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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 635 local $SIG{__WARN__} = sub { $warnings .= shift }
48 :     if $courseEnv->{pg}->{options}->{catchWarnings};
49 : sh002i 414
50 :     # create a Translator
51 : sh002i 558 #warn "PG: creating a Translator\n";
52 : sh002i 414 my $translator = WeBWorK::PG::Translator->new;
53 :    
54 : sh002i 424 # set the directory hash
55 : sh002i 558 #warn "PG: setting the directory hash\n";
56 : sh002i 414 $translator->rh_directories({
57 :     courseScriptsDirectory => $courseEnv->{webworkDirs}->{macros},
58 :     macroDirectory => $courseEnv->{courseDirs}->{macros},
59 :     templateDirectory => $courseEnv->{courseDirs}->{templates},
60 :     tempDirectory => $courseEnv->{courseDirs}->{html_temp},
61 :     });
62 :    
63 : sh002i 424 # evaluate modules and "extra packages"
64 : sh002i 558 #warn "PG: evaluating modules and \"extra packages\"\n";
65 : sh002i 424 my @modules = @{ $courseEnv->{pg}->{modules} };
66 : sh002i 476 foreach my $module_packages_ref (@modules) {
67 :     my ($module, @extra_packages) = @$module_packages_ref;
68 :     # the first item is the main package
69 :     $translator->evaluate_modules($module);
70 : sh002i 424 # the remaining items are "extra" packages
71 : sh002i 476 $translator->load_extra_packages(@extra_packages);
72 : sh002i 414 }
73 :    
74 : sh002i 424 # set the environment (from defineProblemEnvir)
75 : sh002i 558 #warn "PG: setting the environment (from defineProblemEnvir)\n";
76 : sh002i 555 my $envir = defineProblemEnvir(
77 : sh002i 502 $courseEnv,
78 :     $user,
79 :     $key,
80 :     $set,
81 :     $problem,
82 :     $psvn,
83 :     $formFields,
84 :     $translationOptions,
85 : sh002i 555 );
86 :     $translator->environment($envir);
87 : sh002i 414
88 : sh002i 424 # initialize the Translator
89 : sh002i 558 #warn "PG: initializing the Translator\n";
90 : sh002i 414 $translator->initialize();
91 :    
92 : sh002i 612 # load IO.pl, PG.pl, and dangerousMacros.pl using unrestricted_load
93 : sh002i 425 # i'd like to change this at some point to have the same sort of interface to global.conf
94 :     # that the module loading does -- have a list of macros to load unrestrictedly.
95 : sh002i 612 #warn "PG: loading IO.pl, PG.pl, and dangerousMacros.pl using unrestricted_load\n";
96 :     foreach (qw(IO.pl PG.pl dangerousMacros.pl)) {
97 :     my $macroPath = $courseEnv->{webworkDirs}->{macros} . "/$_";
98 :     my $err = $translator->unrestricted_load($macroPath);
99 :     warn "Error while loading $macroPath: $err" if $err;
100 :     }
101 :     #my $pg_pl = $courseEnv->{webworkDirs}->{macros} . "/PG.pl";
102 :     #my $dangerousMacros_pl = $courseEnv->{webworkDirs}->{macros} . "/dangerousMacros.pl";
103 :     #my $io_pl = $courseEnv->{webworkDirs}->{macros} . "/IO.pl";
104 :     #my $err = $translator->unrestricted_load($pg_pl);
105 :     #warn "Error while loading $pg_pl: $err" if $err;
106 :     #$err = $translator->unrestricted_load($dangerousMacros_pl);
107 :     #warn "Error while loading $dangerousMacros_pl: $err" if $err;
108 :     #$err = $translator->unrestricted_load($io_pl);
109 :     #warn "Error while loading $io_pl: $err" if $err;
110 : sh002i 414
111 : sh002i 424 # set the opcode mask (using default values)
112 : sh002i 558 #warn "PG: setting the opcode mask (using default values)\n";
113 : sh002i 414 $translator->set_mask();
114 :    
115 : sh002i 424 # store the problem source
116 : sh002i 558 #warn "PG: storing the problem source\n";
117 : sh002i 492 my $sourceFile = $problem->source_file;
118 :     $sourceFile = $courseEnv->{courseDirs}->{templates}."/".$sourceFile
119 :     unless ($sourceFile =~ /^\//);
120 : sh002i 526 eval { $translator->source_string(readFile($sourceFile)) };
121 :     if ($@) {
122 :     # well, we couldn't get the problem source, for some reason.
