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<a href="#gstreamer-GstIterator.description" class="shortcut">Description</a>
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<h2><span class="refentrytitle"><a name="gstreamer-GstIterator.top_of_page"></a>GstIterator</span></h2>
<p>GstIterator — Object to retrieve multiple elements in a threadsafe
way.</p>
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<a name="gstreamer-GstIterator.synopsis"></a><h2>Synopsis</h2>
<pre class="synopsis">
#include <gst/gst.h>
struct <a class="link" href="gstreamer-GstIterator.html#GstIterator" title="struct GstIterator">GstIterator</a>;
enum <a class="link" href="gstreamer-GstIterator.html#GstIteratorItem" title="enum GstIteratorItem">GstIteratorItem</a>;
enum <a class="link" href="gstreamer-GstIterator.html#GstIteratorResult" title="enum GstIteratorResult">GstIteratorResult</a>;
<span class="returnvalue">void</span> (<a class="link" href="gstreamer-GstIterator.html#GstIteratorCopyFunction" title="GstIteratorCopyFunction ()">*GstIteratorCopyFunction</a>) (<em class="parameter"><code>const <a class="link" href="gstreamer-GstIterator.html#GstIterator" title="struct GstIterator"><span class="type">GstIterator</span></a> *it</code></em>,
<em class="parameter"><code><a class="link" href="gstreamer-GstIterator.html#GstIterator" title="struct GstIterator"><span class="type">GstIterator</span></a> *copy</code></em>);
<a class="link" href="gstreamer-GstIterator.html#GstIteratorResult" title="enum GstIteratorResult"><span class="returnvalue">GstIteratorResult</span></a> (<a class="link" href="gstreamer-GstIterator.html#GstIteratorNextFunction" title="GstIteratorNextFunction ()">*GstIteratorNextFunction</a>) (<em class="parameter"><code><a class="link" href="gstreamer-GstIterator.html#GstIterator" title="struct GstIterator"><span class="type">GstIterator</span></a> *it</code></em>,
<em class="parameter"><code><a href="http://library.gnome.org/devel/gobject/unstable/gobject-Generic-values.html#GValue"><span class="type">GValue</span></a> *result</code></em>);
<a class="link" href="gstreamer-GstIterator.html#GstIteratorItem" title="enum GstIteratorItem"><span class="returnvalue">GstIteratorItem</span></a> (<a class="link" href="gstreamer-GstIterator.html#GstIteratorItemFunction" title="GstIteratorItemFunction ()">*GstIteratorItemFunction</a>) (<em class="parameter"><code><a class="link" href="gstreamer-GstIterator.html#GstIterator" title="struct GstIterator"><span class="type">GstIterator</span></a> *it</code></em>,
<em class="parameter"><code>const <a href="http://library.gnome.org/devel/gobject/unstable/gobject-Generic-values.html#GValue"><span class="type">GValue</span></a> *item</code></em>);
<span class="returnvalue">void</span> (<a class="link" href="gstreamer-GstIterator.html#GstIteratorResyncFunction" title="GstIteratorResyncFunction ()">*GstIteratorResyncFunction</a>) (<em class="parameter"><code><a class="link" href="gstreamer-GstIterator.html#GstIterator" title="struct GstIterator"><span class="type">GstIterator</span></a> *it</code></em>);
<span class="returnvalue">void</span> (<a class="link" href="gstreamer-GstIterator.html#GstIteratorFreeFunction" title="GstIteratorFreeFunction ()">*GstIteratorFreeFunction</a>) (<em class="parameter"><code><a class="link" href="gstreamer-GstIterator.html#GstIterator" title="struct GstIterator"><span class="type">GstIterator</span></a> *it</code></em>);
<span class="returnvalue">void</span> (<a class="link" href="gstreamer-GstIterator.html#GstIteratorForeachFunction" title="GstIteratorForeachFunction ()">*GstIteratorForeachFunction</a>) (<em class="parameter"><code>const <a href="http://library.gnome.org/devel/gobject/unstable/gobject-Generic-values.html#GValue"><span class="type">GValue</span></a> *item</code></em>,
<em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gpointer"><span class="type">gpointer</span></a> user_data</code></em>);
<a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gboolean"><span class="returnvalue">gboolean</span></a> (<a class="link" href="gstreamer-GstIterator.html#GstIteratorFoldFunction" title="GstIteratorFoldFunction ()">*GstIteratorFoldFunction</a>) (<em class="parameter"><code>const <a href="http://library.gnome.org/devel/gobject/unstable/gobject-Generic-values.html#GValue"><span class="type">GValue</span></a> *item</code></em>,
<em class="parameter"><code><a href="http://library.gnome.org/devel/gobject/unstable/gobject-Generic-values.html#GValue"><span class="type">GValue</span></a> *ret</code></em>,
<em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gpointer"><span class="type">gpointer</span></a> user_data</code></em>);
#define <a class="link" href="gstreamer-GstIterator.html#GST-ITERATOR:CAPS" title="GST_ITERATOR()">GST_ITERATOR</a> (it)
#define <a class="link" href="gstreamer-GstIterator.html#GST-ITERATOR-LOCK:CAPS" title="GST_ITERATOR_LOCK()">GST_ITERATOR_LOCK</a> (it)
#define <a class="link" href="gstreamer-GstIterator.html#GST-ITERATOR-COOKIE:CAPS" title="GST_ITERATOR_COOKIE()">GST_ITERATOR_COOKIE</a> (it)
#define <a class="link" href="gstreamer-GstIterator.html#GST-ITERATOR-ORIG-COOKIE:CAPS" title="GST_ITERATOR_ORIG_COOKIE()">GST_ITERATOR_ORIG_COOKIE</a> (it)
<a class="link" href="gstreamer-GstIterator.html#GstIterator" title="struct GstIterator"><span class="returnvalue">GstIterator</span></a> * <a class="link" href="gstreamer-GstIterator.html#gst-iterator-new" title="gst_iterator_new ()">gst_iterator_new</a> (<em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#guint"><span class="type">guint</span></a> size</code></em>,
<em class="parameter"><code><a href="http://library.gnome.org/devel/gobject/unstable/gobject-Type-Information.html#GType"><span class="type">GType</span></a> type</code></em>,
<em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Threads.html#GMutex"><span class="type">GMutex</span></a> *lock</code></em>,
<em class="parameter"><code><span class="type">guint32</span> *master_cookie</code></em>,
<em class="parameter"><code><a class="link" href="gstreamer-GstIterator.html#GstIteratorCopyFunction" title="GstIteratorCopyFunction ()"><span class="type">GstIteratorCopyFunction</span></a> copy</code></em>,
<em class="parameter"><code><a class="link" href="gstreamer-GstIterator.html#GstIteratorNextFunction" title="GstIteratorNextFunction ()"><span class="type">GstIteratorNextFunction</span></a> next</code></em>,
<em class="parameter"><code><a class="link" href="gstreamer-GstIterator.html#GstIteratorItemFunction" title="GstIteratorItemFunction ()"><span class="type">GstIteratorItemFunction</span></a> item</code></em>,
<em class="parameter"><code><a class="link" href="gstreamer-GstIterator.html#GstIteratorResyncFunction" title="GstIteratorResyncFunction ()"><span class="type">GstIteratorResyncFunction</span></a> resync</code></em>,
<em class="parameter"><code><a class="link" href="gstreamer-GstIterator.html#GstIteratorFreeFunction" title="GstIteratorFreeFunction ()"><span class="type">GstIteratorFreeFunction</span></a> free</code></em>);
<a class="link" href="gstreamer-GstIterator.html#GstIterator" title="struct GstIterator"><span class="returnvalue">GstIterator</span></a> * <a class="link" href="gstreamer-GstIterator.html#gst-iterator-new-list" title="gst_iterator_new_list ()">gst_iterator_new_list</a> (<em class="parameter"><code><a href="http://library.gnome.org/devel/gobject/unstable/gobject-Type-Information.html#GType"><span class="type">GType</span></a> type</code></em>,
