From 17365e6e2d1972c9987e2485be79249aa1d1e193 Mon Sep 17 00:00:00 2001
From: Aurelio Buonomo <48835871+auribuo@users.noreply.github.com>
Date: Wed, 30 Apr 2025 17:34:44 +0200
Subject: [PATCH] Added macro nob_da_swap to swap elements in a dynamic array

---
 nob.c           |  1 +
 nob.h           | 12 ++++++++++++
 tests/da_swap.c | 19 +++++++++++++++++++
 3 files changed, 32 insertions(+)
 create mode 100644 tests/da_swap.c

diff --git a/nob.c b/nob.c
index 912e05f..c9bd15b 100644
--- a/nob.c
+++ b/nob.c
@@ -15,6 +15,7 @@ const char *test_names[] = {
     "read_entire_dir",
     "da_resize",
     "da_last",
+    "da_swap",
     "da_remove_unordered",
     "da_append",
     "sb_appendf",
diff --git a/nob.h b/nob.h
index 8ab0cf5..e253557 100644
--- a/nob.h
+++ b/nob.h
@@ -321,6 +321,17 @@ bool nob_delete_file(const char *path);
         (da)->items[j] = (da)->items[--(da)->count]; \
     } while(0)
 
+#define nob_da_swap(da, i, j)                           \
+    do {                                                \
+        size_t ii = (i);                                \
+        size_t jj = (j);                                \
+        NOB_ASSERT(ii < (da)->count);                   \
+        NOB_ASSERT(jj < (da)->count);                   \
+        nob_da_append((da), (da)->items[ii]);           \
+        (da)->items[ii] = (da)->items[jj];              \
+        (da)->items[jj] = (da)->items[--((da)->count)]; \
+    } while(0)
+
 // Foreach over Dynamic Arrays. Example:
 // ```c
 // typedef struct {
@@ -1927,6 +1938,7 @@ int closedir(DIR *dirp)
         #define da_reserve nob_da_reserve
         #define da_last nob_da_last
         #define da_remove_unordered nob_da_remove_unordered
+        #define da_swap nob_da_swap
         #define da_foreach nob_da_foreach
         #define String_Builder Nob_String_Builder
         #define read_entire_file nob_read_entire_file
diff --git a/tests/da_swap.c b/tests/da_swap.c
new file mode 100644
index 0000000..6cd4795
--- /dev/null
+++ b/tests/da_swap.c
@@ -0,0 +1,19 @@
+#define NOB_IMPLEMENTATION
+#define NOB_STRIP_PREFIX
+#include "nob.h"
+
+typedef struct {
+    int *items;
+    size_t count;
+    size_t capacity;
+} Numbers;
+
+int main(void)
+{
+    nob_log(INFO, "da_swap:");
+    Numbers xs = {0};
+    for (int i = 1; i <= 10; ++i) da_append(&xs, i);
+    for (int i = 0; i < 5; ++i) da_swap(&xs, i, xs.count - i - 1);
+    for (int i = 0; i < 10; ++i) nob_log(INFO, "%d", xs.items[i]);
+    return 0;
+}