123 :     return bless {
124 :     translator => $translator,
125 :     head_text => "",
126 :     body_text => <<EOF,
127 :     WeBWorK::Utils::readFile($sourceFile) says:
128 :     $@
129 :     EOF
130 :     answers => {},
131 :     result => {},
132 :     state => {},
133 :     errors => "Failed to read the problem source file.",
134 : sh002i 558 warnings => $warnings,
135 : sh002i 526 flags => {error_flag => 1},
136 :     }, $class;
137 :     }
138 : sh002i 414
139 :     # install a safety filter (&safetyFilter)
140 : sh002i 558 #warn "PG: installing a safety filter\n";
141 : sh002i 414 $translator->rf_safety_filter(\&safetyFilter);
142 :    
143 : sh002i 692 # write timing log entry -- the translator is now all set up
144 :     writeTimingLogEntry($courseEnv, "WeBWorK::PG::new",
145 :     "initialized",
146 :     "intermediate");
147 :    
148 : sh002i 415 # translate the PG source into text
149 : sh002i 558 #warn "PG: translating the PG source into text\n";
150 : sh002i 415 $translator->translate();
151 :    
152 : sh002i 555 # after we're done translating, we may have to clean up after the translator.
153 :     # for example, 'images' mode uses a tempdir for dvipng's temp files. We have
154 :     # to remove it.
155 :     if ($translationOptions->{displayMode} eq 'images' && $envir->{dvipngTempDir}) {
156 : sh002i 558 rmtree($envir->{dvipngTempDir}, 0, 0);
157 : sh002i 555 }
158 :    
159 : sh002i 476 my ($result, $state); # we'll need these on the other side of the if block!
160 :     if ($translationOptions->{processAnswers}) {
161 :    
162 :     # process student answers
163 : sh002i 558 #warn "PG: processing student answers\n";
164 : sh002i 476 $translator->process_answers($formFields);
165 :    
166 :     # retrieve the problem state and give it to the translator
167 : sh002i 558 #warn "PG: retrieving the problem state and giving it to the translator\n";
168 : sh002i 476 $translator->rh_problem_state({
169 :     recorded_score => $problem->status,
170 :     num_of_correct_ans => $problem->num_correct,
171 :     num_of_incorrect_ans => $problem->num_incorrect,
172 :     });
173 :    
174 :     # determine an entry order -- the ANSWER_ENTRY_ORDER flag is built by
175 :     # the PG macro package (PG.pl)
176 : sh002i 558 #warn "PG: determining an entry order\n";
177 : sh002i 476 my @answerOrder =
178 :     $translator->rh_flags->{ANSWER_ENTRY_ORDER}
179 :     ? @{ $translator->rh_flags->{ANSWER_ENTRY_ORDER} }
180 :     : keys %{ $translator->rh_evaluated_answers };
181 :    
182 :     # install a grader -- use the one specified in the problem,
183 :     # or fall back on the default from the course environment.
184 :     # (two magic strings are accepted, to avoid having to
185 :     # reference code when it would be difficult.)
186 : sh002i 558 #warn "PG: installing a grader\n";
187 : sh002i 476 my $grader = $translator->rh_flags->{PROBLEM_GRADER_TO_USE}
188 :     || $courseEnv->{pg}->{options}->{grader};
189 :     $grader = $translator->rf_std_problem_grader
190 :     if $grader eq "std_problem_grader";
191 :     $grader = $translator->rf_avg_problem_grader
192 :     if $grader eq "avg_problem_grader";
193 :     die "Problem grader $grader is not a CODE reference."
194 :     unless ref $grader eq "CODE";
195 :     $translator->rf_problem_grader($grader);
196 :    
197 :     # grade the problem
198 : sh002i 558 #warn "PG: grading the problem\n";
199 : sh002i 476 ($result, $state) = $translator->grade_problem(
200 :     answers_submitted => $translationOptions->{processAnswers},
201 :     ANSWER_ENTRY_ORDER => \@answerOrder,
202 :     );
203 :    
204 :     }
205 : sh002i 415
206 : sh002i 562 # write timing log entry
207 :     writeTimingLogEntry($courseEnv, "WeBWorK::PG::new", "", "end");
208 :    
209 : sh002i 424 # return an object which contains the translator and the results of
210 :     # the translation process. this is DIFFERENT from the "format expected
211 :     # by Webwork.pm (and I believe processProblem8, but check.)"
