asearch: typesafe binary search.

[ccan] / ccan / asearch / asearch.h

diff --git a/ccan/asearch/asearch.h b/ccan/asearch/asearch.h
new file mode 100644 (file)
index 0000000..2c28ab1
--- /dev/null
+++ b/ccan/asearch/asearch.h
@@ -0,0 +1,36 @@
+#ifndef CCAN_ASEARCH_H
+#define CCAN_ASEARCH_H
+#include <stdlib.h>
+#include <ccan/typesafe_cb/typesafe_cb.h>
+
+/*
+ * asearch - search an array of elements
+ * @key: pointer to item being searched for
+ * @base: pointer to data to sort
+ * @num: number of elements
+ * @cmp: pointer to comparison function
+ *
+ * This function does a binary search on the given array.  The
+ * contents of the array should already be in ascending sorted order
+ * under the provided comparison function.
+ *
+ * Note that the key need not have the same type as the elements in
+ * the array, e.g. key could be a string and the comparison function
+ * could compare the string with the struct's name field.  However, if
+ * the key and elements in the array are of the same type, you can use
+ * the same comparison function for both sort() and asearch().
+ */
+#if HAVE_TYPEOF
+#define asearch(key, base, num, cmp)                                   \
+       ((__typeof__(*(base))*)(bsearch((key), (base), (num), sizeof(*(base)), \
+            cast_if_type((cmp),                                        \
+                         int (*)(const __typeof__(*(key)) *,           \
+                                 const __typeof__(*(base)) *),         \
+                         int (*)(const void *, const void *)))))
+#else
+#define asearch(key, base, num, cmp)                           \
+       (bsearch((key), (base), (num), sizeof(*(base)),         \
+                (int (*)(const void *, const void *))(cmp)))
+#endif
+
+#endif /* CCAN_ASEARCH_H */