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A step towards turning select into a really variadic template

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rbock 2014-05-19 22:54:47 +02:00
parent 569f0ff2eb
commit 15e8ca742c
1 changed files with 35 additions and 63 deletions
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98
include/sqlpp11/select.h
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@ -115,9 +115,6 @@ namespace sqlpp
template<typename Needle, typename Replacement> template<typename Needle, typename Replacement>
using _new_statement_t = typename _policies_update_t<Needle, Replacement, FlagList, ColumnList, From, ExtraTables, Where, GroupBy, Having, OrderBy, Limit, Offset>::type; using _new_statement_t = typename _policies_update_t<Needle, Replacement, FlagList, ColumnList, From, ExtraTables, Where, GroupBy, Having, OrderBy, Limit, Offset>::type;
static_assert(is_noop_t<ColumnList>::value or sqlpp::is_select_column_list_t<ColumnList>::value, "column list of select is neither naught nor a valid column list");
static_assert(is_noop_t<From>::value or sqlpp::is_from_t<From>::value, "from() part of select is neither naught nor a valid from()");
using _known_tables = detail::make_joined_set_t<provided_tables_of<_from_t>, extra_tables_of<_extra_tables_t>>; using _known_tables = detail::make_joined_set_t<provided_tables_of<_from_t>, extra_tables_of<_extra_tables_t>>;
template<typename Expression> template<typename Expression>
@ -141,7 +138,7 @@ namespace sqlpp
provided_tables_of<_from_t> // Hint: extra_tables_t is not used here because it is just a helper for dynamic .add_*() methods and should not change the structural integrity provided_tables_of<_from_t> // Hint: extra_tables_t is not used here because it is just a helper for dynamic .add_*() methods and should not change the structural integrity
>; >;
using _result_provider = detail::get_last_if<is_return_value_t, vendor::noop, FlagList, ColumnList, From, ExtraTables, Where, GroupBy, Having, OrderBy, Limit, Offset>; using _result_provider = detail::get_last_if<is_return_value_t, vendor::no_select_column_list_t, FlagList, ColumnList, From, ExtraTables, Where, GroupBy, Having, OrderBy, Limit, Offset>;
// A select can be used as a pseudo table if // A select can be used as a pseudo table if
// - at least one column is selected // - at least one column is selected
@ -171,34 +168,48 @@ namespace sqlpp
}; };
} }
namespace detail
{
template<typename Target, typename Statement, typename Term>
Target pick_arg_impl(Statement statement, Term term, const std::true_type&)
{
return term;
};
template<typename Target, typename Statement, typename Term>
Target pick_arg_impl(Statement statement, Term term, const std::false_type&)
{
return static_cast<Target>(statement);
};
template<typename Target, typename Statement, typename Term>
Target pick_arg(Statement statement, Term term)
{
return pick_arg_impl<Target>(statement, term, std::is_same<Target, Term>());
};
}
// SELECT // SELECT
template<typename Db, template<typename Db,
typename... Policies typename... Policies
> >
struct select_t: struct select_t:
public Policies...,
public detail::select_policies_t<Db, Policies...>::_value_type::template expression_operators<select_t<Db, Policies...>>, public detail::select_policies_t<Db, Policies...>::_value_type::template expression_operators<select_t<Db, Policies...>>,
public detail::select_policies_t<Db, Policies...>::_methods_t public detail::select_policies_t<Db, Policies...>::_methods_t
{ {
using _policies_t = typename detail::select_policies_t<Db, Policies...>; using _policies_t = typename detail::select_policies_t<Db, Policies...>;
using _traits = make_traits<value_type_of<_policies_t>, ::sqlpp::tag::select>; using _traits = make_traits<value_type_of<_policies_t>, ::sqlpp::tag::select>;
using _recursive_traits = typename _policies_t::_recursive_traits; using _recursive_traits = typename _policies_t::_recursive_traits;
using _database_t = typename _policies_t::_database_t; using _database_t = Db;
using _flag_list_t = typename _policies_t::_flag_list_t;
using _column_list_t = typename _policies_t::_column_list_t;
using _from_t = typename _policies_t::_from_t;
using _extra_tables_t = typename _policies_t::_extra_tables_t;
using _where_t = typename _policies_t::_where_t;
using _group_by_t = typename _policies_t::_group_by_t;
using _having_t = typename _policies_t::_having_t;
using _order_by_t = typename _policies_t::_order_by_t;
using _limit_t = typename _policies_t::_limit_t;
using _offset_t = typename _policies_t::_offset_t;
using _is_dynamic = typename std::conditional<std::is_same<_database_t, void>::value, std::false_type, std::true_type>::type; using _is_dynamic = typename std::conditional<std::is_same<_database_t, void>::value, std::false_type, std::true_type>::type;
#warning replace _column_list_t by a more generic name
using _column_list_t = typename _policies_t::_result_provider;
using _parameter_tuple_t = std::tuple<Policies...>; using _parameter_tuple_t = std::tuple<Policies...>;
using _parameter_list_t = typename make_parameter_list_t<select_t>::type; using _parameter_list_t = typename make_parameter_list_t<select_t>::type;
@ -216,17 +227,9 @@ namespace sqlpp
select_t() select_t()
{} {}
template<typename Statement, typename T> template<typename Statement, typename Term>
select_t(Statement s, T t): select_t(Statement statement, Term term):
_flag_list(detail::arg_selector<_flag_list_t>::_(s._flag_list, t)), Policies(detail::pick_arg<Policies>(statement, term))...
