[~andy/gtk] / gtk / gtktextbuffer.c

/* GTK - The GIMP Toolkit
 * gtktextbuffer.c Copyright (C) 2000 Red Hat, Inc.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 02111-1307, USA.
 */

/*
 * Modified by the GTK+ Team and others 1997-2000.  See the AUTHORS
 * file for a list of people on the GTK+ Team.  See the ChangeLog
 * files for a list of changes.  These files are distributed with
 * GTK+ at ftp://ftp.gtk.org/pub/gtk/.
 */


#include <string.h>
#include <stdarg.h>

#define GTK_TEXT_USE_INTERNAL_UNSUPPORTED_API
#include "gtkclipboard.h"
#include "gtkinvisible.h"
#include "gtkmarshalers.h"
#include "gtksignal.h"
#include "gtktextbuffer.h"
#include "gtktextbtree.h"
#include "gtktextiterprivate.h"
#include <string.h>

typedef struct _ClipboardRequest ClipboardRequest;

struct _ClipboardRequest
{
  GtkTextBuffer *buffer;
  gboolean interactive;
  gboolean default_editable;
  gboolean is_clipboard;
  gboolean replace_selection;
};

enum {
  INSERT_TEXT,
  INSERT_PIXBUF,
  INSERT_CHILD_ANCHOR,
  DELETE_RANGE,
  CHANGED,
  MODIFIED_CHANGED,
  MARK_SET,
  MARK_DELETED,
  APPLY_TAG,
  REMOVE_TAG,
  BEGIN_USER_ACTION,
  END_USER_ACTION,
  LAST_SIGNAL
};

enum {
  ARG_0,
  LAST_ARG
};

enum {
  TARGET_STRING,
  TARGET_TEXT,
  TARGET_COMPOUND_TEXT,
  TARGET_UTF8_STRING,
  TARGET_TEXT_BUFFER_CONTENTS
};

static void gtk_text_buffer_init       (GtkTextBuffer      *tkxt_buffer);
static void gtk_text_buffer_class_init (GtkTextBufferClass *klass);
static void gtk_text_buffer_finalize   (GObject            *object);


static void gtk_text_buffer_real_insert_text           (GtkTextBuffer     *buffer,
                                                        GtkTextIter       *iter,
                                                        const gchar       *text,
                                                        gint               len);
static void gtk_text_buffer_real_insert_pixbuf         (GtkTextBuffer     *buffer,
                                                        GtkTextIter       *iter,
                                                        GdkPixbuf         *pixbuf);
static void gtk_text_buffer_real_insert_anchor         (GtkTextBuffer     *buffer,
                                                        GtkTextIter       *iter,
                                                        GtkTextChildAnchor *anchor);
static void gtk_text_buffer_real_delete_range          (GtkTextBuffer     *buffer,
                                                        GtkTextIter       *start,
                                                        GtkTextIter       *end);
static void gtk_text_buffer_real_apply_tag             (GtkTextBuffer     *buffer,
                                                        GtkTextTag        *tag,
                                                        const GtkTextIter *start_char,
                                                        const GtkTextIter *end_char);
static void gtk_text_buffer_real_remove_tag            (GtkTextBuffer     *buffer,
                                                        GtkTextTag        *tag,
                                                        const GtkTextIter *start_char,
                                                        const GtkTextIter *end_char);
static void gtk_text_buffer_real_changed               (GtkTextBuffer     *buffer);

static GtkTextBTree* get_btree (GtkTextBuffer *buffer);
static void          free_log_attr_cache (GtkTextLogAttrCache *cache);

static void remove_all_clipboard_contents_buffers (GtkTextBuffer *buffer);
static void remove_all_selection_clipboards       (GtkTextBuffer *buffer);
static void update_selection_clipboards           (GtkTextBuffer *buffer);

static GtkObjectClass *parent_class = NULL;
static guint signals[LAST_SIGNAL] = { 0 };

GType
gtk_text_buffer_get_type (void)
{
  static GType our_type = 0;

  if (our_type == 0)
    {
      static const GTypeInfo our_info =
      {
        sizeof (GtkTextBufferClass),
        (GBaseInitFunc) NULL,
        (GBaseFinalizeFunc) NULL,
        (GClassInitFunc) gtk_text_buffer_class_init,
        NULL,           /* class_finalize */
        NULL,           /* class_data */
        sizeof (GtkTextBuffer),
        0,              /* n_preallocs */
        (GInstanceInitFunc) gtk_text_buffer_init
      };

      our_type = g_type_register_static (G_TYPE_OBJECT,
                                         "GtkTextBuffer",
                                         &our_info,
                                         0);
    }

  return our_type;
}

static void
gtk_text_buffer_class_init (GtkTextBufferClass *klass)
{
  GObjectClass *object_class = G_OBJECT_CLASS (klass);

  parent_class = g_type_class_peek_parent (klass);

  object_class->finalize = gtk_text_buffer_finalize;

  klass->insert_text = gtk_text_buffer_real_insert_text;
  klass->insert_pixbuf = gtk_text_buffer_real_insert_pixbuf;
  klass->insert_child_anchor = gtk_text_buffer_real_insert_anchor;
  klass->delete_range = gtk_text_buffer_real_delete_range;
  klass->apply_tag = gtk_text_buffer_real_apply_tag;
  klass->remove_tag = gtk_text_buffer_real_remove_tag;
  klass->changed = gtk_text_buffer_real_changed;

  signals[INSERT_TEXT] =
    g_signal_new ("insert_text",
                  G_OBJECT_CLASS_TYPE (object_class),
                  G_SIGNAL_RUN_LAST,
                  G_STRUCT_OFFSET (GtkTextBufferClass, insert_text),
                  NULL, NULL,
                  _gtk_marshal_VOID__BOXED_STRING_INT,
                  GTK_TYPE_NONE,
                  3,
                  GTK_TYPE_TEXT_ITER | G_SIGNAL_TYPE_STATIC_SCOPE,
                  GTK_TYPE_STRING | G_SIGNAL_TYPE_STATIC_SCOPE,
                  GTK_TYPE_INT);

  signals[INSERT_PIXBUF] =
    g_signal_new ("insert_pixbuf",
                  G_OBJECT_CLASS_TYPE (object_class),
                  G_SIGNAL_RUN_LAST,
                  G_STRUCT_OFFSET (GtkTextBufferClass, insert_pixbuf),
                  NULL, NULL,
                  _gtk_marshal_VOID__BOXED_OBJECT,
                  GTK_TYPE_NONE,
                  2,
                  GTK_TYPE_TEXT_ITER | G_SIGNAL_TYPE_STATIC_SCOPE,
                  GDK_TYPE_PIXBUF);

  signals[INSERT_CHILD_ANCHOR] =
    g_signal_new ("insert_child_anchor",
                  G_OBJECT_CLASS_TYPE (object_class),
                  G_SIGNAL_RUN_LAST,
                  G_STRUCT_OFFSET (GtkTextBufferClass, insert_child_anchor),
                  NULL, NULL,
                  _gtk_marshal_VOID__BOXED_OBJECT,
                  GTK_TYPE_NONE,
                  2,
                  GTK_TYPE_TEXT_ITER | G_SIGNAL_TYPE_STATIC_SCOPE,
                  GTK_TYPE_TEXT_CHILD_ANCHOR);
  
  signals[DELETE_RANGE] =
    g_signal_new ("delete_range",
                  G_OBJECT_CLASS_TYPE (object_class),
                  G_SIGNAL_RUN_LAST,
                  G_STRUCT_OFFSET (GtkTextBufferClass, delete_range),
                  NULL, NULL,
                  _gtk_marshal_VOID__BOXED_BOXED,
                  GTK_TYPE_NONE,
                  2,
                  GTK_TYPE_TEXT_ITER | G_SIGNAL_TYPE_STATIC_SCOPE,
                  GTK_TYPE_TEXT_ITER | G_SIGNAL_TYPE_STATIC_SCOPE);

  signals[CHANGED] =
    g_signal_new ("changed",
                  G_OBJECT_CLASS_TYPE (object_class),
                  G_SIGNAL_RUN_LAST,                   
                  G_STRUCT_OFFSET (GtkTextBufferClass, changed),
                  NULL, NULL,
                  _gtk_marshal_VOID__VOID,
                  GTK_TYPE_NONE,
                  0);

  signals[MODIFIED_CHANGED] =
    g_signal_new ("modified_changed",
                  G_OBJECT_CLASS_TYPE (object_class),
                  G_SIGNAL_RUN_LAST,
                  G_STRUCT_OFFSET (GtkTextBufferClass, modified_changed),
                  NULL, NULL,
                  _gtk_marshal_VOID__VOID,
                  GTK_TYPE_NONE,
                  0);

  signals[MARK_SET] =
    g_signal_new ("mark_set",
                  G_OBJECT_CLASS_TYPE (object_class),
                  G_SIGNAL_RUN_LAST,                   
                  G_STRUCT_OFFSET (GtkTextBufferClass, mark_set),
                  NULL, NULL,
                  _gtk_marshal_VOID__BOXED_OBJECT,
                  GTK_TYPE_NONE,
                  2,
                  GTK_TYPE_TEXT_ITER,
                  GTK_TYPE_TEXT_MARK);

  signals[MARK_DELETED] =
    g_signal_new ("mark_deleted",
                  G_OBJECT_CLASS_TYPE (object_class),
                  G_SIGNAL_RUN_LAST,                   
                  G_STRUCT_OFFSET (GtkTextBufferClass, mark_deleted),
                  NULL, NULL,
                  _gtk_marshal_VOID__OBJECT,
                  GTK_TYPE_NONE,
                  1,
                  GTK_TYPE_TEXT_MARK);
  
  signals[APPLY_TAG] =
    g_signal_new ("apply_tag",
                  G_OBJECT_CLASS_TYPE (object_class),
                  G_SIGNAL_RUN_LAST,
                  G_STRUCT_OFFSET (GtkTextBufferClass, apply_tag),
                  NULL, NULL,
                  _gtk_marshal_VOID__OBJECT_BOXED_BOXED,
                  GTK_TYPE_NONE,
                  3,
                  GTK_TYPE_TEXT_TAG,
                  GTK_TYPE_TEXT_ITER,
                  GTK_TYPE_TEXT_ITER);

  signals[REMOVE_TAG] =
    g_signal_new ("remove_tag",
                  G_OBJECT_CLASS_TYPE (object_class),
                  G_SIGNAL_RUN_LAST,
                  G_STRUCT_OFFSET (GtkTextBufferClass, remove_tag),
                  NULL, NULL,
                  _gtk_marshal_VOID__OBJECT_BOXED_BOXED,
                  GTK_TYPE_NONE,
                  3,
                  GTK_TYPE_TEXT_TAG,
                  GTK_TYPE_TEXT_ITER,
                  GTK_TYPE_TEXT_ITER);

  signals[BEGIN_USER_ACTION] =
    g_signal_new ("begin_user_action",
                  G_OBJECT_CLASS_TYPE (object_class),
                  G_SIGNAL_RUN_LAST,                   
                  G_STRUCT_OFFSET (GtkTextBufferClass, begin_user_action),
                  NULL, NULL,
                  _gtk_marshal_VOID__VOID,
                  GTK_TYPE_NONE,
                  0);

  signals[END_USER_ACTION] =
    g_signal_new ("end_user_action",
                  G_OBJECT_CLASS_TYPE (object_class),
                  G_SIGNAL_RUN_LAST,                   
                  G_STRUCT_OFFSET (GtkTextBufferClass, end_user_action),
                  NULL, NULL,
                  _gtk_marshal_VOID__VOID,
                  GTK_TYPE_NONE,
                  0);  
}

static void
gtk_text_buffer_init (GtkTextBuffer *buffer)
{
  buffer->clipboard_contents_buffers = NULL;
}

/**
 * gtk_text_buffer_new:
 * @table: a tag table, or NULL to create a new one
 *
 * Creates a new text buffer.
 *
 * Return value: a new text buffer
 **/
GtkTextBuffer*
gtk_text_buffer_new (GtkTextTagTable *table)
{
  GtkTextBuffer *text_buffer;

  text_buffer = GTK_TEXT_BUFFER (g_object_new (gtk_text_buffer_get_type (), NULL));

  if (table)
    {
      text_buffer->tag_table = table;

      g_object_ref (G_OBJECT (text_buffer->tag_table));

      _gtk_text_tag_table_add_buffer (table, text_buffer);
    }
  
  return text_buffer;
}

static void
gtk_text_buffer_finalize (GObject *object)
{
  GtkTextBuffer *buffer;

  buffer = GTK_TEXT_BUFFER (object);

  remove_all_clipboard_contents_buffers (buffer);
  remove_all_selection_clipboards (buffer);

  if (buffer->tag_table)
    {
      _gtk_text_tag_table_remove_buffer (buffer->tag_table, buffer);
      g_object_unref (G_OBJECT (buffer->tag_table));
      buffer->tag_table = NULL;
    }

  if (buffer->btree)
    {
      _gtk_text_btree_unref (buffer->btree);
      buffer->btree = NULL;
    }

  if (buffer->log_attr_cache)
    free_log_attr_cache (buffer->log_attr_cache);

  buffer->log_attr_cache = NULL;
  
  G_OBJECT_CLASS (parent_class)->finalize (object);
}

static GtkTextTagTable*
get_table (GtkTextBuffer *buffer)
{
  if (buffer->tag_table == NULL)
    {
      buffer->tag_table = gtk_text_tag_table_new ();
      _gtk_text_tag_table_add_buffer (buffer->tag_table, buffer);
    }

  return buffer->tag_table;
}

static GtkTextBTree*
get_btree (GtkTextBuffer *buffer)
{
  if (buffer->btree == NULL)
    buffer->btree = _gtk_text_btree_new (gtk_text_buffer_get_tag_table (buffer),
                                         buffer);

  return buffer->btree;
}

GtkTextBTree*
_gtk_text_buffer_get_btree (GtkTextBuffer *buffer)
{
  return get_btree (buffer);
}

