sqlpp11/include/sqlpp11/on.h

/*
 * 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_ON_H
#define SQLPP_ON_H

#include <sqlpp11/type_traits.h>
#include <sqlpp11/interpret_tuple.h>
#include <sqlpp11/interpretable_list.h>
#include <sqlpp11/logic.h>

namespace sqlpp
{
	template<typename Database, typename... Expressions>
		struct on_t
		{
			using _traits = make_traits<no_value_t, tag::is_on>;
			using _recursive_traits = make_recursive_traits<Expressions...>;

			using _is_dynamic = is_database<Database>;

			static_assert(_is_dynamic::value or sizeof...(Expressions), "at least one expression argument required in on()");

			template<typename Expr>
				void add(Expr expr)
				{
					static_assert(_is_dynamic::value, "on::add() must not be called for static on()");
					static_assert(is_expression_t<Expr>::value, "invalid expression argument in on::add()");
					using _serialize_check = sqlpp::serialize_check_t<typename Database::_serializer_context_t, Expr>;
					_serialize_check::_();

					using ok = logic::all_t<_is_dynamic::value, is_expression_t<Expr>::value, _serialize_check::type::value>;

					_add_impl(expr, ok()); // dispatch to prevent compile messages after the static_assert
				}

		private:
			template<typename Expr>
				void _add_impl(Expr expr, const std::true_type&)
				{
					return _dynamic_expressions.emplace_back(expr);
				}

			template<typename Expr>
				void _add_impl(Expr expr, const std::false_type&);

		public:
			std::tuple<Expressions...> _expressions;
			interpretable_list_t<Database> _dynamic_expressions;
		};

	template<typename Context, typename Database, typename... Expressions>
		struct serializer_t<Context, on_t<Database, Expressions...>>
		{
			using _serialize_check = serialize_check_of<Context, Expressions...>;
			using T = on_t<Database, Expressions...>;

			static Context& _(const T& t, Context& context)
			{
				if (sizeof...(Expressions) == 0 and t._dynamic_expressions.empty())
					return context;
				context << " ON ";
				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;
			}
		};

}

#endif