garray.c 62.5 KB
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/* GLIB - Library of useful routines for C programming
 * Copyright (C) 1995-1997  Peter Mattis, Spencer Kimball and Josh MacDonald
 *
 * This library is free software; you can redistribute it and/or
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 * modify it under the terms of the GNU Lesser General Public
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 * License as published by the Free Software Foundation; either
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 * version 2.1 of the License, or (at your option) any later version.
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 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
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 * Lesser General Public License for more details.
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 *
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 * You should have received a copy of the GNU Lesser General Public
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 * License along with this library; if not, see <http://www.gnu.org/licenses/>.
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 */
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/*
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 * Modified by the GLib Team and others 1997-2000.  See the AUTHORS
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 * file for a list of people on the GLib Team.  See the ChangeLog
 * files for a list of changes.  These files are distributed with
 * GLib at ftp://ftp.gtk.org/pub/gtk/. 
 */

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/* 
 * MT safe
 */

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#include "config.h"
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#include <string.h>
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#include <stdlib.h>
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#include "garray.h"

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#include "gbytes.h"
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#include "ghash.h"
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#include "gslice.h"
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#include "gmem.h"
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#include "gtestutils.h"
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#include "gthread.h"
#include "gmessages.h"
#include "gqsort.h"
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#include "grefcount.h"
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/**
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 * SECTION:arrays
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 * @title: Arrays
 * @short_description: arrays of arbitrary elements which grow
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 *     automatically as elements are added
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 *
 * Arrays are similar to standard C arrays, except that they grow
 * automatically as elements are added.
 *
 * Array elements can be of any size (though all elements of one array
 * are the same size), and the array can be automatically cleared to
 * '0's and zero-terminated.
 *
 * To create a new array use g_array_new().
 *
 * To add elements to an array, use g_array_append_val(),
 * g_array_append_vals(), g_array_prepend_val(), and
 * g_array_prepend_vals().
 *
 * To access an element of an array, use g_array_index().
 *
 * To set the size of an array, use g_array_set_size().
 *
 * To free an array, use g_array_free().
 *
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 * Here is an example that stores integers in a #GArray:
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 * |[<!-- language="C" -->
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 *   GArray *garray;
 *   gint i;
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 *   // We create a new array to store gint values.
 *   // We don't want it zero-terminated or cleared to 0's.
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 *   garray = g_array_new (FALSE, FALSE, sizeof (gint));
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 *   for (i = 0; i < 10000; i++)
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 *     g_array_append_val (garray, i);
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 *   for (i = 0; i < 10000; i++)
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 *     if (g_array_index (garray, gint, i) != i)
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 *       g_print ("ERROR: got %d instead of %d\n",
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 *                g_array_index (garray, gint, i), i);
 *   g_array_free (garray, TRUE);
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 * ]|
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 */
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#define MIN_ARRAY_SIZE  16

typedef struct _GRealArray  GRealArray;

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/**
 * GArray:
 * @data: a pointer to the element data. The data may be moved as
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 *     elements are added to the #GArray.
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 * @len: the number of elements in the #GArray not including the
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 *     possible terminating zero element.
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 *
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 * Contains the public fields of a GArray.
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 */
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struct _GRealArray
{
  guint8 *data;
  guint   len;
  guint   alloc;
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  guint   elt_size;
  guint   zero_terminated : 1;
  guint   clear : 1;
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  gatomicrefcount ref_count;
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  GDestroyNotify clear_func;
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};

