1 files changed, 27 insertions, 0 deletions
diff --git a/Swiften/Base/BoostRandomGenerator.cpp b/Swiften/Base/BoostRandomGenerator.cpp
new file mode 100644
index 0000000..b8c50d0
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+++ b/Swiften/Base/BoostRandomGenerator.cpp
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+/*
+ * Copyright (c) 2012 Remko Tronçon
+ * Licensed under the GNU General Public License v3.
+ * See Documentation/Licenses/GPLv3.txt for more information.
+ */
+
+#include <Swiften/Base/BoostRandomGenerator.h>
+
+#include <numeric>
+#include <boost/random/uniform_real.hpp>
+#include <boost/random/variate_generator.hpp>
+
+namespace Swift {
+
+int BoostRandomGenerator::generateWeighedRandomNumber(std::vector<double>::const_iterator probabilities_begin, std::vector<double>::const_iterator probabilities_end) {
+	// Only works starting boost 1.47
+	//boost::random::discrete_distribution<> distribution(weights.begin(), weights.end());
+	//return distribution(generator);
+
+	std::vector<double> cumulative;
+	std::partial_sum(probabilities_begin, probabilities_end, std::back_inserter(cumulative));
+	boost::uniform_real<> dist(0, cumulative.back());
+	boost::variate_generator<boost::mt19937&, boost::uniform_real<> > die(generator, dist);
+	return std::lower_bound(cumulative.begin(), cumulative.end(), die()) - cumulative.begin();
+}
+
+}