MDL-22308 Update lib/bennu to latest upstream.
[moodle.git] / lib / bennu / iCalendar_components.php
1 <?php
3 /**
4  *  BENNU - PHP iCalendar library
5  *  (c) 2005-2006 Ioannis Papaioannou (pj@moodle.org). All rights reserved.
6  *
7  *  Released under the LGPL.
8  *
9  *  See http://bennu.sourceforge.net/ for more information and downloads.
10  *
11  * @author Ioannis Papaioannou 
12  * @license http://www.gnu.org/copyleft/lesser.html GNU Lesser General Public License
13  */
15 class iCalendar_component {
16     var $name             = NULL;
17     var $properties       = NULL;
18     var $components       = NULL;
19     var $valid_properties = NULL;
20     var $valid_components = NULL;
21     /**
22      * Added to hold errors from last run of unserialize
23      * @var $parser_errors array
24      */
25     var $parser_errors = NULL;
27     function __construct() {
28         // Initialize the components array
29         if(empty($this->components)) {
30             $this->components = array();
31             foreach($this->valid_components as $name) {
32                 $this->components[$name] = array();
33             }
34         }
35     }
37     function get_name() {
38         return $this->name;
39     }
41     function add_property($name, $value = NULL, $parameters = NULL) {
43         // Uppercase first of all
44         $name = strtoupper($name);
46         // Are we trying to add a valid property?
47         $xname = false;
48         if(!isset($this->valid_properties[$name])) {
49             // If not, is it an x-name as per RFC 2445?
50             if(!rfc2445_is_xname($name)) {
51                 return false;
52             }
53             // Since this is an xname, all components are supposed to allow this property
54             $xname = true;
55         }
57         // Create a property object of the correct class
58         if($xname) {
59             $property = new iCalendar_property_x;
60             $property->set_name($name);
61         }
62         else {
63             $classname = 'iCalendar_property_'.strtolower(str_replace('-', '_', $name));
64             $property = new $classname;
65         }
67         // If $value is NULL, then this property must define a default value.
68         if($value === NULL) {
69             $value = $property->default_value();
70             if($value === NULL) {
71                 return false;
72             }
73         }
75         // Set this property's parent component to ourselves, because some
76         // properties behave differently according to what component they apply to.
77         $property->set_parent_component($this->name);
79         // Set parameters before value; this helps with some properties which
80         // accept a VALUE parameter, and thus change their default value type.
82         // The parameters must be valid according to property specifications
83         if(!empty($parameters)) {
84             foreach($parameters as $paramname => $paramvalue) {
85                 if(!$property->set_parameter($paramname, $paramvalue)) {
86                     return false;
87                 }
88             }
90             // Some parameters interact among themselves (e.g. ENCODING and VALUE)
91             // so make sure that after the dust settles, these invariants hold true
92             if(!$property->invariant_holds()) {
93                 return false;
94             }
95         }
97         // $value MUST be valid according to the property data type
98         if(!$property->set_value($value)) {
99             return false;
100         }
102         // Check if the property already exists, and is limited to one occurrance,
103         // DON'T overwrite the value - this can be done explicity with set_value() instead.
104         if(!$xname && $this->valid_properties[$name] & RFC2445_ONCE && isset($this->properties[$name])) {
105             return false;
106         } 
107                 else {
108              // Otherwise add it to the instance array for this property
109             $this->properties[$name][] = $property;
110         }
112         // Finally: after all these, does the component invariant hold?