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/**
 * g_array_index:
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 * @a: a #GArray
 * @t: the type of the elements
 * @i: the index of the element to return
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 *
 * Returns the element of a #GArray at the given index. The return
 * value is cast to the given type.
 *
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 * This example gets a pointer to an element in a #GArray:
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 * |[<!-- language="C" -->
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 *   EDayViewEvent *event;
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 *   // This gets a pointer to the 4th element in the array of
 *   // EDayViewEvent structs.
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 *   event = &g_array_index (events, EDayViewEvent, 3);
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 * ]|
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 *
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 * Returns: the element of the #GArray at the index given by @i
 */
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#define g_array_elt_len(array,i) ((array)->elt_size * (i))
#define g_array_elt_pos(array,i) ((array)->data + g_array_elt_len((array),(i)))
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#define g_array_elt_zero(array, pos, len)                               \
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  (memset (g_array_elt_pos ((array), pos), 0,  g_array_elt_len ((array), len)))
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#define g_array_zero_terminate(array) G_STMT_START{                     \
  if ((array)->zero_terminated)                                         \
    g_array_elt_zero ((array), (array)->len, 1);                        \
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}G_STMT_END
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static guint g_nearest_pow        (guint       num) G_GNUC_CONST;
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static void  g_array_maybe_expand (GRealArray *array,
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                                   guint       len);
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/**
 * g_array_new:
 * @zero_terminated: %TRUE if the array should have an extra element at
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 *     the end which is set to 0
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 * @clear_: %TRUE if #GArray elements should be automatically cleared
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 *     to 0 when they are allocated
 * @element_size: the size of each element in bytes
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 *
 * Creates a new #GArray with a reference count of 1.
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 *
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 * Returns: the new #GArray
 */
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GArray*
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g_array_new (gboolean zero_terminated,
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             gboolean clear,
             guint    elt_size)
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{
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  g_return_val_if_fail (elt_size > 0, NULL);

  return g_array_sized_new (zero_terminated, clear, elt_size, 0);
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}

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/**
 * g_array_sized_new:
 * @zero_terminated: %TRUE if the array should have an extra element at
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 *     the end with all bits cleared
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 * @clear_: %TRUE if all bits in the array should be cleared to 0 on
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 *     allocation
 * @element_size: size of each element in the array
 * @reserved_size: number of elements preallocated
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 *
 * Creates a new #GArray with @reserved_size elements preallocated and
 * a reference count of 1. This avoids frequent reallocation, if you
 * are going to add many elements to the array. Note however that the
 * size of the array is still 0.
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 *
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 * Returns: the new #GArray
 */
GArray*
g_array_sized_new (gboolean zero_terminated,
                   gboolean clear,
                   guint    elt_size,
                   guint    reserved_size)
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{
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  GRealArray *array;
  
  g_return_val_if_fail (elt_size > 0, NULL);

  array = g_slice_new (GRealArray);
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  array->data            = NULL;
  array->len             = 0;
  array->alloc           = 0;
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  array->zero_terminated = (zero_terminated ? 1 : 0);
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  array->clear           = (clear ? 1 : 0);
  array->elt_size        = elt_size;
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  array->clear_func      = NULL;
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  g_atomic_ref_count_init (&array->ref_count);

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  if (array->zero_terminated || reserved_size != 0)
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    {
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      g_array_maybe_expand (array, reserved_size);
      g_array_zero_terminate(array);
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    }

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  return (GArray*) array;
}

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/**
 * g_array_set_clear_func:
 * @array: A #GArray
 * @clear_func: a function to clear an element of @array
 *
 * Sets a function to clear an element of @array.
 *
 * The @clear_func will be called when an element in the array
 * data segment is removed and when the array is freed and data
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 * segment is deallocated as well. @clear_func will be passed a
 * pointer to the element to clear, rather than the element itself.
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 *
 * Note that in contrast with other uses of #GDestroyNotify
 * functions, @clear_func is expected to clear the contents of
 * the array element it is given, but not free the element itself.
 *
 * Since: 2.32
 */
void
g_array_set_clear_func (GArray         *array,
                        GDestroyNotify  clear_func)
{
  GRealArray *rarray = (GRealArray *) array;

  g_return_if_fail (array != NULL);

  rarray->clear_func = clear_func;
}

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/**
 * g_array_ref:
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 * @array: A #GArray
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 *
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 * Atomically increments the reference count of @array by one.
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 * This function is thread-safe and may be called from any thread.
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 *
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 * Returns: The passed in #GArray
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 *
 * Since: 2.22
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 */
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GArray *
g_array_ref (GArray *array)
{
  GRealArray *rarray = (GRealArray*) array;
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  g_return_val_if_fail (array, NULL);
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  g_atomic_ref_count_inc (&rarray->ref_count);
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  return array;
}

