Add new API `mrb_ary_resize`(mruby implementation of `rb_ary_resize`).

include/mruby/array.h

@@ -54,6 +54,7 @@ mrb_value mrb_ary_entry(mrb_value ary, mrb_int offset);
 mrb_value mrb_ary_shift(mrb_state *mrb, mrb_value self);
 mrb_value mrb_ary_clear(mrb_state *mrb, mrb_value self);
 mrb_value mrb_ary_join(mrb_state *mrb, mrb_value ary, mrb_value sep);
+mrb_value mrb_ary_resize(mrb_state *mrb, mrb_value ary, mrb_int len);
 
 static inline mrb_int
 mrb_ary_len(mrb_state *mrb, mrb_value ary)

src/array.c

@@ -231,6 +231,28 @@ ary_shrink_capa(mrb_state *mrb, struct RArray *a)
   }
 }
 
+mrb_value
+mrb_ary_resize(mrb_state *mrb, mrb_value ary, mrb_int new_len)
+{
+  mrb_int old_len;
+  struct RArray *a = mrb_ary_ptr(ary);
+
+  ary_modify(mrb, a);
+  old_len = RARRAY_LEN(ary);
+  if (old_len != new_len) {
+    a->len = new_len;
+    if (new_len < old_len) {
+      ary_shrink_capa(mrb, a);
+    }
+    else {
+      ary_expand_capa(mrb, a, new_len);
+      ary_fill_with_nil(a->ptr + old_len, new_len - old_len);
+    }
+  }
+
+  return ary;
+}
+
 static mrb_value
 mrb_ary_s_create(mrb_state *mrb, mrb_value self)
 {