--- /dev/null
+#include "config.h"
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+
+/**
+ * permutation - Generate permutations
+ *
+ * This module allows you to generate all permutations of a given
+ * number of elements. It can also modify a user-supplied array in
+ * place through all those permutations.
+ *
+ * It uses the "plain changes" method, aka the
+ * Steinhaus-Johnson-Trotter algorithm to generate the permtations.
+ * This has some advantages over a naive recursive algorithm:
+ *
+ * - Each permutation is generated from the last by a single swap of
+ * adjacent elements
+ *
+ * - Constructing each permutation in place from the last takes
+ * amortized O(1) time.
+ *
+ * License: LGPL (v2.1 or any later version)
+ * Example:
+ * // Given "1 2 3" outputs 1 2 3 1 3 2 3 1 2 3 2 1 2 3 1 2 1 3
+ * #include <stdio.h>
+ * #include <ccan/permutation/permutation.h>
+ *
+ * int main(int argc, char *argv[])
+ * {
+ * int i;
+ * struct permutation *pi = permutation_new(argc - 1);
+ *
+ * do {
+ * for (i = 1; i < argc; i++)
+ * printf("%s ", argv[i]);
+ * printf("\n");
+ * } while (permutation_change_array(pi,
+ * &argv[1], sizeof(argv[1])));
+ * exit(0);
+ * }
+ */
+int main(int argc, char *argv[])
+{
+ /* Expect exactly one argument */
+ if (argc != 2)
+ return 1;
+
+ if (strcmp(argv[1], "depends") == 0) {
+ printf("ccan/build_assert\n");
+ printf("ccan/mem\n");
+ return 0;
+ }
+
+ if (strcmp(argv[1], "testdepends") == 0) {
+ printf("ccan/array_size\n");
+ return 0;
+ }
+
+ return 1;
+}