From f07dda91169ec629e45a549aafe1affd21647082 Mon Sep 17 00:00:00 2001
From: Danny Robson <danny@nerdcruft.net>
Date: Wed, 4 Jan 2012 17:03:27 +1100
Subject: [PATCH] Add a random choice from container function

---
 random.hpp | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/random.hpp b/random.hpp
index 5bf64793..9c099b22 100644
--- a/random.hpp
+++ b/random.hpp
@@ -20,12 +20,33 @@
 #ifndef __UTIL_RANDOM_HPP
 #define __UTIL_RANDOM_HPP
 
+#include <iterator>
+
 namespace util {
     template <typename T>
     T& randomise (T &);
 
     template <typename T>
     T random (void);
+
+    template <typename T>
+    typename T::value_type&
+    choose (T &container) {
+        typename T::iterator  cursor = container.begin ();
+        typename T::size_type size   = container.size ();
+        typename T::size_type offset = random<typename T::size_type> () % size;
+        
+        std::advance (cursor, offset);
+        return *cursor;
+    }
+
+    template <typename T>
+    typename T::value_type&
+    choose (T begin, T end) {
+        typename T::difference_type size = std::distance (begin, end);
+        std::advance (begin, random<T::size_type> () % size);
+        return *begin;
+    }
 }
 
 #endif