From a0a6fa061678629599db8fbd4da9a4a516f393b6 Mon Sep 17 00:00:00 2001
From: Peter Dimov <pdimov@gmail.com>
Date: Sun, 17 Oct 2021 02:03:50 +0300
Subject: [PATCH] Move std::complex support to hash.hpp

---
 include/boost/container_hash/extensions.hpp | 13 ---------
 include/boost/container_hash/hash.hpp       | 14 ++++++++++
 test/hash_complex_test.cpp                  | 31 ++++++++++++++++++---
 3 files changed, 41 insertions(+), 17 deletions(-)

diff --git a/include/boost/container_hash/extensions.hpp b/include/boost/container_hash/extensions.hpp
index fa4d4f8..3636060 100644
--- a/include/boost/container_hash/extensions.hpp
+++ b/include/boost/container_hash/extensions.hpp
@@ -21,7 +21,6 @@
 #include <boost/container_hash/hash.hpp>
 #include <boost/core/enable_if.hpp>
 #include <boost/static_assert.hpp>
-#include <complex>
 
 #if !defined(BOOST_NO_CXX11_HDR_TUPLE)
 # include <tuple>
@@ -36,9 +35,6 @@ namespace boost
     template <class A, class B>
     std::size_t hash_value(std::pair<A, B> const&);
 
-    template <class T>
-    std::size_t hash_value(std::complex<T> const&);
-
     template <class A, class B>
     std::size_t hash_value(std::pair<A, B> const& v)
     {
@@ -48,15 +44,6 @@ namespace boost
         return seed;
     }
 
-    template <class T>
-    std::size_t hash_value(std::complex<T> const& v)
-    {
-        boost::hash<T> hasher;
-        std::size_t seed = hasher(v.imag());
-        seed ^= hasher(v.real()) + (seed<<6) + (seed>>2);
-        return seed;
-    }
-
 #if !defined(BOOST_NO_CXX11_HDR_TUPLE)
     namespace hash_detail {
         template <std::size_t I, typename T>
diff --git a/include/boost/container_hash/hash.hpp b/include/boost/container_hash/hash.hpp
index ae89a05..d9e62cf 100644
--- a/include/boost/container_hash/hash.hpp
+++ b/include/boost/container_hash/hash.hpp
@@ -30,6 +30,7 @@
 #include <boost/cstdint.hpp>
 #include <iterator>
 #include <string>
+#include <complex>
 #include <climits>
 
 #if !defined(BOOST_NO_CXX11_HDR_TYPEINDEX)
@@ -153,6 +154,19 @@ namespace boost
         return boost::hash_range( x, x + N );
     }
 
+    // complex
+
+    template <class T>
+    std::size_t hash_value( std::complex<T> const& v )
+    {
+        std::size_t seed = 0;
+
+        boost::hash_combine( seed, v.real() );
+        boost::hash_combine( seed, v.imag() );
+
+        return seed;
+    }
+
     // ranges (list, set, deque...)
 
     template <typename T>
diff --git a/test/hash_complex_test.cpp b/test/hash_complex_test.cpp
index 5afd7ac..2dbad10 100644
--- a/test/hash_complex_test.cpp
+++ b/test/hash_complex_test.cpp
@@ -39,9 +39,10 @@ int main() {}
 #pragma GCC diagnostic ignored "-Wfloat-equal"
 #endif
 
+#include <boost/limits.hpp>
 #include <complex>
 #include <sstream>
-#include <boost/limits.hpp>
+#include <set>
 
 template <class T>
 void generic_complex_tests(std::complex<T> v)
@@ -52,11 +53,11 @@ void generic_complex_tests(std::complex<T> v)
 
     BOOST_HASH_TEST_NAMESPACE::hash<T> real_hasher;
     T real = v.real();
-    T imag = v.imag();
+    // T imag = v.imag();
 
-    BOOST_TEST(real_hasher(real) == complex_hasher(std::complex<T>(real)));
+    // BOOST_TEST(real_hasher(real) == complex_hasher(std::complex<T>(real)));
 
-    if(imag != 0 && real_hasher(real) == complex_hasher(v)) {
+    if(real_hasher(real) == complex_hasher(v)) {
         std::ostringstream os;
         os<<"real_hasher("<<real<<") == complex_hasher("
             <<v.real()<<" + "<<v.imag()<<"i) == "
@@ -88,6 +89,23 @@ void complex_integral_tests(Integer*)
     generic_complex_tests(complex(Integer(-543),Integer(763)));
 }
 
+template<class T> void complex_grid_test()
+{
+    short const N = 16;
+
+    std::set<std::size_t> hashes;
+
+    for( short i = 0; i < N; ++i )
+    {
+        for( short j = 0; j < N; ++j )
+        {
+            hashes.insert( boost::hash< std::complex<T> >()( std::complex<T>( i, j ) ) );
+        }
+    }
+
+    BOOST_TEST_EQ( hashes.size(), N * N );
+}
+
 int main()
 {
     // I've comments out the short and unsigned short tests
@@ -104,6 +122,11 @@ int main()
     complex_integral_tests((unsigned int*) 0);
     complex_integral_tests((unsigned long*) 0);
 
+    complex_grid_test<int>();
+    complex_grid_test<float>();
+    complex_grid_test<double>();
+    complex_grid_test<long double>();
+
     return boost::report_errors();
 }