sqlpp11/include/sqlpp11/max.h

/*
 * Copyright (c) 2013, 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_MAX_H
#define SQLPP_MAX_H

#include <sstream>
#include <sqlpp11/type_traits.h>

namespace sqlpp
{
	namespace vendor
	{
		template<typename Expr>
		struct max_t: public boolean::template operators<max_t<Expr>>
		{
			static_assert(is_value_t<Expr>::value, "max() requires a value expression as argument");

			struct _value_type: public Expr::_value_type::_base_value_type
			{
				using _is_named_expression = std::true_type;
			};

			struct _name_t
			{
				static constexpr const char* _get_name() { return "MAX"; }
				template<typename T>
					struct _member_t
					{
						T max;
						T& operator()() { return max; }
						const T& operator()() const { return max; }
					};
			};

			max_t(Expr expr):
				_expr(expr)
			{}

			max_t(const max_t&) = default;
			max_t(max_t&&) = default;
			max_t& operator=(const max_t&) = default;
			max_t& operator=(max_t&&) = default;
			~max_t() = default;

			Expr _expr;
		};
	}

	namespace vendor
	{
		template<typename Context, typename Expr>
			struct interpreter_t<Context, vendor::max_t<Expr>>
			{
				using T = vendor::max_t<Expr>;

				static Context& _(const T& t, Context& context)
				{
					context << "MAX(";
					interpret(t._expr, context);
					context << ")";
					return context;
				}
			};
	}

	template<typename T>
		auto max(T t) -> typename vendor::max_t<typename operand_t<T, is_value_t>::type>
		{
			return { t };
		}

}

#endif