113         if(!$this->invariant_holds()) {
114             // If not, completely undo the property addition
115             array_pop($this->properties[$name]);
116             if(empty($this->properties[$name])) {
117                 unset($this->properties[$name]);
118             }
119             return false;
120         }
122         return true;        
123         
124     }
126     function add_component($component) {
128         // With the detailed interface, you can add only components with this function
129         if(!is_object($component) || !is_subclass_of($component, 'iCalendar_component')) {
130             return false;
131         }
133         $name = $component->get_name();
135         // Only valid components as specified by this component are allowed
136         if(!in_array($name, $this->valid_components)) {
137             return false;
138         }
140         // Add it
141         $this->components[$name][] = $component;
143         return true;
144     }
146     function get_property_list($name) {
147     }
149     function invariant_holds() {
150         return true;
151     }
153     function is_valid() {
154         // If we have any child components, check that they are all valid
155         if(!empty($this->components)) {
156             foreach($this->components as $component => $instances) {
157                 foreach($instances as $number => $instance) {
158                     if(!$instance->is_valid()) {
159                         return false;
160                     }
161                 }
162             }
163         }
165         // Finally, check the valid property list for any mandatory properties
166         // that have not been set and do not have a default value
167         foreach($this->valid_properties as $property => $propdata) {
168             if(($propdata & RFC2445_REQUIRED) && empty($this->properties[$property])) {
169                 $classname = 'iCalendar_property_'.strtolower(str_replace('-', '_', $property));
170                 $object    = new $classname;
171                 if($object->default_value() === NULL) {
172                     return false;
173                 }
174                 unset($object);
175             }
176         }
178         return true;
179     }
180     
181     function serialize() {
182         // Check for validity of the object
183         if(!$this->is_valid()) {
184             return false;
185         }
187         // Maybe the object is valid, but there are some required properties that
188         // have not been given explicit values. In that case, set them to defaults.
189         foreach($this->valid_properties as $property => $propdata) {
190             if(($propdata & RFC2445_REQUIRED) && empty($this->properties[$property])) {
191                 $this->add_property($property);
192             }
193         }
195         // Start tag
196         $string = rfc2445_fold('BEGIN:'.$this->name) . RFC2445_CRLF;
198         // List of properties
199         if(!empty($this->properties)) {
200             foreach($this->properties as $name => $properties) {
201                 foreach($properties as $property) {
202                     $string .= $property->serialize();
203                 }
204             }
205         }
207         // List of components
208         if(!empty($this->components)) {
209             foreach($this->components as $name => $components) {
210                 foreach($components as $component) {
211                     $string .= $component->serialize();
212                 }
213             }
214         }
216         // End tag
217         $string .= rfc2445_fold('END:'.$this->name) . RFC2445_CRLF;
219         return $string;
220     }
221     
222     /**
223     * unserialize()
224     *
225     * I needed a way to convert an iCalendar component back to a Bennu object so I could
226     * easily access and modify it after it had been stored; if this functionality is already
227     * present somewhere in the library, I apologize for adding it here unnecessarily; however,
228     * I couldn't find it so I added it myself.
229     * @param string $string the iCalendar object to load in to this iCalendar_component
230     * @return bool true if the file parsed with no errors. False if there were errors.
231     */
232     
233     function unserialize($string) {
234         $string = rfc2445_unfold($string); // Unfold any long lines
235         $lines = explode(RFC2445_CRLF, $string); // Create an array of lines
236         
237         $components = array(); // Initialise a stack of components
238         $this->clear_errors();
239         foreach ($lines as $key => $line) {
240             // Divide the line up into label, parameters and data fields.
241             if (!preg_match('#^(?P<label>[-[:alnum:]]+)(?P<params>(?:;(?:(?:[-[:alnum:]]+)=(?:[^[:cntrl:]";:,]+|"[^[:cntrl:]"]+")))*):(?P<data>.*)$#', $line, $match)) {
242                 $this->parser_error('Invalid line: '.$key.', ignoring');
243                 continue;
244             }
246             // parse parameters
247             $params = array();
248             if (preg_match_all('#;(?P<param>[-[:alnum:]]+)=(?P<value>[^[:cntrl:]";:,]+|"[^[:cntrl:]"]+")#', $match['params'], $pmatch)) {
249                 $params = array_combine($pmatch['param'], $pmatch['value']);
250             } 
251             $label = $match['label'];
252             $data  = $match['data'];
253             unset($match, $pmatch);
255             if ($label == 'BEGIN') {
256                 // This is the start of a component.
