From ec197d4bcef3da3965d2fbf515b105383965993a Mon Sep 17 00:00:00 2001
From: Vinnie Falco <vinnie.falco@gmail.com>
Date: Fri, 27 Sep 2019 15:06:30 -0700
Subject: [PATCH] Support pilfer construction

---
 bench/bench.cpp                    | 44 +++++++++++++++++-------------
 include/boost/json/array.hpp       |  4 +++
 include/boost/json/impl/array.ipp  | 15 ++++++++--
 include/boost/json/impl/object.ipp |  8 ++++++
 include/boost/json/impl/value.ipp  | 42 ++++++++++++++++++++++++++++
 include/boost/json/object.hpp      |  4 +++
 include/boost/json/value.hpp       |  5 ++++
 7 files changed, 101 insertions(+), 21 deletions(-)

diff --git a/bench/bench.cpp b/bench/bench.cpp
index aa920e43..060cfd43 100644
--- a/bench/bench.cpp
+++ b/bench/bench.cpp
@@ -50,7 +50,14 @@ public:
 
 class boost_impl : public any_impl
 {
+    json::parser* p_;
+
 public:
+    boost_impl()
+        : p_(new json::parser)
+    {
+    }
+
     boost::string_view
     name() const noexcept override
     {
@@ -61,9 +68,8 @@ public:
     parse(
         boost::string_view s) override
     {
-        json::parser p;
         boost::system::error_code ec;
-        p.write({s.data(), s.size()}, ec);
+        p_->write({s.data(), s.size()}, ec);
     }
 };
 
@@ -337,23 +343,20 @@ benchParse(
     boost::string_view doc,
     any_impl& impl)
 {
-    for(int i = 0; i < 10; ++i)
-    {
-        using clock_type = std::chrono::steady_clock;
-        auto const when = clock_type::now();
-        dout << impl.name();
-        impl.parse(doc);
-        auto const elapsed =
-            std::chrono::duration_cast<
-                std::chrono::milliseconds>(
-                    clock_type::now() - when);
-        dout <<
-            " parse " <<
-            doc.size() << " bytes"
-            " in " << elapsed.count() << "ms" <<
-            "\n";
-        dout.flush();
-    }
+    using clock_type = std::chrono::steady_clock;
+    auto const when = clock_type::now();
+    dout << impl.name();
+    impl.parse(doc);
+    auto const elapsed =
+        std::chrono::duration_cast<
+            std::chrono::milliseconds>(
+                clock_type::now() - when);
+    dout <<
+        " parse " <<
+        doc.size() << " bytes"
+        " in " << elapsed.count() << "ms" <<
+        "\n";
+    dout.flush();
 }
 
 int
@@ -368,15 +371,18 @@ main(int argc, char** argv)
         f.max_depth(i);
         auto const doc = f.make_document();
 #if 0
+        for(int j = 0; j < 10; ++j)
         {
             rapidjson_impl impl;
             benchParse(doc, impl);
         }
+        for(int j = 0; j < 10; ++j)
         {
             nlohmann_impl impl;
             benchParse(doc, impl);
         }
 #endif
+        for(int j = 0; j < 10; ++j)
         {
             boost_impl impl;
             benchParse(doc, impl);
diff --git a/include/boost/json/array.hpp b/include/boost/json/array.hpp
index abbfc906..5cdf729a 100644
--- a/include/boost/json/array.hpp
+++ b/include/boost/json/array.hpp
@@ -13,6 +13,7 @@
 #include <boost/json/detail/config.hpp>
 #include <boost/json/allocator.hpp>
 #include <boost/json/storage.hpp>
+#include <boost/pilfer.hpp>
 #include <cstdlib>
 #include <initializer_list>
 #include <iterator>
@@ -105,6 +106,9 @@ public:
     BOOST_JSON_DECL
     array(array&& other) noexcept;
 
+    BOOST_JSON_DECL
+    array(pilfered<array> other) noexcept;
+
     BOOST_JSON_DECL
     array(
         array&& other,
diff --git a/include/boost/json/impl/array.ipp b/include/boost/json/impl/array.ipp
index a485149c..436aa8ae 100644
--- a/include/boost/json/impl/array.ipp
+++ b/include/boost/json/impl/array.ipp
@@ -13,6 +13,7 @@
 #include <boost/json/array.hpp>
 #include <boost/core/exchange.hpp>
 #include <boost/assert.hpp>
+#include <boost/pilfer.hpp>
 #include <algorithm>
 #include <cstdlib>
 #include <limits>
@@ -220,6 +221,14 @@ array(array&& other) noexcept
 {
 }
 
