.. _program_listing_file_cif++_item.hpp:

Program Listing for File item.hpp
=================================

|exhale_lsh| :ref:`Return to documentation for file <file_cif++_item.hpp>` (``cif++/item.hpp``)

.. |exhale_lsh| unicode:: U+021B0 .. UPWARDS ARROW WITH TIP LEFTWARDS

.. code-block:: cpp

   /*-
    * SPDX-License-Identifier: BSD-2-Clause
    *
    * Copyright (c) 2022 NKI/AVL, Netherlands Cancer Institute
    *
    * Redistribution and use in source and binary forms, with or without
    * modification, are permitted provided that the following conditions are met:
    *
    * 1. Redistributions of source code must retain the above copyright notice, this
    *    list of conditions and the following disclaimer
    * 2. 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 OWNER 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.
    */
   
   #pragma once
   
   #include "cif++/exports.hpp"
   #include "cif++/forward_decl.hpp"
   #include "cif++/text.hpp"
   #include "cif++/utilities.hpp"
   
   #include <cassert>
   #include <charconv>
   #include <cstring>
   #include <iomanip>
   #include <iostream>
   #include <limits>
   #include <memory>
   #include <optional>
   #include <utility>
   
   namespace cif
   {
   
   // --------------------------------------------------------------------
   class item
   {
     public:
       item() = default;
   
       item(std::string_view name)
           : m_name(name)
           , m_value({ '.' })
       {
       }
   
       item(std::string_view name, char value)
           : m_name(name)
           , m_value({ value })
       {
       }
   
       template <typename T, std::enable_if_t<std::is_floating_point_v<T>, int> = 0>
       item(std::string_view name, const T &value, int precision)
           : m_name(name)
       {
           using namespace std;
           using namespace cif;
   
           char buffer[32];
   
           auto r = to_chars(buffer, buffer + sizeof(buffer) - 1, value, chars_format::fixed, precision);
           if ((bool)r.ec)
               throw std::runtime_error("Could not format number");
   
           m_value.assign(buffer, r.ptr - buffer);
       }
   
       template <typename T, std::enable_if_t<std::is_floating_point_v<T>, int> = 0>
       item(const std::string_view name, const T &value)
           : m_name(name)
       {
           using namespace std;
           using namespace cif;
   
           char buffer[32];
   
           auto r = to_chars(buffer, buffer + sizeof(buffer) - 1, value, chars_format::general);
           if ((bool)r.ec)
               throw std::runtime_error("Could not format number");
   
           m_value.assign(buffer, r.ptr - buffer);
       }
   
       template <typename T, std::enable_if_t<std::is_integral_v<T> and not std::is_same_v<T, bool>, int> = 0>
       item(const std::string_view name, const T &value)
           : m_name(name)
       {
           char buffer[32];
   
           auto r = std::to_chars(buffer, buffer + sizeof(buffer) - 1, value);
           if ((bool)r.ec)
               throw std::runtime_error("Could not format number");
   
           m_value.assign(buffer, r.ptr - buffer);
       }
   
       template <typename T, std::enable_if_t<std::is_same_v<T, bool>, int> = 0>
       item(const std::string_view name, const T &value)
           : m_name(name)
       {
           m_value.assign(value ? "y" : "n");
       }
   
       item(const std::string_view name, std::string_view value)
           : m_name(name)
           , m_value(value)
       {
       }
   
       template<typename T, std::enable_if_t<std::is_same_v<T, std::string>, int> = 0>
       item(const std::string_view name, T &&value)
           : m_name(name)
           , m_value(std::move(value))
       {
       }
   
       template <typename T>
       item(const std::string_view name, const std::optional<T> &value)
           : m_name(name)
       {
           if (value.has_value())
           {
               item tmp(name, *value);
               std::swap(tmp.m_value, m_value);
           }
           else
               m_value.assign("?");
       }
   
       template <typename T, std::enable_if_t<std::is_floating_point_v<T>, int> = 0>
       item(std::string_view name, const std::optional<T> &value, int precision)
           : m_name(name)
       {
           if (value.has_value())
           {
               item tmp(name, *value, precision);
               std::swap(tmp.m_value, m_value);
           }
           else
               m_value.assign("?");
       }
   
       item(const item &rhs) = default;
       item(item &&rhs) noexcept = default;
       item &operator=(const item &rhs) = default;
       item &operator=(item &&rhs) noexcept = default;
       std::string_view name() const { return m_name; }   
       std::string_view value() const & { return m_value; } 
       std::string value() const && { return std::move(m_value); } 
   
       void value(std::string_view v) { m_value = v; }
   
       bool empty() const { return m_value.empty(); }
   
       bool is_null() const { return m_value == "."; }
   
       bool is_unknown() const { return m_value == "?"; }
   
       std::size_t length() const { return m_value.length(); }
   
       template <std::size_t N>
       decltype(auto) get() const
       {
           if constexpr (N == 0)
               return name();
           else if constexpr (N == 1)
               return value();
       }
   
     private:
       std::string_view m_name;
       std::string m_value;
   };
   