<em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Threads.html#GMutex"><span class="type">GMutex</span></a> *lock</code></em>,
<em class="parameter"><code><span class="type">guint32</span> *master_cookie</code></em>,
<em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Doubly-Linked-Lists.html#GList"><span class="type">GList</span></a> **list</code></em>,
<em class="parameter"><code><a href="http://library.gnome.org/devel/gobject/unstable/gobject-The-Base-Object-Type.html#GObject"><span class="type">GObject</span></a> *owner</code></em>,
<em class="parameter"><code><a class="link" href="gstreamer-GstIterator.html#GstIteratorItemFunction" title="GstIteratorItemFunction ()"><span class="type">GstIteratorItemFunction</span></a> item</code></em>);
<a class="link" href="gstreamer-GstIterator.html#GstIterator" title="struct GstIterator"><span class="returnvalue">GstIterator</span></a> * <a class="link" href="gstreamer-GstIterator.html#gst-iterator-new-single" title="gst_iterator_new_single ()">gst_iterator_new_single</a> (<em class="parameter"><code><a href="http://library.gnome.org/devel/gobject/unstable/gobject-Type-Information.html#GType"><span class="type">GType</span></a> type</code></em>,
<em class="parameter"><code>const <a href="http://library.gnome.org/devel/gobject/unstable/gobject-Generic-values.html#GValue"><span class="type">GValue</span></a> *object</code></em>);
<a class="link" href="gstreamer-GstIterator.html#GstIterator" title="struct GstIterator"><span class="returnvalue">GstIterator</span></a> * <a class="link" href="gstreamer-GstIterator.html#gst-iterator-copy" title="gst_iterator_copy ()">gst_iterator_copy</a> (<em class="parameter"><code>const <a class="link" href="gstreamer-GstIterator.html#GstIterator" title="struct GstIterator"><span class="type">GstIterator</span></a> *it</code></em>);
<span class="returnvalue">void</span> <a class="link" href="gstreamer-GstIterator.html#gst-iterator-free" title="gst_iterator_free ()">gst_iterator_free</a> (<em class="parameter"><code><a class="link" href="gstreamer-GstIterator.html#GstIterator" title="struct GstIterator"><span class="type">GstIterator</span></a> *it</code></em>);
<a class="link" href="gstreamer-GstIterator.html#GstIteratorResult" title="enum GstIteratorResult"><span class="returnvalue">GstIteratorResult</span></a> <a class="link" href="gstreamer-GstIterator.html#gst-iterator-next" title="gst_iterator_next ()">gst_iterator_next</a> (<em class="parameter"><code><a class="link" href="gstreamer-GstIterator.html#GstIterator" title="struct GstIterator"><span class="type">GstIterator</span></a> *it</code></em>,
<em class="parameter"><code><a href="http://library.gnome.org/devel/gobject/unstable/gobject-Generic-values.html#GValue"><span class="type">GValue</span></a> *elem</code></em>);
<span class="returnvalue">void</span> <a class="link" href="gstreamer-GstIterator.html#gst-iterator-resync" title="gst_iterator_resync ()">gst_iterator_resync</a> (<em class="parameter"><code><a class="link" href="gstreamer-GstIterator.html#GstIterator" title="struct GstIterator"><span class="type">GstIterator</span></a> *it</code></em>);
<span class="returnvalue">void</span> <a class="link" href="gstreamer-GstIterator.html#gst-iterator-push" title="gst_iterator_push ()">gst_iterator_push</a> (<em class="parameter"><code><a class="link" href="gstreamer-GstIterator.html#GstIterator" title="struct GstIterator"><span class="type">GstIterator</span></a> *it</code></em>,
<em class="parameter"><code><a class="link" href="gstreamer-GstIterator.html#GstIterator" title="struct GstIterator"><span class="type">GstIterator</span></a> *other</code></em>);
<a class="link" href="gstreamer-GstIterator.html#GstIterator" title="struct GstIterator"><span class="returnvalue">GstIterator</span></a> * <a class="link" href="gstreamer-GstIterator.html#gst-iterator-filter" title="gst_iterator_filter ()">gst_iterator_filter</a> (<em class="parameter"><code><a class="link" href="gstreamer-GstIterator.html#GstIterator" title="struct GstIterator"><span class="type">GstIterator</span></a> *it</code></em>,
<em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Doubly-Linked-Lists.html#GCompareFunc"><span class="type">GCompareFunc</span></a> func</code></em>,
<em class="parameter"><code>const <a href="http://library.gnome.org/devel/gobject/unstable/gobject-Generic-values.html#GValue"><span class="type">GValue</span></a> *user_data</code></em>);
<a class="link" href="gstreamer-GstIterator.html#GstIteratorResult" title="enum GstIteratorResult"><span class="returnvalue">GstIteratorResult</span></a> <a class="link" href="gstreamer-GstIterator.html#gst-iterator-fold" title="gst_iterator_fold ()">gst_iterator_fold</a> (<em class="parameter"><code><a class="link" href="gstreamer-GstIterator.html#GstIterator" title="struct GstIterator"><span class="type">GstIterator</span></a> *it</code></em>,
<em class="parameter"><code><a class="link" href="gstreamer-GstIterator.html#GstIteratorFoldFunction" title="GstIteratorFoldFunction ()"><span class="type">GstIteratorFoldFunction</span></a> func</code></em>,
<em class="parameter"><code><a href="http://library.gnome.org/devel/gobject/unstable/gobject-Generic-values.html#GValue"><span class="type">GValue</span></a> *ret</code></em>,
<em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gpointer"><span class="type">gpointer</span></a> user_data</code></em>);
<a class="link" href="gstreamer-GstIterator.html#GstIteratorResult" title="enum GstIteratorResult"><span class="returnvalue">GstIteratorResult</span></a> <a class="link" href="gstreamer-GstIterator.html#gst-iterator-foreach" title="gst_iterator_foreach ()">gst_iterator_foreach</a> (<em class="parameter"><code><a class="link" href="gstreamer-GstIterator.html#GstIterator" title="struct GstIterator"><span class="type">GstIterator</span></a> *it</code></em>,
<em class="parameter"><code><a class="link" href="gstreamer-GstIterator.html#GstIteratorForeachFunction" title="GstIteratorForeachFunction ()"><span class="type">GstIteratorForeachFunction</span></a> func</code></em>,
<em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gpointer"><span class="type">gpointer</span></a> user_data</code></em>);
<a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gboolean"><span class="returnvalue">gboolean</span></a> <a class="link" href="gstreamer-GstIterator.html#gst-iterator-find-custom" title="gst_iterator_find_custom ()">gst_iterator_find_custom</a> (<em class="parameter"><code><a class="link" href="gstreamer-GstIterator.html#GstIterator" title="struct GstIterator"><span class="type">GstIterator</span></a> *it</code></em>,
<em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Doubly-Linked-Lists.html#GCompareFunc"><span class="type">GCompareFunc</span></a> func</code></em>,
<em class="parameter"><code><a href="http://library.gnome.org/devel/gobject/unstable/gobject-Generic-values.html#GValue"><span class="type">GValue</span></a> *elem</code></em>,
<em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gpointer"><span class="type">gpointer</span></a> user_data</code></em>);
</pre>
</div>
<div class="refsect1">
<a name="gstreamer-GstIterator.description"></a><h2>Description</h2>
<p>
A GstIterator is used to retrieve multiple objects from another object in
a threadsafe way.
</p>
<p>
Various GStreamer objects provide access to their internal structures using
an iterator.
</p>
<p>
In general, whenever calling a GstIterator function results in your code
receiving a refcounted object, the refcount for that object will have been
increased. Your code is responsible for unrefing that object after use.
