linked_lists_double.sgml

GLib是GTK+和GNOME工程的基础底层核心程序库

<refentry id="glib-Doubly-Linked-Lists">
<refmeta>
<refentrytitle>Doubly-Linked Lists</refentrytitle>
<manvolnum>3</manvolnum>
<refmiscinfo>GLIB Library</refmiscinfo>
</refmeta>

<refnamediv>
<refname>Doubly-Linked Lists</refname><refpurpose>linked lists containing integer values or pointers to data, with the ability
to iterate over the list in both directions.</refpurpose>
</refnamediv>

<refsynopsisdiv><title>Synopsis</title>
<synopsis>

#include &lt;glib.h&gt;


struct      <link linkend="GList">GList</link>;

<link linkend="GList">GList</link>*      <link linkend="g-list-append">g_list_append</link>                   (<link linkend="GList">GList</link> *list,
                                             <link linkend="gpointer">gpointer</link> data);
<link linkend="GList">GList</link>*      <link linkend="g-list-prepend">g_list_prepend</link>                  (<link linkend="GList">GList</link> *list,
                                             <link linkend="gpointer">gpointer</link> data);
<link linkend="GList">GList</link>*      <link linkend="g-list-insert">g_list_insert</link>                   (<link linkend="GList">GList</link> *list,
                                             <link linkend="gpointer">gpointer</link> data,
                                             <link linkend="gint">gint</link> position);
<link linkend="GList">GList</link>*      <link linkend="g-list-insert-before">g_list_insert_before</link>            (<link linkend="GList">GList</link> *list,
                                             <link linkend="GList">GList</link> *sibling,
                                             <link linkend="gpointer">gpointer</link> data);
<link linkend="GList">GList</link>*      <link linkend="g-list-insert-sorted">g_list_insert_sorted</link>            (<link linkend="GList">GList</link> *list,
                                             <link linkend="gpointer">gpointer</link> data,
                                             <link linkend="GCompareFunc">GCompareFunc</link> func);
<link linkend="GList">GList</link>*      <link linkend="g-list-remove">g_list_remove</link>                   (<link linkend="GList">GList</link> *list,
                                             <link linkend="gconstpointer">gconstpointer</link> data);
<link linkend="GList">GList</link>*      <link linkend="g-list-remove-link">g_list_remove_link</link>              (<link linkend="GList">GList</link> *list,
                                             <link linkend="GList">GList</link> *llink);
<link linkend="GList">GList</link>*      <link linkend="g-list-delete-link">g_list_delete_link</link>              (<link linkend="GList">GList</link> *list,
                                             <link linkend="GList">GList</link> *link);
<link linkend="GList">GList</link>*      <link linkend="g-list-remove-all">g_list_remove_all</link>               (<link linkend="GList">GList</link> *list,
                                             <link linkend="gconstpointer">gconstpointer</link> data);
void        <link linkend="g-list-free">g_list_free</link>                     (<link linkend="GList">GList</link> *list);

<link linkend="GList">GList</link>*      <link linkend="g-list-alloc">g_list_alloc</link>                    (void);
void        <link linkend="g-list-free-1">g_list_free_1</link>                   (<link linkend="GList">GList</link> *list);

<link linkend="guint">guint</link>       <link linkend="g-list-length">g_list_length</link>                   (<link linkend="GList">GList</link> *list);
<link linkend="GList">GList</link>*      <link linkend="g-list-copy">g_list_copy</link>                     (<link linkend="GList">GList</link> *list);
<link linkend="GList">GList</link>*      <link linkend="g-list-reverse">g_list_reverse</link>                  (<link linkend="GList">GList</link> *list);
<link linkend="GList">GList</link>*      <link linkend="g-list-sort">g_list_sort</link>                     (<link linkend="GList">GList</link> *list,
                                             <link linkend="GCompareFunc">GCompareFunc</link> compare_func);
<link linkend="gint">gint</link>        (<link linkend="GCompareFunc">*GCompareFunc</link>)                 (<link linkend="gconstpointer">gconstpointer</link> a,
                                             <link linkend="gconstpointer">gconstpointer</link> b);
<link linkend="GList">GList</link>*      <link linkend="g-list-sort-with-data">g_list_sort_with_data</link>           (<link linkend="GList">GList</link> *list,
                                             <link linkend="GCompareDataFunc">GCompareDataFunc</link> compare_func,
                                             <link linkend="gpointer">gpointer</link> user_data);
<link linkend="gint">gint</link>        (<link linkend="GCompareDataFunc">*GCompareDataFunc</link>)             (<link linkend="gconstpointer">gconstpointer</link> a,
                                             <link linkend="gconstpointer">gconstpointer</link> b,
                                             <link linkend="gpointer">gpointer</link> user_data);
<link linkend="GList">GList</link>*      <link linkend="g-list-concat">g_list_concat</link>                   (<link linkend="GList">GList</link> *list1,
                                             <link linkend="GList">GList</link> *list2);
void        <link linkend="g-list-foreach">g_list_foreach</link>                  (<link linkend="GList">GList</link> *list,
                                             <link linkend="GFunc">GFunc</link> func,
                                             <link linkend="gpointer">gpointer</link> user_data);
void        (<link linkend="GFunc">*GFunc</link>)                        (<link linkend="gpointer">gpointer</link> data,
                                             <link linkend="gpointer">gpointer</link> user_data);