/**
 * gtk_text_buffer_get_tag_table:
 * @buffer: a #GtkTextBuffer
 *
 * Get the #GtkTextTagTable associated with this buffer.
 *
 * Return value: the buffer's tag table
 **/
GtkTextTagTable*
gtk_text_buffer_get_tag_table (GtkTextBuffer  *buffer)
{
  g_return_val_if_fail (GTK_IS_TEXT_BUFFER (buffer), NULL);

  return get_table (buffer);
}

/**
 * gtk_text_buffer_set_text:
 * @buffer: a #GtkTextBuffer
 * @text: UTF-8 text to insert
 * @len: length of @text in bytes
 *
 * Deletes current contents of @buffer, and inserts @text instead. If
 * @len is -1, @text must be nul-terminated. @text must be valid UTF-8.
 **/
void
gtk_text_buffer_set_text (GtkTextBuffer *buffer,
                          const gchar   *text,
                          gint           len)
{
  GtkTextIter start, end;

  g_return_if_fail (GTK_IS_TEXT_BUFFER (buffer));
  g_return_if_fail (text != NULL);

  if (len < 0)
    len = strlen (text);

  gtk_text_buffer_get_bounds (buffer, &start, &end);

  gtk_text_buffer_delete (buffer, &start, &end);

  if (len > 0)
    {
      gtk_text_buffer_get_iter_at_offset (buffer, &start, 0);
      gtk_text_buffer_insert (buffer, &start, text, len);
    }
}

/*
 * Insertion
 */

static void
gtk_text_buffer_real_insert_text (GtkTextBuffer *buffer,
                                  GtkTextIter *iter,
                                  const gchar *text,
                                  gint len)
{
  g_return_if_fail (GTK_IS_TEXT_BUFFER (buffer));
  g_return_if_fail (iter != NULL);
  
  _gtk_text_btree_insert (iter, text, len);

  g_signal_emit (G_OBJECT (buffer), signals[CHANGED], 0);
}

static void
gtk_text_buffer_emit_insert (GtkTextBuffer *buffer,
                             GtkTextIter   *iter,
                             const gchar   *text,
                             gint           len)
{
  g_return_if_fail (GTK_IS_TEXT_BUFFER (buffer));
  g_return_if_fail (iter != NULL);
  g_return_if_fail (text != NULL);

  if (len < 0)
    len = strlen (text);

  g_return_if_fail (g_utf8_validate (text, len, NULL));
  
  if (len > 0)
    {
      g_signal_emit (G_OBJECT (buffer), signals[INSERT_TEXT], 0,
                     iter, text, len);
    }
}

/**
 * gtk_text_buffer_insert:
 * @buffer: a #GtkTextBuffer
 * @iter: a position in the buffer
 * @text: UTF-8 format text to insert
 * @len: length of text in bytes, or -1
 *
 * Inserts @len bytes of @text at position @iter.  If @len is -1,
 * @text must be nul-terminated and will be inserted in its
 * entirety. Emits the "insert_text" signal; insertion actually occurs
 * in the default handler for the signal. @iter is invalidated when
 * insertion occurs (because the buffer contents change), but the
 * default signal handler revalidates it to point to the end of the
 * inserted text.
 *
 **/
void
gtk_text_buffer_insert (GtkTextBuffer *buffer,
                        GtkTextIter *iter,
                        const gchar *text,
                        gint len)
{
  g_return_if_fail (GTK_IS_TEXT_BUFFER (buffer));
  g_return_if_fail (iter != NULL);
  g_return_if_fail (text != NULL);
  g_return_if_fail (gtk_text_iter_get_buffer (iter) == buffer);
  
  gtk_text_buffer_emit_insert (buffer, iter, text, len);
}

/**
 * gtk_text_buffer_insert_at_cursor:
 * @buffer: a #GtkTextBuffer
 * @text: some text in UTF-8 format
 * @len: length of text, in bytes
 *
 * Simply calls gtk_text_buffer_insert (), using the current
 * cursor position as the insertion point.
 **/
void
gtk_text_buffer_insert_at_cursor (GtkTextBuffer *buffer,
                                  const gchar *text,
                                  gint len)
{
  GtkTextIter iter;

  g_return_if_fail (GTK_IS_TEXT_BUFFER (buffer));
  g_return_if_fail (text != NULL);

  gtk_text_buffer_get_iter_at_mark (buffer, &iter,
                                    gtk_text_buffer_get_mark (buffer,
                                                              "insert"));

  gtk_text_buffer_insert (buffer, &iter, text, len);
}

/**
 * gtk_text_buffer_insert_interactive:
 * @buffer: a #GtkTextBuffer
 * @iter: a position in @buffer
 * @text: some UTF-8 text
 * @len: length of text in bytes, or -1
 * @default_editable: default editability of buffer
 *
 * Like gtk_text_buffer_insert (), but the insertion will not occur if
 * @iter is at a non-editable location in the buffer.  Usually you
 * want to prevent insertions at ineditable locations if the insertion
 * results from a user action (is interactive).
 *
 * @default_editable indicates the editability of text that doesn't
 * have a tag affecting editability applied to it. Typically the
 * result of gtk_text_view_get_editable() is appropriate here.
 *
 * Return value: whether text was actually inserted
 **/
gboolean
gtk_text_buffer_insert_interactive (GtkTextBuffer *buffer,
                                    GtkTextIter   *iter,
                                    const gchar   *text,
                                    gint           len,
                                    gboolean       default_editable)
{
  g_return_val_if_fail (GTK_IS_TEXT_BUFFER (buffer), FALSE);
  g_return_val_if_fail (text != NULL, FALSE);
  g_return_val_if_fail (gtk_text_iter_get_buffer (iter) == buffer, FALSE);

  if (gtk_text_iter_can_insert (iter, default_editable))
    {
      gtk_text_buffer_begin_user_action (buffer);
      gtk_text_buffer_emit_insert (buffer, iter, text, len);
      gtk_text_buffer_end_user_action (buffer);
      return TRUE;
    }
  else
    return FALSE;
}

/**
 * gtk_text_buffer_insert_interactive_at_cursor:
 * @buffer: a #GtkTextBuffer
 * @text: text in UTF-8 format
 * @len: length of text in bytes, or -1
 * @default_editable: default editability of buffer
 *
 * Calls gtk_text_buffer_insert_interactive () at the cursor
 * position.
 *
 * @default_editable indicates the editability of text that doesn't
 * have a tag affecting editability applied to it. Typically the
 * result of gtk_text_view_get_editable() is appropriate here.
 * 
 * Return value: whether text was actually inserted
 **/
gboolean
gtk_text_buffer_insert_interactive_at_cursor (GtkTextBuffer *buffer,
                                              const gchar   *text,
                                              gint           len,
                                              gboolean       default_editable)
{
  GtkTextIter iter;

  g_return_val_if_fail (GTK_IS_TEXT_BUFFER (buffer), FALSE);
  g_return_val_if_fail (text != NULL, FALSE);

  gtk_text_buffer_get_iter_at_mark (buffer, &iter,
                                    gtk_text_buffer_get_mark (buffer,
                                                              "insert"));

  return gtk_text_buffer_insert_interactive (buffer, &iter, text, len,
                                             default_editable);
}

static gboolean
possibly_not_text (gunichar ch,
                   gpointer user_data)
{
  return ch == GTK_TEXT_UNKNOWN_CHAR;
}

static void
insert_text_range (GtkTextBuffer     *buffer,
                   GtkTextIter       *iter,
                   const GtkTextIter *orig_start,
                   const GtkTextIter *orig_end,
                   gboolean           interactive)
{
  gchar *text;

  text = gtk_text_iter_get_text (orig_start, orig_end);

  gtk_text_buffer_emit_insert (buffer, iter, text, -1);

  g_free (text);
}

typedef struct _Range Range;
struct _Range
{
  GtkTextBuffer *buffer;
  GtkTextMark *start_mark;
  GtkTextMark *end_mark;
  GtkTextMark *whole_end_mark;
  GtkTextIter *range_start;
  GtkTextIter *range_end;
  GtkTextIter *whole_end;
};

static Range*
save_range (GtkTextIter *range_start,
            GtkTextIter *range_end,
            GtkTextIter *whole_end)
{
  Range *r;

  r = g_new (Range, 1);

  r->buffer = gtk_text_iter_get_buffer (range_start);
  g_object_ref (G_OBJECT (r->buffer));
  
  r->start_mark = 
    gtk_text_buffer_create_mark (gtk_text_iter_get_buffer (range_start),
                                 NULL,
                                 range_start,
                                 TRUE);
  r->end_mark = 
    gtk_text_buffer_create_mark (gtk_text_iter_get_buffer (range_start),
                                 NULL,
                                 range_end,
                                 FALSE);

  r->whole_end_mark = 
    gtk_text_buffer_create_mark (gtk_text_iter_get_buffer (range_start),
                                 NULL,
                                 whole_end,
                                 FALSE);

  r->range_start = range_start;
  r->range_end = range_end;
  r->whole_end = whole_end;

  return r;
}

static void
restore_range (Range *r)
{
  gtk_text_buffer_get_iter_at_mark (r->buffer,
                                    r->range_start,
                                    r->start_mark);
      
  gtk_text_buffer_get_iter_at_mark (r->buffer,
                                    r->range_end,
                                    r->end_mark);
      
  gtk_text_buffer_get_iter_at_mark (r->buffer,
                                    r->whole_end,
                                    r->whole_end_mark);
      
  gtk_text_buffer_delete_mark (r->buffer, r->start_mark);
  gtk_text_buffer_delete_mark (r->buffer, r->end_mark);
  gtk_text_buffer_delete_mark (r->buffer, r->whole_end_mark);

  g_object_unref (G_OBJECT (r->buffer));
  g_free (r); 
}

static void
insert_range_untagged (GtkTextBuffer     *buffer,
                       GtkTextIter       *iter,
                       const GtkTextIter *orig_start,
                       const GtkTextIter *orig_end,
                       gboolean           interactive)
{
  GtkTextIter range_start;
  GtkTextIter range_end;
  GtkTextIter start, end;
  GtkTextBuffer *src_buffer;
  Range *r;
  
  if (gtk_text_iter_equal (orig_start, orig_end))
    return;

  start = *orig_start;
  end = *orig_end;
  
  src_buffer = gtk_text_iter_get_buffer (&start);
  
  range_start = start;
  range_end = start;
  
  while (TRUE)
    {
      if (gtk_text_iter_equal (&range_start, &range_end))
        {
          /* Figure out how to move forward */

          g_assert (gtk_text_iter_compare (&range_end, &end) <= 0);
          
          if (gtk_text_iter_equal (&range_end, &end))
            {
              /* nothing left to do */
              break;
            }
          else if (gtk_text_iter_get_char (&range_end) == GTK_TEXT_UNKNOWN_CHAR)
            {
              GdkPixbuf *pixbuf = NULL;
              GtkTextChildAnchor *anchor = NULL;
              pixbuf = gtk_text_iter_get_pixbuf (&range_end);
              anchor = gtk_text_iter_get_child_anchor (&range_end);

              if (pixbuf)
                {
                  r = save_range (&range_start,
                                  &range_end,
                                  &end);

                  gtk_text_buffer_insert_pixbuf (buffer,
                                                 iter,
                                                 pixbuf);

                  restore_range (r);
                  r = NULL;
                  
                  gtk_text_iter_forward_char (&range_end);
                  
                  range_start = range_end;
                }
              else if (anchor)
                {
                  /* Just skip anchors */

                  gtk_text_iter_forward_char (&range_end);
                  range_start = range_end;
                }
              else
                {
                  /* The GTK_TEXT_UNKNOWN_CHAR was in a text segment, so
                   * keep going. 
                   */
                  gtk_text_iter_forward_find_char (&range_end,
                                                   possibly_not_text, NULL,
                                                   &end);
                  
                  g_assert (gtk_text_iter_compare (&range_end, &end) <= 0);
                }
            }
          else
            {
              /* Text segment starts here, so forward search to
               * find its possible endpoint
               */
              gtk_text_iter_forward_find_char (&range_end,
                                               possibly_not_text, NULL,
                                               &end);
              
              g_assert (gtk_text_iter_compare (&range_end, &end) <= 0);
            }
        }
      else
        {
          r = save_range (&range_start,
                          &range_end,
                          &end);
          
          insert_text_range (buffer,
                             iter,
                             &range_start,
                             &range_end,
                             interactive);

          restore_range (r);
          r = NULL;
          
          range_start = range_end;
        }
    }
}

static void
gtk_text_buffer_real_insert_range (GtkTextBuffer     *buffer,
                                   GtkTextIter       *iter,
                                   const GtkTextIter *orig_start,
                                   const GtkTextIter *orig_end,
                                   gboolean           interactive)
{
  /* Find each range of uniformly-tagged text, insert it,
   * then apply the tags.
   */
  GtkTextIter start = *orig_start;
  GtkTextIter end = *orig_end;
  GtkTextIter range_start;
  GtkTextIter range_end;
  GtkTextBuffer *src_buffer;
  Range *r;
  
  if (gtk_text_iter_equal (orig_start, orig_end))
    return;

  if (interactive)
    gtk_text_buffer_begin_user_action (buffer);
  
  src_buffer = gtk_text_iter_get_buffer (orig_start);
  
  gtk_text_iter_order (&start, &end);

  range_start = start;
  range_end = start;

  while (TRUE)
    {
      gint start_offset;
      GtkTextIter start_iter;
      GSList *tags;
      GSList *tmp_list;
      
      if (gtk_text_iter_equal (&range_start, &end))
        break; /* All done */

      g_assert (gtk_text_iter_compare (&range_start, &end) < 0);
      
      gtk_text_iter_forward_to_tag_toggle (&range_end, NULL);

      g_assert (!gtk_text_iter_equal (&range_start, &range_end));

      /* Clamp to the end iterator */
      if (gtk_text_iter_compare (&range_end, &end) > 0)
        range_end = end;
      
