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sqlpp11/include/sqlpp11/vendor/where.h
2014-05-16 09:18:08 +02:00

200 lines
6.7 KiB
C++

/*
* Copyright (c) 2013-2014, Roland Bock
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without modification,
* are permitted provided that the following conditions are met:
*
* Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* Redistributions in binary form must reproduce the above copyright notice, this
* list of conditions and the following disclaimer in the documentation and/or
* other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
* ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
* ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef SQLPP_WHERE_H
#define SQLPP_WHERE_H
#include <sqlpp11/type_traits.h>
#include <sqlpp11/parameter_list.h>
#include <sqlpp11/vendor/expression.h>
#include <sqlpp11/vendor/interpret_tuple.h>
#include <sqlpp11/vendor/interpretable_list.h>
#include <sqlpp11/detail/logic.h>
namespace sqlpp
{
namespace vendor
{
// WHERE
template<typename Database, typename... Expressions>
struct where_t
{
using _traits = make_traits<no_value_t, ::sqlpp::tag::where>;
using _recursive_traits = make_recursive_traits<Expressions...>;
using _is_dynamic = typename std::conditional<std::is_same<Database, void>::value, std::false_type, std::true_type>::type;
static_assert(_is_dynamic::value or sizeof...(Expressions), "at least one expression argument required in where()");
static_assert(sqlpp::detail::none_t<is_assignment_t<Expressions>::value...>::value, "at least one argument is an assignment in where()");
static_assert(sqlpp::detail::all_t<is_expression_t<Expressions>::value...>::value, "at least one argument is not valid expression in where()");
where_t(Expressions... expressions):
_expressions(expressions...)
{}
where_t(const where_t&) = default;
where_t(where_t&&) = default;
where_t& operator=(const where_t&) = default;
where_t& operator=(where_t&&) = default;
~where_t() = default;
template<typename Policies>
struct _methods_t
{
template<typename Expression>
void add_where_ntc(Expression expression)
{
add_where<Expression, std::false_type>(expression);
}
template<typename Expression, typename TableCheckRequired = std::true_type>
void add_where(Expression expression)
{
static_assert(_is_dynamic::value, "add_where can only be called for dynamic_where");
static_assert(is_expression_t<Expression>::value, "invalid expression argument in add_where()");
static_assert(TableCheckRequired::value or Policies::template _no_unknown_tables<Expression>::value, "expression uses tables unknown to this statement in add_where()");
using ok = ::sqlpp::detail::all_t<_is_dynamic::value, is_expression_t<Expression>::value>;
_add_where_impl(expression, ok()); // dispatch to prevent compile messages after the static_assert
}
private:
template<typename Expression>
void _add_where_impl(Expression expression, const std::true_type&)
{
return static_cast<typename Policies::_statement_t*>(this)->_where._dynamic_expressions.emplace_back(expression);
}
template<typename Expression>
void _add_where_impl(Expression expression, const std::false_type&);
};
std::tuple<Expressions...> _expressions;
vendor::interpretable_list_t<Database> _dynamic_expressions;
};
template<>
struct where_t<void, bool>
{
using _traits = make_traits<no_value_t, ::sqlpp::tag::where>;
using _recursive_traits = make_recursive_traits<>;
where_t(bool condition):
_condition(condition)
{}
where_t(const where_t&) = default;
where_t(where_t&&) = default;
where_t& operator=(const where_t&) = default;
where_t& operator=(where_t&&) = default;
~where_t() = default;
template<typename Policies>
struct _methods_t
{
};
bool _condition;
};
struct no_where_t
{
using _traits = make_traits<no_value_t, ::sqlpp::tag::where>;
using _recursive_traits = make_recursive_traits<>;
template<typename Policies>
struct _methods_t
{
using _database_t = typename Policies::_database_t;
template<typename T>
using _new_statement_t = typename Policies::template _new_statement_t<no_where_t, T>;
template<typename... Args>
auto where(Args... args)
-> _new_statement_t<where_t<void, Args...>>
{
return { *static_cast<typename Policies::_statement_t*>(this), where_t<void, Args...>{args...} };
}
template<typename... Args>
auto dynamic_where(Args... args)
-> _new_statement_t<where_t<_database_t, Args...>>
{
static_assert(not std::is_same<_database_t, void>::value, "dynamic_where must not be called in a static statement");
return { *static_cast<typename Policies::_statement_t*>(this), vendor::where_t<_database_t, Args...>{args...} };
}
};
};
// Interpreters
template<typename Context, typename Database, typename... Expressions>
struct serializer_t<Context, where_t<Database, Expressions...>>
{
using T = where_t<Database, Expressions...>;
static Context& _(const T& t, Context& context)
{
if (sizeof...(Expressions) == 0 and t._dynamic_expressions.empty())
return context;
context << " WHERE ";
interpret_tuple(t._expressions, " AND ", context);
if (sizeof...(Expressions) and not t._dynamic_expressions.empty())
context << " AND ";
interpret_list(t._dynamic_expressions, " AND ", context);
return context;
}
};
template<typename Context>
struct serializer_t<Context, where_t<void, bool>>
{
using T = where_t<void, bool>;
static Context& _(const T& t, Context& context)
{
if (not t._condition)
context << " WHERE NULL";
return context;
}
};
template<typename Context>
struct serializer_t<Context, no_where_t>
{
using T = no_where_t;
static Context& _(const T& t, Context& context)
{
return context;
}
};
}
}
#endif