--- a/libcommon/CMakeLists.txt	Mon Aug 21 20:59:18 2017 +0200
+++ b/libcommon/CMakeLists.txt	Sat Sep 02 11:24:42 2017 +0200
@@ -27,6 +27,7 @@
     ${libmlk-common_SOURCE_DIR}/malikania/size.hpp
     ${libmlk-common_SOURCE_DIR}/malikania/tileset.hpp
     ${libmlk-common_SOURCE_DIR}/malikania/util.hpp
+    ${libmlk-common_SOURCE_DIR}/malikania/weak_array.hpp
 )
 
 set(

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/libcommon/malikania/weak_array.hpp	Sat Sep 02 11:24:42 2017 +0200
@@ -0,0 +1,79 @@
+/*
+ * weak_array.hpp -- implement a cache array of weak values
+ *
+ * Copyright (c) 2013-2017 David Demelier <markand@malikania.fr>
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#ifndef MALIKANIA_WEAK_ARRAY_HPP
+#define MALIKANIA_WEAK_ARRAY_HPP
+
+/**
+ * \file weak_array.hpp
+ * \brief Implement a cache array of weak values.
+ */
+
+#include <memory>
+#include <vector>
+
+namespace mlk {
+
+/**
+ * \brief Implement a cache array of weak values.
+ */
+template <typename T>
+class weak_array : public std::vector<std::weak_ptr<T>> {
+public:
+    /**
+     * Find a value by a predicate.
+     *
+     * The predicate must have the following signature:
+     *
+     * ````cpp
+     * bool f(const std::shared_ptr<T>& value) const noexcept
+     * ````
+     *
+     * \param pred the predicate
+     * \return nullptr if not found
+     */
+    template <typename Predicate>
+    std::shared_ptr<T> find_if(Predicate&& pred) const noexcept
+    {
+        for (const auto& value : *this) {
+            auto sp = value.lock();
+
+            if (sp && pred(sp))
+                return sp;
+        }
+
+        return nullptr;
+    }
+
+    /**
+     * Remove values that have no more referenced.
+     */
+    void purge()
+    {
+        for (auto it = this->begin(); it != this->end(); ) {
+            if (!it->lock())
+                it = this->erase(it);
+            else
+                it++;
+        }
+    }
+};
+
+} // !mlk
+
+#endif // !MALIKANIA_WEAK_ARRAY_HPP

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/tests/libcommon/weak_array/CMakeLists.txt	Sat Sep 02 11:24:42 2017 +0200
@@ -0,0 +1,23 @@
+#
+# CMakeLists.txt -- CMake build system for malikania
+#
+# Copyright (c) 2013-2017 Malikania Authors
+#
+# Permission to use, copy, modify, and/or distribute this software for any
+# purpose with or without fee is hereby granted, provided that the above
+# copyright notice and this permission notice appear in all copies.
+#
+# THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+# WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+# MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+# ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+# WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+# ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+# OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+#
+
+malikania_create_test(
+    NAME weak_array
+    LIBRARIES libmlk-common
+    SOURCES ${CMAKE_CURRENT_SOURCE_DIR}/main.cpp
+)

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/tests/libcommon/weak_array/main.cpp	Sat Sep 02 11:24:42 2017 +0200
@@ -0,0 +1,67 @@
+/*
+ * main.cpp -- test weak_array
+ *
+ * Copyright (c) 2013-2017 Malikania Authors
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#define BOOST_TEST_MODULE "weak_array"
+#include <boost/test/unit_test.hpp>
+
+#include <malikania/weak_array.hpp>
+
+namespace mlk {
+
+class weak_array_fixture {
+protected:
+    weak_array<int> array_;
+};
+
+BOOST_FIXTURE_TEST_SUITE(weak_array_suite, weak_array_fixture)
+
+BOOST_AUTO_TEST_CASE(reuse)
+{
+    auto value = std::make_shared<int>(123);
+
+    array_.push_back(value);
+    array_.push_back(std::make_shared<int>(256));
+
+    auto it1 = array_.find_if([] (auto ptr) {
+        return *ptr = 123;
+    });
+    auto it2 = array_.find_if([] (auto ptr) {
+        return *ptr = 123;
+    });
+
+    BOOST_TEST(it1 == value);
+    BOOST_TEST(it2 == value);
+    BOOST_TEST(it1 == it2);
+    BOOST_TEST(*it1 == 123);
+    BOOST_TEST(*it2 == 123);
+}
+
+BOOST_AUTO_TEST_CASE(not_found)
+{
+    array_.push_back(std::make_shared<int>(123));
+
+    auto v = array_.find_if([] (auto ptr) {
+        return *ptr = 123;
+    });
+
+    BOOST_TEST(!v);
+}
+
+BOOST_AUTO_TEST_SUITE_END()
+
+} // !mlk