212 :     return bless {
213 :     translator => $translator,
214 :     head_text => ${ $translator->r_header },
215 :     body_text => ${ $translator->r_text },
216 :     answers => $translator->rh_evaluated_answers,
217 :     result => $result,
218 :     state => $state,
219 : sh002i 558 errors => $translator->errors,
220 :     warnings => $warnings,
221 : sh002i 424 flags => $translator->rh_flags,
222 :     }, $class;
223 : sh002i 414 }
224 :    
225 :     # -----
226 :    
227 : sh002i 424 sub defineProblemEnvir($$$$$$$) {
228 :     my (
229 :     $courseEnv,
230 :     $user,
231 :     $key,
232 :     $set,
233 :     $problem,
234 :     $psvn,
235 :     $formFields,
236 :     $options,
237 :     ) = @_;
238 : sh002i 414
239 :     my %envir;
240 :    
241 :     # PG environment variables
242 :     # from docs/pglanguage/pgreference/environmentvariables as of 06/25/2002
243 :     # any changes are noted by "ADDED:" or "REMOVED:"
244 :    
245 :     # Vital state information
246 : sh002i 612 # ADDED: displayHintsQ, displaySolutionsQ, refreshMath2img,
247 :     # texDisposition
248 : sh002i 414
249 :     $envir{psvn} = $psvn;
250 :     $envir{psvnNumber} = $envir{psvn};
251 :     $envir{probNum} = $problem->id;
252 :     $envir{questionNumber} = $envir{probNum};
253 :     $envir{fileName} = $problem->source_file;
254 :     $envir{probFileName} = $envir{fileName};
255 :     $envir{problemSeed} = $problem->problem_seed;
256 : sh002i 424 $envir{displayMode} = translateDisplayModeNames($options->{displayMode});
257 : sh002i 414 $envir{languageMode} = $envir{displayMode};
258 :     $envir{outputMode} = $envir{displayMode};
259 : sh002i 684 $envir{displayHintsQ} = $options->{showHints};
260 :     $envir{displaySolutionsQ} = $options->{showSolutions};
261 : sh002i 434 $envir{refreshMath2img} = $options->{refreshMath2img};
262 : sh002i 612 $envir{texDisposition} = "pdf"; # in webwork-modperl, we use pdflatex
263 : sh002i 414
264 :     # Problem Information
265 :     # ADDED: courseName
266 :    
267 :     $envir{openDate} = $set->open_date;
268 : sh002i 424 $envir{formattedOpenDate} = formatDateTime($envir{openDate});
269 : sh002i 414 $envir{dueDate} = $set->due_date;
270 : sh002i 424 $envir{formattedDueDate} = formatDateTime($envir{dueDate});
271 : sh002i 414 $envir{answerDate} = $set->answer_date;
272 : sh002i 424 $envir{formattedAnswerDate} = formatDateTime($envir{answerDate});
273 : sh002i 607 $envir{numOfAttempts} = ($problem->num_correct || 0) + ($problem->num_incorrect || 0);
274 : sh002i 414 $envir{problemValue} = $problem->value;
275 : sh002i 424 $envir{sessionKey} = $key;
276 : sh002i 414 $envir{courseName} = $courseEnv->{courseName};
277 :    
278 :     # Student Information
279 :     # ADDED: studentID
280 :    
281 :     $envir{sectionName} = $user->section;
282 :     $envir{sectionNumber} = $envir{sectionName};
283 :     $envir{recitationName} = $user->recitation;
284 :     $envir{recitationNumber} = $envir{recitationName};
285 :     $envir{setNumber} = $set->id;
286 :     $envir{studentLogin} = $user->id;
287 :     $envir{studentName} = $user->first_name . " " . $user->last_name;
288 : sh002i 424 $envir{studentID} = $user->student_id;
289 : sh002i 414
290 :     # Answer Information
291 : sh002i 434 # REMOVED: refSubmittedAnswers
292 : sh002i 414
293 : sh002i 434 $envir{inputs_ref} = $formFields;
294 : sh002i 414
295 : sh002i 433 # External Programs
296 : sh002i 562 # ADDED: externalLaTeXPath, externalDvipngPath,
297 :     # externalGif2EpsPath, externalPng2EpsPath
298 : sh002i 434
299 : sh002i 433 $envir{externalTTHPath} = $courseEnv->{externalPrograms}->{tth};