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typedef enum
{
  FREE_SEGMENT = 1 << 0,
  PRESERVE_WRAPPER = 1 << 1
} ArrayFreeFlags;

static gchar *array_free (GRealArray *, ArrayFreeFlags);

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/**
 * g_array_unref:
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 * @array: A #GArray
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 *
 * Atomically decrements the reference count of @array by one. If the
 * reference count drops to 0, all memory allocated by the array is
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 * released. This function is thread-safe and may be called from any
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 * thread.
 *
 * Since: 2.22
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 */
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void
g_array_unref (GArray *array)
{
  GRealArray *rarray = (GRealArray*) array;
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  g_return_if_fail (array);
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  if (g_atomic_ref_count_dec (&rarray->ref_count))
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    array_free (rarray, FREE_SEGMENT);
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}

/**
 * g_array_get_element_size:
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 * @array: A #GArray
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 *
 * Gets the size of the elements in @array.
 *
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 * Returns: Size of each element, in bytes
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 *
 * Since: 2.22
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 */
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guint
g_array_get_element_size (GArray *array)
{
  GRealArray *rarray = (GRealArray*) array;
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  g_return_val_if_fail (array, 0);

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  return rarray->elt_size;
}

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/**
 * g_array_free:
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 * @array: a #GArray
 * @free_segment: if %TRUE the actual element data is freed as well
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 *
 * Frees the memory allocated for the #GArray. If @free_segment is
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 * %TRUE it frees the memory block holding the elements as well. Pass
 * %FALSE if you want to free the #GArray wrapper but preserve the
 * underlying array for use elsewhere. If the reference count of
 * @array is greater than one, the #GArray wrapper is preserved but
 * the size of  @array will be set to zero.
 *
 * If array contents point to dynamically-allocated memory, they should
 * be freed separately if @free_seg is %TRUE and no @clear_func
 * function has been set for @array.
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 *
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 * This function is not thread-safe. If using a #GArray from multiple
 * threads, use only the atomic g_array_ref() and g_array_unref()
 * functions.
 *
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 * Returns: the element data if @free_segment is %FALSE, otherwise
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 *     %NULL. The element data should be freed using g_free().
 */
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gchar*
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g_array_free (GArray   *farray,
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              gboolean  free_segment)
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{
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  GRealArray *array = (GRealArray*) farray;
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  ArrayFreeFlags flags;
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  g_return_val_if_fail (array, NULL);

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  flags = (free_segment ? FREE_SEGMENT : 0);

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  /* if others are holding a reference, preserve the wrapper but do free/return the data */
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  if (!g_atomic_ref_count_dec (&array->ref_count))
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    flags |= PRESERVE_WRAPPER;

  return array_free (array, flags);
}

static gchar *
array_free (GRealArray     *array,
            ArrayFreeFlags  flags)
{
  gchar *segment;
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  if (flags & FREE_SEGMENT)
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    {
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      if (array->clear_func != NULL)
        {
          guint i;

          for (i = 0; i < array->len; i++)
            array->clear_func (g_array_elt_pos (array, i));
        }

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      g_free (array->data);
      segment = NULL;
    }
  else
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    segment = (gchar*) array->data;
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  if (flags & PRESERVE_WRAPPER)
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    {
      array->data            = NULL;
      array->len             = 0;
      array->alloc           = 0;
    }
  else
    {
      g_slice_free1 (sizeof (GRealArray), array);
    }
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  return segment;
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}

