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a5c0df554e
Thu Sep 7 12:35:35 2000 Owen Taylor <otaylor@redhat.com>
* Some further makefile improvement.
* Restore all the docs that mysteriously vanished earlier.
426 lines
11 KiB
Plaintext
426 lines
11 KiB
Plaintext
<!-- ##### SECTION Title ##### -->
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Doubly-Linked Lists
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<!-- ##### SECTION Short_Description ##### -->
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linked lists containing integer values or pointers to data, with the ability
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to iterate over the list in both directions.
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<!-- ##### SECTION Long_Description ##### -->
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<para>
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The #GList structure and its associated functions provide a standard
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doubly-linked list data structure.
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</para>
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<para>
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Each element in the list contains a piece of data, together with pointers
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which link to the previous and next elements in the list.
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Using these pointers it is possible to move through the list in both
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directions (unlike the
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<link linkend="glib-Singly-Linked-lists">Singly-Linked Lists</link>
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which only allows movement through the list in the forward direction).
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</para>
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<para>
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The data contained in each element can be either integer values, by using one
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of the
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<link linkend="glib-Type-Conversion-Macros">Type Conversion Macros</link>,
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or simply pointers to any type of data.
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</para>
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<para>
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List elements are allocated in blocks using a #GListAllocator, which is
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more efficient than allocating elements individually.
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</para>
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<para>
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Note that most of the #GList functions expect to be passed a pointer to
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the first element in the list. The functions which insert elements return
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the new start of the list, which may have changed.
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</para>
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<para>
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There is no function to create a #GList. NULL is considered to be the empty
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list so you simply set a #GList* to NULL.
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</para>
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<para>
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To add elements, use g_list_append(), g_list_prepend(), g_list_insert()
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and g_list_insert_sorted().
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</para>
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<para>
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To remove elements, use g_list_remove().
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</para>
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<para>
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To find elements in the list use g_list_first(), g_list_last(), g_list_next(),
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g_list_previous(), g_list_nth(), g_list_nth_data(), g_list_find() and
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g_list_find_custom().
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</para>
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<para>
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To find the index of an element use g_list_position() and g_list_index().
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</para>
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<para>
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To call a function for each element in the list use g_list_foreach().
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</para>
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<para>
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To free the entire list, use g_list_free().
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</para>
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<!-- ##### SECTION See_Also ##### -->
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<para>
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</para>
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<!-- ##### STRUCT GList ##### -->
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<para>
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The #GList struct is used for each element in a doubly-linked list.
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The <structfield>data</structfield> field holds the element's data, which can
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be a pointer to any kind of data, or any integer value using the
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<link linkend="glib-Type-Conversion-Macros">Type Conversion Macros</link>.
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The <structfield>next</structfield> and <structfield>prev</structfield>
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pointers are the links to the next and previous elements in the list.
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</para>
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@data:
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@next:
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@prev:
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<!-- ##### FUNCTION g_list_append ##### -->
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<para>
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Adds a new element on to the end of the list.
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</para>
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<note>
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<para>
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The return value is the new start of the list, which may have changed, so
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make sure you store the new value.
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</para>
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</note>
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<informalexample><programlisting>
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/* Notice that these are initialized to the empty list. */
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GList *list = NULL, *number_list = NULL;
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/* This is a list of strings. */
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list = g_list_append (list, "first");
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list = g_list_append (list, "second");
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/* This is a list of integers. */
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number_list = g_list_append (number_list, GINT_TO_POINTER (27));
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number_list = g_list_append (number_list, GINT_TO_POINTER (14));
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</programlisting></informalexample>
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@list: a pointer to a #GList.
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@data: the data for the new element.
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@Returns: the new start of the #GList.
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<!-- ##### FUNCTION g_list_prepend ##### -->
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<para>
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Adds a new element on to the start of the list.
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</para>
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<note>
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<para>
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The return value is the new start of the list, which may have changed, so
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make sure you store the new value.
