sqlpp11/include/sqlpp11/text.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
 * 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_TEXT_H
#define SQLPP_TEXT_H

#include <sqlpp11/assignment.h>
#include <sqlpp11/basic_expression_operators.h>
#include <sqlpp11/type_traits.h>
#include <sqlpp11/exception.h>
#include <sqlpp11/like.h>
#include <sqlpp11/result_field.h>

namespace sqlpp
{
  template <typename... Args>
  struct concat_t;

  // text value type
  struct text
  {
    using _traits = make_traits<text, tag::is_value_type>;
    using _tag = tag::is_text;
    using _cpp_value_type = std::string;

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

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

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

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

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

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

    parameter_value_t& operator=(const std::nullptr_t&)
    {
      _value = "";
      _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_text_parameter(index, &_value, _is_null);
    }

  private:
    _cpp_value_type _value;
    bool _is_null;
  };

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

    template <typename T>
    concat_t<Base, wrap_operand_t<T>> operator+(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), {t}};
    }

    template <typename T>
    like_t<Base, wrap_operand_t<T>> like(T t) const
    {
      using rhs = wrap_operand_t<T>;
      static_assert(_is_valid_operand<rhs>::value, "invalid argument for like()");

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

  // text column operators
  template <typename Base>
  struct column_operators<Base, text>
  {
    template <typename T>
    using _is_valid_operand = is_valid_operand<text, T>;

    template <typename T>
    auto operator+=(T t) const -> assignment_t<Base, concat_t<Base, wrap_operand_t<T>>>
    {
      using rhs = wrap_operand_t<T>;
      static_assert(_is_valid_operand<rhs>::value, "invalid rhs assignment operand");

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

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

    result_field_t() : _is_valid(false), _value_ptr(nullptr), _len(0)
    {
    }

    void _validate()
    {
      _is_valid = true;
    }

    void _invalidate()
    {
      _is_valid = false;
      _value_ptr = nullptr;
      _len = 0;
    }

    bool operator==(const _cpp_value_type& rhs) const
    {
      return value() == rhs;
    }
    bool operator!=(const _cpp_value_type& rhs) const
    {
      return not operator==(rhs);
    }

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

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

      return value() == "";
    }

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

      if (not _value_ptr)
      {
        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 "";
        }
      }
      return std::string(_value_ptr, _value_ptr + _len);
    }

    template <typename Target>
    void _bind(Target& target, size_t i)
    {
      target._bind_text_result(i, &_value_ptr, &_len);
    }

  private:
    bool _is_valid;
    const char* _value_ptr;
    size_t _len;
  };

  template <typename Context, typename Db, typename FieldSpec>
  struct serializer_t<Context, result_field_t<text, Db, FieldSpec>>
  {
    using _serialize_check = consistent_t;
    using T = result_field_t<text, Db, FieldSpec>;

    static Context& _(const T& t, Context& context)
    {
      if (t.is_null() and not null_is_trivial_value_t<T>::value)
      {
        context << "NULL";
      }
      else
      {
        context << '\'' << context.escape(t.value()) << '\'';
      }
      return context;
    }
  };

  template <typename Db, typename FieldSpec>
  inline std::ostream& operator<<(std::ostream& os, const result_field_t<text, Db, FieldSpec>& e)
  {
    if (e.is_null() and not null_is_trivial_value_t<FieldSpec>::value)
    {
      return os << "NULL";
    }
    else
    {
      return os << e.value();
    }
  }

  using blob = text;
  using varchar = text;
  using char_ = text;
}
#endif