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/**
 * g_array_append_vals:
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 * @array: a #GArray
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 * @data: (not nullable): a pointer to the elements to append to the end of the array
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 * @len: the number of elements to append
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 *
 * Adds @len elements onto the end of the array.
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 *
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 * Returns: the #GArray
 */
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/**
 * g_array_append_val:
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 * @a: a #GArray
 * @v: the value to append to the #GArray
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 *
 * Adds the value on to the end of the array. The array will grow in
 * size automatically if necessary.
 *
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 * g_array_append_val() is a macro which uses a reference to the value
 * parameter @v. This means that you cannot use it with literal values
 * such as "27". You must use variables.
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 *
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 * Returns: the #GArray
 */
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GArray*
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g_array_append_vals (GArray       *farray,
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                     gconstpointer data,
                     guint         len)
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{
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  GRealArray *array = (GRealArray*) farray;
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  g_return_val_if_fail (array, NULL);

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  if (len == 0)
    return farray;

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  g_array_maybe_expand (array, len);
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  memcpy (g_array_elt_pos (array, array->len), data, 
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          g_array_elt_len (array, len));
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  array->len += len;

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  g_array_zero_terminate (array);

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  return farray;
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}

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/**
 * g_array_prepend_vals:
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 * @array: a #GArray
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 * @data: (nullable): a pointer to the elements to prepend to the start of the array
 * @len: the number of elements to prepend, which may be zero
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 *
 * Adds @len elements onto the start of the array.
 *
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 * @data may be %NULL if (and only if) @len is zero. If @len is zero, this
 * function is a no-op.
 *
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 * This operation is slower than g_array_append_vals() since the
 * existing elements in the array have to be moved to make space for
 * the new elements.
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 *
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 * Returns: the #GArray
 */
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/**
 * g_array_prepend_val:
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 * @a: a #GArray
 * @v: the value to prepend to the #GArray
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 *
 * Adds the value on to the start of the array. The array will grow in
 * size automatically if necessary.
 *
 * This operation is slower than g_array_append_val() since the
 * existing elements in the array have to be moved to make space for
 * the new element.
 *
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 * g_array_prepend_val() is a macro which uses a reference to the value
 * parameter @v. This means that you cannot use it with literal values
 * such as "27". You must use variables.
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 *
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 * Returns: the #GArray
 */
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GArray*
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g_array_prepend_vals (GArray        *farray,
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                      gconstpointer  data,
                      guint          len)
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{
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  GRealArray *array = (GRealArray*) farray;
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  g_return_val_if_fail (array, NULL);

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  if (len == 0)
    return farray;

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  g_array_maybe_expand (array, len);
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  memmove (g_array_elt_pos (array, len), g_array_elt_pos (array, 0),
           g_array_elt_len (array, array->len));
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  memcpy (g_array_elt_pos (array, 0), data, g_array_elt_len (array, len));
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  array->len += len;

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  g_array_zero_terminate (array);

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  return farray;
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}

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/**
 * g_array_insert_vals:
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 * @array: a #GArray
 * @index_: the index to place the elements at
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 * @data: (nullable): a pointer to the elements to insert
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 * @len: the number of elements to insert
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 *
 * Inserts @len elements into a #GArray at the given index.
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 *
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 * If @index_ is greater than the array’s current length, the array is expanded.
 * The elements between the old end of the array and the newly inserted elements
 * will be initialised to zero if the array was configured to clear elements;
 * otherwise their values will be undefined.
 *
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 * @data may be %NULL if (and only if) @len is zero. If @len is zero, this
 * function is a no-op.
 *
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 * Returns: the #GArray
 */
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/**
 * g_array_insert_val:
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 * @a: a #GArray
 * @i: the index to place the element at
 * @v: the value to insert into the array
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 *
 * Inserts an element into an array at the given index.
 *
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 * g_array_insert_val() is a macro which uses a reference to the value
 * parameter @v. This means that you cannot use it with literal values
 * such as "27". You must use variables.
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 *
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 * Returns: the #GArray
 */
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GArray*
g_array_insert_vals (GArray        *farray,
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                     guint          index_,
                     gconstpointer  data,
                     guint          len)
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{
  GRealArray *array = (GRealArray*) farray;

