#ifndef GTK_TEXT_SEGMENT_H
#define GTK_TEXT_SEGMENT_H

#ifdef __cplusplus
extern "C" {
#endif /* __cplusplus */

/*
 * Segments: each line is divided into one or more segments, where each
 * segment is one of several things, such as a group of characters, a
 * tag toggle, a mark, or an embedded widget.  Each segment starts with
 * a standard header followed by a body that varies from type to type.
 */

/* This header has the segment type, and two specific segments
   (character and toggle segments) */

#include <gtk/gtktexttag.h>
#include <gtk/gtktextiter.h>
#include <gtk/gtktextmarkprivate.h>
#include <gtk/gtktextchild.h>

/* Information a BTree stores about a tag. */
typedef struct _GtkTextTagInfo GtkTextTagInfo;
struct _GtkTextTagInfo {
  GtkTextTag *tag;
  GtkTextBTreeNode *tag_root; /* highest-level node containing the tag */
  gint toggle_count;      /* total toggles of this tag below tag_root */
};

/* Body of a segment that toggles a tag on or off */
struct _GtkTextToggleBody {
  GtkTextTagInfo *info;             /* Tag that starts or ends here. */
  gboolean inNodeCounts;             /* TRUE means this toggle has been
                                      * accounted for in node toggle
                                      * counts; FALSE means it hasn't, yet. */
};


/* Class struct for segments */

typedef GtkTextLineSegment *(* GtkTextLineSegmentSplitFunc)      (GtkTextLineSegment *segPtr,
                                                        int index);
typedef gboolean         (* GtkTextViewSegDeleteFunc)     (GtkTextLineSegment *segPtr,
                                                        GtkTextLine *line,
                                                        gboolean treeGone);
typedef GtkTextLineSegment *(* GtkTextViewSegCleanupFunc)    (GtkTextLineSegment *segPtr,
                                                        GtkTextLine *line);
typedef void             (* GtkTextLineSegmentLineChangeFunc) (GtkTextLineSegment *segPtr,
                                                        GtkTextLine *line);
typedef void             (* GtkTextViewSegCheckFunc)      (GtkTextLineSegment *segPtr,
                                                        GtkTextLine *line);

struct _GtkTextLineSegmentClass {
  char *name;                           /* Name of this kind of segment. */
  gboolean leftGravity;                 /* If a segment has zero size (e.g. a
                                         * mark or tag toggle), does it
                                         * attach to character to its left
                                         * or right?  1 means left, 0 means
                                         * right. */
  GtkTextLineSegmentSplitFunc splitFunc;       /* Procedure to split large segment
                                         * into two smaller ones. */
  GtkTextViewSegDeleteFunc deleteFunc;     /* Procedure to call to delete
                                         * segment. */
  GtkTextViewSegCleanupFunc cleanupFunc;   /* After any change to a line, this
                                         * procedure is invoked for all
                                         * segments left in the line to
                                         * perform any cleanup they wish
                                         * (e.g. joining neighboring
                                         * segments). */
  GtkTextLineSegmentLineChangeFunc lineChangeFunc;
                                         /* Invoked when a segment is about
                                          * to be moved from its current line
                                          * to an earlier line because of
                                          * a deletion.  The line is that
                                          * for the segment's old line.
                                          * CleanupFunc will be invoked after
                                          * the deletion is finished. */

  GtkTextViewSegCheckFunc checkFunc;       /* Called during consistency checks
                                         * to check internal consistency of
                                         * segment. */
};

/*
 * The data structure below defines line segments.
 */

struct _GtkTextLineSegment {
  GtkTextLineSegmentClass *type;                /* Pointer to record describing
                                         * segment's type. */
  GtkTextLineSegment *next;                /* Next in list of segments for this
                                         * line, or NULL for end of list. */

  int char_count;                       /* # of chars of index space occupied */
  
  int byte_count;                       /* Size of this segment (# of bytes
                                         * of index space it occupies). */
  union {
    char chars[4];                      /* Characters that make up character
                                         * info.  Actual length varies to
                                         * hold as many characters as needed.*/
    GtkTextToggleBody toggle;              /* Information about tag toggle. */
    GtkTextMarkBody mark;              /* Information about mark. */
    GtkTextPixmap pixmap;              /* Child pixmap */
#if 0
    GtkTextChild child;                /* child widget */
#endif
  } body;
};


GtkTextLineSegment  *gtk_text_line_segment_split(const GtkTextIter *iter);

GtkTextLineSegment *char_segment_new(const gchar *text, guint len);

GtkTextLineSegment *char_segment_new_from_two_strings(const gchar *text1, guint len1,
                                                   const gchar *text2, guint len2);

GtkTextLineSegment *toggle_segment_new(GtkTextTagInfo *info, gboolean on);

#ifdef __cplusplus
}
#endif /* __cplusplus */

#endif