      /* We have a range with unique tags; insert it, and
       * apply all tags.
       */
      start_offset = gtk_text_iter_get_offset (iter);

      r = save_range (&range_start, &range_end, &end);
      
      insert_range_untagged (buffer, iter, &range_start, &range_end, interactive);

      restore_range (r);
      r = NULL;
      
      gtk_text_buffer_get_iter_at_offset (buffer, &start_iter, start_offset);
      
      tags = gtk_text_iter_get_tags (&range_start);
      tmp_list = tags;
      while (tmp_list != NULL)
        {
          gtk_text_buffer_apply_tag (buffer,
                                     tmp_list->data,
                                     &start_iter,
                                     iter);
          
          tmp_list = g_slist_next (tmp_list);
        }
      g_slist_free (tags);

      range_start = range_end;
    }

  if (interactive)
    gtk_text_buffer_end_user_action (buffer);
}

/**
 * gtk_text_buffer_insert_range:
 * @buffer: a #GtkTextBuffer
 * @iter: a position in @buffer
 * @start: a position in a #GtkTextBuffer
 * @end: another position in the same buffer as @start
 *
 * Copies text, tags, and pixbufs between @start and @end (the order
 * of @start and @end doesn't matter) and inserts the copy at @iter.
 * Used instead of simply getting/inserting text because it preserves
 * images and tags. If @start and @end are in a different buffer from
 * @buffer, the two buffers must share the same tag table.
 *
 * Implemented via emissions of the insert_text and apply_tag signals,
 * so expect those.
 **/
void
gtk_text_buffer_insert_range (GtkTextBuffer     *buffer,
                              GtkTextIter       *iter,
                              const GtkTextIter *start,
                              const GtkTextIter *end)
{
  g_return_if_fail (GTK_IS_TEXT_BUFFER (buffer));
  g_return_if_fail (iter != NULL);
  g_return_if_fail (start != NULL);
  g_return_if_fail (end != NULL);
  g_return_if_fail (gtk_text_iter_get_buffer (start) ==
                    gtk_text_iter_get_buffer (end));
  g_return_if_fail (gtk_text_iter_get_buffer (start)->tag_table ==
                    buffer->tag_table);  
  g_return_if_fail (gtk_text_iter_get_buffer (iter) == buffer);
  
  gtk_text_buffer_real_insert_range (buffer, iter, start, end, FALSE);
}

/**
 * gtk_text_buffer_insert_range_interactive:
 * @buffer: a #GtkTextBuffer
 * @iter: a position in @buffer
 * @start: a position in a #GtkTextBuffer
 * @end: another position in the same buffer as @start
 * @default_editable: default editability of the buffer
 *
 * Same as gtk_text_buffer_insert_range(), but does nothing if the
 * insertion point isn't editable. The @default_editable parameter
 * indicates whether the text is editable at @iter if no tags
 * enclosing @iter affect editability. Typically the result of
 * gtk_text_view_get_editable() is appropriate here.
 *
 * Returns: whether an insertion was possible at @iter
 **/
gboolean
gtk_text_buffer_insert_range_interactive (GtkTextBuffer     *buffer,
                                          GtkTextIter       *iter,
                                          const GtkTextIter *start,
                                          const GtkTextIter *end,
                                          gboolean           default_editable)
{
  g_return_val_if_fail (GTK_IS_TEXT_BUFFER (buffer), FALSE);
  g_return_val_if_fail (iter != NULL, FALSE);
  g_return_val_if_fail (start != NULL, FALSE);
  g_return_val_if_fail (end != NULL, FALSE);
  g_return_val_if_fail (gtk_text_iter_get_buffer (start) ==
                        gtk_text_iter_get_buffer (end), FALSE);
  g_return_val_if_fail (gtk_text_iter_get_buffer (start)->tag_table ==
                        buffer->tag_table, FALSE);


  if (gtk_text_iter_can_insert (iter, default_editable))
    {
      gtk_text_buffer_real_insert_range (buffer, iter, start, end, TRUE);
      return TRUE;
    }
  else
    return FALSE;
}

/**
 * gtk_text_buffer_insert_with_tags:
 * @buffer: a #GtkTextBuffer
 * @iter: an iterator in @buffer
 * @text: UTF-8 text
 * @len: length of @text, or -1
 * @first_tag: first tag to apply to @text
 * @Varargs: NULL-terminated list of tags to apply
 *
 * Inserts @text into @buffer at @iter, applying the list of tags to
 * the newly-inserted text. The last tag specified must be NULL to
 * terminate the list. Equivalent to calling gtk_text_buffer_insert (),
 * then gtk_text_buffer_apply_tag () on the inserted text;
 * gtk_text_buffer_insert_with_tags () is just a convenience function.
 **/
void
gtk_text_buffer_insert_with_tags (GtkTextBuffer *buffer,
                                  GtkTextIter   *iter,
                                  const gchar   *text,
                                  gint           len,
                                  GtkTextTag    *first_tag,
                                  ...)
{
  gint start_offset;
  GtkTextIter start;
  va_list args;
  GtkTextTag *tag;

  g_return_if_fail (GTK_IS_TEXT_BUFFER (buffer));
  g_return_if_fail (iter != NULL);
  g_return_if_fail (text != NULL);
  g_return_if_fail (gtk_text_iter_get_buffer (iter) == buffer);
  
  start_offset = gtk_text_iter_get_offset (iter);

  gtk_text_buffer_insert (buffer, iter, text, len);

  if (first_tag == NULL)
    return;

  gtk_text_buffer_get_iter_at_offset (buffer, &start, start_offset);

  va_start (args, first_tag);
  tag = first_tag;
  while (tag)
    {
      gtk_text_buffer_apply_tag (buffer, tag, &start, iter);

      tag = va_arg (args, GtkTextTag*);
    }

  va_end (args);
}

/**
 * gtk_text_buffer_insert_with_tags_by_name:
 * @buffer: a #GtkTextBuffer
 * @iter: position in @buffer
 * @text: UTF-8 text
 * @len: length of @text, or -1
 * @first_tag_name: name of a tag to apply to @text
 * @Varargs: more tag names
 *
 * Same as gtk_text_buffer_insert_with_tags (), but allows you
 * to pass in tag names instead of tag objects.
 **/
void
gtk_text_buffer_insert_with_tags_by_name  (GtkTextBuffer *buffer,
                                           GtkTextIter   *iter,
                                           const gchar   *text,
                                           gint           len,
                                           const gchar   *first_tag_name,
                                           ...)
{
  gint start_offset;
  GtkTextIter start;
  va_list args;
  const gchar *tag_name;

  g_return_if_fail (GTK_IS_TEXT_BUFFER (buffer));
  g_return_if_fail (iter != NULL);
  g_return_if_fail (text != NULL);
  g_return_if_fail (gtk_text_iter_get_buffer (iter) == buffer);
  
  start_offset = gtk_text_iter_get_offset (iter);

  gtk_text_buffer_insert (buffer, iter, text, len);

  if (first_tag_name == NULL)
    return;

  gtk_text_buffer_get_iter_at_offset (buffer, &start, start_offset);

  va_start (args, first_tag_name);
  tag_name = first_tag_name;
  while (tag_name)
    {
      GtkTextTag *tag;

      tag = gtk_text_tag_table_lookup (buffer->tag_table,
                                       tag_name);

      if (tag == NULL)
        {
          g_warning ("%s: no tag with name '%s'!", G_STRLOC, tag_name);
          return;
        }

      gtk_text_buffer_apply_tag (buffer, tag, &start, iter);

      tag_name = va_arg (args, const gchar*);
    }

  va_end (args);
}


/*
 * Deletion
 */

static void
gtk_text_buffer_real_delete_range (GtkTextBuffer *buffer,
                                   GtkTextIter   *start,
                                   GtkTextIter   *end)
{
  g_return_if_fail (GTK_IS_TEXT_BUFFER (buffer));
  g_return_if_fail (start != NULL);
  g_return_if_fail (end != NULL);

  _gtk_text_btree_delete (start, end);

  /* may have deleted the selection... */
  update_selection_clipboards (buffer);

  g_signal_emit (G_OBJECT (buffer), signals[CHANGED], 0);
}

static void
gtk_text_buffer_emit_delete (GtkTextBuffer *buffer,
                             GtkTextIter *start,
                             GtkTextIter *end)
{
  g_return_if_fail (GTK_IS_TEXT_BUFFER (buffer));
  g_return_if_fail (start != NULL);
  g_return_if_fail (end != NULL);

  if (gtk_text_iter_equal (start, end))
    return;

  gtk_text_iter_order (start, end);

  g_signal_emit (G_OBJECT (buffer),
                 signals[DELETE_RANGE],
                 0,
                 start, end);
}

/**
 * gtk_text_buffer_delete:
 * @buffer: a #GtkTextBuffer
 * @start: a position in @buffer
 * @end: another position in @buffer
 *
 * Deletes text between @start and @end. The order of @start and @end
 * is not actually relevant; gtk_text_buffer_delete () will reorder
 * them. This function actually emits the "delete_range" signal, and
 * the default handler of that signal deletes the text. Because the
 * buffer is modified, all outstanding iterators become invalid after
 * calling this function; however, the @start and @end will be
 * re-initialized to point to the location where text was deleted.
 *
 **/
void
gtk_text_buffer_delete (GtkTextBuffer *buffer,
                        GtkTextIter   *start,
                        GtkTextIter   *end)
{
  g_return_if_fail (GTK_IS_TEXT_BUFFER (buffer));
  g_return_if_fail (start != NULL);
  g_return_if_fail (end != NULL);
  g_return_if_fail (gtk_text_iter_get_buffer (start) == buffer);
  g_return_if_fail (gtk_text_iter_get_buffer (end) == buffer);
  
  gtk_text_buffer_emit_delete (buffer, start, end);
}

/**
 * gtk_text_buffer_delete_interactive:
 * @buffer: a #GtkTextBuffer
 * @start_iter: start of range to delete
 * @end_iter: end of range
 * @default_editable: whether the buffer is editable by default
 *
 * Deletes all <emphasis>editable</emphasis> text in the given range.
 * Calls gtk_text_buffer_delete () for each editable sub-range of
 * [@start,@end). @start and @end are revalidated to point to
 * the location of the last deleted range, or left untouched if
 * no text was deleted.
 *
 * Return value: whether some text was actually deleted
 **/
gboolean
gtk_text_buffer_delete_interactive (GtkTextBuffer *buffer,
                                    GtkTextIter   *start_iter,
                                    GtkTextIter   *end_iter,
                                    gboolean       default_editable)
{
  GtkTextMark *end_mark;
  GtkTextMark *start_mark;
  GtkTextIter iter;
  gboolean current_state;
  gboolean deleted_stuff = FALSE;

  /* Delete all editable text in the range start_iter, end_iter */

  g_return_val_if_fail (GTK_IS_TEXT_BUFFER (buffer), FALSE);
  g_return_val_if_fail (start_iter != NULL, FALSE);
  g_return_val_if_fail (end_iter != NULL, FALSE);
  g_return_val_if_fail (gtk_text_iter_get_buffer (start_iter) == buffer, FALSE);
  g_return_val_if_fail (gtk_text_iter_get_buffer (end_iter) == buffer, FALSE);

  
  gtk_text_buffer_begin_user_action (buffer);
  
  gtk_text_iter_order (start_iter, end_iter);

  start_mark = gtk_text_buffer_create_mark (buffer, NULL,
                                            start_iter, TRUE);
  end_mark = gtk_text_buffer_create_mark (buffer, NULL,
                                          end_iter, FALSE);
  iter = *start_iter;

  current_state = gtk_text_iter_editable (&iter, default_editable);

  while (TRUE)
    {
      gboolean new_state;
      gboolean done = FALSE;
      GtkTextIter end;

      gtk_text_iter_forward_to_tag_toggle (&iter, NULL);

      gtk_text_buffer_get_iter_at_mark (buffer, &end, end_mark);

      if (gtk_text_iter_compare (&iter, &end) >= 0)
        {
          done = TRUE;
          iter = end; /* clamp to the last boundary */
        }

      new_state = gtk_text_iter_editable (&iter, default_editable);

      if (current_state == new_state)
        {
          if (done)
            {
              if (current_state)
                {
                  /* We're ending an editable region. Delete said region. */
                  GtkTextIter start;

                  gtk_text_buffer_get_iter_at_mark (buffer, &start, start_mark);

                  gtk_text_buffer_emit_delete (buffer, &start, &iter);

                  deleted_stuff = TRUE;

                  /* revalidate user's iterators. */
                  *start_iter = start;
                  *end_iter = iter;
                }

              break;
            }
          else
            continue;
        }

      if (current_state && !new_state)
        {
          /* End of an editable region. Delete it. */
          GtkTextIter start;

          gtk_text_buffer_get_iter_at_mark (buffer, &start, start_mark);

          gtk_text_buffer_emit_delete (buffer, &start, &iter);

          current_state = FALSE;
          deleted_stuff = TRUE;

          /* revalidate user's iterators. */
          *start_iter = start;
          *end_iter = iter;
        }
      else
        {
          /* We are at the start of an editable region. We won't be deleting
           * the previous region. Move start mark to start of this region.
           */

          g_assert (!current_state && new_state);

          gtk_text_buffer_move_mark (buffer, start_mark,
                                     &iter);


          current_state = TRUE;
        }

      if (done)
        break;
    }


  gtk_text_buffer_delete_mark (buffer, start_mark);
  gtk_text_buffer_delete_mark (buffer, end_mark);

  gtk_text_buffer_end_user_action (buffer);
  
  return deleted_stuff;
}

/*
 * Extracting textual buffer contents
 */

/**
 * gtk_text_buffer_get_text:
 * @buffer: a #GtkTextBuffer
 * @start: start of a range
 * @end: end of a range
 * @include_hidden_chars: whether to include invisible text
 *
 * Returns the text in the range [@start,@end). Excludes undisplayed
 * text (text marked with tags that set the invisibility attribute) if
 * @include_hidden_chars is FALSE. Does not include characters
 * representing embedded images, so byte and character indexes into
 * the returned string do <emphasis>not</emphasis> correspond to byte
 * and character indexes into the buffer. Contrast with
 * gtk_text_buffer_get_slice ().
 *
 * Return value: an allocated UTF-8 string
 **/
gchar*
gtk_text_buffer_get_text (GtkTextBuffer      *buffer,
                          const GtkTextIter *start,
                          const GtkTextIter *end,
                          gboolean             include_hidden_chars)
{
  g_return_val_if_fail (GTK_IS_TEXT_BUFFER (buffer), NULL);
  g_return_val_if_fail (start != NULL, NULL);
  g_return_val_if_fail (end != NULL, NULL);
  g_return_val_if_fail (gtk_text_iter_get_buffer (start) == buffer, NULL);
  g_return_val_if_fail (gtk_text_iter_get_buffer (end) == buffer, NULL);
  
  if (include_hidden_chars)
    return gtk_text_iter_get_text (start, end);
  else
    return gtk_text_iter_get_visible_text (start, end);
}

/**
 * gtk_text_buffer_get_slice:
 * @buffer: a #GtkTextBuffer
 * @start: start of a range
 * @end: end of a range
 * @include_hidden_chars: whether to include invisible text
 *
 * Returns the text in the range [@start,@end). Excludes undisplayed
 * text (text marked with tags that set the invisibility attribute) if
 * @include_hidden_chars is FALSE. The returned string includes a
 * 0xFFFC character whenever the buffer contains
 * embedded images, so byte and character indexes into
 * the returned string <emphasis>do</emphasis> correspond to byte
 * and character indexes into the buffer. Contrast with
 * gtk_text_buffer_get_text (). Note that 0xFFFC can occur in normal
 * text as well, so it is not a reliable indicator that a pixbuf or
 * widget is in the buffer.
 *
 * Return value: an allocated UTF-8 string
 **/
gchar*
gtk_text_buffer_get_slice (GtkTextBuffer      *buffer,
                           const GtkTextIter *start,
                           const GtkTextIter *end,
                           gboolean             include_hidden_chars)
{
  g_return_val_if_fail (GTK_IS_TEXT_BUFFER (buffer), NULL);
  g_return_val_if_fail (start != NULL, NULL);
  g_return_val_if_fail (end != NULL, NULL);
  g_return_val_if_fail (gtk_text_iter_get_buffer (start) == buffer, NULL);
  g_return_val_if_fail (gtk_text_iter_get_buffer (end) == buffer, NULL);
  
  if (include_hidden_chars)
    return gtk_text_iter_get_slice (start, end);
  else
    return gtk_text_iter_get_visible_slice (start, end);
}

/*
 * Pixbufs
 */

static void
gtk_text_buffer_real_insert_pixbuf (GtkTextBuffer     *buffer,
                                    GtkTextIter       *iter,
                                    GdkPixbuf         *pixbuf)
{ 
  _gtk_text_btree_insert_pixbuf (iter, pixbuf);

  g_signal_emit (G_OBJECT (buffer), signals[CHANGED], 0);
}

/**
 * gtk_text_buffer_insert_pixbuf:
 * @buffer: a #GtkTextBuffer
 * @iter: location to insert the pixbuf
 * @pixbuf: a #GdkPixbuf
 *
 * Inserts an image into the text buffer at @iter. The image will be
 * counted as one character in character counts, and when obtaining
 * the buffer contents as a string, will be represented by the Unicode
 * "object replacement character" 0xFFFC. Note that the "slice"
 * variants for obtaining portions of the buffer as a string include
 * this character for pixbufs, but the "text" variants do
 * not. e.g. see gtk_text_buffer_get_slice() and
 * gtk_text_buffer_get_text().
 * 
 **/
void
gtk_text_buffer_insert_pixbuf         (GtkTextBuffer      *buffer,
                                       GtkTextIter        *iter,
                                       GdkPixbuf          *pixbuf)
{
  g_return_if_fail (GTK_IS_TEXT_BUFFER (buffer));
  g_return_if_fail (iter != NULL);
  g_return_if_fail (GDK_IS_PIXBUF (pixbuf));
  g_return_if_fail (gtk_text_iter_get_buffer (iter) == buffer);
  
  g_signal_emit (G_OBJECT (buffer), signals[INSERT_PIXBUF], 0,
                 iter, pixbuf);
}

/*
 * Child anchor
 */


static void
gtk_text_buffer_real_insert_anchor (GtkTextBuffer      *buffer,
                                    GtkTextIter        *iter,
                                    GtkTextChildAnchor *anchor)
{
  _gtk_text_btree_insert_child_anchor (iter, anchor);

  g_signal_emit (G_OBJECT (buffer), signals[CHANGED], 0);
}

/**
 * gtk_text_buffer_insert_child_anchor:
 * @buffer: a #GtkTextBuffer
 * @iter: location to insert the anchor
 * @anchor: a #GtkTextChildAnchor
 *
 * Inserts a child widget anchor into the text buffer at @iter. The
 * anchor will be counted as one character in character counts, and
 * when obtaining the buffer contents as a string, will be represented
 * by the Unicode "object replacement character" 0xFFFC. Note that the
 * "slice" variants for obtaining portions of the buffer as a string
 * include this character for pixbufs, but the "text" variants do
 * not. e.g. see gtk_text_buffer_get_slice() and
 * gtk_text_buffer_get_text(). Consider
 * gtk_text_buffer_create_child_anchor() as a more convenient
 * alternative to this function. The buffer will add a reference to
 * the anchor, so you can unref it after insertion.
 * 
 **/
void
gtk_text_buffer_insert_child_anchor (GtkTextBuffer      *buffer,
                                     GtkTextIter        *iter,
                                     GtkTextChildAnchor *anchor)
{
  g_return_if_fail (GTK_IS_TEXT_BUFFER (buffer));
  g_return_if_fail (iter != NULL);
  g_return_if_fail (GTK_IS_TEXT_CHILD_ANCHOR (anchor));
  g_return_if_fail (gtk_text_iter_get_buffer (iter) == buffer);
  
  g_signal_emit (G_OBJECT (buffer), signals[INSERT_CHILD_ANCHOR], 0,
                 iter, anchor);
}


/**
 * gtk_text_buffer_create_child_anchor:
 * @buffer: a #GtkTextBuffer
 * @iter: location in the buffer
 * 
 * This is a convenience function which simply creates a child anchor
 * with gtk_text_child_anchor_new() and inserts it into the buffer
 * with gtk_text_buffer_insert_child_anchor().
 * 
 * Return value: the created child anchor
 **/
GtkTextChildAnchor*
gtk_text_buffer_create_child_anchor (GtkTextBuffer *buffer,
                                     GtkTextIter   *iter)
{
  GtkTextChildAnchor *anchor;
  
  g_return_val_if_fail (GTK_IS_TEXT_BUFFER (buffer), NULL);
  g_return_val_if_fail (iter != NULL, NULL);
  g_return_val_if_fail (gtk_text_iter_get_buffer (iter) == buffer, NULL);
  
  anchor = gtk_text_child_anchor_new ();

  gtk_text_buffer_insert_child_anchor (buffer, iter, anchor);

  g_object_unref (G_OBJECT (anchor));

  return anchor;
}

/*
 * Mark manipulation
 */

static void
gtk_text_buffer_mark_set (GtkTextBuffer     *buffer,
                          const GtkTextIter *location,
                          GtkTextMark       *mark)
{
  /* IMO this should NOT work like insert_text and delete_range,
   * where the real action happens in the default handler.
   * 
   * The reason is that the default handler would be _required_,
   * i.e. the whole widget would start breaking and segfaulting if the
   * default handler didn't get run. So you can't really override the
   * default handler or stop the emission; that is, this signal is
   * purely for notification, and not to allow users to modify the
   * default behavior.
   */

  g_object_ref (G_OBJECT (mark));

  g_signal_emit (G_OBJECT (buffer),
                 signals[MARK_SET],
                 0,
                 location,
                 mark);

  g_object_unref (G_OBJECT (mark));
}

/**
 * gtk_text_buffer_set_mark:
 * @buffer:       a #GtkTextBuffer
 * @mark_name:    name of the mark
 * @iter:         location for the mark.
 * @left_gravity: if the mark is created by this function, gravity for the new
 *                mark.
 * @should_exist: if %TRUE, warn if the mark does not exist, and return
 *                immediately.
 *
 * Move the mark to the given position, if not @should_exist, create the mark.
 *
 * Return value: mark
 **/
static GtkTextMark*
gtk_text_buffer_set_mark (GtkTextBuffer *buffer,
                          GtkTextMark *existing_mark,
                          const gchar *mark_name,
                          const GtkTextIter *iter,
                          gboolean left_gravity,
                          gboolean should_exist)
{
  GtkTextIter location;
  GtkTextMark *mark;

  g_return_val_if_fail (gtk_text_iter_get_buffer (iter) == buffer, NULL);
  
  mark = _gtk_text_btree_set_mark (get_btree (buffer),
                                   existing_mark,
                                   mark_name,
                                   left_gravity,
                                   iter,
                                   should_exist);
  
  if (_gtk_text_btree_mark_is_insert (get_btree (buffer), mark) ||
      _gtk_text_btree_mark_is_selection_bound (get_btree (buffer), mark))
    {
      update_selection_clipboards (buffer);
    }

  _gtk_text_btree_get_iter_at_mark (get_btree (buffer),
                                   &location,
                                   mark);

  gtk_text_buffer_mark_set (buffer, &location, mark);

  return mark;
}

/**
 * gtk_text_buffer_create_mark:
 * @buffer: a #GtkTextBuffer
 * @mark_name: name for mark, or %NULL
 * @where: location to place mark
 * @left_gravity: whether the mark has left gravity
 *
 * Creates a mark at position @where. If @mark_name is %NULL, the mark
 * is anonymous; otherwise, the mark can be retrieved by name using
 * gtk_text_buffer_get_mark (). If a mark has left gravity, and text is
 * inserted at the mark's current location, the mark will be moved to
 * the left of the newly-inserted text. If the mark has right gravity
 * (@left_gravity = %FALSE), the mark will end up on the right of
 * newly-inserted text. The standard left-to-right cursor is a mark
 * with right gravity (when you type, the cursor stays on the right
 * side of the text you're typing).
 *
 * The caller of this function does <emphasis>not</emphasis> own a reference
 * to the returned #GtkTextMark, so you can ignore the return value
 * if you like. Marks are owned by the buffer and go away when the
 * buffer does.
 *
 * Emits the "mark_set" signal as notification of the mark's initial
 * placement.
 *
 * Return value: the new #GtkTextMark object
 **/
GtkTextMark*
gtk_text_buffer_create_mark (GtkTextBuffer *buffer,
                             const gchar *mark_name,
                             const GtkTextIter *where,
                             gboolean left_gravity)
{
  g_return_val_if_fail (GTK_IS_TEXT_BUFFER (buffer), NULL);

  return gtk_text_buffer_set_mark (buffer, NULL, mark_name, where,
                                   left_gravity, FALSE);
}

/**
 * gtk_text_buffer_move_mark:
 * @buffer: a #GtkTextBuffer
 * @mark: a #GtkTextMark
 * @where: new location for @mark in @buffer
 *
 * Moves @mark to the new location @where. Emits the "mark_set" signal
 * as notification of the move.
 **/
void
gtk_text_buffer_move_mark (GtkTextBuffer *buffer,
                           GtkTextMark *mark,
                           const GtkTextIter *where)
{
  g_return_if_fail (GTK_IS_TEXT_MARK (mark));
  g_return_if_fail (!gtk_text_mark_get_deleted (mark));
  g_return_if_fail (GTK_IS_TEXT_BUFFER (buffer));

  gtk_text_buffer_set_mark (buffer, mark, NULL, where, FALSE, TRUE);
}

/**
 * gtk_text_buffer_get_iter_at_mark:
 * @buffer: a #GtkTextBuffer
 * @iter: iterator to initialize
 * @mark: a #GtkTextMark in @buffer
 *
 * Initializes @iter with the current position of @mark.
 **/
void
gtk_text_buffer_get_iter_at_mark (GtkTextBuffer *buffer,
                                  GtkTextIter *iter,
                                  GtkTextMark *mark)
{
  g_return_if_fail (GTK_IS_TEXT_MARK (mark));
  g_return_if_fail (!gtk_text_mark_get_deleted (mark));
  g_return_if_fail (GTK_IS_TEXT_BUFFER (buffer));

  _gtk_text_btree_get_iter_at_mark (get_btree (buffer),
                                    iter,
                                    mark);
}

/**
 * gtk_text_buffer_delete_mark:
 * @buffer: a #GtkTextBuffer
 * @mark: a #GtkTextMark in @buffer
 *
 * Deletes @mark, so that it's no longer located anywhere in the
 * buffer. Removes the reference the buffer holds to the mark, so if
 * you haven't called g_object_ref () on the mark, it will be freed. Even
 * if the mark isn't freed, most operations on @mark become
 * invalid. There is no way to undelete a
 * mark. gtk_text_mark_get_deleted () will return TRUE after this
 * function has been called on a mark; gtk_text_mark_get_deleted ()
 * indicates that a mark no longer belongs to a buffer. The "mark_deleted"
 * signal will be emitted as notification after the mark is deleted.
 **/
void
gtk_text_buffer_delete_mark (GtkTextBuffer *buffer,
                             GtkTextMark   *mark)
{
  g_return_if_fail (GTK_IS_TEXT_MARK (mark));
  g_return_if_fail (!gtk_text_mark_get_deleted (mark));
  g_return_if_fail (GTK_IS_TEXT_BUFFER (buffer));

  g_object_ref (G_OBJECT (mark));

  _gtk_text_btree_remove_mark (get_btree (buffer), mark);

