mirror of
https://github.com/rbock/sqlpp11.git
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239 lines
8.1 KiB
C++
239 lines
8.1 KiB
C++
/*
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* Copyright (c) 2013-2014, Roland Bock
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without modification,
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* are permitted provided that the following conditions are met:
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*
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* Redistributions of source code must retain the above copyright notice, this
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* list of conditions and the following disclaimer.
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*
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* Redistributions in binary form must reproduce the above copyright notice, this
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* list of conditions and the following disclaimer in the documentation and/or
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* other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
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* ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
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* ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#ifndef SQLPP_SELECT_H
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#define SQLPP_SELECT_H
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#include <sqlpp11/result.h>
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#include <sqlpp11/parameter_list.h>
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#include <sqlpp11/prepared_select.h>
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#include <sqlpp11/vendor/noop.h>
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#include <sqlpp11/vendor/select_flag_list.h>
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#include <sqlpp11/vendor/select_column_list.h>
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#include <sqlpp11/vendor/from.h>
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#include <sqlpp11/vendor/extra_tables.h>
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#include <sqlpp11/vendor/where.h>
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#include <sqlpp11/vendor/group_by.h>
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#include <sqlpp11/vendor/having.h>
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#include <sqlpp11/vendor/order_by.h>
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#include <sqlpp11/vendor/limit.h>
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#include <sqlpp11/vendor/offset.h>
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#include <sqlpp11/vendor/expression.h>
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#include <sqlpp11/vendor/serializer.h>
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#include <sqlpp11/vendor/wrong.h>
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#include <sqlpp11/vendor/policy_update.h>
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#include <sqlpp11/detail/get_last.h>
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#include <sqlpp11/detail/pick_arg.h>
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namespace sqlpp
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{
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template<typename Db, typename... Policies>
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struct select_t;
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#warning STEPS:
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#warning deal with different return types in the connector (select could be a single value, update could be a range of rows)
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namespace detail
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{
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template<typename Db = void, typename... Policies>
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struct select_policies_t
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{
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using _database_t = Db;
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using _statement_t = select_t<Db, Policies...>;
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struct _methods_t: public Policies::template _methods_t<select_policies_t>...
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{};
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template<typename Needle, typename Replacement>
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struct _policies_update_t
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{
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static_assert(detail::is_element_of<Needle, make_type_set_t<Policies...>>::value, "policies update for non-policy class detected");
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using type = select_t<Db, vendor::policy_update_t<Policies, Needle, Replacement>...>;
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};
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template<typename Needle, typename Replacement>
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using _new_statement_t = typename _policies_update_t<Needle, Replacement>::type;
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using _all_required_tables = detail::make_joined_set_t<required_tables_of<Policies>...>;
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using _all_provided_tables = detail::make_joined_set_t<provided_tables_of<Policies>...>;
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using _all_extra_tables = detail::make_joined_set_t<extra_tables_of<Policies>...>;
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using _known_tables = detail::make_joined_set_t<_all_provided_tables, _all_extra_tables>;
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template<typename Expression>
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using _no_unknown_tables = detail::is_subset_of<required_tables_of<Expression>, _known_tables>;
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// The tables not covered by the from.
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using _required_tables = detail::make_difference_set_t<
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_all_required_tables,
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_all_provided_tables // Hint: extra_tables are not used here because they are just a helper for dynamic .add_*()
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>;
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using _result_type_provider = detail::get_last_if<is_return_value_t, vendor::no_select_column_list_t, Policies...>;
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struct _result_methods_t: public _result_type_provider::template _result_methods_t<select_policies_t>
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{};
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// A select can be used as a pseudo table if
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// - at least one column is selected
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// - the select is complete (leaks no tables)
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using _can_be_used_as_table = typename std::conditional<
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is_select_column_list_t<_result_type_provider>::value and _required_tables::size::value == 0,
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std::true_type,
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std::false_type
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>::type;
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using _value_type = typename std::conditional<
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detail::none_t<is_missing_t<Policies>::value...>::value,
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value_type_of<_result_type_provider>,
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no_value_t // if a required statement part is missing (e.g. columns in a select), then the statement cannot be used as a value
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>::type;
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using _is_expression = typename std::conditional<
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std::is_same<_value_type, no_value_t>::value,
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std::false_type,
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std::true_type>::type;
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using _traits = make_traits<_value_type>;
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struct _recursive_traits
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{
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using _parameters = std::tuple<>; // FIXME
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using _required_tables = _required_tables;
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using _provided_tables = detail::type_set<>;
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using _extra_tables = detail::type_set<>;
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};
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static void _check_consistency()
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{
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#warning check for missing terms here, and for missing tables
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static_assert(not required_tables_of<select_policies_t>::size::value, "one sub expression requires tables which are otherwise not known in the statement");
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}
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};
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}
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// SELECT
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template<typename Db,
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typename... Policies
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>
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struct select_t:
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public Policies...,
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public detail::select_policies_t<Db, Policies...>::_value_type::template expression_operators<select_t<Db, Policies...>>,
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public detail::select_policies_t<Db, Policies...>::_result_methods_t,
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public detail::select_policies_t<Db, Policies...>::_methods_t
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{
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using _policies_t = typename detail::select_policies_t<Db, Policies...>;
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using _traits = make_traits<value_type_of<_policies_t>, ::sqlpp::tag::select, tag::expression_if<typename _policies_t::_is_expression>, tag::named_expression_if<typename _policies_t::_is_expression>>;
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using _recursive_traits = typename _policies_t::_recursive_traits;
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using _result_type_provider = typename _policies_t::_result_type_provider;
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using _requires_braces = std::true_type;
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using _name_t = typename _result_type_provider::_name_t;
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// Constructors
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select_t()
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{}
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template<typename Statement, typename Term>
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select_t(Statement statement, Term term):
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Policies(detail::pick_arg<Policies>(statement, term))...
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{}
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select_t(const select_t& r) = default;
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select_t(select_t&& r) = default;
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select_t& operator=(const select_t& r) = default;
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select_t& operator=(select_t&& r) = default;
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~select_t() = default;
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};
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namespace vendor
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{
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template<typename Context, typename Database, typename... Policies>
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struct serializer_t<Context, select_t<Database, Policies...>>
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{
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using T = select_t<Database, Policies...>;
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static Context& _(const T& t, Context& context)
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{
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context << "SELECT ";
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using swallow = int[];
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(void) swallow{(serialize(static_cast<const Policies&>(t), context), 0)...};
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return context;
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}
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};
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}
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template<typename Database>
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using blank_select_t = select_t<Database,
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vendor::no_select_flag_list_t,
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vendor::no_select_column_list_t,
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vendor::no_from_t,
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vendor::no_extra_tables_t,
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vendor::no_where_t,
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vendor::no_group_by_t,
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vendor::no_having_t,
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vendor::no_order_by_t,
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vendor::no_limit_t,
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vendor::no_offset_t>;
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blank_select_t<void> select() // FIXME: These should be constexpr
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{
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return { };
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}
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template<typename... Columns>
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auto select(Columns... columns)
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-> decltype(blank_select_t<void>().columns(columns...))
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{
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return blank_select_t<void>().columns(columns...);
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}
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template<typename Database>
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blank_select_t<Database> dynamic_select(const Database&)
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{
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return { };
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}
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template<typename Database, typename... Columns>
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auto dynamic_select(const Database&, Columns... columns)
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-> decltype(blank_select_t<Database>().columns(columns...))
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{
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return blank_select_t<Database>().columns(columns...);
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}
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}
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#endif
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