(re-)added move()

mikekazakov · Nov 20, 2022 · fdc096b · fdc096b
1 parent ac53823
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diff --git a/README.md b/README.md
@@ -1,7 +1,7 @@
 ![Build Status](https://github.com/mikekazakov/pstld/actions/workflows/build.yml/badge.svg)
 
 # pstld
-Experimental implementation of ParallelSTL on top of GCD aka libdispatch
+Experimental implementation of ParallelSTL on top of Grand Central Dispatch aka libdispatch
 
 The purpose of this library is to provide a drop-in implementation of C++ parallel algorithms for the Apple platforms.
 Xcode comes with no parallel algorithms in libc++, so this library aims to fill the gap.
@@ -84,7 +84,7 @@ The library is not complete, this table shows which algorithms are currently ava
 25.7.1 | std::copy | ✅ | ✅
 | | std::copy_n | ✅ | ✅
 | | std::copy_if | ✅ | ❌
-25.7.2 | std::move | ✅ | ❌
+25.7.2 | std::move | ✅ | ✅
 25.7.3 | std::swap_ranges | ✅ | ✅
 25.7.4 | std::transform | ✅ | ✅
 25.7.5 | std::replace | ✅ | ✅
@@ -173,6 +173,7 @@ mismatch                       0.30       0.67       0.68       1.10       1.10
 equal                          0.50       0.80       0.76       1.23       1.23       1.27 
 search                         0.50       0.83       1.61       4.22       4.39       4.78 
 copy                           0.29       0.74       0.37       0.73       0.96       1.87 
+move                           0.18       1.09       2.22       1.15       1.11       1.76 
 swap_ranges                    0.35       0.75       0.70       0.80       0.99       1.69 
 transform                      0.14       0.84       0.44       0.76       0.84       2.30 
 replace                        0.12       0.31       0.32       0.85       1.05       1.83 

diff --git a/benchmark/benchmark.cpp b/benchmark/benchmark.cpp
@@ -208,6 +208,24 @@ struct copy { // 25.7.1
     }
 };
 
+template <class ExPo>
+struct move { // 25.7.2
+    auto operator()(size_t size)
+    {
+        std::vector<std::string> v1;
+        std::vector<std::string> v2;
+        return measure(
+            [&] {
+                v1 = std::vector<std::string>(size, "Small string");
+                v2 = std::vector<std::string>(size);
+            },
+            [&] {
+                std::move(ExPo{}, v1.begin(), v1.end(), v2.begin());
+                noopt(v2);
+            });
+    }
+};
+
 template <class ExPo>
 struct swap_ranges { // 25.7.3
     auto operator()(size_t size)
@@ -691,6 +709,7 @@ int main()
     results.emplace_back(record<benchmarks::equal>());
     results.emplace_back(record<benchmarks::search>());
     results.emplace_back(record<benchmarks::copy>());
+    results.emplace_back(record<benchmarks::move>());
     results.emplace_back(record<benchmarks::swap_ranges>());
     results.emplace_back(record<benchmarks::transform>());
     results.emplace_back(record<benchmarks::replace>());

diff --git a/pstld/pstld.h b/pstld/pstld.h
@@ -3354,6 +3354,48 @@ FwdIt destroy_n(FwdIt first, Size count) noexcept
     return std::destroy_n(first, count);
 }
 
+//--------------------------------------------------------------------------------------------------
+// move
+//--------------------------------------------------------------------------------------------------
+
+namespace internal {
+
+template <class It1, class It2>
+struct Move : Dispatchable<Move<It1, It2>> {
+    Partition<It1> m_partition1;
+    Partition<It2> m_partition2;
+
+    Move(size_t count, size_t chunks, It1 first1, It2 first2)
+        : m_partition1(first1, count, chunks), m_partition2(first2, count, chunks)
+    {
+    }
+
+    void run(size_t ind) noexcept
+    {
+        auto p1 = m_partition1.at(ind);
+        auto p2 = m_partition2.at(ind);
+        std::move(p1.first, p1.last, p2.first);
+    }
+};
+
+} // namespace internal
+
+template <class FwdIt1, class FwdIt2>
+FwdIt2 move(FwdIt1 first1, FwdIt1 last1, FwdIt2 first2) noexcept
+{
+    const auto count = std::distance(first1, last1);
+    const auto chunks = internal::work_chunks_min_fraction_1(count);
+    if( chunks > 1 ) {
+        try {
+            internal::Move<FwdIt1, FwdIt2> op{static_cast<size_t>(count), chunks, first1, first2};
+            op.dispatch_apply(chunks);
+            return op.m_partition2.end();
+        } catch( const internal::parallelism_exception & ) {
+        }
+    }
+    return std::move(first1, last1, first2);
+}
+
 #if defined(PSTLD_INTERNAL_ARC)
 } // inline namespace arc
 #endif
@@ -3854,7 +3896,10 @@ template <class ExPo, class It1, class It2>
 execution::__enable_if_execution_policy<ExPo, It2>
 move(ExPo &&, It1 first, It1 last, It2 result) noexcept
 {
-    return ::std::move(first, last, result); // stub only
+    if constexpr( execution::__pstld_enabled<ExPo> )
+        return ::pstld::move(first, last, result);
+    else
+        return ::std::move(first, last, result);
 }
 
 // 25.7.3 - swap_ranges ////////////////////////////////////////////////////////////////////////////