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.
}
/** Build an iterator whose values are iterators too; such a 'subIterator' will end
- * when the value of $callback changes
+ * when the value of $callback changes;
+ * WARNING: will fast-forward the current subiterator until it is over !
* @param iterator The source iterator
* @param callback The callback for detecting changes. XXX: Might be called twice on a given object
* @return an iterator
return new PlSubIterator($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
$callback = new _GetObjectPropertyCallback($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.
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)
{
$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;
}
}
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
private $curval = null;
private $curelt = null;
- private $begin = true;
+ private $val = null;
+ private $pos = 0;
private $stepped = false;
private $over = false;
$this->callback = $callback;
$this->parent = $parent;
$this->next = $next;
+ $this->parent->setNext(null);
}
public function value()
$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;
}
$this->stepped = true;
public function next()
{
+ if ($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;
}
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)
}
}
+// 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:
?>
projects / platal.git / blobdiff