sqlpp11/include/sqlpp11/boolean.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_BOOLEAN_H
#define SQLPP_BOOLEAN_H

#include <cstdlib>
#include <ostream>
#include <sqlpp11/basic_expression_operators.h>
#include <sqlpp11/type_traits.h>
#include <sqlpp11/exception.h>
#include <sqlpp11/tvin.h>
#include <sqlpp11/result_field.h>

namespace sqlpp
{
	// boolean value type
	struct boolean
	{
		using _traits = make_traits<boolean, tag::is_value_type>;
		using _tag = tag::is_boolean;
		using _cpp_value_type = bool;

		template<typename T>
			using _is_valid_operand = is_boolean_t<T>;
	};

	// boolean parameter type
	template<>
		struct parameter_value_t<boolean>
		{
			using _value_type = boolean; // FIXME
			using _cpp_value_type = typename _value_type::_cpp_value_type;

			parameter_value_t():
				_value(false),
				_is_null(true)
			{}

			parameter_value_t(const _cpp_value_type& value):
				_value(value),
				_is_null(false)
			{}

			parameter_value_t& operator=(const _cpp_value_type& value)
			{
				_value = value;
				_is_null = false;
				return *this;
			}

			parameter_value_t& operator=(const tvin_t<wrap_operand_t<_cpp_value_type>>& t)
			{
				if (t._is_trivial())
				{
					_value = false;
					_is_null = true;
				}
				else
				{
					_value = t._value._t;
					_is_null = false;
				}
				return *this;
			}

			parameter_value_t& operator=(const std::nullptr_t&)
			{
				_value = false;
				_is_null = true;
				return *this;
			}

			bool is_null() const
			{ 
				return _is_null; 
			}

			_cpp_value_type value() const
			{
				return _value;
			}

			operator _cpp_value_type() const { return value(); }

			template<typename Target>
				void _bind(Target& target, size_t index) const
				{
					target._bind_boolean_parameter(index, &_value, _is_null);
				}

		private:
			signed char _value;
			bool _is_null;
		};

	// boolean expression operators
	template<typename Base>
		struct expression_operators<Base, boolean>: public basic_expression_operators<Base, boolean>
	{
		template<typename T>
			using _is_valid_operand = is_valid_operand<boolean, T>;

		template<typename T>
			logical_and_t<Base, wrap_operand_t<T>> operator and(T t) const
			{
				using rhs = wrap_operand_t<T>;
				static_assert(_is_valid_operand<rhs>::value, "invalid rhs operand");

				return { *static_cast<const Base*>(this), rhs{t} };
			}

		template<typename T>
			logical_or_t<Base, wrap_operand_t<T>> operator or(T t) const
			{
				using rhs = wrap_operand_t<T>;
				static_assert(_is_valid_operand<rhs>::value, "invalid rhs operand");

				return { *static_cast<const Base*>(this), rhs{t} };
			}

		logical_not_t<Base> operator not() const
		{
			return { *static_cast<const Base*>(this) };
		}
	};

	// boolean column operators
	template<typename Base>
		struct column_operators<Base, boolean>
		{
		};

	// boolean result field
	template<typename Db, typename FieldSpec>
		struct result_field_t<boolean, Db, FieldSpec>: public result_field_methods_t<result_field_t<boolean, Db, FieldSpec>>
	{
		static_assert(std::is_same<value_type_of<FieldSpec>, boolean>::value, "field type mismatch");
		using _cpp_value_type = typename boolean::_cpp_value_type;

		result_field_t():
			_is_valid(false),
			_is_null(true),
			_value(false)
		{}

		void _validate()
		{
			_is_valid = true;
		}

		void _invalidate()
		{
			_is_valid = false;
			_is_null = true;
			_value = 0;
		}

		bool is_null() const
		{ 
			if (not _is_valid)
				throw exception("accessing is_null in non-existing row");
			return _is_null; 
		}

		bool _is_trivial() const
		{
			if (not _is_valid)
				throw exception("accessing is_null in non-existing row");

			return value() == false;
		}

		_cpp_value_type value() const
		{
			if (not _is_valid)
				throw exception("accessing value in non-existing row");

			if (_is_null)
			{
				if (enforce_null_result_treatment_t<Db>::value and not null_is_trivial_value_t<FieldSpec>::value)
				{
					throw exception("accessing value of NULL field");
				}
				else
				{
					return false;
				}
			}
			return _value;
		}

		template<typename Target>
			void _bind(Target& target, size_t i)
			{
				target._bind_boolean_result(i, &_value, &_is_null);
			}

	private:
		bool _is_valid;
		bool _is_null;
		signed char _value;
	};

	template<typename Db, typename FieldSpec>
		inline std::ostream& operator<<(std::ostream& os, const result_field_t<boolean, Db, FieldSpec>& e)
		{
			return serialize(e, os);
		}

}
#endif