feat: add dyn-arr

include/c-libs/dyn-arr.h

@@ -0,0 +1,106 @@
+#ifndef CLIBS_DYN_ARR_H
+#define CLIBS_DYN_ARR_H
+
+#include <stddef.h>
+#include <stdlib.h>
+#include <string.h>
+
+typedef struct {
+  size_t cap;
+  size_t size;
+} DArrHeader;
+
+/// Initialize a dynamic array
+/// @param darr a pointer, which will be overwritten to point to the dynamic
+/// array's data part
+/// @param capacity the initial capacity allocated
+#define darr_init(darr, capacity)                                              \
+  do {                                                                         \
+    size_t c = (capacity);                                                     \
+    DArrHeader *header = malloc(sizeof(DArrHeader) + c * sizeof(*(darr)));     \
+    header->cap = c;                                                           \
+    header->size = 0;                                                          \
+    (darr) = (typeof(darr))(header + 1);                                       \
+  } while (0)
+
+/// Grow an danamic array by an amount
+/// @param darr a pointer initialized with darr_init, will be changed to point
+/// to the new data location
+/// @param extra_cap the extra capacity to add
+#define darr_grow(darr, extra_cap)                                             \
+  do {                                                                         \
+    DArrHeader *header = ((DArrHeader *)(darr)) - 1;                           \
+    header->cap += (extra_cap);                                                \
+                                                                               \
+    header =                                                                   \
+        realloc(header, header->cap * sizeof(*(darr)) + sizeof(DArrHeader));   \
+    (darr) = (typeof((darr)))(header + 1);                                     \
+  } while (0)
+
+/// Append an element to a dynamic array.
+/// @param darr a pointer initialized with darr_init, may be overwritten if
+/// memory changes
+/// @param x the element to insert at darr[darr_size(darr)]
+#define darr_push(darr, x)                                                     \
+  do {                                                                         \
+    DArrHeader *header = ((DArrHeader *)(darr)) - 1;                           \
+                                                                               \
+    if (header->size == header->cap) {                                         \
+      size_t inc = header->cap / 2;                                            \
+      darr_grow(darr, inc ? inc : 1);                                          \
+    }                                                                          \
+                                                                               \
+    header = ((DArrHeader *)(darr)) - 1;                                       \
+    darr[header->size++] = (x);                                                \
+  } while (0)
+
+/// Clone an dynamic array
+/// @param darr a pointer initialized with darr_init
+/// Returns a fresh pointer to the cloned data
+#define darr_clone(darr) (typeof(darr))darr_clone_impl((darr), sizeof(*(darr)))
+
+/// Clone an untyped dynamic array
+/// @param arr any pointer initialized with darr_init
+/// @param elem_size the byte-size of the contained elements
+/// Returns a fresh pointer to the cloned data, must be freed with darr_free
+void *darr_clone_impl(void *arr, size_t elem_size);
+
+/// Get the number of elements in the dynamic array
+/// @param arr a pointer initialized with darr_init
+size_t darr_size(void *arr);
+
+/// Get the capacity of the dynamic array
+/// @param arr a pointer initialized with darr_init
+size_t darr_cap(void *arr);
+
+/// Free a dynamic array
+/// @param arr a pointer initialized with darr_init or returned from darr_clone
+void darr_free(void *arr);
+#endif
+
+#ifdef CLIBS_DYN_ARR_IMPL
+
+size_t darr_size(void *arr) {
+  DArrHeader *header = ((DArrHeader *)arr) - 1;
+  return header->size;
+}
+
+size_t darr_cap(void *arr) {
+  DArrHeader *header = ((DArrHeader *)arr) - 1;
+  return header->cap;
+}
+
+void *darr_clone_impl(void *arr, size_t elem_size) {
+  DArrHeader *header = ((DArrHeader *)arr) - 1;
+  size_t size = sizeof(DArrHeader) + elem_size * header->cap;
+  DArrHeader *tgt = malloc(size);
+  memcpy(tgt, header, size);
+
+  return (void *)(tgt + 1);
+}
+
+void darr_free(void *arr) {
+  DArrHeader *header = ((DArrHeader *)arr) - 1;
+  free(header);
+}
+#endif