add automatic hash function creation

doc/sequence.qbk

@@ -1,6 +1,7 @@
 [/==============================================================================
     Copyright (C) 2001-2011 Joel de Guzman
     Copyright (C) 2006 Dan Marsden
+    Copyright (C) 2014 Christoph Weiss
 
     Use, modification and distribution is subject to the Boost Software
     License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
@@ -1896,6 +1897,87 @@ compile time error.
 
 [endsect]
 
+[section Hashing]
+
+Automatically create a [classref boost::hash] conforming `hash_value` function.
+
+[heading Synopsis]
+
+    template <typename Seq>
+    std::size_t
+    hash_value(Seq const& seq);
+
+[heading Parameters]
+
+[table
+    [[Parameter]    [Requirement]                       [Description]]
+    [[`seq`]        [Instance of __sequence__]          [__sequence__ to compute hash value of]]
+]
+
+[*Return type]: `std::size_t`
+
+[*Requirements]:
+
+For each element `e` in sequence `seq`, `hash_value(seq)` is a valid expression
+returning a type that is convertible to `std::size_t`.
+
+[*Semantics]: Returns a combined hash value for all elements of `seq`.
+
+[heading Header]
+
+    #include <boost/fusion/sequence/hash.hpp>
+    #include <boost/fusion/include/hash.hpp>
+
+[heading Example]
+
+    #include <boost/fusion/include/equal_to.hpp>
+    #include <boost/fusion/include/hash.hpp>
+    #include <boost/fusion/include/vector.hpp>
+    #include <boost/unordered_map.hpp>
+    
+    void foo()
+    {
+        typedef boost::fusion::vector<int, std::string, char> Vec;
+        const Vec v = {42, "Hello World", 't'};
+        // Compute a hash value directly.
+        std::cout << "hash_value(v) = " << boost::fusion::hash_value(v) << '\n';
+        // Or use it to create an unordered_map.
+        boost::unordered_map<Vec, bool> map;
+        map[v] = true;
+        assert(map.size() == 1 && map.count(v) == 1);
+    }
+
+[heading Example]
+
+    #include <boost/fusion/include/define_struct.hpp>
+    #include <boost/fusion/include/equal_to.hpp>
+    #include <boost/fusion/include/hash.hpp>
+    #include <boost/unordered_set.hpp>
+    
+    // We would like to define a struct that we can form unordered_sets of.
+    BOOST_FUSION_DEFINE_STRUCT(
+        (demo), Key,
+        (bool, b)
+        (std::string, s)
+        (int, i)
+    )
+    
+    namespace demo {
+        // Make operator== and hash_value ADL accessible.
+        using boost::fusion::operator==;
+        using boost::fusion::hash_value;
+        typedef boost::unordered_set<demo::Key> Set;
+    }
+    
+    void foo()
+    {
+        demo::Set set;
+        demo::Key key;
+        assert(set.count(key) == 0);
+    }
+
+[endsect]
+
 [endsect]
 
 [endsect]

include/boost/fusion/include/hash.hpp

@@ -0,0 +1,12 @@
+/*=============================================================================
+    Copyright (c) 2014 Christoph Weiss
+
+    Distributed under the Boost Software License, Version 1.0. (See accompanying
+    file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+==============================================================================*/
+#if !defined(FUSION_INCLUDE_HASH)
+#define FUSION_INCLUDE_HASH
+
+#include <boost/fusion/sequence/hash.hpp>
+
+#endif

include/boost/fusion/sequence/hash.hpp

@@ -0,0 +1,42 @@
+/*=============================================================================
+    Copyright (c) 2014 Christoph Weiss
+
+    Distributed under the Boost Software License, Version 1.0. (See accompanying
+    file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+==============================================================================*/
+#if !defined(FUSION_HASH_23072014_1017)
+#define FUSION_HASH_23072014_1017
+
+#include <boost/functional/hash.hpp>
+#include <boost/fusion/algorithm/iteration/fold.hpp>
+#include <boost/fusion/support/is_sequence.hpp>
+#include <boost/utility/enable_if.hpp>
+
+namespace boost { namespace fusion
+{
+	namespace hashing
+	{
+		struct hash_combine_fold
+		{
+			typedef std::size_t result_type;
+			template<typename T>
+			inline std::size_t operator()(std::size_t seed, T const& v)
+			{
+				boost::hash_combine(seed, v);
+				return seed;
+			}
+		};
+
+		template <typename Seq>
+		inline typename
+		boost::enable_if<traits::is_sequence<Seq>, std::size_t>::type
+		hash_value(Seq const& seq)
+		{
+			return fold(seq, 0, hash_combine_fold());
+		}
+	}
+
+	using hashing::hash_value;
+}}
+
+#endif