<link linkend="GList">GList</link>*      <link linkend="g-list-first">g_list_first</link>                    (<link linkend="GList">GList</link> *list);
<link linkend="GList">GList</link>*      <link linkend="g-list-last">g_list_last</link>                     (<link linkend="GList">GList</link> *list);
#define     <link linkend="g-list-previous">g_list_previous</link>                 (list)
#define     <link linkend="g-list-next">g_list_next</link>                     (list)
<link linkend="GList">GList</link>*      <link linkend="g-list-nth">g_list_nth</link>                      (<link linkend="GList">GList</link> *list,
                                             <link linkend="guint">guint</link> n);
<link linkend="gpointer">gpointer</link>    <link linkend="g-list-nth-data">g_list_nth_data</link>                 (<link linkend="GList">GList</link> *list,
                                             <link linkend="guint">guint</link> n);
<link linkend="GList">GList</link>*      <link linkend="g-list-nth-prev">g_list_nth_prev</link>                 (<link linkend="GList">GList</link> *list,
                                             <link linkend="guint">guint</link> n);

<link linkend="GList">GList</link>*      <link linkend="g-list-find">g_list_find</link>                     (<link linkend="GList">GList</link> *list,
                                             <link linkend="gconstpointer">gconstpointer</link> data);
<link linkend="GList">GList</link>*      <link linkend="g-list-find-custom">g_list_find_custom</link>              (<link linkend="GList">GList</link> *list,
                                             <link linkend="gconstpointer">gconstpointer</link> data,
                                             <link linkend="GCompareFunc">GCompareFunc</link> func);
<link linkend="gint">gint</link>        <link linkend="g-list-position">g_list_position</link>                 (<link linkend="GList">GList</link> *list,
                                             <link linkend="GList">GList</link> *llink);
<link linkend="gint">gint</link>        <link linkend="g-list-index">g_list_index</link>                    (<link linkend="GList">GList</link> *list,
                                             <link linkend="gconstpointer">gconstpointer</link> data);

void        <link linkend="g-list-push-allocator">g_list_push_allocator</link>           (<link linkend="GAllocator">GAllocator</link> *allocator);
void        <link linkend="g-list-pop-allocator">g_list_pop_allocator</link>            (void);
</synopsis>
</refsynopsisdiv>





<refsect1>
<title>Description</title>
<para>
The <link linkend="GList">GList</link> structure and its associated functions provide a standard
doubly-linked list data structure.
</para>
<para>
Each element in the list contains a piece of data, together with pointers
which link to the previous and next elements in the list.
Using these pointers it is possible to move through the list in both
directions (unlike the
<link linkend="glib-Singly-Linked-lists">Singly-Linked Lists</link>
which only allows movement through the list in the forward direction).
</para>
<para>
The data contained in each element can be either integer values, by using one
of the
<link linkend="glib-Type-Conversion-Macros">Type Conversion Macros</link>,
or simply pointers to any type of data.
</para>
<para>
List elements are allocated in blocks using a <link linkend="GListAllocator">GListAllocator</link>, which is
more efficient than allocating elements individually.
</para>
<para>
Note that most of the <link linkend="GList">GList</link> functions expect to be passed a pointer to
the first element in the list. The functions which insert elements return
the new start of the list, which may have changed.
</para>
<para>
There is no function to create a <link linkend="GList">GList</link>. <literal>NULL</literal> is considered to be the empty
list so you simply set a <link linkend="GList">GList</link>* to <literal>NULL</literal>.
</para>
<para>
To add elements, use <link linkend="g-list-append">g_list_append</link>(), <link linkend="g-list-prepend">g_list_prepend</link>(), <link linkend="g-list-insert">g_list_insert</link>()
and <link linkend="g-list-insert-sorted">g_list_insert_sorted</link>().
</para>
<para>
To remove elements, use <link linkend="g-list-remove">g_list_remove</link>().
</para>
<para>
To find elements in the list use <link linkend="g-list-first">g_list_first</link>(), <link linkend="g-list-last">g_list_last</link>(), <link linkend="g-list-next">g_list_next</link>(),
<link linkend="g-list-previous">g_list_previous</link>(), <link linkend="g-list-nth">g_list_nth</link>(), <link linkend="g-list-nth-data">g_list_nth_data</link>(), <link linkend="g-list-find">g_list_find</link>() and
<link linkend="g-list-find-custom">g_list_find_custom</link>().
</para>
<para>
To find the index of an element use <link linkend="g-list-position">g_list_position</link>() and <link linkend="g-list-index">g_list_index</link>().
</para>
<para>
To call a function for each element in the list use <link linkend="g-list-foreach">g_list_foreach</link>().
</para>
<para>
To free the entire list, use <link linkend="g-list-free">g_list_free</link>().
</para>
</refsect1>