  /* See rationale above for MARK_SET on why we emit this after
   * removing the mark, rather than removing the mark in a default
   * handler.
   */
  g_signal_emit (G_OBJECT (buffer), signals[MARK_DELETED],
                 0,
                 mark);

  g_object_unref (G_OBJECT (mark));
}

/**
 * gtk_text_buffer_get_mark:
 * @buffer: a #GtkTextBuffer
 * @name: a mark name
 *
 * Returns the mark named @name in buffer @buffer, or NULL if no such
 * mark exists in the buffer.
 *
 * Return value: a #GtkTextMark, or NULL
 **/
GtkTextMark*
gtk_text_buffer_get_mark (GtkTextBuffer      *buffer,
                          const gchar         *name)
{
  GtkTextMark *mark;

  g_return_val_if_fail (GTK_IS_TEXT_BUFFER (buffer), NULL);
  g_return_val_if_fail (name != NULL, NULL);

  mark = _gtk_text_btree_get_mark_by_name (get_btree (buffer), name);

  return mark;
}


/**
 * gtk_text_buffer_move_mark_by_name:
 * @buffer: a #GtkTextBuffer
 * @name: name of a mark
 * @where: new location for mark
 *
 * Moves the mark named @name (which must exist) to location @where.
 * See gtk_text_buffer_move_mark () for details.
 **/
void
gtk_text_buffer_move_mark_by_name (GtkTextBuffer     *buffer,
                                   const gchar       *name,
                                   const GtkTextIter *where)
{
  GtkTextMark *mark;

  g_return_if_fail (GTK_IS_TEXT_BUFFER (buffer));
  g_return_if_fail (name != NULL);

  mark = _gtk_text_btree_get_mark_by_name (get_btree (buffer), name);

  if (mark == NULL)
    {
      g_warning ("%s: no mark named '%s'", G_STRLOC, name);
      return;
    }

  gtk_text_buffer_move_mark (buffer, mark, where);
}

/**
 * gtk_text_buffer_delete_mark_by_name:
 * @buffer: a #GtkTextBuffer
 * @name: name of a mark in @buffer
 *
 * Deletes the mark named @name; the mark must exist. See
 * gtk_text_buffer_delete_mark () for details.
 **/
void
gtk_text_buffer_delete_mark_by_name (GtkTextBuffer     *buffer,
                                     const gchar       *name)
{
  GtkTextMark *mark;

  g_return_if_fail (GTK_IS_TEXT_BUFFER (buffer));
  g_return_if_fail (name != NULL);

  mark = _gtk_text_btree_get_mark_by_name (get_btree (buffer), name);

  if (mark == NULL)
    {
      g_warning ("%s: no mark named '%s'", G_STRLOC, name);
      return;
    }

  gtk_text_buffer_delete_mark (buffer, mark);
}

/**
 * gtk_text_buffer_get_insert:
 * @buffer: a #GtkTextBuffer
 *
 * Returns the mark that represents the cursor (insertion point).
 * Equivalent to calling gtk_text_buffer_get_mark () to get the mark
 * named "insert", but very slightly more efficient, and involves less
 * typing.
 *
 * Return value: insertion point mark
 **/
GtkTextMark*
gtk_text_buffer_get_insert (GtkTextBuffer *buffer)
{
  g_return_val_if_fail (GTK_IS_TEXT_BUFFER (buffer), NULL);

  /* FIXME use struct member in btree */
  return gtk_text_buffer_get_mark (buffer, "insert");
}

/**
 * gtk_text_buffer_get_selection_bound:
 * @buffer: a #GtkTextBuffer
 *
 * Returns the mark that represents the selection bound.  Equivalent
 * to calling gtk_text_buffer_get_mark () to get the mark named
 * "selection_bound", but very slightly more efficient, and involves
 * less typing.
 *
 * The currently-selected text in @buffer is the region between the
 * "selection_bound" and "insert" marks. If "selection_bound" and
 * "insert" are in the same place, then there is no current selection.
 * gtk_text_buffer_get_selection_bounds() is another convenient function
 * for handling the selection, if you just want to know whether there's a
 * selection and what its bounds are.
 *
 * Return value: selection bound mark
 **/
GtkTextMark*
gtk_text_buffer_get_selection_bound (GtkTextBuffer *buffer)
{
  g_return_val_if_fail (GTK_IS_TEXT_BUFFER (buffer), NULL);

  /* FIXME use struct member in btree */
  return gtk_text_buffer_get_mark (buffer, "selection_bound");
}

void
gtk_text_buffer_get_iter_at_child_anchor (GtkTextBuffer      *buffer,
                                          GtkTextIter        *iter,
                                          GtkTextChildAnchor *anchor)
{
  g_return_if_fail (GTK_IS_TEXT_BUFFER (buffer));
  g_return_if_fail (iter != NULL);
  g_return_if_fail (GTK_IS_TEXT_CHILD_ANCHOR (anchor));
  g_return_if_fail (!gtk_text_child_anchor_get_deleted (anchor));
  
  _gtk_text_btree_get_iter_at_child_anchor (get_btree (buffer),
                                           iter,
                                           anchor);
}

/**
 * gtk_text_buffer_place_cursor:
 * @buffer: a #GtkTextBuffer
 * @where: where to put the cursor
 *
 * This function moves the "insert" and "selection_bound" marks
 * simultaneously.  If you move them to the same place in two steps
 * with gtk_text_buffer_move_mark(), you will temporarily select a
 * region in between their old and new locations, which can be pretty
 * inefficient since the temporarily-selected region will force stuff
 * to be recalculated. This function moves them as a unit, which can
 * be optimized.
 **/
void
gtk_text_buffer_place_cursor (GtkTextBuffer     *buffer,
                              const GtkTextIter *where)
{
  GtkTextIter real;

  g_return_if_fail (GTK_IS_TEXT_BUFFER (buffer));

  real = *where;

  _gtk_text_btree_place_cursor (get_btree (buffer), &real);
  gtk_text_buffer_mark_set (buffer, &real,
                            gtk_text_buffer_get_mark (buffer,
                                                      "insert"));
  gtk_text_buffer_mark_set (buffer, &real,
                            gtk_text_buffer_get_mark (buffer,
                                                      "selection_bound"));
}

/*
 * Tags
 */

/**
 * gtk_text_buffer_create_tag:
 * @buffer: a #GtkTextBuffer
 * @tag_name: name of the new tag, or %NULL
 * @first_property_name: name of first property to set, or %NULL
 * @Varargs: %NULL-terminated list of property names and values
 *
 *
 * Creates a tag and adds it to the tag table for @buffer.
 * Equivalent to calling gtk_text_tag_new () and then adding the
 * tag to the buffer's tag table. The returned tag is owned by
 * the buffer's tag table, so the ref count will be equal to one.
 *
 * If @tag_name is %NULL, the tag is anonymous.
 *
 * If @tag_name is non-%NULL, a tag called @tag_name must not already
 * exist in the tag table for this buffer.
 *
 * The @first_property_name argument and subsequent arguments are a list
 * of properties to set on the tag, as with g_object_set().
 *
 * Return value: a new tag
 **/
GtkTextTag*
gtk_text_buffer_create_tag (GtkTextBuffer *buffer,
                            const gchar   *tag_name,
                            const gchar   *first_property_name,
                            ...)
{
  GtkTextTag *tag;
  va_list list;
  
  g_return_val_if_fail (GTK_IS_TEXT_BUFFER (buffer), NULL);

  tag = gtk_text_tag_new (tag_name);

  gtk_text_tag_table_add (get_table (buffer), tag);

  if (first_property_name)
    {
      va_start (list, first_property_name);
      g_object_set_valist (G_OBJECT (tag), first_property_name, list);
      va_end (list);
    }
  
  g_object_unref (tag);

  return tag;
}

static void
gtk_text_buffer_real_apply_tag (GtkTextBuffer *buffer,
                                GtkTextTag *tag,
                                const GtkTextIter *start,
                                const GtkTextIter *end)
{
  if (tag->table != buffer->tag_table)
    {
      g_warning ("Can only apply tags that are in the tag table for the buffer");
      return;
    }
  
  _gtk_text_btree_tag (start, end, tag, TRUE);
}

static void
gtk_text_buffer_real_remove_tag (GtkTextBuffer *buffer,
                                 GtkTextTag *tag,
                                 const GtkTextIter *start,
                                 const GtkTextIter *end)
{
  if (tag->table != buffer->tag_table)
    {
      g_warning ("Can only remove tags that are in the tag table for the buffer");
      return;
    }
  
  _gtk_text_btree_tag (start, end, tag, FALSE);
}

static void
gtk_text_buffer_real_changed (GtkTextBuffer *buffer)
{
  gtk_text_buffer_set_modified (buffer, TRUE);
}

static void
gtk_text_buffer_emit_tag (GtkTextBuffer *buffer,
                          GtkTextTag *tag,
                          gboolean apply,
                          const GtkTextIter *start,
                          const GtkTextIter *end)
{
  GtkTextIter start_tmp = *start;
  GtkTextIter end_tmp = *end;

  g_return_if_fail (tag != NULL);

  gtk_text_iter_order (&start_tmp, &end_tmp);

  if (apply)
    g_signal_emit (G_OBJECT (buffer), signals[APPLY_TAG],
                   0,
                   tag, &start_tmp, &end_tmp);
  else
    g_signal_emit (G_OBJECT (buffer), signals[REMOVE_TAG],
                   0,
                   tag, &start_tmp, &end_tmp);
}


/**
 * gtk_text_buffer_apply_tag:
 * @buffer: a #GtkTextBuffer
 * @tag: a #GtkTextTag
 * @start: one bound of range to be tagged
 * @end: other bound of range to be tagged
 *
 * Emits the "apply_tag" signal on @buffer. The default
 * handler for the signal applies @tag to the given range.
 * @start and @end do not have to be in order.
 * 
 **/
void
gtk_text_buffer_apply_tag (GtkTextBuffer *buffer,
                           GtkTextTag    *tag,
                           const GtkTextIter *start,
                           const GtkTextIter *end)
{
  g_return_if_fail (GTK_IS_TEXT_BUFFER (buffer));
  g_return_if_fail (GTK_IS_TEXT_TAG (tag));
  g_return_if_fail (start != NULL);
  g_return_if_fail (end != NULL);
  g_return_if_fail (gtk_text_iter_get_buffer (start) == buffer);
  g_return_if_fail (gtk_text_iter_get_buffer (end) == buffer);
  g_return_if_fail (tag->table == buffer->tag_table);
  
  gtk_text_buffer_emit_tag (buffer, tag, TRUE, start, end);
}

/**
 * gtk_text_buffer_remove_tag:
 * @buffer: a #GtkTextBuffer
 * @tag: a #GtkTextTag
 * @start: one bound of range to be untagged
 * @end: other bound of range to be untagged
 *
 * Emits the "remove_tag" signal. The default handler for the signal
 * removes all occurrences of @tag from the given range. @start and
 * @end don't have to be in order.
 * 
 **/
void
gtk_text_buffer_remove_tag (GtkTextBuffer *buffer,
                            GtkTextTag    *tag,
                            const GtkTextIter *start,
                            const GtkTextIter *end)

{
  g_return_if_fail (GTK_IS_TEXT_BUFFER (buffer));
  g_return_if_fail (GTK_IS_TEXT_TAG (tag));
  g_return_if_fail (start != NULL);
  g_return_if_fail (end != NULL);
  g_return_if_fail (gtk_text_iter_get_buffer (start) == buffer);
  g_return_if_fail (gtk_text_iter_get_buffer (end) == buffer);
  g_return_if_fail (tag->table == buffer->tag_table);
  
  gtk_text_buffer_emit_tag (buffer, tag, FALSE, start, end);
}


/**
 * gtk_text_buffer_apply_tag_by_name:
 * @buffer: a #GtkTextBuffer
 * @name: name of a named #GtkTextTag
 * @start: one bound of range to be tagged
 * @end: other bound of range to be tagged
 *
 * Calls gtk_text_tag_table_lookup() on the buffer's tag table to
 * get a #GtkTextTag, then calls gtk_text_buffer_apply_tag().
 * 
 **/
void
gtk_text_buffer_apply_tag_by_name (GtkTextBuffer *buffer,
                                   const gchar   *name,
                                   const GtkTextIter *start,
                                   const GtkTextIter *end)
{
  GtkTextTag *tag;

  g_return_if_fail (GTK_IS_TEXT_BUFFER (buffer));
  g_return_if_fail (name != NULL);
  g_return_if_fail (start != NULL);
  g_return_if_fail (end != NULL);
  g_return_if_fail (gtk_text_iter_get_buffer (start) == buffer);
  g_return_if_fail (gtk_text_iter_get_buffer (end) == buffer);

  tag = gtk_text_tag_table_lookup (get_table (buffer),
                                   name);

  if (tag == NULL)
    {
      g_warning ("Unknown tag `%s'", name);
      return;
    }

  gtk_text_buffer_emit_tag (buffer, tag, TRUE, start, end);
}

/**
 * gtk_text_buffer_remove_tag_by_name:
 * @buffer: a #GtkTextBuffer
 * @name: name of a #GtkTextTag
 * @start: one bound of range to be untagged
 * @end: other bound of range to be untagged
 *
 * Calls gtk_text_tag_table_lookup() on the buffer's tag table to
 * get a #GtkTextTag, then calls gtk_text_buffer_remove_tag().
 * 
 * 
 **/
void
gtk_text_buffer_remove_tag_by_name (GtkTextBuffer *buffer,
                                    const gchar *name,
                                    const GtkTextIter *start,
                                    const GtkTextIter *end)
{
  GtkTextTag *tag;

  g_return_if_fail (GTK_IS_TEXT_BUFFER (buffer));
  g_return_if_fail (name != NULL);
  g_return_if_fail (start != NULL);
  g_return_if_fail (end != NULL);
  g_return_if_fail (gtk_text_iter_get_buffer (start) == buffer);
  g_return_if_fail (gtk_text_iter_get_buffer (end) == buffer);
  
  tag = gtk_text_tag_table_lookup (get_table (buffer),
                                   name);

  if (tag == NULL)
    {
      g_warning ("Unknown tag `%s'", name);
      return;
    }

  gtk_text_buffer_emit_tag (buffer, tag, FALSE, start, end);
}

static gint
pointer_cmp (gconstpointer a,
             gconstpointer b)
{
  if (a < b)
    return -1;
  else if (a > b)
    return 1;
  else
    return 0;
}

/**
 * gtk_text_buffer_remove_all_tags:
 * @buffer: a #GtkTextBuffer
 * @start: one bound of range to be untagged
 * @end: other bound of range to be untagged
 * 
 * Removes all tags in the range between @start and @end.  Be careful
 * with this function; it could remove tags added in code unrelated to
 * the code you're currently writing. That is, using this function is
 * probably a bad idea if you have two or more unrelated code sections
 * that add tags.
 **/
void
gtk_text_buffer_remove_all_tags (GtkTextBuffer     *buffer,
                                 const GtkTextIter *start,
                                 const GtkTextIter *end)
{
  GtkTextIter first, second, tmp;
  GSList *tags;
  GSList *tmp_list;
  GSList *prev;
  GtkTextTag *tag;
  
  g_return_if_fail (GTK_IS_TEXT_BUFFER (buffer));
  g_return_if_fail (start != NULL);
  g_return_if_fail (end != NULL);
  g_return_if_fail (gtk_text_iter_get_buffer (start) == buffer);
  g_return_if_fail (gtk_text_iter_get_buffer (end) == buffer);
  
  first = *start;
  second = *end;

  gtk_text_iter_order (&first, &second);