_column_list(detail::arg_selector<_column_list_t>::_(s._column_list, t)),
_from(detail::arg_selector<_from_t>::_(s._from, t)),
_where(detail::arg_selector<_where_t>::_(s._where, t)),
_group_by(detail::arg_selector<_group_by_t>::_(s._group_by, t)),
_having(detail::arg_selector<_having_t>::_(s._having, t)),
_order_by(detail::arg_selector<_order_by_t>::_(s._order_by, t)),
_limit(detail::arg_selector<_limit_t>::_(s._limit, t)),
_offset(detail::arg_selector<_offset_t>::_(s._offset, t))
{} {}
select_t(const select_t& r) = default; select_t(const select_t& r) = default;
@ -253,7 +256,7 @@ namespace sqlpp
const _dynamic_names_t& get_dynamic_names() const const _dynamic_names_t& get_dynamic_names() const
{ {
return _column_list._dynamic_columns._dynamic_expression_names; return static_cast<const _column_list_t&>(*this)._dynamic_columns._dynamic_expression_names;
} }
static constexpr size_t _get_static_no_of_parameters() static constexpr size_t _get_static_no_of_parameters()
@ -271,24 +274,9 @@ namespace sqlpp
return _column_list_t::static_size() + get_dynamic_names().size(); return _column_list_t::static_size() + get_dynamic_names().size();
} }
template<typename A>
struct is_table_subset_of_from
{
static constexpr bool value = ::sqlpp::detail::is_subset_of<required_tables_of<A>, provided_tables_of<_from_t>>::value;
};
void _check_consistency() const void _check_consistency() const
{ {
static_assert(is_select_column_list_t<_column_list_t>::value, "no columns selected"); #warning check for missing terms here, and for missing tables
static_assert(is_table_subset_of_from<_flag_list_t>::value, "flags require additional tables in from()");
static_assert(is_table_subset_of_from<_column_list_t>::value, "selected columns require additional tables in from()");
static_assert(is_table_subset_of_from<_where_t>::value, "where() expression requires additional tables in from()");
static_assert(is_table_subset_of_from<_group_by_t>::value, "group_by() expression requires additional tables in from()");
static_assert(is_table_subset_of_from<_having_t>::value, "having() expression requires additional tables in from()");
static_assert(is_table_subset_of_from<_order_by_t>::value, "order_by() expression requires additional tables in from()");
static_assert(is_table_subset_of_from<_limit_t>::value, "limit() expression requires additional tables in from()");
static_assert(is_table_subset_of_from<_offset_t>::value, "offset() expression requires additional tables in from()");
static_assert(not required_tables_of<_policies_t>::size::value, "one sub expression contains tables which are not in the from()"); static_assert(not required_tables_of<_policies_t>::size::value, "one sub expression contains tables which are not in the from()");
} }
@ -313,15 +301,7 @@ namespace sqlpp
return {{}, get_dynamic_names(), db.prepare_select(*this)}; return {{}, get_dynamic_names(), db.prepare_select(*this)};
} }
_flag_list_t _flag_list; std::tuple<Policies...> _terms;
_column_list_t _column_list;
_from_t _from;
_where_t _where;
_group_by_t _group_by;
_having_t _having;
_order_by_t _order_by;
_limit_t _limit;
_offset_t _offset;
}; };
namespace vendor namespace vendor
@ -335,15 +315,7 @@ namespace sqlpp
{ {
context << "SELECT "; context << "SELECT ";
serialize(t._flag_list, context); interpret_tuple(t._terms, ' ', context);
serialize(t._column_list, context);
serialize(t._from, context);
serialize(t._where, context);
serialize(t._group_by, context);
serialize(t._having, context);
serialize(t._order_by, context);
serialize(t._limit, context);
serialize(t._offset, context);
return context; return context;
} }