</p>
<p>
The basic use pattern of an iterator is as follows:
</p>
<p>
</p>
<div class="example">
<a name="id-1.3.27.4.6.1"></a><p class="title"><b>Example 9. Using an iterator</b></p>
<div class="example-contents">
<table class="listing_frame" border="0" cellpadding="0" cellspacing="0">
<tbody>
<tr>
<td class="listing_lines" align="right"><pre>1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23</pre></td>
<td class="listing_code"><pre class="programlisting">it <span class="gtkdoc opt">=</span> <span class="function">_get_iterator</span><span class="gtkdoc opt">(</span>object<span class="gtkdoc opt">);</span>
done <span class="gtkdoc opt">=</span> FALSE<span class="gtkdoc opt">;</span>
<span class="keyword">while</span> <span class="gtkdoc opt">(!</span>done<span class="gtkdoc opt">) {</span>
<span class="keyword">switch</span> <span class="gtkdoc opt">(</span><span class="function"><a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/gstreamer-GstIterator.html#gst-iterator-next">gst_iterator_next</a></span> <span class="gtkdoc opt">(</span>it<span class="gtkdoc opt">, &</span>item<span class="gtkdoc opt">)) {</span>
<span class="keyword">case</span> GST_ITERATOR_OK<span class="gtkdoc opt">:</span>
<span class="gtkdoc opt">...</span> use<span class="gtkdoc opt">/</span>change item here<span class="gtkdoc opt">...</span>
<span class="function"><a href="http://library.gnome.org/devel/gobject/unstable/gobject-Generic-values.html#g-value-reset">g_value_reset</a></span> <span class="gtkdoc opt">(&</span>item<span class="gtkdoc opt">);</span>
<span class="keyword">break</span><span class="gtkdoc opt">;</span>
<span class="keyword">case</span> GST_ITERATOR_RESYNC<span class="gtkdoc opt">:</span>
<span class="gtkdoc opt">...</span>rollback changes to items<span class="gtkdoc opt">...</span>
<span class="function"><a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/gstreamer-GstIterator.html#gst-iterator-resync">gst_iterator_resync</a></span> <span class="gtkdoc opt">(</span>it<span class="gtkdoc opt">);</span>
<span class="keyword">break</span><span class="gtkdoc opt">;</span>
<span class="keyword">case</span> GST_ITERATOR_ERROR<span class="gtkdoc opt">:</span>
<span class="gtkdoc opt">...</span>wrong parameters were given<span class="gtkdoc opt">...</span>
done <span class="gtkdoc opt">=</span> TRUE<span class="gtkdoc opt">;</span>
<span class="keyword">break</span><span class="gtkdoc opt">;</span>
<span class="keyword">case</span> GST_ITERATOR_DONE<span class="gtkdoc opt">:</span>
done <span class="gtkdoc opt">=</span> TRUE<span class="gtkdoc opt">;</span>
<span class="keyword">break</span><span class="gtkdoc opt">;</span>
<span class="gtkdoc opt">}</span>
<span class="gtkdoc opt">}</span>
<span class="function"><a href="http://library.gnome.org/devel/gobject/unstable/gobject-Generic-values.html#g-value-unset">g_value_unset</a></span> <span class="gtkdoc opt">(&</span>item<span class="gtkdoc opt">);</span>
<span class="function"><a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/gstreamer-GstIterator.html#gst-iterator-free">gst_iterator_free</a></span> <span class="gtkdoc opt">(</span>it<span class="gtkdoc opt">);</span></pre></td>
</tr>
</tbody>
</table>
</div>
</div>
<p><br class="example-break">
</p>
<p>
Last reviewed on 2009-06-16 (0.10.24)
</p>
</div>
<div class="refsect1">
<a name="gstreamer-GstIterator.details"></a><h2>Details</h2>
<div class="refsect2">
<a name="GstIterator"></a><h3>struct GstIterator</h3>
<pre class="programlisting">struct GstIterator {
};
</pre>
<p>
<a class="link" href="gstreamer-GstIterator.html#GstIterator" title="struct GstIterator"><span class="type">GstIterator</span></a> base structure. The values of this structure are
protected for subclasses, use the methods to use the <a class="link" href="gstreamer-GstIterator.html#GstIterator" title="struct GstIterator"><span class="type">GstIterator</span></a>.
</p>
<div class="variablelist"><table border="0" class="variablelist">
<colgroup>
<col align="left" valign="top">
<col>
</colgroup>
<tbody></tbody>
</table></div>
</div>
<hr>
<div class="refsect2">
<a name="GstIteratorItem"></a><h3>enum GstIteratorItem</h3>
<pre class="programlisting">typedef enum {
GST_ITERATOR_ITEM_SKIP = 0,
GST_ITERATOR_ITEM_PASS = 1,
GST_ITERATOR_ITEM_END = 2
} GstIteratorItem;
</pre>
<p>
The result of a <a class="link" href="gstreamer-GstIterator.html#GstIteratorItemFunction" title="GstIteratorItemFunction ()"><span class="type">GstIteratorItemFunction</span></a>.
</p>
<div class="variablelist"><table border="0" class="variablelist">
<colgroup>
<col align="left" valign="top">
<col>
</colgroup>
<tbody>
<tr>
<td><p><a name="GST-ITERATOR-ITEM-SKIP:CAPS"></a><span class="term"><code class="literal">GST_ITERATOR_ITEM_SKIP</code></span></p></td>
<td>Skip this item
</td>
</tr>
<tr>
<td><p><a name="GST-ITERATOR-ITEM-PASS:CAPS"></a><span class="term"><code class="literal">GST_ITERATOR_ITEM_PASS</code></span></p></td>
<td>Return item
</td>
</tr>
<tr>
<td><p><a name="GST-ITERATOR-ITEM-END:CAPS"></a><span class="term"><code class="literal">GST_ITERATOR_ITEM_END</code></span></p></td>
<td>Stop after this item.
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2">
<a name="GstIteratorResult"></a><h3>enum GstIteratorResult</h3>
<pre class="programlisting">typedef enum {
GST_ITERATOR_DONE = 0,
GST_ITERATOR_OK = 1,
GST_ITERATOR_RESYNC = 2,
GST_ITERATOR_ERROR = 3
} GstIteratorResult;
</pre>
<p>
The result of <a class="link" href="gstreamer-GstIterator.html#gst-iterator-next" title="gst_iterator_next ()"><code class="function">gst_iterator_next()</code></a>.
</p>
<div class="variablelist"><table border="0" class="variablelist">
<colgroup>
<col align="left" valign="top">
<col>
</colgroup>
<tbody>
<tr>
<td><p><a name="GST-ITERATOR-DONE:CAPS"></a><span class="term"><code class="literal">GST_ITERATOR_DONE</code></span></p></td>
<td>No more items in the iterator
</td>
</tr>
<tr>
<td><p><a name="GST-ITERATOR-OK:CAPS"></a><span class="term"><code class="literal">GST_ITERATOR_OK</code></span></p></td>
<td>An item was retrieved
</td>
</tr>
<tr>
<td><p><a name="GST-ITERATOR-RESYNC:CAPS"></a><span class="term"><code class="literal">GST_ITERATOR_RESYNC</code></span></p></td>
<td>Datastructure changed while iterating
</td>
</tr>
<tr>
<td><p><a name="GST-ITERATOR-ERROR:CAPS"></a><span class="term"><code class="literal">GST_ITERATOR_ERROR</code></span></p></td>
<td>An error happened
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2">
<a name="GstIteratorCopyFunction"></a><h3>GstIteratorCopyFunction ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span> (*GstIteratorCopyFunction) (<em class="parameter"><code>const <a class="link" href="gstreamer-GstIterator.html#GstIterator" title="struct GstIterator"><span class="type">GstIterator</span></a> *it</code></em>,
<em class="parameter"><code><a class="link" href="gstreamer-GstIterator.html#GstIterator" title="struct GstIterator"><span class="type">GstIterator</span></a> *copy</code></em>);</pre>
<p>
This function will be called when creating a copy of <em class="parameter"><code>it</code></em> and should
create a copy of all custom iterator fields or increase their
reference counts.