  /* Get all tags turned on at the start */
  tags = gtk_text_iter_get_tags (&first);
  
  /* Find any that are toggled on within the range */
  tmp = first;
  while (gtk_text_iter_forward_to_tag_toggle (&tmp, NULL))
    {
      GSList *toggled;
      GSList *tmp_list2;

      if (gtk_text_iter_compare (&tmp, &second) >= 0)
        break; /* past the end of the range */
      
      toggled = gtk_text_iter_get_toggled_tags (&tmp, TRUE);

      /* We could end up with a really big-ass list here.
       * Fix it someday.
       */
      tmp_list2 = toggled;
      while (tmp_list2 != NULL)
        {
          tags = g_slist_prepend (tags, tmp_list2->data);

          tmp_list2 = g_slist_next (tmp_list2);
        }

      g_slist_free (toggled);
    }
  
  /* Sort the list */
  tags = g_slist_sort (tags, pointer_cmp);

  /* Strip duplicates */
  tag = NULL;
  prev = NULL;
  tmp_list = tags;
  while (tmp_list != NULL)
    {
      if (tag == tmp_list->data)
        {
          /* duplicate */
          if (prev)
            prev->next = tmp_list->next;

          tmp_list->next = NULL;

          g_slist_free (tmp_list);

          tmp_list = prev->next;
          /* prev is unchanged */
        }
      else
        {
          /* not a duplicate */
          tag = GTK_TEXT_TAG (tmp_list->data);
          prev = tmp_list;
          tmp_list = tmp_list->next;
        }
    }

  g_slist_foreach (tags, (GFunc) g_object_ref, NULL);
  
  tmp_list = tags;
  while (tmp_list != NULL)
    {
      tag = GTK_TEXT_TAG (tmp_list->data);

      gtk_text_buffer_remove_tag (buffer, tag, &first, &second);
      
      tmp_list = tmp_list->next;
    }

  g_slist_foreach (tags, (GFunc) g_object_unref, NULL);
  
  g_slist_free (tags);
}


/*
 * Obtain various iterators
 */

/**
 * gtk_text_buffer_get_iter_at_line_offset:
 * @buffer: a #GtkTextBuffer
 * @iter: iterator to initialize
 * @line_number: line number counting from 0
 * @char_offset: char offset from start of line
 *
 * Obtains an iterator pointing to @char_offset within the given
 * line. The @char_offset must exist, offsets off the end of the line
 * are not allowed. Note <emphasis>characters</emphasis>, not bytes;
 * UTF-8 may encode one character as multiple bytes.
 * 
 **/
void
gtk_text_buffer_get_iter_at_line_offset (GtkTextBuffer      *buffer,
                                         GtkTextIter        *iter,
                                         gint                line_number,
                                         gint                char_offset)
{
  g_return_if_fail (iter != NULL);
  g_return_if_fail (GTK_IS_TEXT_BUFFER (buffer));

  _gtk_text_btree_get_iter_at_line_char (get_btree (buffer),
                                         iter, line_number, char_offset);
}

/**
 * gtk_text_buffer_get_iter_at_line_index:
 * @buffer: a #GtkTextBuffer 
 * @iter: iterator to initialize 
 * @line_number: line number counting from 0
 * @byte_index: byte index from start of line
 *
 * Obtains an iterator pointing to @byte_index within the given line.
 * @byte_index must be the start of a UTF-8 character, and must not be
 * beyond the end of the line.  Note <emphasis>bytes</emphasis>, not
 * characters; UTF-8 may encode one character as multiple bytes.
 * 
 **/
void
gtk_text_buffer_get_iter_at_line_index  (GtkTextBuffer *buffer,
                                         GtkTextIter   *iter,
                                         gint           line_number,
                                         gint           byte_index)
{
  g_return_if_fail (iter != NULL);
  g_return_if_fail (GTK_IS_TEXT_BUFFER (buffer));

  _gtk_text_btree_get_iter_at_line_byte (get_btree (buffer),
                                         iter, line_number, byte_index);
}

/**
 * gtk_text_buffer_get_iter_at_line:
 * @buffer: a #GtkTextBuffer 
 * @iter: iterator to initialize
 * @line_number: line number counting from 0
 * 
 * Initializes @iter to the start of the given line.
 **/
void
gtk_text_buffer_get_iter_at_line    (GtkTextBuffer      *buffer,
                                     GtkTextIter        *iter,
                                     gint                line_number)
{
  g_return_if_fail (iter != NULL);
  g_return_if_fail (GTK_IS_TEXT_BUFFER (buffer));

  gtk_text_buffer_get_iter_at_line_offset (buffer, iter, line_number, 0);
}

/**
 * gtk_text_buffer_get_iter_at_offset:
 * @buffer: a #GtkTextBuffer 
 * @iter: iterator to initialize
 * @char_offset: char offset from start of buffer, counting from 0
 *
 * Initializes @iter to a position @char_offset chars from the start
 * of the entire buffer.
 * 
 **/
void
gtk_text_buffer_get_iter_at_offset         (GtkTextBuffer      *buffer,
                                            GtkTextIter        *iter,
                                            gint                char_offset)
{
  g_return_if_fail (iter != NULL);
  g_return_if_fail (GTK_IS_TEXT_BUFFER (buffer));

  _gtk_text_btree_get_iter_at_char (get_btree (buffer), iter, char_offset);
}

/**
 * gtk_text_buffer_get_start_iter:
 * @buffer: a #GtkTextBuffer
 * @iter: iterator to initialize
 *
 * Initialized @iter with the first position in the text buffer. This
 * is the same as using gtk_text_buffer_get_iter_at_offset() to get
 * the iter at character offset 0.
 * 
 **/
void
gtk_text_buffer_get_start_iter (GtkTextBuffer *buffer,
                                GtkTextIter   *iter)
{
  g_return_if_fail (iter != NULL);
  g_return_if_fail (GTK_IS_TEXT_BUFFER (buffer));

  _gtk_text_btree_get_iter_at_char (get_btree (buffer), iter, 0);
}

/**
 * gtk_text_buffer_get_end_iter:
 * @buffer: a #GtkTextBuffer 
 * @iter: iterator to initialize
 *
 * Initializes @iter with the "end iterator," one past the last valid
 * character in the text buffer. If dereferenced with
 * gtk_text_iter_get_char(), the end iterator has a character value of
 * 0. The entire buffer lies in the range from the first position in
 * the buffer (call gtk_text_buffer_get_start_iter() to get
 * character position 0) to the end iterator.
 * 
 **/
void
gtk_text_buffer_get_end_iter         (GtkTextBuffer      *buffer,
                                       GtkTextIter        *iter)
{
  g_return_if_fail (iter != NULL);
  g_return_if_fail (GTK_IS_TEXT_BUFFER (buffer));

  _gtk_text_btree_get_end_iter (get_btree (buffer), iter);
}

/**
 * gtk_text_buffer_get_bounds:
 * @buffer: a #GtkTextBuffer 
 * @start: iterator to initialize with first position in the buffer
 * @end: iterator to initialize with the end iterator
 *
 * Retrieves the first and last iterators in the buffer, i.e. the
 * entire buffer lies within the range [@start,@end).
 * 
 **/
void
gtk_text_buffer_get_bounds (GtkTextBuffer *buffer,
                            GtkTextIter   *start,
                            GtkTextIter   *end)
{
  g_return_if_fail (start != NULL);
  g_return_if_fail (end != NULL);
  g_return_if_fail (GTK_IS_TEXT_BUFFER (buffer));

  _gtk_text_btree_get_iter_at_char (get_btree (buffer), start, 0);
  _gtk_text_btree_get_end_iter (get_btree (buffer), end);
}

/*
 * Modified flag
 */

/**
 * gtk_text_buffer_get_modified:
 * @buffer: a #GtkTextBuffer 
 * 
 * Indicates whether the buffer has been modified since the last call
 * to gtk_text_buffer_set_modified() set the modification flag to
 * %FALSE. Used for example to enable a "save" function in a text
 * editor.
 * 
 * Return value: %TRUE if the buffer has been modified
 **/
gboolean
gtk_text_buffer_get_modified (GtkTextBuffer *buffer)
{
  g_return_val_if_fail (GTK_IS_TEXT_BUFFER (buffer), FALSE);

  return buffer->modified;
}

/**
 * gtk_text_buffer_set_modified:
 * @buffer: a #GtkTextBuffer 
 * @setting: modification flag setting
 *
 * Used to keep track of whether the buffer has been modified since the
 * last time it was saved. Whenever the buffer is saved to disk, call
 * gtk_text_buffer_set_modified (@buffer, FALSE). When the buffer is modified,
 * it will automatically toggled on the modified bit again. When the modified
 * bit flips, the buffer emits a "modified_changed" signal.
 * 
 **/
void
gtk_text_buffer_set_modified (GtkTextBuffer      *buffer,
                              gboolean             setting)
{
  gboolean fixed_setting;

  g_return_if_fail (GTK_IS_TEXT_BUFFER (buffer));

  fixed_setting = setting != FALSE;

  if (buffer->modified == fixed_setting)
    return;
  else
    {
      buffer->modified = fixed_setting;
      g_signal_emit (G_OBJECT (buffer), signals[MODIFIED_CHANGED], 0);
    }
}


/*
 * Assorted other stuff
 */

/**
 * gtk_text_buffer_get_line_count:
 * @buffer: a #GtkTextBuffer 
 * 
 * Obtains the number of lines in the buffer. This value is cached, so
 * the function is very fast.
 * 
 * Return value: number of lines in the buffer
 **/
gint
gtk_text_buffer_get_line_count (GtkTextBuffer *buffer)
{
  g_return_val_if_fail (GTK_IS_TEXT_BUFFER (buffer), 0);

  return _gtk_text_btree_line_count (get_btree (buffer));
}

/**
 * gtk_text_buffer_get_char_count:
 * @buffer: a #GtkTextBuffer 
 * 
 * Gets the number of characters in the buffer; note that characters
 * and bytes are not the same, you can't e.g. expect the contents of
 * the buffer in string form to be this many bytes long. The character
 * count is cached, so this function is very fast.
 * 
 * Return value: number of characters in the buffer
 **/
gint
gtk_text_buffer_get_char_count (GtkTextBuffer *buffer)
{
  g_return_val_if_fail (GTK_IS_TEXT_BUFFER (buffer), 0);

  return _gtk_text_btree_char_count (get_btree (buffer));
}

/* Called when we lose the primary selection.
 */
static void
clipboard_clear_selection_cb (GtkClipboard *clipboard,
                              gpointer      data)
{
  /* Move selection_bound to the insertion point */
  GtkTextIter insert;
  GtkTextIter selection_bound;
  GtkTextBuffer *buffer = GTK_TEXT_BUFFER (data);

  gtk_text_buffer_get_iter_at_mark (buffer, &insert,
                                    gtk_text_buffer_get_mark (buffer, "insert"));
  gtk_text_buffer_get_iter_at_mark (buffer, &selection_bound,
                                    gtk_text_buffer_get_mark (buffer, "selection_bound"));

  if (!gtk_text_iter_equal (&insert, &selection_bound))
    gtk_text_buffer_move_mark (buffer,
                               gtk_text_buffer_get_mark (buffer, "selection_bound"),
                               &insert);
}

/* Called when we have the primary selection and someone else wants our
 * data in order to paste it.
 */
static void
clipboard_get_selection_cb (GtkClipboard     *clipboard,
                            GtkSelectionData *selection_data,
                            guint             info,
                            gpointer          data)
{
  GtkTextBuffer *buffer = GTK_TEXT_BUFFER (data);
  GtkTextIter start, end;

  if (gtk_text_buffer_get_selection_bounds (buffer, &start, &end))
    {
      if (selection_data->target ==
          gdk_atom_intern ("GTK_TEXT_BUFFER_CONTENTS", FALSE))
        {
          /* Provide the address of the buffer; this will only be
           * used within-process
           */
          gtk_selection_data_set (selection_data,
                                  gdk_atom_intern ("GTK_TEXT_BUFFER_CONTENTS", FALSE),
                                  8, /* bytes */
                                  (void*)&buffer,
                                  sizeof (buffer));
        }
      else
        {
          gchar *str;
          
          str = gtk_text_iter_get_visible_text (&start, &end);
          gtk_selection_data_set_text (selection_data, str, -1);
          g_free (str);
        }
    }
}

typedef struct
{
  GtkClipboard *clipboard;
  GtkTextBuffer *buffer;
} ContentsBuffer;

static void
remove_all_clipboard_contents_buffers (GtkTextBuffer *buffer)
{
  GSList *tmp_list = buffer->clipboard_contents_buffers;
  while (tmp_list)
    {
      ContentsBuffer *contents_buffer = tmp_list->data;

      g_object_unref (contents_buffer->buffer);
      g_free (contents_buffer);
          
      tmp_list = tmp_list->next;
    }

  g_slist_free (buffer->clipboard_contents_buffers);
  buffer->clipboard_contents_buffers = NULL;
}

static void
remove_clipboard_contents_buffer (GtkTextBuffer *buffer,
                                  GtkClipboard  *clipboard)
{
  GSList *tmp_list = buffer->clipboard_contents_buffers;
  while (tmp_list)
    {
      ContentsBuffer *contents_buffer = tmp_list->data;
      
      if (contents_buffer->clipboard == clipboard)
        {
          buffer->clipboard_contents_buffers = g_slist_remove (buffer->clipboard_contents_buffers, contents_buffer);
          
          g_object_unref (contents_buffer->buffer);
          g_free (contents_buffer);
          
