Merge commit 'efcea3a80da7c4479d5fe168435ecc9fd06bdc72' as 'subprojects/boost-sqlite'

1 files changed, 202 insertions, 0 deletions

diff --git a/subprojects/boost-sqlite/example/describe.cpp b/subprojects/boost-sqlite/example/describe.cpp
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+//
+// Copyright (c) 2022 Klemens Morgenstern (klemens.morgenstern@gmx.net)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#include <boost/sqlite.hpp>
+#include <boost/unordered_map.hpp>
+#include <boost/describe.hpp>
+#include <boost/variant2/variant.hpp>
+
+#include <iomanip>
+#include <iostream>
+
+// This example shows how a virtual table can be created using boost.describe
+
+using namespace boost;
+
+// add more conversions here if you need more types in the described struct
+void assign_value(std::int64_t & res, sqlite::value val) { res = val.get_int();}
+void assign_value(std::string & res, sqlite::value val) { res = val.get_text();}
+
+template<typename T>
+struct describe_cursor final : sqlite::vtab::cursor<>
+{
+  describe_cursor(
+      typename boost::unordered_map<sqlite3_int64, T>::const_iterator itr,
+      typename boost::unordered_map<sqlite3_int64, T>::const_iterator end
+      ) : itr(itr), end(end)
+  {
+  }
+
+  typename boost::unordered_map<sqlite3_int64, T>::const_iterator itr, end;
+  constexpr static std::size_t column_count = mp11::mp_size<describe::describe_members<T, describe::mod_any_access>>::value;
+
+  sqlite::result<void> next() {itr++; return {};}
+  sqlite::result<sqlite3_int64> row_id() {return itr->first;}
+
+  void column(sqlite::context<> ctx, int i, bool /* no_change */)
+  {
+    mp11::mp_with_index<column_count>(
+        i, [&](auto Idx)
+        {
+          using type = mp11::mp_at_c<describe::describe_members<T, describe::mod_public>, Idx>;
+          ctx.set_result(itr->second.*type::pointer);
+        });
+  }
+
+  bool eof() noexcept {return itr == end;}
+};
+
+template<typename T>
+struct describe_table final :
+    sqlite::vtab::table<describe_cursor<T>>,
+    sqlite::vtab::modifiable
+{
+  boost::unordered_map<sqlite3_int64, T> &data;
+  describe_table(boost::unordered_map<sqlite3_int64, T> &data) : data(data) {}
+
+  std::string decl;
+  const char * declaration()
+  {
+    if (!decl.empty())
+      return decl.c_str();
+    mp11::mp_for_each<describe::describe_members<T, describe::mod_public>>(
+        [&](auto elem)
+        {
+            if (decl.empty())
+              decl += "create table x(";
+            else
+              decl += ", ";
+
+            decl += elem.name;
+        });
+    decl += ");";
+    return decl.c_str();
+  }
+
+
+  sqlite3_int64 last_index = 0;
+
+  sqlite::result<describe_cursor<T>> open()
+  {
+    return describe_cursor<T>{data.begin(), data.end()};
+  }
+
+  sqlite::result<void> delete_(sqlite::value key)
+  {
+    data.erase(key.get_int());
+    return {};
+  }
+  sqlite::result<sqlite_int64> insert(sqlite::value key, span<sqlite::value> values, int /*on_conflict*/)
+  {
+    T res;
+    sqlite_int64 id = key.is_null() ? last_index++ : key.get_int();
+    auto vtr = values.begin();
+    mp11::mp_for_each<describe::describe_members<T, describe::mod_public>>(
+        [&](auto elem)
+        {
+          assign_value(res.*elem.pointer , *vtr);
+          vtr++;
+        });
+
+    auto itr = data.emplace(id, std::move(res)).first;
+    return itr->first;
+
+  }
+  sqlite::result<sqlite_int64> update(sqlite::value old_key, sqlite::value new_key,
+                      span<sqlite::value> values, int /*on_conflict*/)
+  {
+    if (new_key.get_int() != old_key.get_int())
+      data.erase(old_key.get_int());
+    auto & res = data[new_key.get_int()];
+
+    auto vtr = values.begin();
+    mp11::mp_for_each<describe::describe_members<T, describe::mod_public>>(
+        [&](auto elem)
+        {
+          assign_value(res.*elem.pointer , *vtr);
+          vtr++;
+        });
+    return 0u;
+  }
+};
+
+template<typename T>
+struct describe_module final : sqlite::vtab::eponymous_module<describe_table<T>>
+{
+  boost::unordered_map<sqlite3_int64, T> data;
+  constexpr static std::size_t column_count = mp11::mp_size<describe::describe_members<T, describe::mod_any_access>>::value;
+  sqlite::result<describe_table<T>> connect(sqlite::connection ,
+                                            int, const char * const [])
+  {
+    return describe_table<T>{data};
+  }
+};
+
+
+void print_table(std::ostream & str, sqlite::resultset res)
+{
+  for (auto i = 0u; i < res.column_count(); i ++)
+    str << "| " << std::setfill(' ') << std::setw(15) << res.column_name(i) << " ";
+
+  str << "|\n";
+
+  for (auto i = 0u; i < res.column_count(); i ++)
+    str << "|-----------------";
+  str << "|\n";
+
+  for (auto && r : res)
+  {
+    for (auto i = 0u; i < res.column_count(); i ++)
+      str << "| " << std::setfill(' ') << std::setw(15) << r.at(i).get_text() << " ";
+
+    str << "|\n" ;
+  }
+  str << std::endl;
+}
+
+
+struct boost_library
+{
+  std::string name;
+  std::int64_t first_released;
+  std::int64_t standard;
+};
+
+BOOST_DESCRIBE_STRUCT(boost_library, (), (name, first_released, standard));
+
+
+int main (int /*argc*/, char * /*argv*/[])
+{
+  sqlite::connection conn{":memory:"};
+  auto & md = sqlite::create_module(conn, "boost_libraries", describe_module<boost_library>());
+
+  {
+    auto p = conn.prepare("insert into boost_libraries (name, first_released, standard) values ($name, $version, $std);");
+    p.execute({{"name", "process"},         {"version", 64}, {"std", 11}});
+    p.execute({{"name", "asio"},            {"version", 35}, {"std", 98}});
+    p.execute({{"name", "bimap"},           {"version", 35}, {"std", 98}});
+    p.execute({{"name", "circular_buffer"}, {"version", 35}, {"std", 98}});
+    p.execute({{"name", "mpi"},             {"version", 35}, {"std", 98}});
+    p.execute({{"name", "beast"},           {"version", 66}, {"std", 11}});
+    p.execute({{"name", "describe"},        {"version", 77}, {"std", 14}});
+  }
+
+
+  print_table(std::cout, conn.query("select * from boost_libraries;"));
+
+  // same as conn.execute("update boost_libraries set standard = 11 where standard = 98;");
+  for (auto & p : md.data)
+    if (p.second.standard == 98)
+      p.second.standard = 11;
+
+  print_table(std::cout, conn.query("select * from boost_libraries;"));
+
+  conn.prepare("delete from boost_libraries where name = ?").execute({"mpi"});
+  print_table(std::cout, conn.query("select * from boost_libraries;"));
+
+  return 0;
+}