</p>
<div class="variablelist"><table border="0" class="variablelist">
<colgroup>
<col align="left" valign="top">
<col>
</colgroup>
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>it</code></em> :</span></p></td>
<td>The original iterator</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>copy</code></em> :</span></p></td>
<td>The copied iterator</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2">
<a name="GstIteratorNextFunction"></a><h3>GstIteratorNextFunction ()</h3>
<pre class="programlisting"><a class="link" href="gstreamer-GstIterator.html#GstIteratorResult" title="enum GstIteratorResult"><span class="returnvalue">GstIteratorResult</span></a> (*GstIteratorNextFunction) (<em class="parameter"><code><a class="link" href="gstreamer-GstIterator.html#GstIterator" title="struct GstIterator"><span class="type">GstIterator</span></a> *it</code></em>,
<em class="parameter"><code><a href="http://library.gnome.org/devel/gobject/unstable/gobject-Generic-values.html#GValue"><span class="type">GValue</span></a> *result</code></em>);</pre>
<p>
The function that will be called when the next element of the iterator
should be retrieved.
</p>
<p>
Implementors of a <a class="link" href="gstreamer-GstIterator.html#GstIterator" title="struct GstIterator"><span class="type">GstIterator</span></a> should implement this
function and pass it to the constructor of the custom iterator.
The function will be called with the iterator lock held.
</p>
<div class="variablelist"><table border="0" class="variablelist">
<colgroup>
<col align="left" valign="top">
<col>
</colgroup>
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>it</code></em> :</span></p></td>
<td>the iterator</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>result</code></em> :</span></p></td>
<td>a pointer to hold the next item</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td>the result of the operation.</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2">
<a name="GstIteratorItemFunction"></a><h3>GstIteratorItemFunction ()</h3>
<pre class="programlisting"><a class="link" href="gstreamer-GstIterator.html#GstIteratorItem" title="enum GstIteratorItem"><span class="returnvalue">GstIteratorItem</span></a> (*GstIteratorItemFunction) (<em class="parameter"><code><a class="link" href="gstreamer-GstIterator.html#GstIterator" title="struct GstIterator"><span class="type">GstIterator</span></a> *it</code></em>,
<em class="parameter"><code>const <a href="http://library.gnome.org/devel/gobject/unstable/gobject-Generic-values.html#GValue"><span class="type">GValue</span></a> *item</code></em>);</pre>
<p>
The function that will be called after the next item of the iterator
has been retrieved. This function can be used to skip items or stop
the iterator.
</p>
<p>
The function will be called with the iterator lock held.
</p>
<div class="variablelist"><table border="0" class="variablelist">
<colgroup>
<col align="left" valign="top">
<col>
</colgroup>
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>it</code></em> :</span></p></td>
<td>the iterator</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>item</code></em> :</span></p></td>
<td>the item being retrieved.</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td>the result of the operation.</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2">
<a name="GstIteratorResyncFunction"></a><h3>GstIteratorResyncFunction ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span> (*GstIteratorResyncFunction) (<em class="parameter"><code><a class="link" href="gstreamer-GstIterator.html#GstIterator" title="struct GstIterator"><span class="type">GstIterator</span></a> *it</code></em>);</pre>
<p>
This function will be called whenever a concurrent update happened
to the iterated datastructure. The implementor of the iterator should
restart the iterator from the beginning and clean up any state it might
have.
</p>
<p>
Implementors of a <a class="link" href="gstreamer-GstIterator.html#GstIterator" title="struct GstIterator"><span class="type">GstIterator</span></a> should implement this
function and pass it to the constructor of the custom iterator.
The function will be called with the iterator lock held.
</p>
<div class="variablelist"><table border="0" class="variablelist">
<colgroup>
<col align="left" valign="top">
<col>
</colgroup>
<tbody><tr>
<td><p><span class="term"><em class="parameter"><code>it</code></em> :</span></p></td>
<td>the iterator</td>
</tr></tbody>
</table></div>
</div>
<hr>
<div class="refsect2">
<a name="GstIteratorFreeFunction"></a><h3>GstIteratorFreeFunction ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span> (*GstIteratorFreeFunction) (<em class="parameter"><code><a class="link" href="gstreamer-GstIterator.html#GstIterator" title="struct GstIterator"><span class="type">GstIterator</span></a> *it</code></em>);</pre>
<p>
This function will be called when the iterator is freed.
</p>
<p>
Implementors of a <a class="link" href="gstreamer-GstIterator.html#GstIterator" title="struct GstIterator"><span class="type">GstIterator</span></a> should implement this
function and pass it to the constructor of the custom iterator.
The function will be called with the iterator lock held.
</p>
<div class="variablelist"><table border="0" class="variablelist">
<colgroup>
<col align="left" valign="top">
<col>
</colgroup>
<tbody><tr>
<td><p><span class="term"><em class="parameter"><code>it</code></em> :</span></p></td>
<td>the iterator</td>
</tr></tbody>
</table></div>
</div>
<hr>
<div class="refsect2">
<a name="GstIteratorForeachFunction"></a><h3>GstIteratorForeachFunction ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span> (*GstIteratorForeachFunction) (<em class="parameter"><code>const <a href="http://library.gnome.org/devel/gobject/unstable/gobject-Generic-values.html#GValue"><span class="type">GValue</span></a> *item</code></em>,
<em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gpointer"><span class="type">gpointer</span></a> user_data</code></em>);</pre>
<p>
A function that is called by <a class="link" href="gstreamer-GstIterator.html#gst-iterator-foreach" title="gst_iterator_foreach ()"><code class="function">gst_iterator_foreach()</code></a> for every element.
</p>
<div class="variablelist"><table border="0" class="variablelist">
<colgroup>
<col align="left" valign="top">
<col>
</colgroup>
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>item</code></em> :</span></p></td>
<td>The item</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>user_data</code></em> :</span></p></td>
<td>User data</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2">
<a name="GstIteratorFoldFunction"></a><h3>GstIteratorFoldFunction ()</h3>
<pre class="programlisting"><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gboolean"><span class="returnvalue">gboolean</span></a> (*GstIteratorFoldFunction) (<em class="parameter"><code>const <a href="http://library.gnome.org/devel/gobject/unstable/gobject-Generic-values.html#GValue"><span class="type">GValue</span></a> *item</code></em>,
<em class="parameter"><code><a href="http://library.gnome.org/devel/gobject/unstable/gobject-Generic-values.html#GValue"><span class="type">GValue</span></a> *ret</code></em>,
<em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gpointer"><span class="type">gpointer</span></a> user_data</code></em>);</pre>
<p>
A function to be passed to <a class="link" href="gstreamer-GstIterator.html#gst-iterator-fold" title="gst_iterator_fold ()"><code class="function">gst_iterator_fold()</code></a>.
</p>
<div class="variablelist"><table border="0" class="variablelist">
<colgroup>
<col align="left" valign="top">
<col>
</colgroup>
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>item</code></em> :</span></p></td>
<td>the item to fold</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>ret</code></em> :</span></p></td>
<td>a <a href="http://library.gnome.org/devel/gobject/unstable/gobject-Generic-values.html#GValue"><span class="type">GValue</span></a> collecting the result</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>user_data</code></em> :</span></p></td>
<td>data passed to <a class="link" href="gstreamer-GstIterator.html#gst-iterator-fold" title="gst_iterator_fold ()"><code class="function">gst_iterator_fold()</code></a>
</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td>TRUE if the fold should continue, FALSE if it should stop.</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2">
<a name="GST-ITERATOR:CAPS"></a><h3>GST_ITERATOR()</h3>
<pre class="programlisting">#define GST_ITERATOR(it) ((GstIterator*)(it))
</pre>
<p>
Macro to cast to a <a class="link" href="gstreamer-GstIterator.html#GstIterator" title="struct GstIterator"><span class="type">GstIterator</span></a>
</p>
<div class="variablelist"><table border="0" class="variablelist">
<colgroup>
<col align="left" valign="top">
<col>
</colgroup>
<tbody><tr>
<td><p><span class="term"><em class="parameter"><code>it</code></em> :</span></p></td>
<td>the <a class="link" href="gstreamer-GstIterator.html#GstIterator" title="struct GstIterator"><span class="type">GstIterator</span></a> value</td>
</tr></tbody>
</table></div>
</div>
<hr>
<div class="refsect2">
<a name="GST-ITERATOR-LOCK:CAPS"></a><h3>GST_ITERATOR_LOCK()</h3>
<pre class="programlisting">#define GST_ITERATOR_LOCK(it) (GST_ITERATOR(it)->lock)
</pre>
<p>
Macro to get the lock protecting the datastructure being iterated.
