includes/Categoryfinder.php

   1 <?php
   2
   3 /**
   4  * The "Categoryfinder" class takes a list of articles, creates an internal
   5  * representation of all their parent categories (as well as parents of
   6  * parents etc.). From this representation, it determines which of these
   7  * articles are in one or all of a given subset of categories.
   8  *
   9  * Example use :
  10  * <code>
  11  *      # Determines whether the article with the page_id 12345 is in both
  12  *      # "Category 1" and "Category 2" or their subcategories, respectively
  13  *
  14  *      $cf = new Categoryfinder ;
  15  *      $cf->seed (
  16  *              array ( 12345 ) ,
  17  *              array ( "Category 1","Category 2" ) ,
  18  *              "AND"
  19  *      ) ;
  20  *      $a = $cf->run() ;
  21  *      print implode ( "," , $a ) ;
  22  * </code>
  23  *
  24  */
  25 class Categoryfinder {
  26
  27         var $articles = array () ; # The original article IDs passed to the seed function
  28         var $deadend = array () ; # Array of DBKEY category names for categories that don't have a page
  29         var $parents = array () ; # Array of [ID => array()]
  30         var $next = array () ; # Array of article/category IDs
  31         var $targets = array () ; # Array of DBKEY category names
  32         var $name2id = array () ;
  33         var $mode ; # "AND" or "OR"
  34         var $dbr ; # Read-DB slave
  35
  36         /**
  37          * Constructor (currently empty).
  38          */
  39         function __construct() {
  40         }
  41
  42         /**
  43          * Initializes the instance. Do this prior to calling run().
  44          * @param $article_ids Array of article IDs
  45          * @param $categories FIXME
  46          * @param $mode String: FIXME, default 'AND'.
  47          */
  48         function seed ( $article_ids , $categories , $mode = "AND" ) {
  49                 $this->articles = $article_ids ;
  50                 $this->next = $article_ids ;
  51                 $this->mode = $mode ;
  52
  53                 # Set the list of target categories; convert them to DBKEY form first
  54                 $this->targets = array () ;
  55                 foreach ( $categories AS $c ) {
  56                         $ct = Title::makeTitleSafe( NS_CATEGORY, $c );
  57                         if( $ct ) {
  58                                 $c = $ct->getDBkey();
  59                                 $this->targets[$c] = $c;
  60                         }
  61                 }
  62         }
  63
  64         /**
  65          * Iterates through the parent tree starting with the seed values,
  66          * then checks the articles if they match the conditions
  67          * @return array of page_ids (those given to seed() that match the conditions)
  68          */
  69         function run () {
  70                 $this->dbr = wfGetDB( DB_SLAVE );
  71                 while ( count ( $this->next ) > 0 ) {
  72                         $this->scan_next_layer () ;
  73                 }
  74
  75                 # Now check if this applies to the individual articles
  76                 $ret = array () ;
  77                 foreach ( $this->articles AS $article ) {
  78                         $conds = $this->targets ;
  79                         if ( $this->check ( $article , $conds ) ) {
  80                                 # Matches the conditions
  81                                 $ret[] = $article ;
  82                         }
  83                 }
  84                 return $ret ;
  85         }
  86
  87         /**
  88          * This functions recurses through the parent representation, trying to match the conditions
  89          * @param $id The article/category to check
  90          * @param $conds The array of categories to match
  91          * @param $path used to check for recursion loops
  92          * @return bool Does this match the conditions?
  93          */
  94         function check ( $id , &$conds, $path=array() ) {
  95                 // Check for loops and stop!
  96                 if( in_array( $id, $path ) )
  97                         return false;
  98                 $path[] = $id;
  99
 100                 # Shortcut (runtime paranoia): No contitions=all matched
 101                 if ( count ( $conds ) == 0 ) return true ;
 102
 103                 if ( !isset ( $this->parents[$id] ) ) return false ;
 104
 105                 # iterate through the parents
 106                 foreach ( $this->parents[$id] AS $p ) {
 107                         $pname = $p->cl_to ;
 108
 109                         # Is this a condition?
 110                         if ( isset ( $conds[$pname] ) ) {
 111                                 # This key is in the category list!
 112                                 if ( $this->mode == "OR" ) {
 113                                         # One found, that's enough!
 114                                         $conds = array () ;
 115                                         return true ;
 116                                 } else {
 117                                         # Assuming "AND" as default
 118                                         unset ( $conds[$pname] ) ;
 119                                         if ( count ( $conds ) == 0 ) {
 120                                                 # All conditions met, done
 121                                                 return true ;
 122                                         }
 123                                 }
 124                         }
 125
 126                         # Not done yet, try sub-parents
 127                         if ( !isset ( $this->name2id[$pname] ) ) {
 128                                 # No sub-parent
 129                                 continue ;
 130                         }
 131                         $done = $this->check ( $this->name2id[$pname] , $conds, $path );
 132                         if ( $done OR count ( $conds ) == 0 ) {
 133                                 # Subparents have done it!
 134                                 return true ;
 135                         }
 136                 }
 137                 return false ;
 138         }
 139
 140         /**
 141          * Scans a "parent layer" of the articles/categories in $this->next
 142          */
 143         function scan_next_layer () {
 144                 $fname = "Categoryfinder::scan_next_layer" ;
 145
 146                 # Find all parents of the article currently in $this->next
 147                 $layer = array () ;
 148                 $res = $this->dbr->select(
 149                                 /* FROM   */ 'categorylinks',
 150                                 /* SELECT */ '*',
 151                                 /* WHERE  */ array( 'cl_from' => $this->next ),
 152                                 $fname."-1"
 153                 );
 154                 while ( $o = $this->dbr->fetchObject( $res ) ) {
 155                         $k = $o->cl_to ;
 156
 157                         # Update parent tree
 158                         if ( !isset ( $this->parents[$o->cl_from] ) ) {
 159                                 $this->parents[$o->cl_from] = array () ;
 160                         }
 161                         $this->parents[$o->cl_from][$k] = $o ;
 162
 163                         # Ignore those we already have
 164                         if ( in_array ( $k , $this->deadend ) ) continue ;
 165                         if ( isset ( $this->name2id[$k] ) ) continue ;
 166
 167                         # Hey, new category!
 168                         $layer[$k] = $k ;
 169                 }
 170                 $this->dbr->freeResult( $res ) ;
 171
 172                 $this->next = array() ;
 173
 174                 # Find the IDs of all category pages in $layer, if they exist
 175                 if ( count ( $layer ) > 0 ) {
 176                         $res = $this->dbr->select(
 177                                         /* FROM   */ 'page',
 178                                         /* SELECT */ 'page_id,page_title',
 179                                         /* WHERE  */ array( 'page_namespace' => NS_CATEGORY , 'page_title' => $layer ),
 180                                         $fname."-2"
 181                         );
 182                         while ( $o = $this->dbr->fetchObject( $res ) ) {
 183                                 $id = $o->page_id ;
 184                                 $name = $o->page_title ;
 185                                 $this->name2id[$name] = $id ;
 186                                 $this->next[] = $id ;
 187                                 unset ( $layer[$name] ) ;
 188                         }
 189                         $this->dbr->freeResult( $res ) ;
 190                         }
 191
 192                 # Mark dead ends
 193                 foreach ( $layer AS $v ) {
 194                         $this->deadend[$v] = $v ;
 195                 }
 196         }
 197
 198 } # END OF CLASS "Categoryfinder"