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</para>
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</note>
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<informalexample><programlisting>
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/* Notice that it is initialized to the empty list. */
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GList *list = NULL;
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list = g_list_prepend (list, "last");
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list = g_list_prepend (list, "first");
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</programlisting></informalexample>
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@list: a pointer to a #GList.
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@data: the data for the new element.
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@Returns: the new start of the #GList.
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<!-- ##### FUNCTION g_list_insert ##### -->
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<para>
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Inserts a new element into the list at the given position.
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</para>
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@list: a pointer to a #GList.
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@data: the data for the new element.
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@position: the position to insert the element. If this is negative, or is
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larger than the number of elements in the list, the new element is added on
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to the end of the list.
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@Returns: the new start of the #GList.
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<!-- ##### FUNCTION g_list_insert_sorted ##### -->
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<para>
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Inserts a new element into the list, using the given comparison function
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to determine its position.
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</para>
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@list: a pointer to a #GList.
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@data: the data for the new element.
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@func: the function to compare elements in the list. It should return a
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number > 0 if the first parameter comes after the second parameter in
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the sort order.
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@Returns: the new start of the #GList.
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<!-- ##### FUNCTION g_list_remove ##### -->
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<para>
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Removes an element from a #GList.
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If two elements contain the same data, only the first is removed.
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If none of the elements contain the data, the #GList is unchanged.
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</para>
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@list: a #GList.
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@data: the data of the element to remove.
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@Returns: the new start of the #GList.
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<!-- ##### FUNCTION g_list_remove_link ##### -->
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<para>
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Removes an element from a #GList, without freeing the element.
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The removed element's prev and next links are set to NULL, so that it becomes a
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self-contained list with one element.
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</para>
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@list: a #GList.
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@llink: an element in the #GList.
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@Returns: the new start of the #GList, without the element.
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<!-- ##### FUNCTION g_list_delete_link ##### -->
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<para>
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</para>
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@list:
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@link:
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@Returns:
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<!-- ##### FUNCTION g_list_free ##### -->
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<para>
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Frees all of the memory used by a #GList.
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The freed elements are added to the #GListAllocator free list.
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</para>
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<note>
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<para>
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If list elements contain dynamically-allocated memory, they should be freed
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first.
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</para>
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</note>
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@list:
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<!-- ##### FUNCTION g_list_alloc ##### -->
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<para>
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Allocates space for one #GList element.
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It is called by g_list_append(), g_list_prepend(), g_list_insert() and
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g_list_insert_sorted() and so is rarely used on its own.
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</para>
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@Returns: a pointer to the newly-allocated #GList element.
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<!-- ##### FUNCTION g_list_free_1 ##### -->
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<para>
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Frees one #GList element.
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It is usually used after g_list_remove_link().
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</para>
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@list: a #GList element.
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<!-- ##### FUNCTION g_list_length ##### -->
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<para>
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Gets the number of elements in a #GList.
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</para>
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@list: a #GList.
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@Returns: the number of elements in the #GList.
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<!-- ##### FUNCTION g_list_copy ##### -->
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<para>
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Copies a #GList.
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</para>
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<para>
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Note that this is a "shallow" copy. If the list elements consist of pointers
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to data, the pointers are copied but the actual data isn't.
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</para>
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@list: a #GList.
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@Returns: a copy of @list.
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<!-- ##### FUNCTION g_list_reverse ##### -->
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<para>
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Reverses a #GList.
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It simply switches the next and prev pointers of each element.
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</para>
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@list: a #GList.
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@Returns: the start of the reversed #GList.
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<!-- ##### FUNCTION g_list_sort ##### -->
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<para>
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Sorts a #GList using the given comparison function.
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</para>
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@list: a #GList.
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@compare_func: the comparison function used to sort the #GList. This function
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is passed 2 elements of the #GList and should return 0 if they are equal,
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a negative value if the first element comes before the second, or a positive
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value if the first element comes after the second.
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@Returns: the start of the sorted #GList.
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<!-- ##### FUNCTION g_list_concat ##### -->
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<para>
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Adds the second #GList onto the end of the first #GList.