          return;
        }

      tmp_list = tmp_list->next;
    }
}

static GtkTextBuffer *
get_clipboard_contents_buffer (GtkTextBuffer *buffer,
                               GtkClipboard  *clipboard,
                               gboolean       create)
{
  ContentsBuffer *contents_buffer;
  GSList *tmp_list;

  tmp_list = buffer->clipboard_contents_buffers;
  while (tmp_list)
    {
      contents_buffer = tmp_list->data;
      if (contents_buffer->clipboard == clipboard)
        return contents_buffer->buffer;
    }
  
  if (create)
    {
      contents_buffer = g_new (ContentsBuffer, 1);
      contents_buffer->clipboard = clipboard;
      contents_buffer->buffer = gtk_text_buffer_new (gtk_text_buffer_get_tag_table (buffer));

      g_object_set_data (G_OBJECT (contents_buffer->buffer), "gtk-text-buffer-clipboard",
                         GUINT_TO_POINTER (1));

      buffer->clipboard_contents_buffers = g_slist_prepend (buffer->clipboard_contents_buffers, contents_buffer);

      
      return contents_buffer->buffer;
    }
  else
    return NULL;
}

/* Provide cut/copied data */
static void
clipboard_get_contents_cb (GtkClipboard     *clipboard,
                           GtkSelectionData *selection_data,
                           guint             info,
                           gpointer          data)
{
  GtkTextBuffer *buffer = GTK_TEXT_BUFFER (data);
  GtkTextBuffer *contents = get_clipboard_contents_buffer (buffer, clipboard, FALSE);

  g_assert (contents); /* This should never be called unless we own the clipboard */

  if (selection_data->target ==
      gdk_atom_intern ("GTK_TEXT_BUFFER_CONTENTS", FALSE))
    {
      /* Provide the address of the clipboard buffer; this will only
       * be used within-process. OK to supply a NULL value for contents.
       */
      gtk_selection_data_set (selection_data,
                              gdk_atom_intern ("GTK_TEXT_BUFFER_CONTENTS", FALSE),
                              8, /* bytes */
                              (void*)&contents,
                              sizeof (contents));
    }
  else
    {
      gchar *str;
      GtkTextIter start, end;
      
      gtk_text_buffer_get_bounds (contents, &start, &end);
      
      str = gtk_text_iter_get_visible_text (&start, &end);
      gtk_selection_data_set_text (selection_data, str, -1);
      g_free (str);
    }
}

static void
clipboard_clear_contents_cb (GtkClipboard *clipboard,
                             gpointer      data)
{
  GtkTextBuffer *buffer = GTK_TEXT_BUFFER (data);

  remove_clipboard_contents_buffer (buffer, clipboard);
}

static void
get_paste_point (GtkTextBuffer *buffer,
                 GtkTextIter   *iter,
                 gboolean       clear_afterward)
{
  GtkTextIter insert_point;
  GtkTextMark *paste_point_override;

  paste_point_override = gtk_text_buffer_get_mark (buffer,
                                                   "gtk_paste_point_override");

  if (paste_point_override != NULL)
    {
      gtk_text_buffer_get_iter_at_mark (buffer, &insert_point,
                                        paste_point_override);
      if (clear_afterward)
        gtk_text_buffer_delete_mark (buffer,
                                     gtk_text_buffer_get_mark (buffer,
                                                               "gtk_paste_point_override"));
    }
  else
    {
      gtk_text_buffer_get_iter_at_mark (buffer, &insert_point,
                                        gtk_text_buffer_get_mark (buffer,
                                                                  "insert"));
    }

  *iter = insert_point;
}

static void
pre_paste_prep (ClipboardRequest *request_data,
                GtkTextIter      *insert_point)
{
  GtkTextBuffer *buffer = request_data->buffer;
  
  get_paste_point (buffer, insert_point, TRUE);

  /* If we're going to replace the selection, we insert before it to
   * avoid messing it up, then we delete the selection after inserting.
   */
  if (request_data->replace_selection)
    {
      GtkTextIter start, end;
      
      if (gtk_text_buffer_get_selection_bounds (buffer, &start, &end))
        *insert_point = start;
    }
}

static void
post_paste_cleanup (ClipboardRequest *request_data)
{
  if (request_data->replace_selection)
    {
      GtkTextIter start, end;
      
      if (gtk_text_buffer_get_selection_bounds (request_data->buffer,
                                                &start, &end))
        {
          if (request_data->interactive)
            gtk_text_buffer_delete_interactive (request_data->buffer,
                                                &start,
                                                &end,
                                                request_data->default_editable);
          else
            gtk_text_buffer_delete (request_data->buffer, &start, &end);
        }
    }
}

/* Called when we request a paste and receive the text data
 */
static void
clipboard_text_received (GtkClipboard *clipboard,
                         const gchar  *str,
                         gpointer      data)
{
  ClipboardRequest *request_data = data;
  GtkTextBuffer *buffer = request_data->buffer;

  if (str)
    {
      GtkTextIter insert_point;

      pre_paste_prep (request_data, &insert_point);
      
      if (request_data->interactive)
        gtk_text_buffer_insert_interactive (buffer, &insert_point,
                                            str, -1, request_data->default_editable);
      else
        gtk_text_buffer_insert (buffer, &insert_point,
                                str, -1);

      post_paste_cleanup (request_data);
    }

  g_object_unref (G_OBJECT (buffer));
  g_free (request_data);
}

static GtkTextBuffer*
selection_data_get_buffer (GtkSelectionData *selection_data,
                           ClipboardRequest *request_data)
{
  GdkWindow *owner;
  GtkTextBuffer *src_buffer = NULL;

  /* If we can get the owner, the selection is in-process */
  owner = gdk_selection_owner_get (selection_data->selection);

  if (owner == NULL)
    return NULL;
  
  if (selection_data->type != gdk_atom_intern ("GTK_TEXT_BUFFER_CONTENTS", FALSE))
    return NULL;

  if (selection_data->length != sizeof (src_buffer))
    return NULL;
          
  memcpy (&src_buffer, selection_data->data, sizeof (src_buffer));

  if (src_buffer == NULL)
    return NULL;
  
  g_return_val_if_fail (GTK_IS_TEXT_BUFFER (src_buffer), NULL);

  if (gtk_text_buffer_get_tag_table (src_buffer) !=
      gtk_text_buffer_get_tag_table (request_data->buffer))
    return NULL;
  
  return src_buffer;
}

#if 0
/* These are pretty handy functions; maybe something like them
 * should be in the public API. Also, there are other places in this
 * file where they could be used.
 */
static gpointer
save_iter (const GtkTextIter *iter,
           gboolean           left_gravity)
{
  return gtk_text_buffer_create_mark (gtk_text_iter_get_buffer (iter),
                                      NULL,
                                      iter,
                                      TRUE);
}

static void
restore_iter (const GtkTextIter *iter,
              gpointer           save_id)
{
  gtk_text_buffer_get_iter_at_mark (gtk_text_mark_get_buffer (save_id),
                                    (GtkTextIter*) iter,
                                    save_id);
  gtk_text_buffer_delete_mark (gtk_text_mark_get_buffer (save_id),
                               save_id);
}
#endif

static void
paste_from_buffer (ClipboardRequest    *request_data,
                   GtkTextBuffer       *src_buffer,
                   const GtkTextIter   *start,
                   const GtkTextIter   *end)
{
  GtkTextIter insert_point;
  
  /* We're about to emit a bunch of signals, so be safe */
  g_object_ref (G_OBJECT (src_buffer));
  
  pre_paste_prep (request_data, &insert_point);
  
  if (!gtk_text_iter_equal (start, end))
    {
      gtk_text_buffer_real_insert_range (request_data->buffer,
                                         &insert_point,
                                         start,
                                         end,
                                         request_data->interactive);
    }

  post_paste_cleanup (request_data);
      
  g_object_unref (G_OBJECT (src_buffer));
}

static void
clipboard_clipboard_buffer_received (GtkClipboard     *clipboard,
                                     GtkSelectionData *selection_data,
                                     gpointer          data)
{
  ClipboardRequest *request_data = data;
  GtkTextBuffer *src_buffer;
  
  src_buffer = selection_data_get_buffer (selection_data, request_data); 

  if (src_buffer)
    {
      GtkTextIter start, end;

      if (g_object_get_data (G_OBJECT (src_buffer), "gtk-text-buffer-clipboard"))
        {
          gtk_text_buffer_get_bounds (src_buffer, &start, &end);
      
          paste_from_buffer (request_data, src_buffer,
                             &start, &end);
        }
      else
        {
          if (gtk_text_buffer_get_selection_bounds (src_buffer, &start, &end))
            paste_from_buffer (request_data, src_buffer,
                               &start, &end);
        }
    }
  else
    {
      /* Request the text selection instead */
      gtk_clipboard_request_text (clipboard,
                                  clipboard_text_received,
                                  data);
    }
}

static const GtkTargetEntry targets[] = {
  { "STRING", 0, TARGET_STRING },
  { "TEXT",   0, TARGET_TEXT },
  { "COMPOUND_TEXT", 0, TARGET_COMPOUND_TEXT },
  { "UTF8_STRING", 0, TARGET_UTF8_STRING },
  { "GTK_TEXT_BUFFER_CONTENTS", 0, TARGET_TEXT_BUFFER_CONTENTS }
};

typedef struct
{
  GtkClipboard *clipboard;
  guint ref_count;
} SelectionClipboard;

static void
update_selection_clipboards (GtkTextBuffer *buffer)
{
  GSList *tmp_list = buffer->selection_clipboards;
  while (tmp_list)
    {
      GtkTextIter start;
      GtkTextIter end;
      
      SelectionClipboard *selection_clipboard = tmp_list->data;
      GtkClipboard *clipboard = selection_clipboard->clipboard;

      /* Determine whether we have a selection and adjust X selection
       * accordingly.
       */
      if (!gtk_text_buffer_get_selection_bounds (buffer, &start, &end))
        {
          if (gtk_clipboard_get_owner (clipboard) == G_OBJECT (buffer))
            gtk_clipboard_clear (clipboard);
        }
      else
        {
          /* Even if we already have the selection, we need to update our
           * timestamp.
           */
          if (!gtk_clipboard_set_with_owner (clipboard, targets, G_N_ELEMENTS (targets),
                                             clipboard_get_selection_cb,
                                             clipboard_clear_selection_cb,
                                             G_OBJECT (buffer)))
            clipboard_clear_selection_cb (clipboard, buffer);
        }

      tmp_list = tmp_list->next;
    }
}

static SelectionClipboard *
find_selection_clipboard (GtkTextBuffer *buffer,
                          GtkClipboard  *clipboard)
{
  GSList *tmp_list = buffer->selection_clipboards;
  while (tmp_list)
    {
      SelectionClipboard *selection_clipboard = tmp_list->data;
      if (selection_clipboard->clipboard == clipboard)
        return selection_clipboard;
      
      tmp_list = tmp_list->next;
    }

  return NULL;
}

/**
 * gtk_text_buffer_add_selection_clipboard:
 * @buffer: a #GtkTextBuffer
 * @clipboard: a #GtkClipboard
 * 
 * Adds @clipboard to the list of clipboards in which the selection contents
 * of @buffer are available. In most cases, @clipboard will be the #GtkClipboard
 * of type %GDK_SELECTION_PRIMARY for a view of @buffer.
 **/
void
gtk_text_buffer_add_selection_clipboard (GtkTextBuffer *buffer,
                                         GtkClipboard  *clipboard)
{
  SelectionClipboard *selection_clipboard;

  g_return_if_fail (GTK_IS_TEXT_BUFFER (buffer));
  g_return_if_fail (clipboard != NULL);

  selection_clipboard = find_selection_clipboard (buffer, clipboard);
  if (selection_clipboard)
    {
      selection_clipboard->ref_count++;
    }
  else
    {
      selection_clipboard = g_new (SelectionClipboard, 1);

      selection_clipboard->clipboard = clipboard;
      selection_clipboard->ref_count = 1;

      buffer->selection_clipboards = g_slist_prepend (buffer->selection_clipboards, selection_clipboard);
    }
}

/**
 * gtk_text_buffer_remove_selection_clipboard:
 * @buffer: a #GtkTextBuffer
 * @clipboard: a #GtkClipboard added to @buffer by gtk_text_buffer_add_selection_clipboard().
 * 
 * Removes a #GtkClipboard added with gtk_text_buffer_add_selection_clipboard()
 **/
void 
gtk_text_buffer_remove_selection_clipboard (GtkTextBuffer *buffer,
                                            GtkClipboard  *clipboard)
{
  SelectionClipboard *selection_clipboard;

  g_return_if_fail (GTK_IS_TEXT_BUFFER (buffer));
  g_return_if_fail (clipboard != NULL);

  selection_clipboard = find_selection_clipboard (buffer, clipboard);
  g_return_if_fail (selection_clipboard != NULL);

  selection_clipboard->ref_count--;
  if (selection_clipboard->ref_count == 0)
    {
      if (gtk_clipboard_get_owner (selection_clipboard->clipboard) == G_OBJECT (buffer))
        gtk_clipboard_clear (selection_clipboard->clipboard);

      buffer->selection_clipboards = g_slist_remove (buffer->selection_clipboards,
                                                     selection_clipboard);
      
      g_free (selection_clipboard);
    }
}

static void
remove_all_selection_clipboards (GtkTextBuffer *buffer)
{
  GSList *tmp_list = buffer->selection_clipboards;
  while (tmp_list)
    {
      SelectionClipboard *selection_clipboard = tmp_list->data;
      
      if (gtk_clipboard_get_owner (selection_clipboard->clipboard) == G_OBJECT (buffer))
        gtk_clipboard_clear (selection_clipboard->clipboard);
      
      g_free (selection_clipboard);

      tmp_list = tmp_list->next;
    }

  g_slist_free (buffer->selection_clipboards);
  buffer->selection_clipboards = NULL;
}