257                 $current_component = array_pop($components); // Get the current component off the stack so we can check its valid components
258                 if ($current_component == null) { // If there's nothing on the stack
259                     $current_component = $this; // use the iCalendar
260                 }
261                 if (in_array($data, $current_component->valid_components)) { // Check that the new component is a valid subcomponent of the current one
262                     if($current_component != $this) {
263                         array_push($components, $current_component); // We're done with the current component, put it back on the stack.
264                     }
265                     if(strpos($data, 'V') === 0) {
266                         $data = substr($data, 1);
267                     }
268                     $cname = 'iCalendar_' . strtolower($data);
269                     $new_component = new $cname;
270                     array_push($components, $new_component); // Push a new component onto the stack
271                 } else {
272                     if($current_component != $this) {
273                         array_push($components, $current_component);
274                         $this->parser_error('Invalid component type on line '.$key);
275                     }                        
276                 }
277                 unset($current_component, $new_component);
278             } else if ($label == 'END') {
279                 // It's the END of a component.
280                 $component = array_pop($components); // Pop the top component off the stack - we're now done with it
281                 $parent_component = array_pop($components); // Pop the component's conatining component off the stack so we can add this component to it.
282                 if($parent_component == null) {
283                     $parent_component = $this; // If there's no components on the stack, use the iCalendar object
284                 }
285                 if ($parent_component->add_component($component) === false) {
286                     $this->parser_error("Failed to add component on line $key");
287                 }
288                 if ($parent_component != $this) { // If we're not using the iCalendar
289                         array_push($components, $parent_component); // Put the component back on the stack
290                 }
291                 unset($parent_component, $component);
292             } else {
293                 
294                 $component = array_pop($components); // Get the component off the stack so we can add properties to it
295                 if ($component == null) { // If there's nothing on the stack
296                     $component = $this; // use the iCalendar
297                 }
299                 if ($component->add_property($label, $data, $params) === false) {
300                     $this->parser_error("Failed to add property '$label' on line $key");
301                 }
303                 if($component != $this) { // If we're not using the iCalendar
304                     array_push($components, $component); // Put the component back on the stack
305                 }
306                 unset($component);
307             }
309         }
310         
311     }
313     function clear_errors() {
314         $this->parser_errors = array();
315     }
317     function parser_error($error) {
318         $this->parser_errors[] = $error;
319     }
323 class iCalendar extends iCalendar_component {
324     var $name = 'VCALENDAR';
326     function __construct() {
327         $this->valid_properties = array(
328             'CALSCALE'    => RFC2445_OPTIONAL | RFC2445_ONCE,
329             'METHOD'      => RFC2445_OPTIONAL | RFC2445_ONCE,
330             'PRODID'      => RFC2445_REQUIRED | RFC2445_ONCE,
331             'VERSION'     => RFC2445_REQUIRED | RFC2445_ONCE,
332             RFC2445_XNAME => RFC2445_OPTIONAL 
333         );
335         $this->valid_components = array(
336             'VEVENT', 'VTODO', 'VJOURNAL', 'VFREEBUSY', 'VTIMEZONE', 'VALARM'
337         );
338         parent::__construct();
339     }
343 class iCalendar_event extends iCalendar_component {
345     var $name       = 'VEVENT';
346     var $properties;
347     
348     function __construct() {
349         
350         $this->valid_components = array('VALARM');
352         $this->valid_properties = array(
353             'CLASS'          => RFC2445_OPTIONAL | RFC2445_ONCE,
354             'CREATED'        => RFC2445_OPTIONAL | RFC2445_ONCE,
355             'DESCRIPTION'    => RFC2445_OPTIONAL | RFC2445_ONCE,
356             // Standard ambiguous here: in 4.6.1 it says that DTSTAMP in optional,
357             // while in 4.8.7.2 it says it's REQUIRED. Go with REQUIRED.
358             'DTSTAMP'        => RFC2445_REQUIRED | RFC2445_ONCE,
359             // Standard ambiguous here: in 4.6.1 it says that DTSTART in optional,
360             // while in 4.8.2.4 it says it's REQUIRED. Go with REQUIRED.
