processor. The translator will look for fields
454 :     like "AnSwEr[0-9]" containing submitted student answers.
455 :    
456 : sh002i 440 =item OPTIONS
457 :    
458 :     a reference to a hash containing the following data:
459 :    
460 :     =over
461 :    
462 :     =item displayMode
463 :    
464 :     one of "plainText", "formattedText", or "images"
465 :    
466 :     =item showHints
467 :    
468 :     boolean, render hints
469 :    
470 :     =item showSolutions
471 :    
472 :     boolean, render solutions
473 :    
474 :     =item refreshMath2img
475 :    
476 :     boolean, force images created by math2img (in "images" mode) to be recreated,
477 :     even if the PG source has not been updated.
478 :    
479 :     =item processAnswers
480 :    
481 :     boolean, call answer evaluators and graders
482 :    
483 :     =back
484 :    
485 :     =back
486 :    
487 :     =head2 RETURN VALUE
488 :    
489 :     The C<new> method returns a blessed hash reference containing the following
490 :     fields. More information can be found in the documentation for
491 :     WeBWorK::PG::Translator.
492 :    
493 :     =over
494 :    
495 :     =item translator
496 :    
497 :     The WeBWorK::PG::Translator object used to render the problem.
498 :    
499 :     =item head_text
500 :    
501 :     HTML code for the E<lt>headE<gt> block of an resulting web page. Used for
502 :     JavaScript features.
503 :    
504 :     =item body_text
505 :    
506 :     HTML code for the E<lt>bodyE<gt> block of an resulting web page.
507 :    
508 :     =item answers
509 :    
510 :     An C<AnswerHash> object containing submitted answers, and results of answer
511 :     evaluation.
512 :    
513 :     =item result
514 :    
515 :     A hash containing the results of grading the problem.
516 :    
517 :     =item state
518 :    
519 :     A hash containing the new problem state.
520 :    
521 :     =item errors
522 :    
523 :     A string containing any errors encountered while rendering the problem.
524 :    
525 :     =item warnings
526 :    
527 :     A string containing any warnings encountered while rendering the problem.
528 :    
529 :     =item flags
530 :    
531 :     A hash containing PG_flags (see the Translator docs).
532 :    
533 :     =back
534 :    
535 :     =head1 OPERATION
536 :    
537 :     WeBWorK::PG goes through the following operations when constructed:
538 :    
539 :     =over
540 :    
541 :     =item Get database information
542 :    
543 :     Retrieve information about the current user, set, and problem from the
544 :     database.
545 :    
546 :     =item Create a translator
547 :    
548 :     Instantiate a WeBWorK::PG::Translator object.
549 :    
550 :     =item Set the directory hash
551 :    
552 :     Set the translator's directory hash (courseScripts, macros, templates, and temp
553 :     directories) from the course environment.
554 :    
555 :     =item Evaluate PG modules
556 :    
557 :     Using the module list from the course environment (pg->modules), perform a
558 :     "use"-like operation to evaluate modules at runtime.
559 :    
560 :     =item Set the problem environment
561 :    
562 :     Use data from the user, set, and problem, as well as the course environemnt and
563 :     translation options, to set the problem environment.
564 :    
565 :     =item Initialize the translator
566 :    
567 :     Call &WeBWorK::PG::Translator::initialize. What more do you want?
568 :    
569 :     =item Load PG.pl and dangerousMacros.pl
570 :    
571 :     These macros must be loaded without opcode masking, so they are loaded here.
572 :    
573 :     =item Set the opcode mask
574 :    
575 :     Set the opcode mask to the default specified by WeBWorK::PG::Translator.
576 :    
577 :     =item Load the problem source
578 :    
579 :     Give the problem source to the translator.
580 :    
581 :     =item Install a safety filter
582 :    
583 :     The safety filter is used to preprocess student input before evaluation. The
584 :     default safety filter, &WeBWorK::PG::safetyFilter, is used.
585 :    
586 :     =item Translate the problem source
587 :    
588 :     Call &WeBWorK::PG::Translator::translate to render the problem source into the
589 :     format given by the display mode.
590 :    
591 :     =item Process student answers
592 :    
593 :     Use form field inputs to evaluate student answers.
594 :    
595 :     =item Load the problem state
596 :    
597 :     Use values from the database to initialize the problem state, so that the
598 :     grader will have a point of reference.
599 :    
600 :     =item Determine an entry order
601 :    
602 :     Use the ANSWER_ENTRY_ORDER flag to determine the order of answers in the
603 :     problem. This is important for problems with dependancies among parts.
604 :    
605 :     =item Install a grader
606 :    
607 :     Use the PROBLEM_GRADER_TO_USE flag, or a default from the course environment,
608 :     to install a grader.
609 :    
610 :     =item Grade the problem
611 :    
612 :     Use the selected grader to grade the problem.
613 :    
614 :     =back
615 :    
616 :     =head1 AUTHOR
617 :    
618 :     Written by Sam Hathaway, sh002i (at) math.rochester.edu.
619 :    
620 :     =cut

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