Improvements to git_array

This changes the size data to uint32_t, fixes the array growth
logic to use a simple 1.5x multiplier, and uses a generic inline
function for growing the array to make the git_array_alloc API
feel more natural (i.e. it returns a pointer to the new item).

1 files changed, 38 insertions, 13 deletions

diff --git a/src/array.h b/src/array.h
index aadd021f1..2d77c71a0 100644
--- a/src/array.h
+++ b/src/array.h
@@ -9,7 +9,23 @@
 
 #include "util.h"
 
-#define git_array_t(type) struct { type *ptr; size_t size, asize; }
+/*
+ * Use this to declare a typesafe resizable array of items, a la:
+ *
+ *     git_array_t(int) my_ints = GIT_ARRAY_INIT;
+ *     ...
+ *     int *i = git_array_alloc(my_ints);
+ *     GITERR_CHECK_ALLOC(i);
+ *     ...
+ *     git_array_clear(my_ints);
+ *
+ * You may also want to do things like:
+ *
+ *     typedef git_array_t(my_struct) my_struct_array_t;
+ */
+#define git_array_t(type) struct { type *ptr; uint32_t size, asize; }
+
+#define GIT_ARRAY_INIT { NULL, 0, 0 }
 
 #define git_array_init(a) \
 	do { (a).size = (a).asize = 0; (a).ptr = NULL; } while (0)
@@ -17,20 +33,29 @@
 #define git_array_clear(a) \
 	do { git__free((a).ptr); git_array_init(a); } while (0)
 
-#define git_array_grow(a) do { \
-	void *new_array; size_t new_size = \
-	((a).asize >= 256) ? (a).asize + 256 : ((a).asize >= 8) ? (a).asize * 2 : 8; \
-	new_array = git__realloc((a).ptr, new_size * sizeof(*(a).ptr)); \
-	if (!new_array) { git_array_clear(a); } \
-	else { (a).ptr = new_array; (a).asize = new_size; } \
-	} while (0)
-
 #define GITERR_CHECK_ARRAY(a) GITERR_CHECK_ALLOC((a).ptr)
 
-#define git_array_alloc(a, el) do { \
-	if ((a).size >= (a).asize) git_array_grow(a); \
-	(el) = (a).ptr ? &(a).ptr[(a).size++] : NULL; \
-	} while (0)
+
+typedef git_array_t(void) git_array_generic_t;
+
+/* use a generic array for growth so this can return the new item */
+GIT_INLINE(void *) git_array_grow(git_array_generic_t *a, size_t item_size)
+{
+	uint32_t new_size = (a->size < 8) ? 8 : a->asize * 3 / 2;
+	void *new_array = git__realloc(a->ptr, new_size * item_size);
+	if (!new_array) {
+		git_array_clear(*a);
+		return NULL;
+	} else {
+		a->ptr = new_array; a->asize = new_size; a->size++;
+		return (((char *)a->ptr) + (a->size - 1) * item_size);
+	}
+}
+
+#define git_array_alloc(a) \
+	((a).size >= (a).asize) ? \
+	git_array_grow((git_array_generic_t *)&(a), sizeof(*(a).ptr)) :	\
+	(a).ptr ? &(a).ptr[(a).size++] : NULL
 
 #define git_array_last(a) ((a).size ? &(a).ptr[(a).size - 1] : NULL)