   // --------------------------------------------------------------------
   
   struct item_value
   {
       item_value() = default;
       item_value(std::string_view text)
           : m_length(text.length())
           , m_storage(0)
       {
           if (m_length >= kBufferSize)
           {
               m_data = new char[m_length + 1];
               std::copy(text.begin(), text.end(), m_data);
               m_data[m_length] = 0;
           }
           else
           {
               std::copy(text.begin(), text.end(), m_local_data);
               m_local_data[m_length] = 0;
           }
       }
   
       item_value(item_value &&rhs) noexcept
           : m_length(std::exchange(rhs.m_length, 0))
           , m_storage(std::exchange(rhs.m_storage, 0))
       {
       }
   
       item_value &operator=(item_value &&rhs) noexcept
       {
           std::swap(m_length, rhs.m_length);
           std::swap(m_storage, rhs.m_storage);
           return *this;
       }
   
       ~item_value()
       {
           if (m_length >= kBufferSize)
               delete[] m_data;
           m_storage = 0;
           m_length = 0;
       }
   
       item_value(const item_value &) = delete;
       item_value &operator=(const item_value &) = delete;
       explicit operator bool() const
       {
           return m_length != 0;
       }
   
       std::size_t m_length = 0; 
       union
       {
           char m_local_data[8]; 
           char *m_data;         
           uint64_t m_storage;   
       };
   
       static constexpr std::size_t kBufferSize = sizeof(m_local_data);
   
       // By using std::string_view instead of c_str we obain a
       // nice performance gain since we avoid many calls to strlen.
   
       constexpr inline std::string_view text() const
       {
           return { m_length >= kBufferSize ? m_data : m_local_data, m_length };
       }
   };
   
   // --------------------------------------------------------------------
   // Transient object to access stored data
   
   
   struct item_handle
   {
     public:
       // conversion helper class
       template <typename T, typename = void>
       struct item_value_as;
       template <typename T>
       item_handle &operator=(const T &value)
       {
           assign_value(item{ "", value }.value());
           return *this;
       }
   
       template <typename T>
       item_handle &operator=(T &&value)
       {
           assign_value(item{ "", std::forward<T>(value) }.value());
           return *this;
       }
   
       template <std::size_t N>
       item_handle &operator=(const char (&value)[N])
       {
           assign_value(item{ "", std::move(value) }.value());
           return *this;
       }
   
       template <typename... Ts>
       void os(const Ts &...v)
       {
           std::ostringstream ss;
           ((ss << v), ...);
           this->operator=(ss.str());
       }
   
       void swap(item_handle &b);
   
       template <typename T = std::string>
       auto as() const -> T
       {
           using value_type = std::remove_cv_t<std::remove_reference_t<T>>;
           return item_value_as<value_type>::convert(*this);
       }
   
       template <typename T>
       auto value_or(const T &dv) const
       {
           return empty() ? dv : this->as<T>();
       }
   
       template <typename T>
       int compare(const T &value, bool icase = true) const
       {
           return item_value_as<T>::compare(*this, value, icase);
       }
   
       template <typename T>
       bool operator==(const T &value) const
       {
           // TODO: icase or not icase?
           return item_value_as<T>::compare(*this, value, true) == 0;
       }
   
       // We may not have C++20 yet...
   
       template <typename T>
       bool operator!=(const T &value) const
       {
           return not operator==(value);
       }
   
       bool empty() const
       {
           auto txt = text();
           return txt.empty() or (txt.length() == 1 and (txt.front() == '.' or txt.front() == '?'));
       }
   
       explicit operator bool() const { return not empty(); }
   
       bool is_null() const
       {
           auto txt = text();
           return txt.length() == 1 and txt.front() == '.';
       }
   
       bool is_unknown() const
       {
           auto txt = text();
           return txt.length() == 1 and txt.front() == '?';
       }
   
       std::string_view text() const;
   
       item_handle(uint16_t item, row_handle &row)
           : m_item_ix(item)
           , m_row_handle(row)
       {
       }
   
       CIFPP_EXPORT static const item_handle s_null_item;
   
       friend void swap(item_handle a, item_handle b)
       {
           a.swap(b);
       }
   
     private:
       item_handle();
   
       uint16_t m_item_ix;
       row_handle &m_row_handle;
   
       void assign_value(std::string_view value);
   };
   
   // So sad that older gcc implementations of from_chars did not support floats yet...
   
   template <typename T>
   struct item_handle::item_value_as<T, std::enable_if_t<std::is_arithmetic_v<T> and not std::is_same_v<T, bool>>>
   {
       using value_type = std::remove_reference_t<std::remove_cv_t<T>>;
   
       static value_type convert(const item_handle &ref)
       {
           value_type result = {};
   
           if (not ref.empty())
           {
               auto txt = ref.text();
   
               auto b = txt.data();
               auto e = txt.data() + txt.size();
   
               std::from_chars_result r = (b + 1 < e and *b == '+' and std::isdigit(b[1])) ? selected_charconv<value_type>::from_chars(b + 1, e, result) : selected_charconv<value_type>::from_chars(b, e, result);
   
