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#include "all.h"
struct edit {
unsigned offset;
int bytes; /* negative means "inserted" */
};
struct undo {
struct buffer *edits, *deleted;
unsigned redo, saved;
};
static struct edit *last_edit(struct text *text)
{
char *raw = NULL;
if (text->undo &&
text->undo->redo &&
text->undo->redo == buffer_bytes(text->undo->edits))
buffer_raw(text->undo->edits, &raw,
text->undo->redo - sizeof(struct edit),
sizeof(struct edit));
return (struct edit *) raw;
}
static void resume_editing(struct text *text)
{
if (!text->undo) {
text->undo = allocate0(sizeof *text->undo);
text->undo->edits = buffer_create(NULL);
text->undo->deleted = buffer_create(NULL);
}
buffer_delete(text->undo->edits, text->undo->redo,
buffer_bytes(text->undo->edits) - text->undo->redo);
buffer_delete(text->undo->deleted, text->undo->saved,
buffer_bytes(text->undo->deleted) - text->undo->saved);
}
static int in_view(struct view *view, unsigned *offset, unsigned *bytes)
{
if (*offset < view->start) {
if (*offset + *bytes <= view->start)
return 0;
*bytes -= view->start - *offset;
*offset = 0;
} else {
*offset -= view->start;
if (*offset >= view->bytes)
return 0;
if (*offset + *bytes > view->bytes)
*bytes = view->bytes - *offset;
}
return 1;
}
static void view_hint_deleting(struct view *view, unsigned offset, unsigned bytes)
{
if (!view->window || !in_view(view, &offset, &bytes))
return;
window_hint_deleting(view->window, offset, bytes);
}
static void view_hint_inserted(struct view *view, unsigned offset, unsigned bytes)
{
if (!view->window || !in_view(view, &offset, &bytes))
return;
window_hint_inserted(view->window, offset, bytes);
}
unsigned text_delete(struct text *text, unsigned offset, unsigned bytes)
{
char *old;
struct edit edit, *last;
struct view *view;
if (!bytes)
return 0;
text_dirty(text);
edit.offset = offset;
edit.bytes = buffer_raw(text->buffer, &old, offset, bytes);
bytes = edit.bytes;
if ((last = last_edit(text)) &&
last->bytes >= 0 &&
last->offset == offset)
last->bytes += bytes;
else {
resume_editing(text);
buffer_insert(text->undo->edits, &edit,
text->undo->redo, sizeof edit);
text->undo->redo += sizeof edit;
}
for (view = text->views; view; view = view->next)
view_hint_deleting(view, offset, bytes);
buffer_move(text->undo->deleted, text->undo->saved,
text->buffer, offset, bytes);
text->undo->saved += bytes;
text_adjust_loci(text, offset, -bytes);
return bytes;
}
unsigned text_insert(struct text *text, const void *in,
unsigned offset, unsigned bytes)
{
struct edit edit, *last;
struct view *view;
if (!bytes)
return 0;
text_dirty(text);
bytes = buffer_insert(text->buffer, in, offset, bytes);
if ((last = last_edit(text)) &&
last->bytes < 0 &&
last->offset - last->bytes == offset)
last->bytes -= bytes;
else {
resume_editing(text);
edit.offset = offset;
edit.bytes = -bytes;
buffer_insert(text->undo->edits, &edit, text->undo->redo,
sizeof edit);
text->undo->redo += sizeof edit;
}
text_adjust_loci(text, offset, bytes);
for (view = text->views; view; view = view->next)
view_hint_inserted(view, offset, bytes);
return bytes;
}
int text_undo(struct text *text)
{
char *raw;
struct edit *edit;
if (!text->undo || !text->undo->redo)
return -1;
text_dirty(text);
buffer_raw(text->undo->edits, &raw, text->undo->redo -= sizeof *edit,
sizeof *edit);
edit = (struct edit *) raw;
if (edit->bytes >= 0)
buffer_move(text->buffer, edit->offset, text->undo->deleted,
text->undo->saved -= edit->bytes, edit->bytes);
else
buffer_move(text->undo->deleted, text->undo->saved,
text->buffer, edit->offset, -edit->bytes);
text_adjust_loci(text, edit->offset, edit->bytes);
return edit->offset;
}
int text_redo(struct text *text)
{
char *raw;
struct edit *edit;
if (!text->undo ||
text->undo->redo == buffer_bytes(text->undo->edits))
return -1;
text_dirty(text);
buffer_raw(text->undo->edits, &raw, text->undo->redo, sizeof *edit);
edit = (struct edit *) raw;
text->undo->redo += sizeof *edit;
if (edit->bytes >= 0) {
buffer_move(text->undo->deleted, text->undo->saved,
text->buffer, edit->offset, edit->bytes);
text->undo->saved += edit->bytes;
} else
buffer_move(text->buffer, edit->offset, text->undo->deleted,
text->undo->saved, -edit->bytes);
text_adjust_loci(text, edit->offset, -edit->bytes);
return edit->offset;
}
void text_forget_undo(struct text *text)
{
if (text->undo) {
buffer_destroy(text->undo->edits);
buffer_destroy(text->undo->deleted);
allocate(text->undo, 0);
text->undo = NULL;
}
}
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