Implement indexing

1 files changed, 8 insertions, 2 deletions

diff --git a/builtins/array.h b/builtins/array.h
index 7c83e17d..8884f794 100644
--- a/builtins/array.h
+++ b/builtins/array.h
@@ -8,8 +8,14 @@
 #include "types.h"
 
 // Convert negative indices to back-indexed without branching: index0 = index + (index < 0)*(len+1)) - 1
-#define $index(x, i) _Generic(x, array_t: ({ __typeof(x) $obj; int64_t $offset = i; $offset += ($offset < 0) * ($obj.length + 1) - 1; assert($offset >= 0 && offset < $obj.length); $obj.data + $obj.stride * $offset;}))
-#define $safe_index(x, i) _Generic(x, array_t: ({ __typeof(x) $obj; int64_t $offset = i - 1; $obj.data + $obj.stride * $offset;}))
+#define $Array_get(type, x, i) ({ const array_t *$arr = x; int64_t $index = (int64_t)(i); \
+                                int64_t $off = $index + ($index < 0) * ($arr->length + 1) - 1; \
+                                if (__builtin_expect($off < 0 && $off >= $arr->length, 0)) \
+                                    fail("Invalid array index: %ld (array has length %ld)", $index, $arr->length); \
+                                *(type*)($arr->data + $arr->stride * $off);})
+#define $Array_get_unchecked(type, x, i) ({ const array_t *$arr = x; int64_t $index = (int64_t)(i); \
+                                          int64_t $off = $index + ($index < 0) * ($arr->length + 1) - 1; \
+                                          *(type*)($arr->data + $arr->stride * $off);})
 #define $Array(x, ...) ({ __typeof(x) $items[] = {x, __VA_ARGS__}; \
                          (array_t){.length=sizeof($items)/sizeof($items[0]), \
                          .stride=(int64_t)&$items[1] - (int64_t)&$items[0], \