Introduce ga_append_via_ptr() and GA_APPEND_VIA_PTR()

Similar to GA_APPEND(). Replaces this pattern:

    ga_grow(&ga, 1);
    item_type *p = ((item_type *)ga.ga_data) + ga.ga_len;
    p->field1 = v1;
    p->field2 = v2;
    ga.ga_len++;

1 files changed, 15 insertions, 0 deletions

diff --git a/src/nvim/garray.h b/src/nvim/garray.h
index ed5e2dbada..5a90da21c2 100644
--- a/src/nvim/garray.h
+++ b/src/nvim/garray.h
@@ -1,6 +1,8 @@
 #ifndef NVIM_GARRAY_H
 #define NVIM_GARRAY_H
 
+#include "nvim/log.h"
+
 /// Structure used for growing arrays.
 /// This is used to store information that only grows, is deleted all at
 /// once, and needs to be accessed by index.  See ga_clear() and ga_grow().
@@ -22,7 +24,20 @@ typedef struct growarray {
     ((item_type *)(gap)->ga_data)[(gap)->ga_len++] = (item);               \
   } while (0)
 
+#define GA_APPEND_VIA_PTR(item_type, gap) \
+  ga_append_via_ptr(gap, sizeof(item_type))
+
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "garray.h.generated.h"
 #endif
+
+static inline void *ga_append_via_ptr(garray_T *gap, size_t item_size)
+{
+  if ((int)item_size != gap->ga_itemsize) {
+    ELOG("wrong item size in garray(%d), should be %d", item_size);
+  }
+  ga_grow(gap, 1);
+  return ((char *)gap->ga_data) + (item_size * (size_t)gap->ga_len++);
+}
+
 #endif  // NVIM_GARRAY_H