add the std::sort::binarysearch module

Signed-off-by: Pierre Curto <pierre.curto@gmail.com>

test/unit/stdlib/sort/binarysearch.c3

@@ -0,0 +1,37 @@
+module binarysearch_test @test;
+import std::sort::binarysearch;
+
+struct SearchTest
+{
+    int[] data;
+    int x;
+    int index;
+}
+
+fn void search()
+{
+    SearchTest[] tcases = {
+        { {}, 0, 0 },
+        { {1, 2, 3}, 1, 0 },
+        { {1, 2, 3}, 2, 1 },
+        { {1, 2, 3}, 3, 2 },
+        { {1, 2, 3}, 4, 3 },
+        { {10, 20, 30}, 14, 1 },
+        { {10, 20, 30}, 26, 2 },
+    };
+
+    foreach (tc : tcases)
+    {
+        usz idx = binarysearch::search(tc.data, tc.x);
+        assert(idx == tc.index, "%s: got %d; want %d", tc.data, idx, tc.index);
+
+        usz cmp_idx = binarysearch::cmp_search(tc.data, tc.x, &cmp_int);
+        assert(cmp_idx == tc.index, "%s: got %d; want %d", tc.data, cmp_idx, tc.index);
+    }
+}
+
+module binarysearch_test;
+
+fn int cmp_int(void* x, void* y) {
+    return *(int*)x - *(int*)y;
+}