kvec,typval_encode: Add new vector: the one with preallocated array

1 files changed, 94 insertions, 0 deletions

diff --git a/src/nvim/lib/kvec.h b/src/nvim/lib/kvec.h
index dcc69f7b26..36c91c86b2 100644
--- a/src/nvim/lib/kvec.h
+++ b/src/nvim/lib/kvec.h
@@ -38,6 +38,7 @@
 #define NVIM_LIB_KVEC_H
 
 #include <stdlib.h>
+#include <string.h>
 
 #include "nvim/memory.h"
 
@@ -96,4 +97,97 @@
          : 0)), \
      (v).items[(i)])
 
+/// Type of a vector with a few first members allocated on stack
+///
+/// Is compatible with #kv_A, #kv_pop, #kv_size, #kv_max, #kv_last.
+/// Is not compatible with #kv_resize, #kv_resize_full, #kv_copy, #kv_push,
+/// #kv_pushp, #kv_a, #kv_destroy.
+///
+/// @param[in]  type  Type of vector elements.
+/// @param[in]  init_size  Number of the elements in the initial array.
+#define kvec_withinit_t(type, INIT_SIZE) \
+    struct { \
+      size_t size; \
+      size_t capacity; \
+      type *items; \
+      type init_array[INIT_SIZE]; \
+    }
+
+/// Initialize vector with preallocated array
+///
+/// @param[out]  v  Vector to initialize.
+#define kvi_init(v) \
+    ((v).capacity = ARRAY_SIZE((v).init_array), \
+     (v).size = 0, \
+     (v).items = (v).init_array)
+
+/// Move data to a new destination and free source
+static inline void *_memcpy_free(void *const restrict dest,
+                                 void *const restrict src,
+                                 const size_t size)
+  FUNC_ATTR_NONNULL_ALL FUNC_ATTR_NONNULL_RET FUNC_ATTR_ALWAYS_INLINE
+{
+  memcpy(dest, src, size);
+  xfree(src);
+  return dest;
+}
+
+/// Resize vector with preallocated array
+///
+/// @param[out]  v  Vector to resize.
+/// @param[in]  s  New size.
+#define kvi_resize(v, s) \
+    ((v).capacity = ((s) > ARRAY_SIZE((v).init_array) \
+                     ? (s) \
+                     : ARRAY_SIZE((v).init_array)), \
+     (v).items = ((v).capacity == ARRAY_SIZE((v).init_array) \
+                  ? ((v).items == (v).init_array \
+                     ? (v).items \
+                     : _memcpy_free((v).init_array, (v).items, \
+                                    (v).size * sizeof((v).items[0]))) \
+                  : ((v).items == (v).init_array \
+                     ? memcpy(xmalloc((v).capacity * sizeof((v).items[0])), \
+                              (v).items, \
+                              (v).size * sizeof((v).items[0])) \
+                     : xrealloc((v).items, \
+                                (v).capacity * sizeof((v).items[0])))))
+
+/// Resize vector with preallocated array when it is full
+///
+/// @param[out]  v  Vector to resize.
+#define kvi_resize_full(v) \
+    /* ARRAY_SIZE((v).init_array) is the minimal capacity of this vector. */ \
+    /* Thus when vector is full capacity may not be zero and it is safe */ \
+    /* not to bother with checking whether (v).capacity is 0. But now */ \
+    /* capacity is not guaranteed to have size that is a power of 2. */ \
+    kvi_resize(v, ((v).capacity == ARRAY_SIZE((v).init_array) \
+                   ? ((v).capacity++, kv_roundup32((v).capacity)) \
+                   : (v).capacity << 1))
+
+/// Get location where to store new element to a vector with preallocated array
+///
+/// @param[in,out]  v  Vector to push to.
+///
+/// @return Pointer to the place where new value should be stored.
+#define kvi_pushp(v) \
+    ((((v).size == (v).capacity) ? (kvi_resize_full(v), 0) : 0), \
+     ((v).items + ((v).size++)))
+
+/// Push value to a vector with preallocated array
+///
+/// @param[out]  v  Vector to push to.
+/// @param[in]  x  Value to push.
+#define kvi_push(v, x) \
+    (*kvi_pushp(v) = (x))
+
+/// Free array of elements of a vector with preallocated array if needed
+///
+/// @param[out]  v  Vector to free.
+#define kvi_destroy(v) \
+    do { \
+      if ((v).items != (v).init_array) { \
+        xfree((v).items); \
+      } \
+    } while (0)
+
 #endif  // NVIM_LIB_KVEC_H