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  g_return_val_if_fail (array, NULL);

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  if (len == 0)
    return farray;

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  /* Is the index off the end of the array, and hence do we need to over-allocate
   * and clear some elements? */
  if (index_ >= array->len)
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    {
      g_array_maybe_expand (array, index_ - array->len + len);
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      return g_array_append_vals (g_array_set_size (farray, index_), data, len);
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    }
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  g_array_maybe_expand (array, len);

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  memmove (g_array_elt_pos (array, len + index_),
           g_array_elt_pos (array, index_),
           g_array_elt_len (array, array->len - index_));
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  memcpy (g_array_elt_pos (array, index_), data, g_array_elt_len (array, len));
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  array->len += len;

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  g_array_zero_terminate (array);

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  return farray;
}

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/**
 * g_array_set_size:
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 * @array: a #GArray
 * @length: the new size of the #GArray
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 *
 * Sets the size of the array, expanding it if necessary. If the array
 * was created with @clear_ set to %TRUE, the new elements are set to 0.
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 *
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 * Returns: the #GArray
 */
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GArray*
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g_array_set_size (GArray *farray,
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                  guint   length)
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{
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  GRealArray *array = (GRealArray*) farray;
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  g_return_val_if_fail (array, NULL);

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  if (length > array->len)
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    {
      g_array_maybe_expand (array, length - array->len);
      
      if (array->clear)
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        g_array_elt_zero (array, array->len, length - array->len);
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    }
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  else if (length < array->len)
    g_array_remove_range (farray, length, array->len - length);
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  array->len = length;
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  g_array_zero_terminate (array);
  
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  return farray;
}
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/**
 * g_array_remove_index:
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 * @array: a #GArray
 * @index_: the index of the element to remove
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 *
 * Removes the element at the given index from a #GArray. The following
 * elements are moved down one place.
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 *
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 * Returns: the #GArray
 */
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GArray*
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g_array_remove_index (GArray *farray,
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                      guint   index_)
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{
  GRealArray* array = (GRealArray*) farray;

  g_return_val_if_fail (array, NULL);

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  g_return_val_if_fail (index_ < array->len, NULL);
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  if (array->clear_func != NULL)
    array->clear_func (g_array_elt_pos (array, index_));

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  if (index_ != array->len - 1)
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    memmove (g_array_elt_pos (array, index_),
             g_array_elt_pos (array, index_ + 1),
             g_array_elt_len (array, array->len - index_ - 1));
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  array->len -= 1;

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  if (G_UNLIKELY (g_mem_gc_friendly))
    g_array_elt_zero (array, array->len, 1);
  else
    g_array_zero_terminate (array);
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  return farray;
}

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/**
 * g_array_remove_index_fast:
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 * @array: a @GArray
 * @index_: the index of the element to remove
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 *
 * Removes the element at the given index from a #GArray. The last
 * element in the array is used to fill in the space, so this function
 * does not preserve the order of the #GArray. But it is faster than
 * g_array_remove_index().
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 *
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 * Returns: the #GArray
 */
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GArray*
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g_array_remove_index_fast (GArray *farray,
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                           guint   index_)
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{
  GRealArray* array = (GRealArray*) farray;

  g_return_val_if_fail (array, NULL);

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  g_return_val_if_fail (index_ < array->len, NULL);
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  if (array->clear_func != NULL)
    array->clear_func (g_array_elt_pos (array, index_));

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  if (index_ != array->len - 1)
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    memcpy (g_array_elt_pos (array, index_),
            g_array_elt_pos (array, array->len - 1),
            g_array_elt_len (array, 1));
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  array->len -= 1;

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  if (G_UNLIKELY (g_mem_gc_friendly))
    g_array_elt_zero (array, array->len, 1);
  else
    g_array_zero_terminate (array);
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  return farray;
}