/**
 * gtk_text_buffer_paste_clipboard:
 * @buffer: a #GtkTextBuffer
 * @clipboard: the #GtkClipboard to paste from
 * @override_location: location to insert pasted text, or %NULL for at the cursor
 * @default_editable: whether the buffer is editable by default
 *
 * Pastes the contents of a clipboard at the insertion point, or at @override_location.
 * (Note: pasting is asynchronous, that is, we'll ask for the paste data and
 * return, and at some point later after the main loop runs, the paste
 * data will be inserted.)
 * 
 **/
void
gtk_text_buffer_paste_clipboard (GtkTextBuffer *buffer,
                                 GtkClipboard  *clipboard,
                                 GtkTextIter   *override_location,
                                 gboolean       default_editable)
{
  ClipboardRequest *data = g_new (ClipboardRequest, 1);
  GtkTextIter paste_point;
  GtkTextIter start, end;

  if (override_location != NULL)
    gtk_text_buffer_create_mark (buffer,
                                 "gtk_paste_point_override",
                                 override_location, FALSE);

  data->buffer = buffer;
  g_object_ref (G_OBJECT (buffer));
  data->interactive = TRUE;
  data->default_editable = default_editable;

  /* When pasting with the cursor inside the selection area, you
   * replace the selection with the new text, otherwise, you
   * simply insert the new text at the point where the click
   * occured, unselecting any selected text. The replace_selection
   * flag toggles this behavior.
   */
  data->replace_selection = FALSE;
  
  get_paste_point (buffer, &paste_point, FALSE);
  if (gtk_text_buffer_get_selection_bounds (buffer, &start, &end) &&
      (gtk_text_iter_in_range (&paste_point, &start, &end) ||
       gtk_text_iter_equal (&paste_point, &end)))
    data->replace_selection = TRUE;

  gtk_clipboard_request_contents (clipboard,
                                  gdk_atom_intern ("GTK_TEXT_BUFFER_CONTENTS", FALSE),
                                  clipboard_clipboard_buffer_received, data);
}

/**
 * gtk_text_buffer_delete_selection:
 * @buffer: a #GtkTextBuffer 
 * @interactive: whether the deletion is caused by user interaction
 * @default_editable: whether the buffer is editable by default
 *
 * Deletes the range between the "insert" and "selection_bound" marks,
 * that is, the currently-selected text. If @interactive is %TRUE,
 * the editability of the selection will be considered (users can't delete
 * uneditable text).
 * 
 * Return value: whether there was a non-empty selection to delete
 **/
gboolean
gtk_text_buffer_delete_selection (GtkTextBuffer *buffer,
                                  gboolean interactive,
                                  gboolean default_editable)
{
  GtkTextIter start;
  GtkTextIter end;

  if (!gtk_text_buffer_get_selection_bounds (buffer, &start, &end))
    {
      return FALSE; /* No selection */
    }
  else
    {
      if (interactive)
        {
          gtk_text_buffer_begin_user_action (buffer);
          gtk_text_buffer_delete_interactive (buffer, &start, &end, default_editable);
          gtk_text_buffer_end_user_action (buffer);
        }
      else
        gtk_text_buffer_delete (buffer, &start, &end);

      return TRUE; /* We deleted stuff */
    }
}

static void
cut_or_copy (GtkTextBuffer *buffer,
             GtkClipboard  *clipboard,
             gboolean       delete_region_after,
             gboolean       interactive,
             gboolean       default_editable)
{
  /* We prefer to cut the selected region between selection_bound and
   * insertion point. If that region is empty, then we cut the region
   * between the "anchor" and the insertion point (this is for
   * C-space and M-w and other Emacs-style copy/yank keys). Note that
   * insert and selection_bound are guaranteed to exist, but the
   * anchor only exists sometimes.
   */
  GtkTextIter start;
  GtkTextIter end;

  remove_clipboard_contents_buffer (buffer, clipboard);
  
  if (!gtk_text_buffer_get_selection_bounds (buffer, &start, &end))
    {
      /* Let's try the anchor thing */
      GtkTextMark * anchor = gtk_text_buffer_get_mark (buffer, "anchor");

      if (anchor == NULL)
        return;
      else
        {
          gtk_text_buffer_get_iter_at_mark (buffer, &end, anchor);
          gtk_text_iter_order (&start, &end);
        }
    }

  if (!gtk_text_iter_equal (&start, &end))
    {
      GtkTextIter ins;
      GtkTextBuffer *contents;
      
      contents = get_clipboard_contents_buffer (buffer, clipboard, TRUE);

      gtk_text_buffer_get_iter_at_offset (contents, &ins, 0);
      
      gtk_text_buffer_insert_range (contents, &ins, &start, &end);
                                    
      if (!gtk_clipboard_set_with_owner (clipboard, targets, G_N_ELEMENTS (targets),
                                         clipboard_get_contents_cb,
                                         clipboard_clear_contents_cb,
                                         G_OBJECT (buffer)))
        clipboard_clear_contents_cb (clipboard, buffer);      

      if (delete_region_after)
        {
          if (interactive)
            gtk_text_buffer_delete_interactive (buffer, &start, &end,
                                                default_editable);
          else
            gtk_text_buffer_delete (buffer, &start, &end);
        }
    }
}

/**
 * gtk_text_buffer_cut_clipboard:
 * @buffer: a #GtkTextBuffer
 * @clipboard: the #GtkClipboard object to cut to.
 * @default_editable: default editability of the buffer
 *
 * Copies the currently-selected text to a clipboard, then deletes
 * said text if it's editable.
 * 
 **/
void
gtk_text_buffer_cut_clipboard (GtkTextBuffer *buffer,
                               GtkClipboard  *clipboard,
                               gboolean       default_editable)
{
  gtk_text_buffer_begin_user_action (buffer);
  cut_or_copy (buffer, clipboard, TRUE, TRUE, default_editable);
  gtk_text_buffer_end_user_action (buffer);
}

/**
 * gtk_text_buffer_copy_clipboard:
 * @buffer: a #GtkTextBuffer 
 * @clipboard: the #GtkClipboard object to copy to.
 *
 * Copies the currently-selected text to a clipboard.
 * 
 **/
void
gtk_text_buffer_copy_clipboard (GtkTextBuffer *buffer,
                                GtkClipboard  *clipboard)
{
  gtk_text_buffer_begin_user_action (buffer);
  cut_or_copy (buffer, clipboard, FALSE, TRUE, TRUE);
  gtk_text_buffer_end_user_action (buffer);
}


/**
 * gtk_text_buffer_get_selection_bounds:
 * @buffer: a #GtkTextBuffer a #GtkTextBuffer
 * @start: iterator to initialize with selection start
 * @end: iterator to initialize with selection end
 *
 * Returns %TRUE if some text is selected; places the bounds
 * of the selection in @start and @end (if the selection has length 0,
 * then @start and @end are filled in with the same value).
 * @start and @end will be in ascending order. If @start and @end are
 * NULL, then they are not filled in, but the return value still indicates
 * whether text is selected.
 *
 * Return value: whether the selection has nonzero length
 **/
gboolean
gtk_text_buffer_get_selection_bounds   (GtkTextBuffer      *buffer,
                                        GtkTextIter        *start,
                                        GtkTextIter        *end)
{
  g_return_val_if_fail (GTK_IS_TEXT_BUFFER (buffer), FALSE);

  return _gtk_text_btree_get_selection_bounds (get_btree (buffer), start, end);
}

/**
 * gtk_text_buffer_begin_user_action:
 * @buffer: a #GtkTextBuffer
 * 
 * Called to indicate that the buffer operations between here and a
 * call to gtk_text_buffer_end_user_action() are part of a single
 * user-visible operation. The operations between
 * gtk_text_buffer_begin_user_action() and
 * gtk_text_buffer_end_user_action() can then be grouped when creating
 * an undo stack. #GtkTextBuffer maintains a count of calls to
 * gtk_text_buffer_begin_user_action() that have not been closed with
 * a call to gtk_text_buffer_end_user_action(), and emits the "begin_user_action"
 * and "end_user_action" signals only for the outermost pair of calls.
 * This allows you to build user actions from other user actions.
 *
 * The "interactive" buffer mutation functions, such as
 * gtk_text_buffer_insert_interactive(), automatically call begin/end
 * user action around the buffer operations they perform, so there's
 * no need to add extra calls if you user action consists solely of a
 * single call to one of those functions.
 **/
void
gtk_text_buffer_begin_user_action (GtkTextBuffer *buffer)
{
  g_return_if_fail (GTK_IS_TEXT_BUFFER (buffer));

  buffer->user_action_count += 1;
  
  if (buffer->user_action_count == 1)
    {
      /* Outermost nested user action begin emits the signal */
      g_signal_emit (G_OBJECT (buffer), signals[BEGIN_USER_ACTION], 0);
    }
}

/**
 * gtk_text_buffer_end_user_action:
 * @buffer: a #GtkTextBuffer
 * 
 * Should be paired with a call to gtk_text_buffer_begin_user_action().
 * See that function for a full explanation.
 **/
void
gtk_text_buffer_end_user_action (GtkTextBuffer *buffer)
{
  g_return_if_fail (GTK_IS_TEXT_BUFFER (buffer));
  g_return_if_fail (buffer->user_action_count > 0);
  
  buffer->user_action_count -= 1;
  
  if (buffer->user_action_count == 0)
    {
      /* Ended the outermost-nested user action end, so emit the signal */
      g_signal_emit (G_OBJECT (buffer), signals[END_USER_ACTION], 0);
    }
}

/*
 * Logical attribute cache
 */

#define ATTR_CACHE_SIZE 2

typedef struct _CacheEntry CacheEntry;
struct _CacheEntry
{
  gint line;
  gint char_len;
  PangoLogAttr *attrs;
};


struct _GtkTextLogAttrCache
{
  gint chars_changed_stamp;
  CacheEntry entries[ATTR_CACHE_SIZE];
};

static void
free_log_attr_cache (GtkTextLogAttrCache *cache)
{
  gint i = 0;
  while (i < ATTR_CACHE_SIZE)
    {
      g_free (cache->entries[i].attrs);
      ++i;
    }
  g_free (cache);
}

static void
clear_log_attr_cache (GtkTextLogAttrCache *cache)
{
  gint i = 0;
  while (i < ATTR_CACHE_SIZE)
    {
      g_free (cache->entries[i].attrs);
      cache->entries[i].attrs = NULL;
      ++i;
    }
}

static PangoLogAttr*
compute_log_attrs (const GtkTextIter *iter,
                   gint              *char_lenp)
{
  GtkTextIter start;
  GtkTextIter end;
  gchar *paragraph;
  gint char_len, byte_len;
  PangoLogAttr *attrs = NULL;
  
  start = *iter;
  end = *iter;

  gtk_text_iter_set_line_offset (&start, 0);
  gtk_text_iter_forward_line (&end);

  paragraph = gtk_text_iter_get_slice (&start, &end);
  char_len = g_utf8_strlen (paragraph, -1);
  byte_len = strlen (paragraph);

  g_assert (char_len > 0);

  if (char_lenp)
    *char_lenp = char_len;
  
  attrs = g_new (PangoLogAttr, char_len + 1);

  /* FIXME we need to follow PangoLayout and allow different language
   * tags within the paragraph
   */
  pango_get_log_attrs (paragraph, byte_len, -1,
                       gtk_text_iter_get_language (&start),
                       attrs,
                       char_len + 1);
  
  g_free (paragraph);

  return attrs;
}

/* The return value from this is valid until you call this a second time.
 */
const PangoLogAttr*
_gtk_text_buffer_get_line_log_attrs (GtkTextBuffer     *buffer,
                                     const GtkTextIter *anywhere_in_line,
                                     gint              *char_len)
{
  gint line;
  GtkTextLogAttrCache *cache;
  gint i;
  
  g_return_val_if_fail (GTK_IS_TEXT_BUFFER (buffer), NULL);
  g_return_val_if_fail (anywhere_in_line != NULL, NULL);

  /* special-case for empty last line in buffer */
  if (gtk_text_iter_is_end (anywhere_in_line) &&
      gtk_text_iter_get_line_offset (anywhere_in_line) == 0)
    {
      if (char_len)
        *char_len = 0;
      return NULL;
    }
  
  /* FIXME we also need to recompute log attrs if the language tag at
   * the start of a paragraph changes
   */
  
  if (buffer->log_attr_cache == NULL)
    {
      buffer->log_attr_cache = g_new0 (GtkTextLogAttrCache, 1);
      buffer->log_attr_cache->chars_changed_stamp =
        _gtk_text_btree_get_chars_changed_stamp (get_btree (buffer));
    }
  else if (buffer->log_attr_cache->chars_changed_stamp !=
           _gtk_text_btree_get_chars_changed_stamp (get_btree (buffer)))
    {
      clear_log_attr_cache (buffer->log_attr_cache);
    }
  
  cache = buffer->log_attr_cache;
  line = gtk_text_iter_get_line (anywhere_in_line);

  i = 0;
  while (i < ATTR_CACHE_SIZE)
    {
      if (cache->entries[i].attrs &&
          cache->entries[i].line == line)
        {
          if (char_len)
            *char_len = cache->entries[i].char_len;
          return cache->entries[i].attrs;
        }
      ++i;
    }
  
  /* Not in cache; open up the first cache entry */
  if (cache->entries[ATTR_CACHE_SIZE-1].attrs)
    g_free (cache->entries[ATTR_CACHE_SIZE-1].attrs);
  
  g_memmove (cache->entries + 1, cache->entries,
             sizeof (CacheEntry) * (ATTR_CACHE_SIZE - 1));

  cache->entries[0].line = line;
  cache->entries[0].attrs = compute_log_attrs (anywhere_in_line,
                                               &cache->entries[0].char_len);

  if (char_len)
    *char_len = cache->entries[0].char_len;
  
  return cache->entries[0].attrs;
}

void
_gtk_text_buffer_notify_will_remove_tag (GtkTextBuffer *buffer,
                                         GtkTextTag    *tag)
{
  /* This removes tag from the buffer, but DOESN'T emit the
   * remove_tag signal, because we can't afford to have user
   * code messing things up at this point; the tag MUST be removed
   * entirely.
   */
  if (buffer->btree)
    _gtk_text_btree_notify_will_remove_tag (buffer->btree, tag);
}

/*
 * Debug spew
 */

void
_gtk_text_buffer_spew (GtkTextBuffer *buffer)
{
  _gtk_text_btree_spew (get_btree (buffer));
}