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-rw-r--r--lib/ccan/asearch/asearch.h37
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diff --git a/lib/ccan/asearch/asearch.h b/lib/ccan/asearch/asearch.h
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+++ b/lib/ccan/asearch/asearch.h
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+#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)), \
+ typesafe_cb_cast(int (*)(const void *, const void *), \
+ int (*)(const __typeof__(*(key)) *, \
+ const __typeof__(*(base)) *), \
+ (cmp)))))
+
+#else
+#define asearch(key, base, num, cmp) \
+ (bsearch((key), (base), (num), sizeof(*(base)), \
+ (int (*)(const void *, const void *))(cmp)))
+#endif
+
+#endif /* CCAN_ASEARCH_H */