CE optimize KB_DELETE

ce/gapbuffer.c

@@ -113,9 +113,25 @@ char* gapbuffer_string_at (gb_malloc_func_t mallocfn, void* ctx, struct gapbuffe
   return res;
 }
 
-char gapbuffer_at (struct gapbuffer* gb, size_t index) {
-  if (index < gb->gap_start)
-    return gb->buffer[index];
-  else
-    return gb->buffer[index + (gb->gap_end - gb->gap_start)];
+void gapbuffer_concat (gb_realloc_func_t reallocfn, void* ctx, struct gapbuffer* dest,
+                       struct gapbuffer* src) {
+  size_t src_len = gapbuffer_length (src);
+
+  if (src_len == 0)
+    return;
+
+  while ((dest->gap_end - dest->gap_start) < src_len)
+    gapbuffer_grow (reallocfn, ctx, dest);
+
+  gapbuffer_move (dest, gapbuffer_length (dest));
+
+  size_t part1_len = src->gap_start;
+  memcpy (dest->buffer + dest->gap_start, src->buffer, part1_len);
+  dest->gap_start += part1_len;
+
+  size_t part2_len = src->size - src->gap_end;
+  if (part2_len > 0) {
+    memcpy (dest->buffer + dest->gap_start, src->buffer + src->gap_end, part2_len);
+    dest->gap_start += part2_len;
+  }
 }