</p>
<div class="variablelist"><table border="0" class="variablelist">
<colgroup>
<col align="left" valign="top">
<col>
</colgroup>
<tbody><tr>
<td><p><span class="term"><em class="parameter"><code>it</code></em> :</span></p></td>
<td>the <a class="link" href="gstreamer-GstIterator.html#GstIterator" title="struct GstIterator"><span class="type">GstIterator</span></a> to get the lock of</td>
</tr></tbody>
</table></div>
</div>
<hr>
<div class="refsect2">
<a name="GST-ITERATOR-COOKIE:CAPS"></a><h3>GST_ITERATOR_COOKIE()</h3>
<pre class="programlisting">#define GST_ITERATOR_COOKIE(it) (GST_ITERATOR(it)->cookie)
</pre>
<p>
Macro to get the cookie of a <a class="link" href="gstreamer-GstIterator.html#GstIterator" title="struct GstIterator"><span class="type">GstIterator</span></a>. The cookie of the
iterator is the value of the master cookie when the iterator
was created.
Whenever the iterator is iterated, the value is compared to the
value of the master cookie. If they are different, a concurrent
modification happened to the iterator and a resync is needed.
</p>
<div class="variablelist"><table border="0" class="variablelist">
<colgroup>
<col align="left" valign="top">
<col>
</colgroup>
<tbody><tr>
<td><p><span class="term"><em class="parameter"><code>it</code></em> :</span></p></td>
<td>the <a class="link" href="gstreamer-GstIterator.html#GstIterator" title="struct GstIterator"><span class="type">GstIterator</span></a> to get the cookie of</td>
</tr></tbody>
</table></div>
</div>
<hr>
<div class="refsect2">
<a name="GST-ITERATOR-ORIG-COOKIE:CAPS"></a><h3>GST_ITERATOR_ORIG_COOKIE()</h3>
<pre class="programlisting">#define GST_ITERATOR_ORIG_COOKIE(it) (GST_ITERATOR(it)->master_cookie)
</pre>
<p>
Macro to get a pointer to where the master cookie is stored. The
master cookie protects the structure being iterated and gets updated
whenever the datastructure changes.
</p>
<div class="variablelist"><table border="0" class="variablelist">
<colgroup>
<col align="left" valign="top">
<col>
</colgroup>
<tbody><tr>
<td><p><span class="term"><em class="parameter"><code>it</code></em> :</span></p></td>
<td>the <a class="link" href="gstreamer-GstIterator.html#GstIterator" title="struct GstIterator"><span class="type">GstIterator</span></a> to get the master cookie of</td>
</tr></tbody>
</table></div>
</div>
<hr>
<div class="refsect2">
<a name="gst-iterator-new"></a><h3>gst_iterator_new ()</h3>
<pre class="programlisting"><a class="link" href="gstreamer-GstIterator.html#GstIterator" title="struct GstIterator"><span class="returnvalue">GstIterator</span></a> * gst_iterator_new (<em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#guint"><span class="type">guint</span></a> size</code></em>,
<em class="parameter"><code><a href="http://library.gnome.org/devel/gobject/unstable/gobject-Type-Information.html#GType"><span class="type">GType</span></a> type</code></em>,
<em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Threads.html#GMutex"><span class="type">GMutex</span></a> *lock</code></em>,
<em class="parameter"><code><span class="type">guint32</span> *master_cookie</code></em>,
<em class="parameter"><code><a class="link" href="gstreamer-GstIterator.html#GstIteratorCopyFunction" title="GstIteratorCopyFunction ()"><span class="type">GstIteratorCopyFunction</span></a> copy</code></em>,
<em class="parameter"><code><a class="link" href="gstreamer-GstIterator.html#GstIteratorNextFunction" title="GstIteratorNextFunction ()"><span class="type">GstIteratorNextFunction</span></a> next</code></em>,
<em class="parameter"><code><a class="link" href="gstreamer-GstIterator.html#GstIteratorItemFunction" title="GstIteratorItemFunction ()"><span class="type">GstIteratorItemFunction</span></a> item</code></em>,
<em class="parameter"><code><a class="link" href="gstreamer-GstIterator.html#GstIteratorResyncFunction" title="GstIteratorResyncFunction ()"><span class="type">GstIteratorResyncFunction</span></a> resync</code></em>,
<em class="parameter"><code><a class="link" href="gstreamer-GstIterator.html#GstIteratorFreeFunction" title="GstIteratorFreeFunction ()"><span class="type">GstIteratorFreeFunction</span></a> free</code></em>);</pre>
<p>
Create a new iterator. This function is mainly used for objects
implementing the next/resync/free function to iterate a data structure.
</p>
<p>
For each item retrieved, the <em class="parameter"><code>item</code></em> function is called with the lock
held. The <em class="parameter"><code>free</code></em> function is called when the iterator is freed.
</p>
<div class="variablelist"><table border="0" class="variablelist">
<colgroup>
<col align="left" valign="top">
<col>
</colgroup>
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>size</code></em> :</span></p></td>
<td>the size of the iterator structure</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>type</code></em> :</span></p></td>
<td>
<a href="http://library.gnome.org/devel/gobject/unstable/gobject-Type-Information.html#GType"><span class="type">GType</span></a> of children</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>lock</code></em> :</span></p></td>
<td>pointer to a <a href="http://library.gnome.org/devel/glib/unstable/glib-Threads.html#GMutex"><span class="type">GMutex</span></a>.</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>master_cookie</code></em> :</span></p></td>
<td>pointer to a guint32 that is changed when the items in the
iterator changed.</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>copy</code></em> :</span></p></td>
<td>copy function</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>next</code></em> :</span></p></td>
<td>function to get next item</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>item</code></em> :</span></p></td>
<td>function to call on each item retrieved</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>resync</code></em> :</span></p></td>
<td>function to resync the iterator</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>free</code></em> :</span></p></td>
<td>function to free the iterator</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td>the new <a class="link" href="gstreamer-GstIterator.html#GstIterator" title="struct GstIterator"><span class="type">GstIterator</span></a>.
MT safe.</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2">
<a name="gst-iterator-new-list"></a><h3>gst_iterator_new_list ()</h3>
<pre class="programlisting"><a class="link" href="gstreamer-GstIterator.html#GstIterator" title="struct GstIterator"><span class="returnvalue">GstIterator</span></a> * gst_iterator_new_list (<em class="parameter"><code><a href="http://library.gnome.org/devel/gobject/unstable/gobject-Type-Information.html#GType"><span class="type">GType</span></a> type</code></em>,
<em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Threads.html#GMutex"><span class="type">GMutex</span></a> *lock</code></em>,
<em class="parameter"><code><span class="type">guint32</span> *master_cookie</code></em>,
<em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Doubly-Linked-Lists.html#GList"><span class="type">GList</span></a> **list</code></em>,
<em class="parameter"><code><a href="http://library.gnome.org/devel/gobject/unstable/gobject-The-Base-Object-Type.html#GObject"><span class="type">GObject</span></a> *owner</code></em>,
<em class="parameter"><code><a class="link" href="gstreamer-GstIterator.html#GstIteratorItemFunction" title="GstIteratorItemFunction ()"><span class="type">GstIteratorItemFunction</span></a> item</code></em>);</pre>
<p>
Create a new iterator designed for iterating <em class="parameter"><code>list</code></em>.
</p>
<p>
The list you iterate is usually part of a data structure <em class="parameter"><code>owner</code></em> and is
protected with <em class="parameter"><code>lock</code></em>.