               if ((bool)r.ec or r.ptr != e)
               {
                   result = {};
                   if (cif::VERBOSE)
                   {
                       if (r.ec == std::errc::invalid_argument)
                           std::cerr << "Attempt to convert " << std::quoted(txt) << " into a number\n";
                       else if (r.ec == std::errc::result_out_of_range)
                           std::cerr << "Conversion of " << std::quoted(txt) << " into a type that is too small\n";
                       else
                           std::cerr << "Not a valid number " << std::quoted(txt) << '\n';
                   }
               }
           }
   
           return result;
       }
   
       static int compare(const item_handle &ref, const T &value, bool icase)
       {
           int result = 0;
   
           auto txt = ref.text();
   
           if (ref.empty())
               result = 1;
           else
           {
               value_type v = {};
   
               auto b = txt.data();
               auto e = txt.data() + txt.size();
   
               std::from_chars_result r = (b + 1 < e and *b == '+' and std::isdigit(b[1])) ? selected_charconv<value_type>::from_chars(b + 1, e, v) : selected_charconv<value_type>::from_chars(b, e, v);
   
               if ((bool)r.ec or r.ptr != e)
               {
                   if (cif::VERBOSE)
                   {
                       if (r.ec == std::errc::invalid_argument)
                           std::cerr << "Attempt to convert " << std::quoted(txt) << " into a number\n";
                       else if (r.ec == std::errc::result_out_of_range)
                           std::cerr << "Conversion of " << std::quoted(txt) << " into a type that is too small\n";
                       else
                           std::cerr << "Not a valid number " << std::quoted(txt) << '\n';
                   }
                   result = 1;
               }
               else if (std::abs(v - value) <= std::numeric_limits<value_type>::epsilon())
                   result = 0;
               else if (v < value)
                   result = -1;
               else if (v > value)
                   result = 1;
           }
   
           return result;
       }
   };
   
   template <typename T>
   struct item_handle::item_value_as<std::optional<T>>
   {
       static std::optional<T> convert(const item_handle &ref)
       {
           std::optional<T> result;
           if (ref)
               result = ref.as<T>();
           return result;
       }
   
       static int compare(const item_handle &ref, std::optional<T> value, bool icase)
       {
           if (ref.empty() and not value)
               return 0;
   
           if (ref.empty())
               return -1;
           else if (not value)
               return 1;
           else
               return ref.compare(*value, icase);
       }
   };
   
   template <typename T>
   struct item_handle::item_value_as<T, std::enable_if_t<std::is_same_v<T, bool>>>
   {
       static bool convert(const item_handle &ref)
       {
           bool result = false;
           if (not ref.empty())
               result = iequals(ref.text(), "y");
           return result;
       }
   
       static int compare(const item_handle &ref, bool value, bool icase)
       {
           bool rv = convert(ref);
           return value && rv ? 0
                              : (rv < value ? -1 : 1);
       }
   };
   
   template <std::size_t N>
   struct item_handle::item_value_as<char[N]>
   {
       static std::string convert(const item_handle &ref)
       {
           if (ref.empty())
               return {};
           return { ref.text().data(), ref.text().size() };
       }
   
       static int compare(const item_handle &ref, const char (&value)[N], bool icase)
       {
           return icase ? cif::icompare(ref.text(), value) : ref.text().compare(value);
       }
   };
   
   template <typename T>
   struct item_handle::item_value_as<T, std::enable_if_t<std::is_same_v<T, const char *>>>
   {
       static std::string convert(const item_handle &ref)
       {
           if (ref.empty())
               return {};
           return { ref.text().data(), ref.text().size() };
       }
   
       static int compare(const item_handle &ref, const char *value, bool icase)
       {
           return icase ? cif::icompare(ref.text(), value) : ref.text().compare(value);
       }
   };
   
   template <typename T>
   struct item_handle::item_value_as<T, std::enable_if_t<std::is_same_v<T, std::string_view>>>
   {
       static std::string convert(const item_handle &ref)
       {
           if (ref.empty())
               return {};
           return { ref.text().data(), ref.text().size() };
       }
   
       static int compare(const item_handle &ref, const std::string_view &value, bool icase)
       {
           return icase ? cif::icompare(ref.text(), value) : ref.text().compare(value);
       }
   };
   
   template <typename T>
   struct item_handle::item_value_as<T, std::enable_if_t<std::is_same_v<T, std::string>>>
   {
       static std::string convert(const item_handle &ref)
       {
           if (ref.empty())
               return {};
           return { ref.text().data(), ref.text().size() };
       }
   
       static int compare(const item_handle &ref, const std::string &value, bool icase)
       {
           return icase ? cif::icompare(ref.text(), value) : ref.text().compare(value);
       }
   };
   
   } // namespace cif
   
   namespace std
   {
   
   template <>
   struct tuple_size<::cif::item>
       : public std::integral_constant<std::size_t, 2>
   {
   };
   
   template <>
   struct tuple_element<0, ::cif::item>
   {
       using type = decltype(std::declval<::cif::item>().name());
   };
   
   template <>
   struct tuple_element<1, ::cif::item>
   {
       using type = decltype(std::declval<::cif::item>().value());
   };
   
   } // namespace std