X-Git-Url: http://git.polytechnique.org/?a=blobdiff_plain;f=classes%2Fpliteratorutils.php;h=33dbfab19300abf7469dfba5b192417146b1cfa8;hb=1623168586bac6073585130fc2aa864345463ac6;hp=ca71c3c922bff158a6db7a3091ee3b1f2619b5b3;hpb=21f0c57c1dbf7312d76c119faa1413cab5e7fa45;p=platal.git

diff --git a/classes/pliteratorutils.php b/classes/pliteratorutils.php
index ca71c3c..33dbfab 100644
--- a/classes/pliteratorutils.php
+++ b/classes/pliteratorutils.php
@@ -1,6 +1,6 @@
 <?php
 /***************************************************************************
- *  Copyright (C) 2003-2010 Polytechnique.org                              *
+ *  Copyright (C) 2003-2011 Polytechnique.org                              *
  *  http://opensource.polytechnique.org/                                   *
  *                                                                         *
  *  This program is free software; you can redistribute it and/or modify   *
@@ -21,6 +21,13 @@
 
 class PlIteratorUtils
 {
+    /** Builds a new empty iterator
+     */
+    public static function emptyIterator()
+    {
+        return new PlEmptyIterator();
+    }
+
     /** Build an iterator over an array.
      * @param array The array.
      * @param depth The depth of iteration.
@@ -86,7 +93,8 @@ class PlIteratorUtils
     }
 
     /** Build an iterator whose values are iterators too; such a 'subIterator' will end
-     * when the value of $callback changes
+     * when the value of $callback changes;
+     * WARNING: will fast-forward the current subiterator until it is over !
      * @param iterator The source iterator
      * @param callback The callback for detecting changes. XXX: Might be called twice on a given object
      * @return an iterator
@@ -96,6 +104,18 @@ class PlIteratorUtils
         return new PlSubIterator($iterator, $callback);
     }
 
+    /** Build an iterator that will iterate over the given set of iterators, returning consistent
+     * sets of values (i.e only the values for which the result of the callback is the same as that
+     * for the master)
+     * @param iterators The set of iterators
+     * @param callbacks A list of callbacks (one for each iterator), or a single, common, callback
+     * @param master The id of the "master" iterator in the first list
+     */
+    public static function parallelIterator(array $iterators, $callbacks, $master)
+    {
+        return new PlParallelIterator($iterators, $callbacks, $master);
+    }
+
     /** Returns the callback for '$x -> $x[$key]';
      * @param $key the index to retrieve in arrays
      * @return a callback
@@ -115,6 +135,38 @@ class PlIteratorUtils
         $callback = new _GetObjectPropertyCallback($property);
         return array($callback, 'get');
     }
+
+    /** Returns a wrapper around the PlIterator suitable for foreach() iterations
+     */
+    public static function foreachIterator(PlIterator $iterator)
+    {
+        return new SPLIterator($iterator);
+    }
+}
+
+/** Empty iterator
+ */
+class PlEmptyIterator implements PlIterator
+{
+    public function first()
+    {
+        return false;
+    }
+
+    public function last()
+    {
+        return false;
+    }
+
+    public function next()
+    {
+        return null;
+    }
+
+    public function total()
+    {
+        return 0;
+    }
 }
 
 /** Iterates over an array.
@@ -412,6 +464,8 @@ class PlSubIterator implements PlIterator
     private $source;
     private $callback;
     private $next = null; // The next item, if it has been fetched too early by a subiterator
+    private $pos = 0;
+    private $sub = null;
 
     public function __construct(PlIterator $source, $callback)
     {
@@ -419,12 +473,26 @@ class PlSubIterator implements PlIterator
         $this->callback = $callback;
     }
 
+    /** WARNING: this will "fast-forward" the subiterator to its end
+     */
     public function next()
     {
         if ($this->last()) {
             return null;
         } else {
-            return new PlInnerSubIterator($this->source, $this->callback, $this, $this->next);
+            if ($this->sub != null) {
+                while (!$this->sub->last()) {
+                    $this->sub->next();
+                }
+            }
+
+            if ($this->last()) {
+                return null;
+            }
+
+            ++$this->pos;
+            $this->sub = new PlInnerSubIterator($this->source, $this->callback, $this, $this->next);
+            return $this->sub;
         }
     }
 