+array::
+array(pilfered<array> other) noexcept
+    : tab_(boost::exchange(
+        other.get().tab_, nullptr))
+    , sp_(other.get().sp_)
+{
+}
+
 array::
 array(
     array&& other,
@@ -497,10 +506,12 @@ reserve(size_type new_capacity)
     }
 
     for(size_type i = 0; i < tab_->size; ++i)
-        ::new(&tab->begin()[i]) value_type(
-            std::move(tab_->begin()[i]));
+        relocate(
+            &tab->begin()[i],
+            tab_->begin()[i]);
     tab->size = tab_->size;
     std::swap(tab, tab_);
+    tab->size = 0; // VFALCO Hack
     table::destroy(tab, sp_);
 }
 
diff --git a/include/boost/json/impl/object.ipp b/include/boost/json/impl/object.ipp
index f9bfd01b..25163e7e 100644
--- a/include/boost/json/impl/object.ipp
+++ b/include/boost/json/impl/object.ipp
@@ -327,6 +327,14 @@ object(object&& other) noexcept
 {
 }
 
+object::
+object(pilfered<object> other) noexcept
+    : sp_(std::move(other.get().sp_))
+    , tab_(boost::exchange(
+        other.get().tab_, nullptr))
+{
+}
+
 object::
 object(
     object&& other,
diff --git a/include/boost/json/impl/value.ipp b/include/boost/json/impl/value.ipp
index fd75de75..41117a69 100644
--- a/include/boost/json/impl/value.ipp
+++ b/include/boost/json/impl/value.ipp
@@ -82,6 +82,48 @@ value(value&& other) noexcept
     other.kind_ = json::kind::null;
 }
 
+value::
+value(pilfered<value> p) noexcept
+{
+    auto& other = p.get();
+    switch(other.kind_)
+    {
+    case json::kind::object:
+        ::new(&obj_) object(
+            pilfer(other.obj_));
+        break;
+
+    case json::kind::array:
+        ::new(&arr_) array(
+            std::move(other.arr_));
+        break;
+
+    case json::kind::string:
+        ::new(&str_) string(
+            std::move(other.str_));
+        break;
+
+    case json::kind::number:
+        ::new(&nat_.sp_) storage_ptr(
+            std::move(other.nat_.sp_));
+        ::new(&nat_.num_) number(
+            std::move(other.nat_.num_));
+        break;
+
+    case json::kind::boolean:
+        ::new(&nat_.sp_) storage_ptr(
+            std::move(other.nat_.sp_));
+        nat_.bool_ = other.nat_.bool_;
+        break;
+
+    case json::kind::null:
+        ::new(&nat_.sp_) storage_ptr(
+            std::move(other.nat_.sp_));
+        break;
+    }
+    kind_ = other.kind_;
+}
+
 value::
 value(
     value&& other,
diff --git a/include/boost/json/object.hpp b/include/boost/json/object.hpp
index 177abceb..f79a71e5 100644
--- a/include/boost/json/object.hpp
+++ b/include/boost/json/object.hpp
@@ -13,6 +13,7 @@
 #include <boost/json/detail/config.hpp>
 #include <boost/json/storage.hpp>
 #include <boost/utility/string_view.hpp>
+#include <boost/pilfer.hpp>
 #include <cstdlib>
 #include <initializer_list>
 #include <iterator>
@@ -139,6 +140,9 @@ public:
     BOOST_JSON_DECL
     object(object&& other) noexcept;
 
+    BOOST_JSON_DECL
+    object(pilfered<object> other) noexcept;
+
     BOOST_JSON_DECL
     object(
         object&& other,
diff --git a/include/boost/json/value.hpp b/include/boost/json/value.hpp
index 6997bcc0..19946791 100644
--- a/include/boost/json/value.hpp
+++ b/include/boost/json/value.hpp
@@ -21,6 +21,7 @@
 #include <boost/json/detail/value.hpp>
 #include <boost/type_traits/make_void.hpp>
 #include <boost/utility/string_view.hpp>
+#include <boost/pilfer.hpp>
 #include <cstdlib>
 #include <initializer_list>
 #include <iosfwd>
@@ -133,6 +134,10 @@ public:
     BOOST_JSON_DECL
     value(value&& other) noexcept;
 
+    /// Pilfer constructor
+    BOOST_JSON_DECL
+    value(pilfered<value> other) noexcept;
+
     /// Move construct a value, using the specified storage
     BOOST_JSON_DECL
     value(