test/Jamfile

@@ -63,6 +63,7 @@ project
     [ run sequence/boost_tuple.cpp :  :  :  : ]
     [ run sequence/cons.cpp :  :  :  : ]
     [ run sequence/filter_view.cpp :  :  :  : ]
+    [ run sequence/hash.cpp :  :  :  : ]
     [ run sequence/io.cpp :  :  :  : ]
     [ run sequence/iterator_range.cpp :  :  :  : ]
     [ run sequence/joint_view.cpp :  :  :  : ]
@@ -70,6 +71,7 @@ project
     [ run sequence/list_construction.cpp :  :  :  : ]
     [ run sequence/list_copy.cpp :  :  :  : ]
     [ run sequence/list_iterator.cpp :  :  :  : ]
+    [ run sequence/list_hash.cpp :  :  :  : ]
     [ run sequence/list_make.cpp :  :  :  : ]
     [ run sequence/list_misc.cpp :  :  :  : ]
     [ run sequence/list_mutate.cpp :  :  :  : ]
@@ -79,6 +81,7 @@ project
     [ run sequence/deque_construction.cpp :  :  :  : ]
     [ run sequence/deque_copy.cpp :  :  :  : ]
     [ run sequence/deque_iterator.cpp :  :  :  : ]
+    [ run sequence/deque_hash.cpp :  :  :  : ]
     [ run sequence/deque_make.cpp :  :  :  : ]
     [ run sequence/deque_misc.cpp :  :  :  : ]
     [ run sequence/deque_move.cpp :  :  :  : ]
@@ -112,6 +115,7 @@ project
     [ run sequence/tuple_make.cpp :  :  :  : ]
     [ run sequence/tuple_misc.cpp :  :  :  : ]
     [ run sequence/tuple_mutate.cpp :  :  :  : ]
+    [ run sequence/tuple_hash.cpp :  :  :  : ]
     [ run sequence/tuple_tie.cpp :  :  :  : ]
     [ run sequence/tr1_tuple_auto_conv.cpp :  :  :  : ]
     [ run sequence/transform_view.cpp :  :  :  : ]
@@ -124,6 +128,7 @@ project
     [ run sequence/vector_move.cpp :  :  :  : ]
     [ run sequence/vector_mutate.cpp :  :  :  : ]
     [ run sequence/vector_n.cpp :  :  :  : ]
+    [ run sequence/vector_hash.cpp :  :  :  : ]
     [ run sequence/vector_tie.cpp :  :  :  : ]
     [ run sequence/vector_value_at.cpp :  :  :  : ]
     [ run sequence/zip_view.cpp : : : : ]

test/sequence/deque_hash.cpp

@@ -0,0 +1,16 @@
+/*=============================================================================
+    Copyright (c) 2014 Christoph Weiss
+
+    Distributed under the Boost Software License, Version 1.0. (See accompanying 
+    file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+==============================================================================*/
+#include <boost/fusion/container/deque/deque.hpp>
+
+#define FUSION_SEQUENCE deque
+#include "hash.hpp"
+
+int main()
+{
+    hash_test();
+    return boost::report_errors();
+}