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/**
 * g_array_remove_range:
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 * @array: a @GArray
 * @index_: the index of the first element to remove
 * @length: the number of elements to remove
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 *
 * Removes the given number of elements starting at the given index
 * from a #GArray.  The following elements are moved to close the gap.
 *
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 * Returns: the #GArray
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 *
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 * Since: 2.4
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 */
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GArray*
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g_array_remove_range (GArray *farray,
                      guint   index_,
                      guint   length)
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{
  GRealArray *array = (GRealArray*) farray;

  g_return_val_if_fail (array, NULL);
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  g_return_val_if_fail (index_ <= array->len, NULL);
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  g_return_val_if_fail (index_ + length <= array->len, NULL);

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  if (array->clear_func != NULL)
    {
      guint i;

      for (i = 0; i < length; i++)
        array->clear_func (g_array_elt_pos (array, index_ + i));
    }

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  if (index_ + length != array->len)
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    memmove (g_array_elt_pos (array, index_),
             g_array_elt_pos (array, index_ + length),
             (array->len - (index_ + length)) * array->elt_size);
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  array->len -= length;
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  if (G_UNLIKELY (g_mem_gc_friendly))
    g_array_elt_zero (array, array->len, length);
  else
    g_array_zero_terminate (array);
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  return farray;
}

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/**
 * g_array_sort:
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 * @array: a #GArray
 * @compare_func: comparison function
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 *
 * Sorts a #GArray using @compare_func which should be a qsort()-style
 * comparison function (returns less than zero for first arg is less
 * than second arg, zero for equal, greater zero if first arg is
 * greater than second arg).
 *
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 * This is guaranteed to be a stable sort since version 2.32.
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 */
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void
g_array_sort (GArray       *farray,
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              GCompareFunc  compare_func)
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{
  GRealArray *array = (GRealArray*) farray;

  g_return_if_fail (array != NULL);

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  /* Don't use qsort as we want a guaranteed stable sort */
  g_qsort_with_data (array->data,
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                     array->len,
                     array->elt_size,
                     (GCompareDataFunc)compare_func,
                     NULL);
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}

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/**
 * g_array_sort_with_data:
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 * @array: a #GArray
 * @compare_func: comparison function
 * @user_data: data to pass to @compare_func
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 *
 * Like g_array_sort(), but the comparison function receives an extra
 * user data argument.
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 *
 * This is guaranteed to be a stable sort since version 2.32.
 *
 * There used to be a comment here about making the sort stable by
 * using the addresses of the elements in the comparison function.
 * This did not actually work, so any such code should be removed.
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 */
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void
g_array_sort_with_data (GArray           *farray,
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                        GCompareDataFunc  compare_func,
                        gpointer          user_data)
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{
  GRealArray *array = (GRealArray*) farray;

  g_return_if_fail (array != NULL);

  g_qsort_with_data (array->data,
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                     array->len,
                     array->elt_size,
                     compare_func,
                     user_data);
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}

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/**
 * g_array_binary_search:
 * @array: a #GArray.
 * @target: a pointer to the item to look up.
 * @compare_func: A #GCompareFunc used to locate @target.
 * @out_match_index: (optional) (out caller-allocates): return location
 *    for the index of the element, if found.
 *
 * Checks whether @target exists in @array by performing a binary
 * search based on the given comparison function @compare_func which
 * get pointers to items as arguments. If the element is found, %TRUE
 * is returned and the element’s index is returned in @out_match_index
 * (if non-%NULL). Otherwise, %FALSE is returned and @out_match_index
 * is undefined. If @target exists multiple times in @array, the index
 * of the first instance is returned. This search is using a binary
 * search, so the @array must absolutely be sorted to return a correct
 * result (if not, the function may produce false-negative).
 *
 * This example defines a comparison function and search an element in a #GArray:
 * |[<!-- language="C" -->
 * static gint*
 * cmpint (gconstpointer a, gconstpointer b)
 * {
 *   const gint *_a = a;
 *   const gint *_b = b;
 *
 *   return *_a - *_b;
 * }
 * ...
 * gint i = 424242;
 * guint matched_index;
 * gboolean result = g_array_binary_search (garray, &i, cmpint, &matched_index);
 * ...
 * ]|
 *
 * Returns: %TRUE if @target is one of the elements of @array, %FALSE otherwise.
 *
 * Since: 2.62
 */
gboolean
g_array_binary_search (GArray        *array,
                       gconstpointer  target,
                       GCompareFunc   compare_func,
                       guint         *out_match_index)
{
  gboolean result = FALSE;
  GRealArray *_array = (GRealArray *) array;
  guint left, middle, right;
  gint val;