361             'DTSTART'        => RFC2445_REQUIRED | RFC2445_ONCE,
362             'GEO'            => RFC2445_OPTIONAL | RFC2445_ONCE,
363             'LAST-MODIFIED'  => RFC2445_OPTIONAL | RFC2445_ONCE,
364             'LOCATION'       => RFC2445_OPTIONAL | RFC2445_ONCE,
365             'ORGANIZER'      => RFC2445_OPTIONAL | RFC2445_ONCE,
366             'PRIORITY'       => RFC2445_OPTIONAL | RFC2445_ONCE,
367             'SEQUENCE'       => RFC2445_OPTIONAL | RFC2445_ONCE,
368             'STATUS'         => RFC2445_OPTIONAL | RFC2445_ONCE,
369             'SUMMARY'        => RFC2445_OPTIONAL | RFC2445_ONCE,
370             'TRANSP'         => RFC2445_OPTIONAL | RFC2445_ONCE,
371             // Standard ambiguous here: in 4.6.1 it says that UID in optional,
372             // while in 4.8.4.7 it says it's REQUIRED. Go with REQUIRED.
373             'UID'            => RFC2445_REQUIRED | RFC2445_ONCE,
374             'URL'            => RFC2445_OPTIONAL | RFC2445_ONCE,
375             'RECURRENCE-ID'  => RFC2445_OPTIONAL | RFC2445_ONCE,
376             'DTEND'          => RFC2445_OPTIONAL | RFC2445_ONCE,
377             'DURATION'       => RFC2445_OPTIONAL | RFC2445_ONCE,
378             'ATTACH'         => RFC2445_OPTIONAL,
379             'ATTENDEE'       => RFC2445_OPTIONAL,
380             'CATEGORIES'     => RFC2445_OPTIONAL,
381             'COMMENT'        => RFC2445_OPTIONAL,
382             'CONTACT'        => RFC2445_OPTIONAL,
383             'EXDATE'         => RFC2445_OPTIONAL,
384             'EXRULE'         => RFC2445_OPTIONAL,
385             'REQUEST-STATUS' => RFC2445_OPTIONAL,
386             'RELATED-TO'     => RFC2445_OPTIONAL,
387             'RESOURCES'      => RFC2445_OPTIONAL,
388             'RDATE'          => RFC2445_OPTIONAL,
389             'RRULE'          => RFC2445_OPTIONAL,
390             RFC2445_XNAME    => RFC2445_OPTIONAL
391         );
393         parent::__construct();
394     }
396     function invariant_holds() {
397         // DTEND and DURATION must not appear together
398         if(isset($this->properties['DTEND']) && isset($this->properties['DURATION'])) {
399             return false;
400         }
402         
403         if(isset($this->properties['DTEND']) && isset($this->properties['DTSTART'])) {
404             // DTEND must be later than DTSTART
405             // The standard is not clear on how to hande different value types though
406             // TODO: handle this correctly even if the value types are different
407             if($this->properties['DTEND'][0]->value <= $this->properties['DTSTART'][0]->value) {
408                 return false;
409             }
411             // DTEND and DTSTART must have the same value type
412             if($this->properties['DTEND'][0]->val_type != $this->properties['DTSTART'][0]->val_type) {
413                 return false;
414             }
416         }
417         return true;
418     }
422 class iCalendar_todo extends iCalendar_component {
423     var $name       = 'VTODO';
424     var $properties;
426     function __construct() {
427         
428         $this->valid_components = array('VALARM');
430         $this->valid_properties = array(
431             'CLASS'       => RFC2445_OPTIONAL | RFC2445_ONCE,
432             'COMPLETED'   => RFC2445_OPTIONAL | RFC2445_ONCE,
433             'CREATED'     => RFC2445_OPTIONAL | RFC2445_ONCE,
434             'DESCRIPTION' => RFC2445_OPTIONAL | RFC2445_ONCE,
435             'DTSTAMP'     => RFC2445_OPTIONAL | RFC2445_ONCE,
436             'DTSTAP'      => RFC2445_OPTIONAL | RFC2445_ONCE,
437             'GEO'         => RFC2445_OPTIONAL | RFC2445_ONCE,