@@ -435,14 +503,20 @@ class PlSubIterator implements PlIterator
         return $this->source->total();
     }
 
+    /** This will only return true if the current subiterator was the last one,
+     * and if it has been fully used
+     */
     public function last()
     {
+        if ($this->sub != null && !$this->sub->last()) {
+            return false;
+        }
         return ($this->source->last() && $this->next == null);
     }
 
     public function first()
     {
-        return $this->source->first();
+        return $this->pos == 1;
     }
 
     // Called by a subiterator to "rewind" the core iterator
@@ -462,7 +536,8 @@ class PlInnerSubIterator implements PlIterator
 
     private $curval = null;
     private $curelt = null;
-    private $begin = true;
+    private $val = null;
+    private $pos = 0;
     private $stepped = false;
     private $over = false;
 
@@ -472,6 +547,7 @@ class PlInnerSubIterator implements PlIterator
         $this->callback = $callback;
         $this->parent = $parent;
         $this->next = $next;
+        $this->parent->setNext(null);
     }
 
     public function value()
@@ -491,12 +567,18 @@ class PlInnerSubIterator implements PlIterator
             $this->curelt = $this->next;
             $this->next = null;
         } else {
+            if ($this->source->last()) {
+                $this->over = true;
+                return;
+            }
             $this->curelt = $this->source->next();
         }
 
-        if ($this->begin) {
+        if ($this->pos == 0) {
+            $this->val = call_user_func($this->callback, $this->curelt);
+            $this->curval = $this->val;
+        } else {
             $this->curval = call_user_func($this->callback, $this->curelt);
-            $this->begin = false;
         }
 
         $this->stepped = true;
@@ -504,18 +586,24 @@ class PlInnerSubIterator implements PlIterator
 
     public function next()
     {
+        if ($this->over) {
+            return null;
+        }
+
         $this->_step();
+
+        if ($this->over) {
+            return null;
+        }
+
+        ++$this->pos;
         $this->stepped = false;
 
-        if ($this->curelt) {
-            $val = call_user_func($this->callback, $this->curelt);
-            if ($val == $this->curval) {
-                $this->curval = $val;
-                return $this->curelt;
-            } else {
-                $this->parent->setNext($this->curelt);
-            }
+        if ($this->val == $this->curval) {
+            return $this->curelt;
         }
+
+        $this->parent->setNext($this->curelt);
         $this->over = true;
         return null;
     }
@@ -529,14 +617,160 @@ class PlInnerSubIterator implements PlIterator
 
     public function last()
     {
-        return $this->over;
+        if ($this->over) {
+            return true;
+        }
+        $this->_step();
+        return $this->over || ($this->val != $this->curval);
     }
 
