addition: next and peek, need testing

include/arraylist.h

@@ -19,6 +19,7 @@ typedef enum {
     ARRLIST_INVALID_ELEM_SIZE,
     ARRLIST_INVALID_CAPACITY,
     ARRLIST_IS_BORROWED,
+    ARRLIST_INVALID_SLICE,
 } ArrayListErr;
 
 ArrayList *arraylist_init(size_t capacity, size_t elem_size);
@@ -52,16 +53,14 @@ ArrayListErr arrayslice_destroy(ArraySlice **slice);
 
 bool arrayslice_is_valid(const ArraySlice *slice);
 size_t arrayslice_size(const ArraySlice *slice);
-bool arrayslice_empty(const ArraySlice *slice);
 
 // peek and next can be null, get can't, like, why would you use get without
 // actually getting something?, for validating an index?, use size idiot
-ArrayListErr *arrayslice_peek(const ArraySlice *slice, void *out);
-ArrayListErr *arrayslice_next(ArraySlice *slice, void *out);
-ArrayListErr *arrayslice_get(const ArraySlice *slice, void *out);
+ArrayListErr arrayslice_peek(const ArraySlice *slice, void *out);
+ArrayListErr arrayslice_next(ArraySlice *slice, void *out);
 
-ArrayListErr *arrayslice_reset(ArraySlice *slice);
-ArrayListErr *arrayslice_advance(ArraySlice *slice, size_t n);
+ArrayListErr arrayslice_reset(ArraySlice *slice);
+ArrayListErr arrayslice_advance(ArraySlice *slice, size_t n);
 
 ArrayList *arrayslice_to_arraylist(const ArraySlice *slice);
 

src/arraylist.c

@@ -506,3 +506,50 @@ ArrayListErr arrayslice_destroy(ArraySlice **slice) {
 
     return ARRLIST_OK;
 }
+
+bool arrayslice_is_valid(const ArraySlice *slice) {
+    if (slice == NULL) {
+        return false;
+    }
+
+    return slice->current != slice->end;
+}
+
+size_t arrayslice_size(const ArraySlice *slice) {
+    if (slice == NULL) {
+        return 0;
+    }
+
+    return slice->end - slice->start;
+}
+
+ArrayListErr arrayslice_peek(const ArraySlice *slice, void *out) {
+    if (slice == NULL || out == NULL) {
+        return ARRLIST_NULL_ARG;
+    }
+
+    if (slice->current == slice->end) {
+        return ARRLIST_INVALID_SLICE;
+    }
+
+    arraylist_get(slice->arr, slice->current, out);
+
+    return ARRLIST_OK;
+}
+
+ArrayListErr arrayslice_next(ArraySlice *slice, void *out) {
+    // HERE, it makes sense that you want to advance to the next
+    // without actually getting the value so it's good
+    if (slice == NULL) {
+        return ARRLIST_NULL_ARG;
+    }
+
+    if (slice->current == slice->end) {
+        return ARRLIST_INVALID_SLICE;
+    }
+
+    arraylist_get(slice->arr, slice->current, out);
+
+    slice->current++;
+    return ARRLIST_OK;
+}