darray: Add darray_insert() to insert a value at a specified index

This module currently supports removing but not inserting at a
specified index, so this adds that along with some tests. Inserting a
value moves all existing data beyond index over one element.
Signed-off-by: Damien Grassart <damien@grassart.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

ccan/darray/darray.h

@@ -56,6 +56,7 @@
  *
  *     void   darray_append(darray(T) arr, T item);
  *     void   darray_prepend(darray(T) arr, T item);
+ *     void   darray_insert(darray(T) arr, size_t index, T item);
  *     void   darray_push(darray(T) arr, T item); // same as darray_append
  *
  * Insertion (multiple items):
@@ -169,6 +170,12 @@ typedef darray(unsigned long)  darray_ulong;
 		memmove((arr).item+1, (arr).item, ((arr).size-1)*sizeof(*(arr).item)); \
 		(arr).item[0] = (__VA_ARGS__); \
 	} while(0)
+#define darray_insert(arr, index, ...) do { \
+		size_t __index = index; \
+		darray_resize(arr, (arr).size+1); \
+		memmove((arr).item+__index+1, (arr).item+__index, ((arr).size-__index-1)*sizeof(*(arr).item)); \
+		(arr).item[__index] = (__VA_ARGS__); \
+	} while(0)
 #define darray_push(arr, ...) darray_append(arr, __VA_ARGS__)
 
 

ccan/darray/test/run.c

@@ -38,7 +38,7 @@ int main(void) {
 	trace("Generating amalgams (internal)");
 	generateAmalgams();
 	
-	plan_tests(41);
+	plan_tests(47);
 	
 	testLits();
 	
@@ -70,7 +70,25 @@ int main(void) {
 		ok1(darray_size(arr) == 0);
 	}
 	reset(arr);
-	
+
+	testing(darray_insert);
+	{
+		size_t middle_i;
+
+		for (i=0; i < ARRAY_SIZE(lotsOfNumbers); i++)
+			darray_insert(arr, i, lotsOfNumbers[i]);
+		ok1(darray_size(arr) == ARRAY_SIZE(lotsOfNumbers));
+		ok1(darray_alloc(arr) >= darray_size(arr));
+		ok1(!memcmp(arr.item, lotsOfNumbers, sizeof(lotsOfNumbers)));
+
+		middle_i = ARRAY_SIZE(lotsOfNumbers) / 2;
+		darray_insert(arr, middle_i, 42);
+		ok1(darray_size(arr) == ARRAY_SIZE(lotsOfNumbers) + 1);
+		ok1(arr.item[middle_i] == 42);
+		ok1(arr.item[middle_i + 1] == lotsOfNumbers[middle_i]);
+	}
+	reset(arr);
+
 	testing(darray_from_c, darray_foreach, darray_foreach_reverse);
 	{
 		long   *i;