     public function first()
     {
-        return false;
+        return $this->pos == 1;
+    }
+
+}
+
+/** Builds an iterator over a set of iterators, from which one is given as 'master';
+ * The arguments are :
+ *  - An array of iterators, to iterate simultaneously
+ *  - An array of callbacks (one attached to each iterator), or a single callback (to
+ *      use for all iterators)
+ *  - The id of the 'master' iterator
+ *
+ * This ParallelIterator will iterate over the iterators, and, at each
+ * step of the master iterator, it will apply the callbacks to the corresponding
+ * iterators and return the values of the "slaves" for which the callback returned the
+ * same value as the callback of the master.
+ *
+ * The callback should compute some kind of index, and never return the same value
+ * twice for a given iterator
+ *
+ * It is assumed that, if the callback for a slave doesn't have the same value
+ * as the value for the master, this means that there is a "hole" in the values
+ * of that slave.
+ *
+ * Example :
+ *   - The callback is 'get the first cell'
+ *   - The master is :
+ *      [0, 1], [1, 13], [2, 42]
+ *   - The first slave (slave1) is :
+ *      [0, 'a'], [2, 'b']
+ *   - The second slave (slave2) is :
+ *      [1, 42], [2, 0]
+ * The resulting iterator would yield :
+ * - array(master => [0, 1], slave1 => [0, 'a'], slave2 => null)
+ * - array(master => [1, 13], slave1 => null, slave2 => [1, 42])
+ * - array(master => [2, 42], slave1 => [1, 'b'], slave2 => [2, 0])
+ */
+class PlParallelIterator implements PlIterator
+{
+    private $iterators;
+    private $ids;
+    private $callbacks;
+
+    private $master_id;
+    private $master;
+
+    private $over = array();
+    private $stepped = array();
+    private $current_elts = array();
+    private $callback_res = array();
+
+    public function __construct(array $iterators, $callbacks, $master)
+    {
+        $this->iterators = $iterators;
+        $this->master_id = $master;
+        $this->master = $iterators[$master];
+
+        $this->ids = array_keys($iterators);
+
+        $v = array_values($callbacks);
+        if (is_array($v[0])) {
+            $this->callbacks = $callbacks;
+        } else {
+            $this->callbacks = array();
+            foreach ($this->ids as $id) {
+                $this->callbacks[$id] = $callbacks;
+            }
+        }
+
+        foreach ($this->ids as $id) {
+            $this->stepped[$id] = false;
+            $this->over[$id] = false;
+            $this->current_elts[$id] = null;
+            $this->callback_res[$id] = null;
+        }
+    }
+
+    private function step($id)
+    {
+        if ($this->stepped[$id]) {
+            return;
+        }
+
+        // Don't do anything if the iterator is at its end
+        if ($this->over[$id]) {
+            $this->stepped[$id] = true;
+            return;
+        }
+
+        $it = $this->iterators[$id];
+        $nxt = $it->next();
+        $this->stepped[$id] = true;
+        if ($nxt === null) {
+            $this->over[$id] = true;
+            $this->current_elts[$id] = null;
+            $this->callback_res[$id] = null;
+            return;
+        }
+        $res = call_user_func($this->callbacks[$id], $nxt);
+        $this->current_elts[$id] = $nxt;
+        $this->callback_res[$id] = $res;
+    }
+
+    private function stepAll()
+    {
+        foreach ($this->ids as $id) {
+            $this->step($id);
+        }
+    }
+
+    public function next()
+    {
+        $this->stepAll();
+        if ($this->current_elts[$this->master_id] === null) {
+            return null;
+        }
+
+        $res = array();
+        $master = $this->callback_res[$this->master_id];
+        foreach ($this->ids as $id) {
+            if ($this->callback_res[$id] == $master) {
+                $res[$id] = $this->current_elts[$id];
+                $this->stepped[$id] = false;
+            } else {
+                $res[$id] = null;
+            }
+        }
+
+        return $res;
+    }
+
+    public function first()
+    {
+        return $this->master->first();
     }
 
+    public function total()
+    {
+        return $this->master->total();
+    }
+
+    public function last()
+    {
+        return $this->master->last();
+    }
 }
 
 // Wrapper class for 'arrayValueCallback' (get field $key of the given array)
@@ -576,5 +810,48 @@ class _GetObjectPropertyCallback
     }
 }
 
+// Wrapper class to build a SPL iterator from a PlIterator
+class SPLIterator implements Iterator
+{
+    private $it;
+    private $pos;
+    private $value;
+
+    public function __construct(PlIterator $it)
+    {
+        $this->it = $it;
+        $this->pos = 0;
+        $this->value = $this->it->next();
+    }
+
+    public function rewind()
+    {
+        if ($this->pos != 0) {
+            throw new Exception("Rewind not supported on this iterator");
+        }
+    }
+
+    public function current()
+    {
+        return $this->value;
+    }
+
+    public function key()
+    {
+        return $this->pos;
+    }
+
+    public function next()
+    {
+        ++$this->pos;
+        $this->value = $this->it->next();
+    }
+
+    public function valid()
+    {
+        return !!$this->value;
+    }
+}
+
 // vim:set et sw=4 sts=4 sws=4 foldmethod=marker enc=utf-8:
 ?>