</p>
<p>
The iterator will use <em class="parameter"><code>lock</code></em> to retrieve the next item of the list and it
will then call the <em class="parameter"><code>item</code></em> function before releasing <em class="parameter"><code>lock</code></em> again.
</p>
<p>
When a concurrent update to the list is performed, usually by <em class="parameter"><code>owner</code></em> while
holding <em class="parameter"><code>lock</code></em>, <em class="parameter"><code>master_cookie</code></em> will be updated. The iterator implementation
will notice the update of the cookie and will return <a class="link" href="gstreamer-GstIterator.html#GST-ITERATOR-RESYNC:CAPS"><code class="literal">GST_ITERATOR_RESYNC</code></a> to
the user of the iterator in the next call to <a class="link" href="gstreamer-GstIterator.html#gst-iterator-next" title="gst_iterator_next ()"><code class="function">gst_iterator_next()</code></a>.
</p>
<div class="variablelist"><table border="0" class="variablelist">
<colgroup>
<col align="left" valign="top">
<col>
</colgroup>
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>type</code></em> :</span></p></td>
<td>
<a href="http://library.gnome.org/devel/gobject/unstable/gobject-Type-Information.html#GType"><span class="type">GType</span></a> of elements</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>lock</code></em> :</span></p></td>
<td>pointer to a <a href="http://library.gnome.org/devel/glib/unstable/glib-Threads.html#GMutex"><span class="type">GMutex</span></a> protecting the list.</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>master_cookie</code></em> :</span></p></td>
<td>pointer to a guint32 that is incremented when the list
is changed.</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>list</code></em> :</span></p></td>
<td>pointer to the list</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>owner</code></em> :</span></p></td>
<td>object owning the list</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>item</code></em> :</span></p></td>
<td>function to call on each item retrieved</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td>the new <a class="link" href="gstreamer-GstIterator.html#GstIterator" title="struct GstIterator"><span class="type">GstIterator</span></a> for <em class="parameter"><code>list</code></em>.
MT safe.</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2">
<a name="gst-iterator-new-single"></a><h3>gst_iterator_new_single ()</h3>
<pre class="programlisting"><a class="link" href="gstreamer-GstIterator.html#GstIterator" title="struct GstIterator"><span class="returnvalue">GstIterator</span></a> * gst_iterator_new_single (<em class="parameter"><code><a href="http://library.gnome.org/devel/gobject/unstable/gobject-Type-Information.html#GType"><span class="type">GType</span></a> type</code></em>,
<em class="parameter"><code>const <a href="http://library.gnome.org/devel/gobject/unstable/gobject-Generic-values.html#GValue"><span class="type">GValue</span></a> *object</code></em>);</pre>
<p>
This <a class="link" href="gstreamer-GstIterator.html#GstIterator" title="struct GstIterator"><span class="type">GstIterator</span></a> is a convenient iterator for the common
case where a <a class="link" href="gstreamer-GstIterator.html#GstIterator" title="struct GstIterator"><span class="type">GstIterator</span></a> needs to be returned but only
a single object has to be considered. This happens often
for the <a class="link" href="GstPad.html#GstPadIterIntLinkFunction" title="GstPadIterIntLinkFunction ()"><span class="type">GstPadIterIntLinkFunction</span></a>.
</p>
<div class="variablelist"><table border="0" class="variablelist">
<colgroup>
<col align="left" valign="top">
<col>
</colgroup>
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>type</code></em> :</span></p></td>
<td>
<a href="http://library.gnome.org/devel/gobject/unstable/gobject-Type-Information.html#GType"><span class="type">GType</span></a> of the passed object</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>object</code></em> :</span></p></td>
<td>object that this iterator should return</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td>the new <a class="link" href="gstreamer-GstIterator.html#GstIterator" title="struct GstIterator"><span class="type">GstIterator</span></a> for <em class="parameter"><code>object</code></em>.</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2">
<a name="gst-iterator-copy"></a><h3>gst_iterator_copy ()</h3>
<pre class="programlisting"><a class="link" href="gstreamer-GstIterator.html#GstIterator" title="struct GstIterator"><span class="returnvalue">GstIterator</span></a> * gst_iterator_copy (<em class="parameter"><code>const <a class="link" href="gstreamer-GstIterator.html#GstIterator" title="struct GstIterator"><span class="type">GstIterator</span></a> *it</code></em>);</pre>
<p>
Copy the iterator and its state.
</p>
<div class="variablelist"><table border="0" class="variablelist">
<colgroup>
<col align="left" valign="top">
<col>
</colgroup>
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>it</code></em> :</span></p></td>
<td>a <a class="link" href="gstreamer-GstIterator.html#GstIterator" title="struct GstIterator"><span class="type">GstIterator</span></a>
</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td>a new copy of <em class="parameter"><code>it</code></em>.</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2">
<a name="gst-iterator-free"></a><h3>gst_iterator_free ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span> gst_iterator_free (<em class="parameter"><code><a class="link" href="gstreamer-GstIterator.html#GstIterator" title="struct GstIterator"><span class="type">GstIterator</span></a> *it</code></em>);</pre>
<p>
Free the iterator.
</p>
<p>
MT safe.
</p>
<div class="variablelist"><table border="0" class="variablelist">
<colgroup>
<col align="left" valign="top">
<col>
</colgroup>
<tbody><tr>
<td><p><span class="term"><em class="parameter"><code>it</code></em> :</span></p></td>
<td>The <a class="link" href="gstreamer-GstIterator.html#GstIterator" title="struct GstIterator"><span class="type">GstIterator</span></a> to free</td>
</tr></tbody>
</table></div>
</div>
<hr>
<div class="refsect2">
<a name="gst-iterator-next"></a><h3>gst_iterator_next ()</h3>
<pre class="programlisting"><a class="link" href="gstreamer-GstIterator.html#GstIteratorResult" title="enum GstIteratorResult"><span class="returnvalue">GstIteratorResult</span></a> gst_iterator_next (<em class="parameter"><code><a class="link" href="gstreamer-GstIterator.html#GstIterator" title="struct GstIterator"><span class="type">GstIterator</span></a> *it</code></em>,
<em class="parameter"><code><a href="http://library.gnome.org/devel/gobject/unstable/gobject-Generic-values.html#GValue"><span class="type">GValue</span></a> *elem</code></em>);</pre>
<p>
Get the next item from the iterator in <em class="parameter"><code>elem</code></em>.
</p>
<p>
Only when this function returns <a class="link" href="gstreamer-GstIterator.html#GST-ITERATOR-OK:CAPS"><code class="literal">GST_ITERATOR_OK</code></a>, <em class="parameter"><code>elem</code></em> will contain a valid
value. <em class="parameter"><code>elem</code></em> must have been initialized to the type of the iterator or
initialized to zeroes with <a href="http://library.gnome.org/devel/gobject/unstable/gobject-Generic-values.html#g-value-unset"><code class="function">g_value_unset()</code></a>. The caller is responsible for
unsetting or resetting <em class="parameter"><code>elem</code></em> with <a href="http://library.gnome.org/devel/gobject/unstable/gobject-Generic-values.html#g-value-unset"><code class="function">g_value_unset()</code></a> or <a href="http://library.gnome.org/devel/gobject/unstable/gobject-Generic-values.html#g-value-reset"><code class="function">g_value_reset()</code></a>
after usage.
</p>
<p>
When this function returns <a class="link" href="gstreamer-GstIterator.html#GST-ITERATOR-DONE:CAPS"><code class="literal">GST_ITERATOR_DONE</code></a>, no more elements can be
retrieved from <em class="parameter"><code>it</code></em>.
</p>
<p>
A return value of <a class="link" href="gstreamer-GstIterator.html#GST-ITERATOR-RESYNC:CAPS"><code class="literal">GST_ITERATOR_RESYNC</code></a> indicates that the element list was
concurrently updated. The user of <em class="parameter"><code>it</code></em> should call <a class="link" href="gstreamer-GstIterator.html#gst-iterator-resync" title="gst_iterator_resync ()"><code class="function">gst_iterator_resync()</code></a> to
get the newly updated list.