438             'LAST-MODIFIED' => RFC2445_OPTIONAL | RFC2445_ONCE,
439             'LOCATION'    => RFC2445_OPTIONAL | RFC2445_ONCE,
440             'ORGANIZER'   => RFC2445_OPTIONAL | RFC2445_ONCE,
441             'PERCENT'     => RFC2445_OPTIONAL | RFC2445_ONCE,
442             'PRIORITY'    => RFC2445_OPTIONAL | RFC2445_ONCE,
443             'RECURID'     => RFC2445_OPTIONAL | RFC2445_ONCE,
444             'SEQUENCE'    => RFC2445_OPTIONAL | RFC2445_ONCE,
445             'STATUS'      => RFC2445_OPTIONAL | RFC2445_ONCE,
446             'SUMMARY'     => RFC2445_OPTIONAL | RFC2445_ONCE,
447             'UID'         => RFC2445_OPTIONAL | RFC2445_ONCE,
448             'URL'         => RFC2445_OPTIONAL | RFC2445_ONCE,
449             'DUE'         => RFC2445_OPTIONAL | RFC2445_ONCE,
450             'DURATION'    => RFC2445_OPTIONAL | RFC2445_ONCE,
451             'ATTACH'      => RFC2445_OPTIONAL,
452             'ATTENDEE'    => RFC2445_OPTIONAL,
453             'CATEGORIES'  => RFC2445_OPTIONAL,
454             'COMMENT'     => RFC2445_OPTIONAL,
455             'CONTACT'     => RFC2445_OPTIONAL,
456             'EXDATE'      => RFC2445_OPTIONAL,
457             'EXRULE'      => RFC2445_OPTIONAL,
458             'RSTATUS'     => RFC2445_OPTIONAL,
459             'RELATED'     => RFC2445_OPTIONAL,
460             'RESOURCES'   => RFC2445_OPTIONAL,
461             'RDATE'       => RFC2445_OPTIONAL,
462             'RRULE'       => RFC2445_OPTIONAL,
463             RFC2445_XNAME => RFC2445_OPTIONAL
464         );
466         parent::__construct();
467     }
468     
469     function invariant_holds() {
470         // DTEND and DURATION must not appear together
471         if(isset($this->properties['DTEND']) && isset($this->properties['DURATION'])) {
472             return false;
473         }
475         
476         if(isset($this->properties['DTEND']) && isset($this->properties['DTSTART'])) {
477             // DTEND must be later than DTSTART
478             // The standard is not clear on how to hande different value types though
479             // TODO: handle this correctly even if the value types are different
480             if($this->properties['DTEND'][0]->value <= $this->properties['DTSTART'][0]->value) {
481                 return false;
482             }
484             // DTEND and DTSTART must have the same value type
485             if($this->properties['DTEND'][0]->val_type != $this->properties['DTSTART'][0]->val_type) {
486                 return false;
487             }
489         }
490         
491         if(isset($this->properties['DUE']) && isset($this->properties['DTSTART'])) {
492             if($this->properties['DUE'][0]->value <= $this->properties['DTSTART'][0]->value) {
493                 return false;
494             }   
495         }
496         
497         return true;
498     }
499     
502 class iCalendar_journal extends iCalendar_component {
503     var $name = 'VJOURNAL';
504     var $properties;
505     
506     function __construct() {
507         
508         $this->valid_properties = array(
509             'CLASS'         => RFC2445_OPTIONAL | RFC2445_ONCE,
510             'CREATED'       => RFC2445_OPTIONAL | RFC2445_ONCE,
511             'DESCRIPTION'   => RFC2445_OPTIONAL | RFC2445_ONCE,
512             'DTSTART'       => RFC2445_OPTIONAL | RFC2445_ONCE,
513             'DTSTAMP'       => RFC2445_OPTIONAL | RFC2445_ONCE,
514             'LAST-MODIFIED' => RFC2445_OPTIONAL | RFC2445_ONCE,
515             'ORGANIZER'     => RFC2445_OPTIONAL | RFC2445_ONCE,
516             'RECURRANCE-ID' => RFC2445_OPTIONAL | RFC2445_ONCE,
