Add insert function for vectors

3 files changed, 47 insertions, 1 deletions

diff --git a/collections/vector/vector.adoc b/collections/vector/vector.adoc
index ee453ff..9e61a43 100644
--- a/collections/vector/vector.adoc
+++ b/collections/vector/vector.adoc
@@ -1,7 +1,7 @@
 Vector
 ======
 Tucker Evans
-v0.12, 2020-07-03
+v0.13, 2020-07-03
 
 A basic vector, that hold pointers to your data structures.
 
@@ -257,6 +257,33 @@ vec_push(vector, str_dup(str3));
 assert(str_cmp(vec_index(vector, 1), str2) == 0);
 ----
 
+[[vec_insert]]
++void vec_insert(vec *self, int index, void *item)+
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Inserts +item+ into vector +self+ at index +index+, all items after the index
+are pushed toward the end.
+
+Examples
+^^^^^^^^
+[source,c]
+----
+#include "vector.h"
+#include <string.h>
+
+char *str1 = "ONE";
+char *str2 = "TWO";
+char *str3 = "THREE";
+
+vec *vector = vec_new();
+vec_push(vector, str_dup(str1));
+vec_push(vector, str_dup(str2));
+
+vec_insert(vector, 1, str_dup(str3));
+
+assert(str_cmp(vec_index(vector, 1), str3) == 0);
+assert(str_cmp(vec_index(vector, 2), str2) == 0);
+----
+
 [[vec_swap]]
 +void vec_swap(vec *self, int i, int j)+
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
diff --git a/collections/vector/vector.c b/collections/vector/vector.c
index 79e31a4..2ae748f 100644
--- a/collections/vector/vector.c
+++ b/collections/vector/vector.c
@@ -174,6 +174,23 @@ int index;
 	return root->base[index];
 }
 
+void vec_insert(root, index, item)
+vec *root;
+int index;
+void *item;
+{
+	if (!root || index > root->end || index < 0)
+		return;
+
+	if (root->end >= root->limit)
+		vec_resize(root);
+
+	memmove(root->base + index + 1, root->base + index,
+			(root->end++ - index) * sizeof(void*));
+
+	root->base[index] = item;
+}
+
 void vec_swap(root, i, j)
 vec *root;
 int i,j;
diff --git a/collections/vector/vector.h b/collections/vector/vector.h
index 55e9481..1b47642 100644
--- a/collections/vector/vector.h
+++ b/collections/vector/vector.h
@@ -21,6 +21,8 @@ void* vec_back(vec*);
 void vec_set(vec*, int, void*);
 void* vec_index(vec*, int);
 
+void vec_insert(vec*, int, void*);
+
 void vec_swap(vec*, int, int);
 void* vec_swap_pop(vec*, int);