include/o3tl/concepts.hxx | 7 +++
include/o3tl/hash_combine.hxx | 15 +++-----
o3tl/CppunitTest_o3tl_tests.mk | 1
o3tl/qa/test-hash_combine.cxx | 73 +++++++++++++++++++++++++++++++++++++++++
4 files changed, 88 insertions(+), 8 deletions(-)
New commits:
commit 794e86b99dae26358b9837645a5db95073dfccd4
Author: Tomaž Vajngerl <tomaz.vajng...@collabora.co.uk>
AuthorDate: Thu Feb 27 10:49:44 2025 +0900
Commit: Tomaž Vajngerl <qui...@gmail.com>
CommitDate: Mon Mar 3 09:43:18 2025 +0100
o3tl: Add concepts for 32/64 bit types, use in hash_combine
This simplifies determining what the byte size of the template type
is, so we can write a specific implementation for 32 and 64 bit
seeds for hash_combine.
Change-Id: Icd68e4618151957ecc00585dd521adf11fe3931a
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/182266
Tested-by: Jenkins
Reviewed-by: Tomaž Vajngerl <qui...@gmail.com>
diff --git a/include/o3tl/concepts.hxx b/include/o3tl/concepts.hxx
index f47aef5f256d..07ddcdc459ea 100644
--- a/include/o3tl/concepts.hxx
+++ b/include/o3tl/concepts.hxx
@@ -45,4 +45,11 @@ template <typename T> concept floating_point =
std::is_floating_point_v<T>;
#endif
+// Common concepts
+namespace o3tl
+{
+template <typename T> concept type_32_bit = sizeof(T) == 4;
+template <typename T> concept type_64_bit = sizeof(T) == 8;
+}
+
/* vim:set shiftwidth=4 softtabstop=4 expandtab cinoptions=b1,g0,N-s
cinkeys+=0=break: */
diff --git a/include/o3tl/hash_combine.hxx b/include/o3tl/hash_combine.hxx
index 48e14262228e..80b2a7fa0825 100644
--- a/include/o3tl/hash_combine.hxx
+++ b/include/o3tl/hash_combine.hxx
@@ -12,11 +12,12 @@
#include <cstddef>
#include <functional>
#include <type_traits>
+#include <o3tl/concepts.hxx>
namespace o3tl
{
-template <typename T, typename N>
-inline std::enable_if_t<(sizeof(N) == 4)> hash_combine(N& nSeed, T const*
pValue, size_t nCount)
+template <typename T, type_32_bit N>
+inline void hash_combine(N& nSeed, T const* pValue, size_t nCount)
{
static_assert(sizeof(nSeed) == 4);
for (size_t i = 0; i < nCount; ++i)
@@ -26,15 +27,14 @@ inline std::enable_if_t<(sizeof(N) == 4)> hash_combine(N&
nSeed, T const* pValue
}
}
-template <typename T, typename N>
-inline std::enable_if_t<(sizeof(N) == 4)> hash_combine(N& nSeed, T const&
nValue)
+template <typename T, type_32_bit N> inline void hash_combine(N& nSeed, T
const& nValue)
{
static_assert(sizeof(nSeed) == 4);
nSeed ^= std::hash<T>{}(nValue) + 0x9E3779B9u + (nSeed << 6) + (nSeed >>
2);
}
-template <typename T, typename N>
-inline std::enable_if_t<(sizeof(N) == 8)> hash_combine(N& nSeed, T const*
pValue, size_t nCount)
+template <typename T, type_64_bit N>
+inline void hash_combine(N& nSeed, T const* pValue, size_t nCount)
{
static_assert(sizeof(nSeed) == 8);
for (size_t i = 0; i < nCount; ++i)
@@ -44,8 +44,7 @@ inline std::enable_if_t<(sizeof(N) == 8)> hash_combine(N&
nSeed, T const* pValue
}
}
-template <typename T, typename N>
-inline std::enable_if_t<(sizeof(N) == 8)> hash_combine(N& nSeed, T const&
nValue)
+template <typename T, type_64_bit N> inline void hash_combine(N& nSeed, T
const& nValue)
{
static_assert(sizeof(nSeed) == 8);
nSeed ^= std::hash<T>{}(nValue) + 0x9E3779B97F4A7C15llu + (nSeed << 12) +
(nSeed >> 4);
diff --git a/o3tl/CppunitTest_o3tl_tests.mk b/o3tl/CppunitTest_o3tl_tests.mk
index 1715659ffbee..01f6e410a1b2 100644
--- a/o3tl/CppunitTest_o3tl_tests.mk
+++ b/o3tl/CppunitTest_o3tl_tests.mk
@@ -39,6 +39,7 @@ $(eval $(call
gb_CppunitTest_add_exception_objects,o3tl_tests,\
o3tl/qa/test-typed_flags \
o3tl/qa/test-unit_conversion \
o3tl/qa/test-vector_pool \
+ o3tl/qa/test-hash_combine \
))
# vim: set noet sw=4:
diff --git a/o3tl/qa/test-hash_combine.cxx b/o3tl/qa/test-hash_combine.cxx
new file mode 100644
index 000000000000..0bf72036ed10
--- /dev/null
+++ b/o3tl/qa/test-hash_combine.cxx
@@ -0,0 +1,73 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/*
+ * This file is part of the LibreOffice project.
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ *
+ */
+
+#include <cppunit/TestAssert.h>
+#include <cppunit/TestFixture.h>
+#include <cppunit/extensions/HelperMacros.h>
+
+#include <sal/types.h>
+#include <rtl/ustring.hxx>
+#include <o3tl/hash_combine.hxx>
+
+namespace
+{
+struct TestStruct
+{
+};
+
+class HashCombineTest : public CppUnit::TestFixture
+{
+public:
+ void testBaseUsage()
+ {
+ TestStruct objectA;
+ TestStruct objectB;
+
+ {
+ sal_uInt64 seed(0);
+ o3tl::hash_combine(seed, OUString("Hmm-.."));
+ o3tl::hash_combine(seed, 24);
+ o3tl::hash_combine(seed, 42u);
+ o3tl::hash_combine(seed, 5.1);
+ o3tl::hash_combine(seed, &objectA);
+ o3tl::hash_combine(seed, &objectB);
+ CPPUNIT_ASSERT(seed != sal_uInt64(0));
+
+ static_assert(sizeof(seed) == 8);
+ }
+
+ {
+ sal_uInt32 seed(0);
+ o3tl::hash_combine(seed, OUString("Hmm-.."));
+ o3tl::hash_combine(seed, 24);
+ o3tl::hash_combine(seed, 42u);
+ o3tl::hash_combine(seed, 5.1);
+ o3tl::hash_combine(seed, &objectA);
+ o3tl::hash_combine(seed, &objectB);
+ CPPUNIT_ASSERT(seed != sal_uInt32(0));
+
+ static_assert(sizeof(seed) == 4);
+ }
+
+ // No assert of the actual value - we just check this compiles and
runs. Hash algorithm is probably
+ // also implementation specific.
+
+ // Using sal_uInt16 for seed doesn't compile as there is not
compatible hash_combine override for seed that is 16 bit.
+ }
+
+ CPPUNIT_TEST_SUITE(HashCombineTest);
+ CPPUNIT_TEST(testBaseUsage);
+ CPPUNIT_TEST_SUITE_END();
+};
+}
+
+CPPUNIT_TEST_SUITE_REGISTRATION(HashCombineTest);
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */
