commit b07a2ebe1dfe2a137800f51852d9b0a4f9c0d04b
author William A. Kennington III <wak@google.com> Tue Jan 03 18:14:40 2023 -0800
committer William A. Kennington III <wak@google.com> Thu May 25 14:59:48 2023 -0700
tree dbedfe039113154961afe2d9f372fc4f08b79f7c
parent 403cda2c32f6ea27e4ad075910eb347c4a4e4963

hash: Add support for tuples

There is now builtin support for stdplus::hash<> and
stdplus::hashMulti(...) hashing std::tuple containers.

Change-Id: I0e0983c04d54302f00c811e5de0d949accee03d7
Signed-off-by: William A. Kennington III <wak@google.com>

include/meson.build

diff --git a/include/meson.build b/include/meson.build
index 358bc32..fc304f3 100644
--- a/include/meson.build
+++ b/include/meson.build
@@ -7,6 +7,7 @@
   'stdplus/handle/copyable.hpp',
   'stdplus/handle/managed.hpp',
   'stdplus/hash.hpp',
+  'stdplus/hash/tuple.hpp',
   'stdplus/pinned.hpp',
   'stdplus/raw.hpp',
   'stdplus/signal.hpp',

include/stdplus/hash.hpp

diff --git a/include/stdplus/hash.hpp b/include/stdplus/hash.hpp
index 44cc6a6..f3aa8e6 100644
--- a/include/stdplus/hash.hpp
+++ b/include/stdplus/hash.hpp
@@ -1,5 +1,6 @@
 #pragma once
 #include <cstddef>
+#include <tuple>
 #include <utility>
 
 namespace std
@@ -65,4 +66,14 @@
 struct hash : std::hash<Key>
 {};
 
+template <typename... Ts>
+struct hash<std::tuple<Ts...>>
+{
+    constexpr std::size_t operator()(const std::tuple<Ts...>& ts) noexcept(
+        noexcept(hashMulti(std::declval<Ts>()...)))
+    {
+        return std::apply(hashMulti<Ts...>, ts);
+    }
+};
+
 } // namespace stdplus

include/stdplus/hash/tuple.hpp

diff --git a/include/stdplus/hash/tuple.hpp b/include/stdplus/hash/tuple.hpp
new file mode 100644
index 0000000..be7a45e
--- /dev/null
+++ b/include/stdplus/hash/tuple.hpp
@@ -0,0 +1,14 @@
+#pragma once
+#include <stdplus/hash.hpp>
+
+#include <tuple>
+
+template <typename... Ts>
+struct std::hash<std::tuple<Ts...>>
+{
+    constexpr auto operator()(const std::tuple<Ts...>& ts) const noexcept(
+        noexcept(stdplus::hashMulti(std::declval<std::tuple<Ts...>>())))
+    {
+        return stdplus::hashMulti(ts);
+    }
+};

src/hash/tuple.cpp

diff --git a/src/hash/tuple.cpp b/src/hash/tuple.cpp
new file mode 100644
index 0000000..1cba27e
--- /dev/null
+++ b/src/hash/tuple.cpp
@@ -0,0 +1 @@
+#include <stdplus/hash/tuple.hpp>

src/meson.build

diff --git a/src/meson.build b/src/meson.build
index c4662ad..ed994ea 100644
--- a/src/meson.build
+++ b/src/meson.build
@@ -48,6 +48,7 @@
   'handle/copyable.cpp',
   'handle/managed.cpp',
   'hash.cpp',
+  'hash/tuple.cpp',
   'pinned.cpp',
   'raw.cpp',
   'signal.cpp',

test/hash.cpp

diff --git a/test/hash.cpp b/test/hash.cpp
index 23e0e26..d9bcd48 100644
--- a/test/hash.cpp
+++ b/test/hash.cpp
@@ -1,6 +1,7 @@
 #include <stdplus/hash.hpp>
 
 #include <string>
+#include <tuple>
 
 #include <gtest/gtest.h>
 
@@ -11,7 +12,8 @@
 {
     EXPECT_EQ(0, hashMulti());
     EXPECT_EQ(2654435834, hashMulti(1, 2));
-    hashMulti(1, std::string("bacon"), nullptr);
+    std::tuple<std::string, int> t = {"s", 8};
+    hashMulti(1, std::string("bacon"), nullptr, t);
 }
 
 } // namespace stdplus

test/hash/tuple.cpp

diff --git a/test/hash/tuple.cpp b/test/hash/tuple.cpp
new file mode 100644
index 0000000..1e87df6
--- /dev/null
+++ b/test/hash/tuple.cpp
@@ -0,0 +1,16 @@
+#include <stdplus/hash/tuple.hpp>
+
+#include <string>
+
+#include <gtest/gtest.h>
+
+namespace stdplus
+{
+
+TEST(HashTuple, Basic)
+{
+    std::tuple<std::string, int> a{"bacon", 2};
+    std::hash<decltype(a)>{}(a);
+}
+
+} // namespace stdplus

test/meson.build

diff --git a/test/meson.build b/test/meson.build
index 98435bf..ab788ff 100644
--- a/test/meson.build
+++ b/test/meson.build
@@ -4,6 +4,7 @@
   'handle/copyable': [stdplus_dep, gtest_main_dep],
   'handle/managed': [stdplus_dep, gtest_main_dep],
   'hash': [stdplus_dep, gtest_main_dep],
+  'hash/tuple': [stdplus_dep, gtest_main_dep],
   'pinned': [stdplus_dep, gtest_main_dep],
   'raw': [stdplus_dep, gmock_dep, gtest_main_dep],
   'signal': [stdplus_dep, gtest_main_dep],