300 : sh002i 526 $envir{externalLaTeXPath} = $courseEnv->{externalPrograms}->{latex};
301 :     $envir{externalDvipngPath} = $courseEnv->{externalPrograms}->{dvipng};
302 : sh002i 562 $envir{externalGif2EpsPath} = $courseEnv->{externalPrograms}->{gif2eps};
303 :     $envir{externalPng2EpsPath} = $courseEnv->{externalPrograms}->{png2eps};
304 : sh002i 612 $envir{externalGif2PngPath} = $courseEnv->{externalPrograms}->{gif2png};
305 : sh002i 414
306 :     # Directories and URLs
307 :     # REMOVED: courseName
308 : sh002i 526 # ADDED: dvipngTempDir
309 : sh002i 414
310 :     $envir{cgiDirectory} = undef;
311 :     $envir{cgiURL} = undef;
312 :     $envir{classDirectory} = undef;
313 : sh002i 424 $envir{courseScriptsDirectory} = $courseEnv->{webworkDirs}->{macros}."/";
314 :     $envir{htmlDirectory} = $courseEnv->{courseDirs}->{html}."/";
315 : sh002i 562 $envir{htmlURL} = $courseEnv->{courseURLs}->{html}."/";
316 : sh002i 424 $envir{macroDirectory} = $courseEnv->{courseDirs}->{macros}."/";
317 :     $envir{templateDirectory} = $courseEnv->{courseDirs}->{templates}."/";
318 :     $envir{tempDirectory} = $courseEnv->{courseDirs}->{html_temp}."/";
319 : sh002i 562 $envir{tempURL} = $courseEnv->{courseURLs}->{html_temp}."/";
320 : sh002i 414 $envir{scriptDirectory} = undef;
321 : sh002i 562 $envir{webworkDocsURL} = $courseEnv->{webworkURLs}->{docs}."/";
322 : sh002i 555 $envir{dvipngTempDir} = $options->{displayMode} eq 'images'
323 : sh002i 558 ? tempdir("webwork-dvipng-XXXXXXXX", DIR => $envir{tempDirectory})
324 : sh002i 555 : undef;
325 : sh002i 414
326 : sh002i 623 # Information for sending mail
327 :    
328 :     $envir{mailSmtpServer} = $courseEnv->{mail}->{smtpServer};
329 :     $envir{mailSmtpSender} = $courseEnv->{mail}->{smtpSender};
330 :    
331 : sh002i 433 # Default values for evaluating answers
332 : sh002i 425
333 : sh002i 433 my $ansEvalDefaults = $courseEnv->{pg}->{ansEvalDefaults};
334 :     $envir{$_} = $ansEvalDefaults->{$_} foreach (keys %$ansEvalDefaults);
335 :    
336 :     # Other things...
337 :    
338 : sh002i 425 $envir{PROBLEM_GRADER_TO_USE} = $courseEnv->{pg}->{options}->{grader};
339 :    
340 : sh002i 414 return \%envir;
341 :     }
342 :    
343 : sh002i 424 sub translateDisplayModeNames($) {
344 :     my $name = shift;
345 :     return {
346 : sh002i 476 tex => "TeX",
347 : sh002i 424 plainText => "HTML",
348 :     formattedText => "HTML_tth",
349 : sh002i 433 images => "HTML_img"
350 : sh002i 424 }->{$name};
351 :     }
352 :    
353 : sh002i 414 sub safetyFilter {
354 : sh002i 415 my $answer = shift; # accepts one answer and checks it
355 : sh002i 414 my $submittedAnswer = $answer;
356 :     $answer = '' unless defined $answer;
357 :     my ($errorno);
358 :     $answer =~ tr/\000-\037/ /;
359 :     # Return if answer field is empty
360 :     unless ($answer =~ /\S/) {
361 :     #$errorno = "<BR>No answer was submitted.";
362 :     $errorno = 0; ## don't report blank answer as error
363 :     return ($answer,$errorno);
364 :     }
365 :     # replace ^ with ** (for exponentiation)
366 :     # $answer =~ s/\^/**/g;
367 : sh002i 623 # Return if forbidden characters are found
368 : sh002i 414 unless ($answer =~ /^[a-zA-Z0-9_\-\+ \t\/@%\*\.\n^\(\)]+$/ ) {
369 :     $answer =~ tr/a-zA-Z0-9_\-\+ \t\/@%\*\.\n^\(\)/#/c;
370 :     $errorno = "<BR>There are forbidden characters in your answer: $submittedAnswer<BR>";
371 :     return ($answer,$errorno);
372 :     }
373 :     $errorno = 0;
374 :     return($answer, $errorno);
375 :     }
376 :    
377 :     1;
378 : sh002i 440
379 :     __END__
380 :    
381 :     =head1 SYNOPSIS
382 :    
383 :     $pg = WeBWorK::PG->new(
384 : sh002i 502 $courseEnv, # a WeBWorK::CourseEnvironment object
385 :     $user, # a WeBWorK::User object
386 : sh002i 440 $sessionKey,
387 : sh002i 502 $set, # a WeBWorK::Set object
388 :     $problem, # a WeBWorK::Problem object
389 :     $psvn,
390 :     $formFields # in &WeBWorK::Form::Vars format
391 : sh002i 440 { # translation options
392 :     displayMode => "images", # (plainText|formattedText|images)
393 :     showHints => 1, # (0|1)
394 :     showSolutions => 0, # (0|1)
395 :     refreshMath2img => 0, # (0|1)
396 :     processAnswers => 1, # (0|1)
397 :     },
398 :     );
399 :    
400 :     $translator = $pg->{translator}; # WeBWorK::PG::Translator
401 :     $body = $pg->{body_text}; # text string
402 :     $header = $pg->{head_text}; # text string
403 :     $answerHash = $pg->{answers}; # WeBWorK::PG::AnswerHash
404 :     $result = $pg->{result}; # hash reference
405 :     $state = $pg->{state}; # hash reference
406 :     $errors = $pg->{errors}; # text string
407 :     $warnings = $pg->{warnings}; # text string
408 :     $flags = $pg->{flags}; # hash reference
409 :    
410 :     =head1 DESCRIPTION
411 :    
412 :     WeBWorK::PG encapsulates the PG translation process, making multiple calls to
413 :     WeBWorK::PG::Translator. Much of the flexibility of the Translator is hidden,
414 :     instead making choices that are appropriate for the webwork-modperl system.
415 :    
416 :     =head1 CONSTRUCTION
417 :    
418 :     =over
419 :    
420 : sh002i 502 =item new (ENVIRONMENT, USER, KEY, SET, PROBLEM, PSVN, FIELDS, OPTIONS)
421 : sh002i 440
422 :     The C<new> method creates a translator, initializes it using the parameters
423 :     specified, translates a PG file, and processes answers. It returns a reference
424 :     to a blessed hash containing the results of the translation process.
425 :    
426 :     =back
427 :    
428 :     =head2 Parameters
429 :    
430 :     =over
431 :    
432 :     =item ENVIRONMENT
433 :    
434 :     a WeBWorK::CourseEnvironment object
435 :    
436 :     =item USER
437 :    
438 : sh002i 502 a WeBWorK::User object
439 : sh002i 440
440 :     =item KEY
441 :    
442 :     the session key of the current session
443 :    
444 :     =item SET
445 :    
446 : sh002i 502 a WeBWorK::Set object
447 : sh002i 440
448 :     =item PROBLEM
449 :    
450 : sh002i 526 a WeBWorK::Problem object. The contents of the source_file field can specify a
451 :     PG file either by absolute path or path relative to the "templates" directory.
452 :     I<The caller should remove taint from this value before passing!>
453 : sh002i 440
454 : sh002i 502 =item PSVN
455 :    
456 :     the problem set version number
457 :    
458 :     =item FIELDS
459 :    
460 :     a reference to a hash (as returned by &WeBWorK::Form::Vars) containing form
461 :     fields submitted by a problem processor. The translator will look for fields
462 :     like "AnSwEr[0-9]" containing submitted student answers.
463 :    
464 : sh002i 440 =item OPTIONS
465 :    
466 :     a reference to a hash containing the following data:
467 :    
468 :     =over
469 :    
470 :     =item displayMode
471 :    
472 :     one of "plainText", "formattedText", or "images"
473 :    
474 :     =item showHints
475 :    
476 :     boolean, render hints
477 :    
478 :     =item showSolutions
479 :    
480 :     boolean, render solutions
481 :    
482 :     =item refreshMath2img
483 :    
484 :     boolean, force images created by math2img (in "images" mode) to be recreated,
485 :     even if the PG source has not been updated.