</p>
<p>
A return value of <a class="link" href="gstreamer-GstIterator.html#GST-ITERATOR-ERROR:CAPS"><code class="literal">GST_ITERATOR_ERROR</code></a> indicates an unrecoverable fatal error.
</p>
<div class="variablelist"><table border="0" class="variablelist">
<colgroup>
<col align="left" valign="top">
<col>
</colgroup>
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>it</code></em> :</span></p></td>
<td>The <a class="link" href="gstreamer-GstIterator.html#GstIterator" title="struct GstIterator"><span class="type">GstIterator</span></a> to iterate</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>elem</code></em> :</span></p></td>
<td>pointer to hold next element. <span class="annotation">[<acronym title="Out parameter, where caller must allocate storage."><span class="acronym">out caller-allocates</span></acronym>]</span>
</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td>The result of the iteration. Unset <em class="parameter"><code>elem</code></em> after usage.
MT safe.</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2">
<a name="gst-iterator-resync"></a><h3>gst_iterator_resync ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span> gst_iterator_resync (<em class="parameter"><code><a class="link" href="gstreamer-GstIterator.html#GstIterator" title="struct GstIterator"><span class="type">GstIterator</span></a> *it</code></em>);</pre>
<p>
Resync the iterator. this function is mostly called
after <a class="link" href="gstreamer-GstIterator.html#gst-iterator-next" title="gst_iterator_next ()"><code class="function">gst_iterator_next()</code></a> returned <a class="link" href="gstreamer-GstIterator.html#GST-ITERATOR-RESYNC:CAPS"><code class="literal">GST_ITERATOR_RESYNC</code></a>.
</p>
<p>
When an iterator was pushed on <em class="parameter"><code>it</code></em>, it will automatically be popped again
with this function.
</p>
<p>
MT safe.
</p>
<div class="variablelist"><table border="0" class="variablelist">
<colgroup>
<col align="left" valign="top">
<col>
</colgroup>
<tbody><tr>
<td><p><span class="term"><em class="parameter"><code>it</code></em> :</span></p></td>
<td>The <a class="link" href="gstreamer-GstIterator.html#GstIterator" title="struct GstIterator"><span class="type">GstIterator</span></a> to resync</td>
</tr></tbody>
</table></div>
</div>
<hr>
<div class="refsect2">
<a name="gst-iterator-push"></a><h3>gst_iterator_push ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span> gst_iterator_push (<em class="parameter"><code><a class="link" href="gstreamer-GstIterator.html#GstIterator" title="struct GstIterator"><span class="type">GstIterator</span></a> *it</code></em>,
<em class="parameter"><code><a class="link" href="gstreamer-GstIterator.html#GstIterator" title="struct GstIterator"><span class="type">GstIterator</span></a> *other</code></em>);</pre>
<p>
Pushes <em class="parameter"><code>other</code></em> iterator onto <em class="parameter"><code>it</code></em>. All calls performed on <em class="parameter"><code>it</code></em> are
forwarded to <em class="parameter"><code>other</code></em>. If <em class="parameter"><code>other</code></em> returns <a class="link" href="gstreamer-GstIterator.html#GST-ITERATOR-DONE:CAPS"><code class="literal">GST_ITERATOR_DONE</code></a>, it is
popped again and calls are handled by <em class="parameter"><code>it</code></em> again.
</p>
<p>
This function is mainly used by objects implementing the iterator
next function to recurse into substructures.
</p>
<p>
When <a class="link" href="gstreamer-GstIterator.html#gst-iterator-resync" title="gst_iterator_resync ()"><code class="function">gst_iterator_resync()</code></a> is called on <em class="parameter"><code>it</code></em>, <em class="parameter"><code>other</code></em> will automatically be
popped.
</p>
<p>
MT safe.
</p>
<div class="variablelist"><table border="0" class="variablelist">
<colgroup>
<col align="left" valign="top">
<col>
</colgroup>
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>it</code></em> :</span></p></td>
<td>The <a class="link" href="gstreamer-GstIterator.html#GstIterator" title="struct GstIterator"><span class="type">GstIterator</span></a> to use</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>other</code></em> :</span></p></td>
<td>The <a class="link" href="gstreamer-GstIterator.html#GstIterator" title="struct GstIterator"><span class="type">GstIterator</span></a> to push</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2">
<a name="gst-iterator-filter"></a><h3>gst_iterator_filter ()</h3>
<pre class="programlisting"><a class="link" href="gstreamer-GstIterator.html#GstIterator" title="struct GstIterator"><span class="returnvalue">GstIterator</span></a> * gst_iterator_filter (<em class="parameter"><code><a class="link" href="gstreamer-GstIterator.html#GstIterator" title="struct GstIterator"><span class="type">GstIterator</span></a> *it</code></em>,
<em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Doubly-Linked-Lists.html#GCompareFunc"><span class="type">GCompareFunc</span></a> func</code></em>,
<em class="parameter"><code>const <a href="http://library.gnome.org/devel/gobject/unstable/gobject-Generic-values.html#GValue"><span class="type">GValue</span></a> *user_data</code></em>);</pre>
<p>
Create a new iterator from an existing iterator. The new iterator
will only return those elements that match the given compare function <em class="parameter"><code>func</code></em>.
The first parameter that is passed to <em class="parameter"><code>func</code></em> is the <a href="http://library.gnome.org/devel/gobject/unstable/gobject-Generic-values.html#GValue"><span class="type">GValue</span></a> of the current
iterator element and the second parameter is <em class="parameter"><code>user_data</code></em>. <em class="parameter"><code>func</code></em> should
return 0 for elements that should be included in the filtered iterator.
</p>
<p>
When this iterator is freed, <em class="parameter"><code>it</code></em> will also be freed.
</p>
<div class="variablelist"><table border="0" class="variablelist">
<colgroup>
<col align="left" valign="top">
<col>
</colgroup>
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>it</code></em> :</span></p></td>
<td>The <a class="link" href="gstreamer-GstIterator.html#GstIterator" title="struct GstIterator"><span class="type">GstIterator</span></a> to filter</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>func</code></em> :</span></p></td>
<td>the compare function to select elements. <span class="annotation">[<acronym title="The callback is valid only during the call to the method."><span class="acronym">scope call</span></acronym>]</span>
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>user_data</code></em> :</span></p></td>
<td>user data passed to the compare function. <span class="annotation">[<acronym title="This parameter is a 'user_data', for callbacks; many bindings can pass NULL here."><span class="acronym">closure</span></acronym>]</span>
</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td>a new <a class="link" href="gstreamer-GstIterator.html#GstIterator" title="struct GstIterator"><span class="type">GstIterator</span></a>.
MT safe. <span class="annotation">[<acronym title="Free data after the code is done."><span class="acronym">transfer full</span></acronym>]</span>
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2">
<a name="gst-iterator-fold"></a><h3>gst_iterator_fold ()</h3>
<pre class="programlisting"><a class="link" href="gstreamer-GstIterator.html#GstIteratorResult" title="enum GstIteratorResult"><span class="returnvalue">GstIteratorResult</span></a> gst_iterator_fold (<em class="parameter"><code><a class="link" href="gstreamer-GstIterator.html#GstIterator" title="struct GstIterator"><span class="type">GstIterator</span></a> *it</code></em>,
<em class="parameter"><code><a class="link" href="gstreamer-GstIterator.html#GstIteratorFoldFunction" title="GstIteratorFoldFunction ()"><span class="type">GstIteratorFoldFunction</span></a> func</code></em>,
<em class="parameter"><code><a href="http://library.gnome.org/devel/gobject/unstable/gobject-Generic-values.html#GValue"><span class="type">GValue</span></a> *ret</code></em>,
<em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gpointer"><span class="type">gpointer</span></a> user_data</code></em>);</pre>
<p>
Folds <em class="parameter"><code>func</code></em> over the elements of <em class="parameter"><code>iter</code></em>. That is to say, <em class="parameter"><code>func</code></em> will be called
as <em class="parameter"><code>func</code></em> (object, <em class="parameter"><code>ret</code></em>, <em class="parameter"><code>user_data</code></em>) for each object in <em class="parameter"><code>it</code></em>. The normal use
of this procedure is to accumulate the results of operating on the objects in
<em class="parameter"><code>ret</code></em>.