<refsect1>
<title>Details</title>
<refsect2>
<title><anchor id="GList">struct GList</title>
<programlisting>struct GList
{
  gpointer data;
  GList *next;
  GList *prev;
};
</programlisting>
<para>
The <link linkend="GList">GList</link> struct is used for each element in a doubly-linked list.
The <structfield>data</structfield> field holds the element's data, which can
be a pointer to any kind of data, or any integer value using the
<link linkend="glib-Type-Conversion-Macros">Type Conversion Macros</link>.
The <structfield>next</structfield> and <structfield>prev</structfield>
pointers are the links to the next and previous elements in the list.
</para></refsect2>
<refsect2>
<title><anchor id="g-list-append">g_list_append ()</title>
<programlisting><link linkend="GList">GList</link>*      g_list_append                   (<link linkend="GList">GList</link> *list,
                                             <link linkend="gpointer">gpointer</link> data);</programlisting>
<para>
Adds a new element on to the end of the list.
</para>
<note>
<para>
The return value is the new start of the list, which may have changed, so
make sure you store the new value.
</para>
</note>
<informalexample><programlisting>
  /* Notice that these are initialized to the empty list. */
  GList *list = NULL, *number_list = NULL;

  /* This is a list of strings. */
  list = g_list_append (list, "first");
  list = g_list_append (list, "second");

  /* This is a list of integers. */
  number_list = g_list_append (number_list, GINT_TO_POINTER (27));
  number_list = g_list_append (number_list, GINT_TO_POINTER (14));
</programlisting></informalexample><informaltable pgwide="1" frame="none" role="params">
<tgroup cols="2">
<colspec colwidth="2*">
<colspec colwidth="8*">
<tbody>
<row><entry align="right"><parameter>list</parameter>&nbsp;:</entry>
<entry>a pointer to a <link linkend="GList">GList</link>.
</entry></row>
<row><entry align="right"><parameter>data</parameter>&nbsp;:</entry>
<entry>the data for the new element.
</entry></row>
<row><entry align="right"><emphasis>Returns</emphasis> :</entry><entry>the new start of the <link linkend="GList">GList</link>.


</entry></row>
</tbody></tgroup></informaltable></refsect2>
<refsect2>
<title><anchor id="g-list-prepend">g_list_prepend ()</title>
<programlisting><link linkend="GList">GList</link>*      g_list_prepend                  (<link linkend="GList">GList</link> *list,
                                             <link linkend="gpointer">gpointer</link> data);</programlisting>
<para>
Adds a new element on to the start of the list.
</para>
<note>
<para>
The return value is the new start of the list, which may have changed, so
make sure you store the new value.
</para>
</note>
<informalexample><programlisting>
  /* Notice that it is initialized to the empty list. */
  GList *list = NULL;
  list = g_list_prepend (list, "last");
  list = g_list_prepend (list, "first");
</programlisting></informalexample><informaltable pgwide="1" frame="none" role="params">
<tgroup cols="2">
<colspec colwidth="2*">
<colspec colwidth="8*">
<tbody>
<row><entry align="right"><parameter>list</parameter>&nbsp;:</entry>
<entry>a pointer to a <link linkend="GList">GList</link>.
</entry></row>
<row><entry align="right"><parameter>data</parameter>&nbsp;:</entry>
<entry>the data for the new element.
</entry></row>
<row><entry align="right"><emphasis>Returns</emphasis> :</entry><entry>the new start of the <link linkend="GList">GList</link>.


</entry></row>
</tbody></tgroup></informaltable></refsect2>
<refsect2>