test/sequence/hash.cpp

@@ -0,0 +1,58 @@
+/*=============================================================================
+    Copyright (c) 2014 Christoph Weiss
+
+    Distributed under the Boost Software License, Version 1.0. (See accompanying 
+    file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+==============================================================================*/
+
+#include <string>
+
+#include <boost/detail/lightweight_test.hpp>
+#include <boost/fusion/include/adapt_struct.hpp>
+#include <boost/fusion/sequence/hash.hpp>
+
+struct test_struct
+{
+	test_struct(bool bb, int ii, char cc, std::string const& ss) :
+		b(bb),
+		i(ii),
+		c(cc),
+		s(ss) {}
+
+	bool b;
+	int i;
+	char c;
+	std::string s;
+};
+
+BOOST_FUSION_ADAPT_STRUCT(
+	test_struct,
+	(bool, b)
+	(int, i)
+	(char, c)
+	(std::string, s)
+)
+
+int main()
+{
+	using boost::fusion::hash_value;
+
+	const test_struct a0(false, 1, 'c', "Hello Nurse"),
+		a1(false, 1, 'c', "Hello Nurse"),
+		b(true, 1, 'c', "Hello Nurse"),
+		c(false, 0, 'c', "Hello Nurse"),
+		d(false, 1, 'd', "Hello Nurse"),
+		e(false, 1, 'c', "Hello World");
+
+	BOOST_TEST(hash_value(a0) == hash_value(a1));
+	BOOST_TEST(hash_value(a0) != hash_value(b));
+	BOOST_TEST(hash_value(a0) != hash_value(c));
+	BOOST_TEST(hash_value(a0) != hash_value(d));
+	BOOST_TEST(hash_value(a0) != hash_value(e));
+	BOOST_TEST(hash_value(b) != hash_value(c));
+	BOOST_TEST(hash_value(b) != hash_value(d));
+	BOOST_TEST(hash_value(b) != hash_value(d));
+	BOOST_TEST(hash_value(c) != hash_value(d));
+	BOOST_TEST(hash_value(c) != hash_value(e));
+	BOOST_TEST(hash_value(d) != hash_value(e));
+}

test/sequence/hash.hpp

@@ -0,0 +1,34 @@
+/*=============================================================================
+    Copyright (c) 2014 Christoph Weiss
+
+    Distributed under the Boost Software License, Version 1.0. (See accompanying 
+    file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+==============================================================================*/
+#include <string>
+#include <utility>
+
+#include <boost/detail/lightweight_test.hpp>
+#include <boost/fusion/sequence/hash.hpp>
+#include <boost/functional/hash.hpp>
+
+void
+hash_test()
+{
+    using namespace boost::fusion;
+
+    const FUSION_SEQUENCE<int, char, bool, std::string> v0(42, 'x', false, "Aurea prima");
+    const FUSION_SEQUENCE<int, char, bool, std::string> v1(42, 'x', false, "Aurea prima");
+    BOOST_TEST(hash_value(v0) == hash_value(v1));
+    
+    const FUSION_SEQUENCE<int, char, bool, std::string> w(41, 'x', false, "Aurea prima");
+    BOOST_TEST(hash_value(w) != hash_value(v0));
+    
+    const FUSION_SEQUENCE<int, char, bool, std::string> x(42, 'y', false, "Aurea prima");
+    BOOST_TEST(hash_value(x) != hash_value(v0));
+    
+    const FUSION_SEQUENCE<int, char, bool, std::string> y(42, 'x', true, "Aurea prima");
+    BOOST_TEST(hash_value(y) != hash_value(v0));
+    
+    const FUSION_SEQUENCE<int, char, bool, std::string> z(42, 'x', false, "quae vindice nullo");
+    BOOST_TEST(hash_value(z) != hash_value(v0));
+}

test/sequence/list_hash.cpp

@@ -0,0 +1,16 @@
+/*=============================================================================
+    Copyright (c) 2014 Christoph Weiss
+
+    Distributed under the Boost Software License, Version 1.0. (See accompanying 
+    file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+==============================================================================*/
+#include <boost/fusion/container/list/list.hpp>
+
+#define FUSION_SEQUENCE list
+#include "hash.hpp"
+
+int main()
+{
+    hash_test();
+    return boost::report_errors();
+}

test/sequence/tuple_hash.cpp

@@ -0,0 +1,16 @@
+/*=============================================================================
+    Copyright (c) 2014 Christoph Weiss
+
+    Distributed under the Boost Software License, Version 1.0. (See accompanying 
+    file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+==============================================================================*/
+#include <boost/fusion/tuple/tuple.hpp>
+
+#define FUSION_SEQUENCE tuple
+#include "hash.hpp"
+
+int main()
+{
+    hash_test();
+    return boost::report_errors();
+}

test/sequence/vector_hash.cpp

@@ -0,0 +1,16 @@
+/*=============================================================================
+    Copyright (c) 2014 Christoph Weiss
+
+    Distributed under the Boost Software License, Version 1.0. (See accompanying 
+    file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+==============================================================================*/
+#include <boost/fusion/container/vector/vector.hpp>
+
+#define FUSION_SEQUENCE vector 
+#include "hash.hpp"
+
+int main()
+{
+    hash_test();
+    return boost::report_errors();
+}