</p>
<p>
This procedure can be used (and is used internally) to implement the
<a class="link" href="gstreamer-GstIterator.html#gst-iterator-foreach" title="gst_iterator_foreach ()"><code class="function">gst_iterator_foreach()</code></a> and <a class="link" href="gstreamer-GstIterator.html#gst-iterator-find-custom" title="gst_iterator_find_custom ()"><code class="function">gst_iterator_find_custom()</code></a> operations.
</p>
<p>
The fold will proceed as long as <em class="parameter"><code>func</code></em> returns TRUE. When the iterator has no
more arguments, <a class="link" href="gstreamer-GstIterator.html#GST-ITERATOR-DONE:CAPS"><code class="literal">GST_ITERATOR_DONE</code></a> will be returned. If <em class="parameter"><code>func</code></em> returns FALSE,
the fold will stop, and <a class="link" href="gstreamer-GstIterator.html#GST-ITERATOR-OK:CAPS"><code class="literal">GST_ITERATOR_OK</code></a> will be returned. Errors or resyncs
will cause fold to return <a class="link" href="gstreamer-GstIterator.html#GST-ITERATOR-ERROR:CAPS"><code class="literal">GST_ITERATOR_ERROR</code></a> or <a class="link" href="gstreamer-GstIterator.html#GST-ITERATOR-RESYNC:CAPS"><code class="literal">GST_ITERATOR_RESYNC</code></a> as
appropriate.
</p>
<p>
The iterator will not be freed.
</p>
<div class="variablelist"><table border="0" class="variablelist">
<colgroup>
<col align="left" valign="top">
<col>
</colgroup>
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>it</code></em> :</span></p></td>
<td>The <a class="link" href="gstreamer-GstIterator.html#GstIterator" title="struct GstIterator"><span class="type">GstIterator</span></a> to fold over</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>func</code></em> :</span></p></td>
<td>the fold function. <span class="annotation">[<acronym title="The callback is valid only during the call to the method."><span class="acronym">scope call</span></acronym>]</span>
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>ret</code></em> :</span></p></td>
<td>the seed value passed to the fold function</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>user_data</code></em> :</span></p></td>
<td>user data passed to the fold function. <span class="annotation">[<acronym title="This parameter is a 'user_data', for callbacks; many bindings can pass NULL here."><span class="acronym">closure</span></acronym>]</span>
</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td>A <a class="link" href="gstreamer-GstIterator.html#GstIteratorResult" title="enum GstIteratorResult"><span class="type">GstIteratorResult</span></a>, as described above.
MT safe.</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2">
<a name="gst-iterator-foreach"></a><h3>gst_iterator_foreach ()</h3>
<pre class="programlisting"><a class="link" href="gstreamer-GstIterator.html#GstIteratorResult" title="enum GstIteratorResult"><span class="returnvalue">GstIteratorResult</span></a> gst_iterator_foreach (<em class="parameter"><code><a class="link" href="gstreamer-GstIterator.html#GstIterator" title="struct GstIterator"><span class="type">GstIterator</span></a> *it</code></em>,
<em class="parameter"><code><a class="link" href="gstreamer-GstIterator.html#GstIteratorForeachFunction" title="GstIteratorForeachFunction ()"><span class="type">GstIteratorForeachFunction</span></a> func</code></em>,
<em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gpointer"><span class="type">gpointer</span></a> user_data</code></em>);</pre>
<p>
Iterate over all element of <em class="parameter"><code>it</code></em> and call the given function <em class="parameter"><code>func</code></em> for
each element.
</p>
<div class="variablelist"><table border="0" class="variablelist">
<colgroup>
<col align="left" valign="top">
<col>
</colgroup>
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>it</code></em> :</span></p></td>
<td>The <a class="link" href="gstreamer-GstIterator.html#GstIterator" title="struct GstIterator"><span class="type">GstIterator</span></a> to iterate</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>func</code></em> :</span></p></td>
<td>the function to call for each element. <span class="annotation">[<acronym title="The callback is valid only during the call to the method."><span class="acronym">scope call</span></acronym>]</span>
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>user_data</code></em> :</span></p></td>
<td>user data passed to the function. <span class="annotation">[<acronym title="This parameter is a 'user_data', for callbacks; many bindings can pass NULL here."><span class="acronym">closure</span></acronym>]</span>
</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td>the result call to <a class="link" href="gstreamer-GstIterator.html#gst-iterator-fold" title="gst_iterator_fold ()"><code class="function">gst_iterator_fold()</code></a>. The iterator will not be
freed.
MT safe.</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2">
<a name="gst-iterator-find-custom"></a><h3>gst_iterator_find_custom ()</h3>
<pre class="programlisting"><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gboolean"><span class="returnvalue">gboolean</span></a> gst_iterator_find_custom (<em class="parameter"><code><a class="link" href="gstreamer-GstIterator.html#GstIterator" title="struct GstIterator"><span class="type">GstIterator</span></a> *it</code></em>,
<em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Doubly-Linked-Lists.html#GCompareFunc"><span class="type">GCompareFunc</span></a> func</code></em>,
<em class="parameter"><code><a href="http://library.gnome.org/devel/gobject/unstable/gobject-Generic-values.html#GValue"><span class="type">GValue</span></a> *elem</code></em>,
<em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gpointer"><span class="type">gpointer</span></a> user_data</code></em>);</pre>
<p>
Find the first element in <em class="parameter"><code>it</code></em> that matches the compare function <em class="parameter"><code>func</code></em>.
<em class="parameter"><code>func</code></em> should return 0 when the element is found. The first parameter
to <em class="parameter"><code>func</code></em> will be the current element of the iterator and the
second parameter will be <em class="parameter"><code>user_data</code></em>.
The result will be stored in <em class="parameter"><code>elem</code></em> if a result is found.
</p>
<p>
The iterator will not be freed.
</p>
<p>
This function will return FALSE if an error happened to the iterator
or if the element wasn't found.
</p>
<div class="variablelist"><table border="0" class="variablelist">
<colgroup>
<col align="left" valign="top">
<col>
</colgroup>
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>it</code></em> :</span></p></td>
<td>The <a class="link" href="gstreamer-GstIterator.html#GstIterator" title="struct GstIterator"><span class="type">GstIterator</span></a> to iterate</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>func</code></em> :</span></p></td>
<td>the compare function to use. <span class="annotation">[<acronym title="The callback is valid only during the call to the method."><span class="acronym">scope call</span></acronym>]</span>
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>elem</code></em> :</span></p></td>
<td>pointer to a <a href="http://library.gnome.org/devel/gobject/unstable/gobject-Generic-values.html#GValue"><span class="type">GValue</span></a> where to store the result. <span class="annotation">[<acronym title="Parameter for returning results. Default is transfer full."><span class="acronym">out</span></acronym>]</span>
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>user_data</code></em> :</span></p></td>
<td>user data passed to the compare function. <span class="annotation">[<acronym title="This parameter is a 'user_data', for callbacks; many bindings can pass NULL here."><span class="acronym">closure</span></acronym>]</span>
</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td>Returns TRUE if the element was found, else FALSE.
MT safe.</td>
</tr>
</tbody>
</table></div>
</div>
</div>
<div class="refsect1">
<a name="gstreamer-GstIterator.see-also"></a><h2>See Also</h2>
<a class="link" href="GstElement.html" title="GstElement"><span class="type">GstElement</span></a>, <a class="link" href="GstBin.html" title="GstBin"><span class="type">GstBin</span></a>
</div>
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