517             'SEQUENCE'      => RFC2445_OPTIONAL | RFC2445_ONCE,
518             'STATUS'        => RFC2445_OPTIONAL | RFC2445_ONCE,
519             'SUMMARY'       => RFC2445_OPTIONAL | RFC2445_ONCE,
520             'UID'           => RFC2445_OPTIONAL | RFC2445_ONCE,
521             'URL'           => RFC2445_OPTIONAL | RFC2445_ONCE,
522             'ATTACH'        => RFC2445_OPTIONAL,
523             'ATTENDEE'      => RFC2445_OPTIONAL,
524             'CATEGORIES'    => RFC2445_OPTIONAL,
525             'COMMENT'       => RFC2445_OPTIONAL,
526             'CONTACT'       => RFC2445_OPTIONAL,
527             'EXDATE'        => RFC2445_OPTIONAL,
528             'EXRULE'        => RFC2445_OPTIONAL,
529             'RELATED-TO'    => RFC2445_OPTIONAL,
530             'RDATE'         => RFC2445_OPTIONAL,
531             'RRULE'         => RFC2445_OPTIONAL,
532             RFC2445_XNAME   => RFC2445_OPTIONAL            
533         );
534         
535          parent::__construct();
536         
537     }
540 class iCalendar_freebusy extends iCalendar_component {
541     var $name       = 'VFREEBUSY';
542     var $properties;
544     function __construct() {
545         $this->valid_components = array();
546         $this->valid_properties = array(
547             'CONTACT'       => RFC2445_OPTIONAL | RFC2445_ONCE,
548             'DTSTART'       => RFC2445_OPTIONAL | RFC2445_ONCE,
549             'DTEND'         => RFC2445_OPTIONAL | RFC2445_ONCE,
550             'DURATION'      => RFC2445_OPTIONAL | RFC2445_ONCE,
551             'DTSTAMP'       => RFC2445_OPTIONAL | RFC2445_ONCE,
552             'ORGANIZER'     => RFC2445_OPTIONAL | RFC2445_ONCE,
553             'UID'           => RFC2445_OPTIONAL | RFC2445_ONCE,
554             'URL'           => RFC2445_OPTIONAL | RFC2445_ONCE,
555             // TODO: the next two are components of their own!
556             'ATTENDEE'      => RFC2445_OPTIONAL,
557             'COMMENT'       => RFC2445_OPTIONAL,
558             'FREEBUSY'      => RFC2445_OPTIONAL,
559             'RSTATUS'       => RFC2445_OPTIONAL,
560             RFC2445_XNAME   => RFC2445_OPTIONAL
561         );
562         
563         parent::__construct();
564     }
565     
566     function invariant_holds() {
567         // DTEND and DURATION must not appear together
568         if(isset($this->properties['DTEND']) && isset($this->properties['DURATION'])) {
569             return false;
570         }
572         
573         if(isset($this->properties['DTEND']) && isset($this->properties['DTSTART'])) {
574             // DTEND must be later than DTSTART
575             // The standard is not clear on how to hande different value types though
576             // TODO: handle this correctly even if the value types are different
577             if($this->properties['DTEND'][0]->value <= $this->properties['DTSTART'][0]->value) {
578                 return false;
579             }
581             // DTEND and DTSTART must have the same value type
582             if($this->properties['DTEND'][0]->val_type != $this->properties['DTSTART'][0]->val_type) {
583                 return false;
584             }
586         }
587         return true;
588     }
591 class iCalendar_alarm extends iCalendar_component {
592     var $name       = 'VALARM';
593     var $properties;
595     function __construct() {
596         $this->valid_components = array();
597         $this->valid_properties = array(
598             'ACTION'    => RFC2445_REQUIRED | RFC2445_ONCE,
599             'TRIGGER'   => RFC2445_REQUIRED | RFC2445_ONCE,
600             // If one of these 2 occurs, so must the other.
