add delete! and objarr_delete

5 files changed, 41 insertions, 0 deletions

diff --git a/lib.c b/lib.c
index b4f5015..f4e9758 100644
--- a/lib.c
+++ b/lib.c
@@ -68,6 +68,15 @@ static Val fn_append(State *S, int nargs, Val *args) {
 	objarr_append(S, a, args[1]);
 	return args[0];
 }
+static Val fn_delete(State *S, int nargs, Val *args) {
+	CHECK(nargs == 2, "need 2 args to delete!");
+	CHECK(IS_ARR(args[0]), "can only delete from arr");
+	CHECK(IS_NUM(args[1]), "can only delete using num index");
+	ObjArr *a = AS_ARR(args[0]);
+	size_t ix = (size_t)AS_NUM(args[1]);
+	objarr_delete(S, a, ix);
+	return args[0];
+}
 static Val fn_len(State *S, int nargs, Val *args) {
 	CHECK(nargs == 1, "need 1 arg to len");
 	CHECK(IS_ARR(args[0]), "can only take length of arr");
@@ -174,6 +183,7 @@ static BuiltinFunc builtin_funcs[] = {
 
 	{ "arr", fn_arr },
 	{ "append!", fn_append },
+	{ "delete!", fn_delete },
 	{ "#", fn_len },
 	{ ",", fn_pend },
 	{ "s,", fn_spend },
diff --git a/tests/delete.bth b/tests/delete.bth
new file mode 100644
index 0000000..58063a3
--- /dev/null
+++ b/tests/delete.bth
@@ -0,0 +1,16 @@
+(let (a [10 20 30 40 50])
+	(delete! a 0)
+	(say a))
+
+(let (a [10 20 30 40 50])
+	(delete! a 3)
+	(say a))
+
+(let (a [10 20 30 40 50])
+	(delete! a 4)
+	(say a))
+
+(let (a [10 20 30 40 50])
+	(delete! a 5)
+	(say a))
+
diff --git a/tests/delete.out b/tests/delete.out
new file mode 100644
index 0000000..d5ec9d6
--- /dev/null
+++ b/tests/delete.out
@@ -0,0 +1,4 @@
+[20 30 40 50]
+[10 20 30 50]
+[10 20 30 40]
+array index out of bounds
diff --git a/val.c b/val.c
index ed375ac..3e8558f 100644
--- a/val.c
+++ b/val.c
@@ -98,6 +98,16 @@ void objarr_insert(State *S, ObjArr *arr, size_t ix, Val v) {
 		arr->d[ix] = v;
 	}
 }
+void objarr_delete(State *S, ObjArr *arr, size_t ix) {
+	CHECK(ix < arr->len, "array index out of bounds");
+	if (ix < arr->len - 1) {
+		size_t nix = ix+1;
+		size_t n = arr->len - nix;
+		memmove(&arr->d[ix], &arr->d[ix+1], n*sizeof(Val));
+	}
+	arr->len --;
+}
+
 
 static void print_val_h(Val v, int depth);
 void print_val(Val v) { 
diff --git a/val.h b/val.h
index 097c06a..7f8fd81 100644
--- a/val.h
+++ b/val.h
@@ -86,6 +86,7 @@ Val objarr_get(State *S, ObjArr *arr, size_t ix);
 void objarr_append(State *S, ObjArr *arr, Val v);
 void objarr_put(State *S, ObjArr *arr, size_t ix, Val v);
 void objarr_insert(State *S, ObjArr *arr, size_t ix, Val v);
+void objarr_delete(State *S, ObjArr *arr, size_t ix);
 
 #define IS_NIL(x) (x.ty == TY_NIL)
 #define IS_NUM(x) (x.ty == TY_NUM)