1 files changed, 55 insertions, 0 deletions

diff --git a/src/bootstrap/darray.h b/src/bootstrap/darray.h
new file mode 100644
index 0000000..bb49cdd
--- /dev/null
+++ b/src/bootstrap/darray.h
@@ -0,0 +1,55 @@
+#ifndef BDL_DARRAY_H
+#define BDL_DARRAY_H
+
+#include <string.h>
+
+typedef struct ArrayHeader {
+    size_t size;
+    size_t cap;
+} ArrayHeader;
+
+// Header/Size/capacity accessors.
+#define array_head(ARR) ((ArrayHeader *)((char *)(ARR) - sizeof(ArrayHeader)))
+#define array_size(ARR) ((ARR) ? array_head(ARR)->size : 0)
+#define array_cap(ARR)  ((ARR) ? array_head(ARR)->cap : 0)
+
+// Initialize a dynamic array ARR with N elements. The initialization doesn't
+// zero out the data, so thread carefully..
+#define array_init(ARR,N) ((ARR) = _array_reserve(N, sizeof(*(ARR))))
+
+// Push a given element T to the dynamic array ARR.
+#define array_push(ARR, T) \
+    ((ARR) = _array_maybe_grow(ARR, sizeof(T)),  \
+     (ARR)[array_head(ARR)->size++] = (T))
+
+// Return the last element of the array. Can be used to build stacks.
+#define array_pop(ARR) (ARR)[--array_head(ARR)->size]
+
+// Free the memory from the original allocated position.
+#define array_free(ARR)   ((ARR) ? free(array_head(ARR)), (ARR) = NULL : 0)
+
+static inline void *
+_array_reserve(size_t num_elem, size_t type_size) {
+    char *p = malloc(num_elem * type_size + sizeof(ArrayHeader));
+    p += sizeof(ArrayHeader);
+    array_head(p)->size = 0;
+    array_head(p)->cap = num_elem;
+    return p;
+}
+
+static inline void *
+_array_maybe_grow(void *arr, size_t type_size) {
+    ArrayHeader *head = array_head(arr);
+    if (head->cap == head->size) {
+        if (head->cap == 0) {
+            head->cap++;
+        } else {
+            head->cap *= 2;
+        }
+        head = realloc(head, head->cap * type_size + sizeof(ArrayHeader));
+    }
+    arr = (char *)head + sizeof(ArrayHeader);
+    return arr;
+}
+
+#endif // BDL_DARRAY_H