  g_return_val_if_fail (_array != NULL, FALSE);
  g_return_val_if_fail (compare_func != NULL, FALSE);

  if (G_LIKELY(_array->len))
    {
      left = 0;
      right = _array->len - 1;

      while (left <= right)
        {
          middle = (left + right) / 2;

          val = compare_func (_array->data + (_array->elt_size * middle), target);
          if (val < 0)
            left = middle + 1;
          else if (val > 0)
            right = middle - 1;
          else
            {
              result = TRUE;
              break;
            }
        }
    }

  if (result && out_match_index != NULL)
    *out_match_index = middle;

  return result;
}

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/* Returns the smallest power of 2 greater than n, or n if
 * such power does not fit in a guint
 */
static guint
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g_nearest_pow (guint num)
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{
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  guint n = 1;
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  while (n < num && n > 0)
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    n <<= 1;

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  return n ? n : num;
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}

static void
g_array_maybe_expand (GRealArray *array,
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                      guint       len)
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{
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  guint want_alloc;

  /* Detect potential overflow */
  if G_UNLIKELY ((G_MAXUINT - array->len) < len)
    g_error ("adding %u to array would overflow", len);

  want_alloc = g_array_elt_len (array, array->len + len +
                                array->zero_terminated);
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  if (want_alloc > array->alloc)
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    {
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      want_alloc = g_nearest_pow (want_alloc);
      want_alloc = MAX (want_alloc, MIN_ARRAY_SIZE);
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      array->data = g_realloc (array->data, want_alloc);

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      if (G_UNLIKELY (g_mem_gc_friendly))
        memset (array->data + array->alloc, 0, want_alloc - array->alloc);
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      array->alloc = want_alloc;
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    }
}
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/**
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 * SECTION:arrays_pointer
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 * @title: Pointer Arrays
 * @short_description: arrays of pointers to any type of data, which
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 *     grow automatically as new elements are added
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 *
 * Pointer Arrays are similar to Arrays but are used only for storing
 * pointers.
 *
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 * If you remove elements from the array, elements at the end of the
 * array are moved into the space previously occupied by the removed
 * element. This means that you should not rely on the index of particular
 * elements remaining the same. You should also be careful when deleting
 * elements while iterating over the array.
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 *
 * To create a pointer array, use g_ptr_array_new().
 *
 * To add elements to a pointer array, use g_ptr_array_add().
 *
 * To remove elements from a pointer array, use g_ptr_array_remove(),
 * g_ptr_array_remove_index() or g_ptr_array_remove_index_fast().
 *
 * To access an element of a pointer array, use g_ptr_array_index().
 *
 * To set the size of a pointer array, use g_ptr_array_set_size().
 *
 * To free a pointer array, use g_ptr_array_free().
 *
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 * An example using a #GPtrArray:
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 * |[<!-- language="C" -->
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 *   GPtrArray *array;
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 *   gchar *string1 = "one";
 *   gchar *string2 = "two";
 *   gchar *string3 = "three";
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 *
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 *   array = g_ptr_array_new ();
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 *   g_ptr_array_add (array, (gpointer) string1);
 *   g_ptr_array_add (array, (gpointer) string2);
 *   g_ptr_array_add (array, (gpointer) string3);
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 *
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 *   if (g_ptr_array_index (array, 0) != (gpointer) string1)
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 *     g_print ("ERROR: got %p instead of %p\n",
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 *              g_ptr_array_index (array, 0), string1);
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 *
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 *   g_ptr_array_free (array, TRUE);
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 * ]|
 */
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typedef struct _GRealPtrArray  GRealPtrArray;

