sqlpp11/include/sqlpp11/basic_expression_operators.h

/*
 * Copyright (c) 2013-2015, 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
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 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
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 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#ifndef SQLPP_DETAIL_BASIC_EXPRESSION_OPERATORS_H
#define SQLPP_DETAIL_BASIC_EXPRESSION_OPERATORS_H

#include <sqlpp11/value_type_fwd.h>
#include <sqlpp11/alias.h>
#include <sqlpp11/sort_order.h>
#include <sqlpp11/expression_fwd.h>
#include <sqlpp11/in_fwd.h>
#include <sqlpp11/is_null_fwd.h>
#include <sqlpp11/wrap_operand_fwd.h>
#include <sqlpp11/logic.h>

namespace sqlpp
{
  // basic operators
  template <typename Expr, typename ValueType>
  struct basic_expression_operators
  {
    template <typename T>
    struct _is_valid_comparison_operand
    {
      static constexpr bool value =
          (is_expression_t<T>::value  // expressions are OK
           or
           is_multi_expression_t<T>::value)  // multi-expressions like ANY are OK for comparisons, too
          and
          ValueType::template _is_valid_operand<T>::value  // the correct value type is required, of course
          ;
    };

    template <typename T>
    equal_to_t<Expr, wrap_operand_t<T>> operator==(T t) const
    {
      using rhs = wrap_operand_t<T>;
      static_assert(_is_valid_comparison_operand<rhs>::value, "invalid rhs operand in comparison");

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

    template <typename T>
    not_equal_to_t<Expr, wrap_operand_t<T>> operator!=(T t) const
    {
      using rhs = wrap_operand_t<T>;
      static_assert(_is_valid_comparison_operand<rhs>::value, "invalid rhs operand in comparison");

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

    template <typename T>
    less_than_t<Expr, wrap_operand_t<T>> operator<(T t) const
    {
      using rhs = wrap_operand_t<T>;
      static_assert(_is_valid_comparison_operand<rhs>::value, "invalid rhs operand in comparison");

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

    template <typename T>
    less_equal_t<Expr, wrap_operand_t<T>> operator<=(T t) const
    {
      using rhs = wrap_operand_t<T>;
      static_assert(_is_valid_comparison_operand<rhs>::value, "invalid rhs operand in comparison");

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

    template <typename T>
    greater_than_t<Expr, wrap_operand_t<T>> operator>(T t) const
    {
      using rhs = wrap_operand_t<T>;
      static_assert(_is_valid_comparison_operand<rhs>::value, "invalid rhs operand in comparison");

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

    template <typename T>
    greater_equal_t<Expr, wrap_operand_t<T>> operator>=(T t) const
    {
      using rhs = wrap_operand_t<T>;
      static_assert(_is_valid_comparison_operand<rhs>::value, "invalid rhs operand in comparison");

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

    is_null_t<Expr> is_null() const
    {
      return {*static_cast<const Expr*>(this)};
    }

    is_not_null_t<Expr> is_not_null() const
    {
      return {*static_cast<const Expr*>(this)};
    }

    sort_order_t<Expr, sort_type::asc> asc() const
    {
      return {*static_cast<const Expr*>(this)};
    }

    sort_order_t<Expr, sort_type::desc> desc() const
    {
      return {*static_cast<const Expr*>(this)};
    }

    // Hint: use value_list wrapper for containers...
    template <typename... T>
    in_t<Expr, wrap_operand_t<T>...> in(T... t) const
    {
      static_assert(logic::all_t<_is_valid_comparison_operand<wrap_operand_t<T>>::value...>::value,
                    "at least one operand of in() is not valid");
      return {*static_cast<const Expr*>(this), wrap_operand_t<T>{t}...};
    }

    template <typename... T>
    not_in_t<Expr, wrap_operand_t<T>...> not_in(T... t) const
    {
      static_assert(logic::all_t<_is_valid_comparison_operand<wrap_operand_t<T>>::value...>::value,
                    "at least one operand of in() is not valid");
      return {*static_cast<const Expr*>(this), wrap_operand_t<T>{t}...};
    }
  };

  template <typename Expr>
  struct alias_operators
  {
    template <typename alias_provider>
    expression_alias_t<Expr, alias_provider> as(const alias_provider&) const
    {
      return {*static_cast<const Expr*>(this)};
    }
  };
}
#endif