601             'DURATION'  => RFC2445_OPTIONAL | RFC2445_ONCE,
602             'REPEAT'    => RFC2445_OPTIONAL | RFC2445_ONCE, 
603             // The following is required if action == "PROCEDURE" | "AUDIO"           
604             'ATTACH'    => RFC2445_OPTIONAL,
605             // The following is required if trigger == "EMAIL" | "DISPLAY" 
606             'DESCRIPTION'  => RFC2445_OPTIONAL | RFC2445_ONCE,
607             // The following are required if action == "EMAIL"
608             'SUMMARY'   => RFC2445_OPTIONAL | RFC2445_ONCE,
609             'ATTENDEE'  => RFC2445_OPTIONAL,
610             RFC2445_XNAME   => RFC2445_OPTIONAL
611         );
612      
613         parent::__construct();
614     }
615         
616     function invariant_holds() {
617         // DTEND and DURATION must not appear together
618         if(isset($this->properties['ACTION'])) {
619             switch ($this->properties['ACTION'][0]->value) {
620                 case 'AUDIO':
621                     if (!isset($this->properties['ATTACH'])) {
622                         return false;
623                     }
624                     break;
625                 case 'DISPLAY':
626                     if (!isset($this->properties['DESCRIPTION'])) {
627                         return false;
628                     }
629                     break;
630                 case 'EMAIL':
631                     if (!isset($this->properties['DESCRIPTION']) || !isset($this->properties['SUMMARY']) || !isset($this->properties['ATTACH'])) {
632                         return false;
633                     }
634                     break;
635                 case 'PROCEDURE':
636                     if (!isset($this->properties['ATTACH']) || count($this->properties['ATTACH']) > 1) {
637                         return false;
638                     }
639                     break;
640             }
641         }
642         return true;
643     }
644         
645         
648 class iCalendar_timezone extends iCalendar_component {
649     var $name       = 'VTIMEZONE';
650     var $properties;
652     function __construct() {
654         $this->valid_components = array('STANDARD', 'DAYLIGHT');
656         $this->valid_properties = array(
657             'TZID'        => RFC2445_REQUIRED | RFC2445_ONCE,
658             'LAST-MODIFIED'    => RFC2445_OPTIONAL | RFC2445_ONCE,
659             'TZURL'       => RFC2445_OPTIONAL | RFC2445_ONCE,
660             RFC2445_XNAME => RFC2445_OPTIONAL
661         );
662         
663         parent::__construct();
664     }
668 class iCalendar_standard extends iCalendar_component {
669     var $name       = 'STANDARD';
670     var $properties;
671     
672     function __construct() {
673         $this->valid_components = array();
674         $this->valid_properties = array(
675             'DTSTART'   =>  RFC2445_REQUIRED | RFC2445_ONCE,
676             'TZOFFSETTO'    =>  RFC2445_REQUIRED | RFC2445_ONCE,
677             'TZOFFSETFROM'  =>  RFC2445_REQUIRED | RFC2445_ONCE,
678             'COMMENT'   =>  RFC2445_OPTIONAL,
679             'RDATE'   =>  RFC2445_OPTIONAL,
680             'RRULE'   =>  RFC2445_OPTIONAL,
681             'TZNAME'   =>  RFC2445_OPTIONAL,
682             RFC2445_XNAME   =>  RFC2445_OPTIONAL,
683         ); 
684         parent::__construct();
685     }
688 class iCalendar_daylight extends iCalendar_standard {
689     var $name   =   'DAYLIGHT';
692 // REMINDER: DTEND must be later than DTSTART for all components which support both
693 // REMINDER: DUE must be later than DTSTART for all components which support both