486 :    
487 :     =item processAnswers
488 :    
489 :     boolean, call answer evaluators and graders
490 :    
491 :     =back
492 :    
493 :     =back
494 :    
495 :     =head2 RETURN VALUE
496 :    
497 :     The C<new> method returns a blessed hash reference containing the following
498 :     fields. More information can be found in the documentation for
499 :     WeBWorK::PG::Translator.
500 :    
501 :     =over
502 :    
503 :     =item translator
504 :    
505 :     The WeBWorK::PG::Translator object used to render the problem.
506 :    
507 :     =item head_text
508 :    
509 :     HTML code for the E<lt>headE<gt> block of an resulting web page. Used for
510 :     JavaScript features.
511 :    
512 :     =item body_text
513 :    
514 :     HTML code for the E<lt>bodyE<gt> block of an resulting web page.
515 :    
516 :     =item answers
517 :    
518 :     An C<AnswerHash> object containing submitted answers, and results of answer
519 :     evaluation.
520 :    
521 :     =item result
522 :    
523 :     A hash containing the results of grading the problem.
524 :    
525 :     =item state
526 :    
527 :     A hash containing the new problem state.
528 :    
529 :     =item errors
530 :    
531 :     A string containing any errors encountered while rendering the problem.
532 :    
533 :     =item warnings
534 :    
535 :     A string containing any warnings encountered while rendering the problem.
536 :    
537 :     =item flags
538 :    
539 :     A hash containing PG_flags (see the Translator docs).
540 :    
541 :     =back
542 :    
543 :     =head1 OPERATION
544 :    
545 :     WeBWorK::PG goes through the following operations when constructed:
546 :    
547 :     =over
548 :    
549 :     =item Get database information
550 :    
551 :     Retrieve information about the current user, set, and problem from the
552 :     database.
553 :    
554 :     =item Create a translator
555 :    
556 :     Instantiate a WeBWorK::PG::Translator object.
557 :    
558 :     =item Set the directory hash
559 :    
560 :     Set the translator's directory hash (courseScripts, macros, templates, and temp
561 :     directories) from the course environment.
562 :    
563 :     =item Evaluate PG modules
564 :    
565 :     Using the module list from the course environment (pg->modules), perform a
566 :     "use"-like operation to evaluate modules at runtime.
567 :    
568 :     =item Set the problem environment
569 :    
570 :     Use data from the user, set, and problem, as well as the course environemnt and
571 :     translation options, to set the problem environment.
572 :    
573 :     =item Initialize the translator
574 :    
575 :     Call &WeBWorK::PG::Translator::initialize. What more do you want?
576 :    
577 :     =item Load PG.pl and dangerousMacros.pl
578 :    
579 :     These macros must be loaded without opcode masking, so they are loaded here.
580 :    
581 :     =item Set the opcode mask
582 :    
583 :     Set the opcode mask to the default specified by WeBWorK::PG::Translator.
584 :    
585 :     =item Load the problem source
586 :    
587 :     Give the problem source to the translator.
588 :    
589 :     =item Install a safety filter
590 :    
591 :     The safety filter is used to preprocess student input before evaluation. The
592 :     default safety filter, &WeBWorK::PG::safetyFilter, is used.
593 :    
594 :     =item Translate the problem source
595 :    
596 :     Call &WeBWorK::PG::Translator::translate to render the problem source into the
597 :     format given by the display mode.
598 :    
599 :     =item Process student answers
600 :    
601 :     Use form field inputs to evaluate student answers.
602 :    
603 :     =item Load the problem state
604 :    
605 :     Use values from the database to initialize the problem state, so that the
606 :     grader will have a point of reference.
607 :    
608 :     =item Determine an entry order
609 :    
610 :     Use the ANSWER_ENTRY_ORDER flag to determine the order of answers in the
611 :     problem. This is important for problems with dependancies among parts.
612 :    
613 :     =item Install a grader
614 :    
615 :     Use the PROBLEM_GRADER_TO_USE flag, or a default from the course environment,
616 :     to install a grader.
617 :    
618 :     =item Grade the problem
619 :    
620 :     Use the selected grader to grade the problem.
621 :    
622 :     =back
623 :    
624 :     =head1 AUTHOR
625 :    
626 :     Written by Sam Hathaway, sh002i (at) math.rochester.edu.
627 :    
628 :     =cut

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