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/**
 * GPtrArray:
 * @pdata: points to the array of pointers, which may be moved when the
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 *     array grows
 * @len: number of pointers in the array
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 *
 * Contains the public fields of a pointer array.
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 */
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struct _GRealPtrArray
{
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  gpointer       *pdata;
  guint           len;
  guint           alloc;
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  gatomicrefcount ref_count;
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  GDestroyNotify  element_free_func;
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};

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/**
 * g_ptr_array_index:
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 * @array: a #GPtrArray
 * @index_: the index of the pointer to return
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 *
 * Returns the pointer at the given index of the pointer array.
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 *
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 * This does not perform bounds checking on the given @index_,
 * so you are responsible for checking it against the array length.
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 *
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 * Returns: the pointer at the given index
 */
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static void g_ptr_array_maybe_expand (GRealPtrArray *array,
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                                      guint          len);
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/**
 * g_ptr_array_new:
 *
 * Creates a new #GPtrArray with a reference count of 1.
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 *
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 * Returns: the new #GPtrArray
 */
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GPtrArray*
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g_ptr_array_new (void)
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{
  return g_ptr_array_sized_new (0);
}

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/**
 * g_ptr_array_copy:
 * @array: #GPtrArray to duplicate
 * @func: (nullable): a copy function used to copy every element in the array
 * @user_data: user data passed to the copy function @func, or %NULL
 *
 * Makes a full (deep) copy of a #GPtrArray.
 *
 * @func, as a #GCopyFunc, takes two arguments, the data to be copied
 * and a @user_data pointer. On common processor architectures, it's safe to
 * pass %NULL as @user_data if the copy function takes only one argument. You
 * may get compiler warnings from this though if compiling with GCC’s
 * `-Wcast-function-type` warning.
 *
 * If @func is %NULL, then only the pointers (and not what they are
 * pointing to) are copied to the new #GPtrArray.
 *
 * Returns: (transfer full): a deep copy of the initial #GPtrArray.
 *
 * Since: 2.62
 **/
GPtrArray *
g_ptr_array_copy (GPtrArray *array,
                  GCopyFunc  func,
                  gpointer   user_data)
{
  gsize i;
  GPtrArray *new_array;

  g_return_val_if_fail (array != NULL, NULL);

  new_array = g_ptr_array_sized_new (array->len);
  if (func != NULL)
    {
      for (i = 0; i < array->len; i++)
        new_array->pdata[i] = func (array->pdata[i], user_data);
    }
  else
    {
      memcpy (new_array->pdata, array->pdata,
              array->len * sizeof (*array->pdata));
    }

  return new_array;
}

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/**
 * g_ptr_array_sized_new:
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 * @reserved_size: number of pointers preallocated
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 *
 * Creates a new #GPtrArray with @reserved_size pointers preallocated
 * and a reference count of 1. This avoids frequent reallocation, if
 * you are going to add many pointers to the array. Note however that
 * the size of the array is still 0.
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 *
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 * Returns: the new #GPtrArray
 */
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GPtrArray*  
g_ptr_array_sized_new (guint reserved_size)
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{
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  GRealPtrArray *array;

  array = g_slice_new (GRealPtrArray);
1069
1070
1071
1072

  array->pdata = NULL;
  array->len = 0;
  array->alloc = 0;
1073
  array->element_free_func = NULL;
1074

1075
1076
  g_atomic_ref_count_init (&array->ref_count);

1077
1078
1079
1080
  if (reserved_size != 0)
    g_ptr_array_maybe_expand (array, reserved_size);

  return (GPtrArray*) array;  
1081
1082
}

1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105