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Note that the elements of the second #GList are not copied.
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They are used directly.
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</para>
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@list1: a #GList.
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@list2: the #GList to add to the end of the first #GList.
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@Returns: the start of the new #GList.
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<!-- ##### FUNCTION g_list_foreach ##### -->
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<para>
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Calls a function for each element of a #GList.
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</para>
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@list: a #GList.
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@func: the function to call with each element's data.
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@user_data: user data to pass to the function.
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<!-- ##### USER_FUNCTION GFunc ##### -->
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<para>
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Specifies the type of functions passed to g_list_foreach() and
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g_slist_foreach().
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</para>
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@data: the element's data.
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@user_data: user data passed to g_list_foreach() or g_slist_foreach().
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<!-- ##### FUNCTION g_list_first ##### -->
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<para>
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Gets the first element in a #GList.
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</para>
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@list: a #GList.
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@Returns: the first element in a #GList, or NULL if the #GList has no elements.
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<!-- ##### FUNCTION g_list_last ##### -->
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<para>
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Gets the last element in a #GList.
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</para>
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@list: a #GList.
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@Returns: the last element in the #GList, or NULL if the #GList has no
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elements.
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<!-- ##### MACRO g_list_previous ##### -->
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<para>
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A convenience macro to gets the previous element in a #GList.
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</para>
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@list: an element in a #GList.
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@Returns: the previous element, or NULL if there are no previous elements.
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<!-- ##### MACRO g_list_next ##### -->
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<para>
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A convenience macro to gets the next element in a #GList.
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</para>
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@list: an element in a #GList.
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@Returns: the next element, or NULL if there are no more elements.
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<!-- ##### FUNCTION g_list_nth ##### -->
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<para>
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Gets the element at the given position in a #GList.
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</para>
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@list: a #GList.
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@n: the position of the element, counting from 0.
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@Returns: the element, or NULL if the position is off the end of the #GList.
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<!-- ##### FUNCTION g_list_nth_data ##### -->
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<para>
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Gets the data of the element at the given position.
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</para>
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@list: a #GList.
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@n: the position of the element.
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@Returns: the element's data, or NULL if the position is off the end of the
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#GList.
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<!-- ##### FUNCTION g_list_find ##### -->
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<para>
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Finds the element in a #GList which contains the given data.
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</para>
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@list: a #GList.
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@data: the element data to find.
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@Returns: the found #GList element, or NULL if it is not found.
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<!-- ##### FUNCTION g_list_find_custom ##### -->
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<para>
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Finds an element in a #GList, using a supplied function to find the desired
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element.
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It iterates over the list, calling the given function which should return 0
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when the desired element is found.
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The function takes two #gconstpointer arguments, the #GList element's data
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and the given user data.
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</para>
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@list: a #GList.
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@data: user data passed to the function.
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@func: the function to call for each element. It should return 0 when the
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desired element is found.
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@Returns: the found #GList element, or NULL if it is not found.
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<!-- ##### FUNCTION g_list_position ##### -->
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<para>
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Gets the position of the given element in the #GList (starting from 0).
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</para>
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@list: a #GList.
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@llink: an element in the #GList.
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@Returns: the position of the element in the #GList, or -1 if the element is
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not found.
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<!-- ##### FUNCTION g_list_index ##### -->
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<para>
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Gets the position of the element containing the given data (starting from 0).
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</para>
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@list: a #GList.
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@data: the data to find.
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@Returns: the index of the element containing the data, or -1 if the data
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is not found.
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<!-- ##### FUNCTION g_list_push_allocator ##### -->
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<para>
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Sets the allocator to use to allocate #GList elements.
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Use g_list_pop_allocator() to restore the previous allocator.
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</para>
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@allocator: the #GAllocator to use when allocating #GList elements.
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<!-- ##### FUNCTION g_list_pop_allocator ##### -->
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<para>
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Restores the previous #GAllocator, used when allocating #GList elements.
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</para>
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