path: root/src/openvic-dataloader/csv/CsvGrammar.hpp

#pragma once

#include <initializer_list>
#include <string>
#include <tuple>
#include <type_traits>
#include <vector>

#include <openvic-dataloader/csv/LineObject.hpp>
#include <openvic-dataloader/csv/Parser.hpp>

#include <lexy/_detail/config.hpp>
#include <lexy/callback.hpp>
#include <lexy/dsl.hpp>
#include <lexy/encoding.hpp>

#include "detail/Convert.hpp"
#include "detail/InternalConcepts.hpp"
#include "detail/dsl.hpp"

// Grammar Definitions //
namespace ovdl::csv::grammar {
   struct ParseOptions {
      /// @brief Seperator character
      char SepChar;
      /// @brief Determines whether StringValue is supported
      bool SupportStrings;
      /// @brief Paradox-style localization escape characters
      /// @note Is ignored if SupportStrings is true
      char EscapeChar;
   };

   struct ConvertErrorHandler {
      static constexpr void on_invalid_character(detail::IsStateType auto& state, auto reader) {
         state.logger().warning("invalid character value '{}' found", static_cast<int>(reader.peek())) //
            .primary(BasicNodeLocation { reader.position() }, "here")
            .finish();
      }
   };

   constexpr bool IsUtf8(auto encoding) {
      return std::same_as<std::decay_t<decltype(encoding)>, lexy::utf8_char_encoding>;
   }

   template<ParseOptions Options, typename String>
   constexpr auto convert_as_string = convert::convert_as_string<
      String,
      ConvertErrorHandler>;

   constexpr auto ansi_character = lexy::dsl::ascii::character / dsl::lit_b_range<0x80, 0xFF>;
   constexpr auto ansi_control =
      lexy::dsl::ascii::control /
      lexy::dsl::lit_b<0x81> / lexy::dsl::lit_b<0x8D> / lexy::dsl::lit_b<0x8F> /
      lexy::dsl::lit_b<0x90> / lexy::dsl::lit_b<0x9D>;

   constexpr auto utf_character = lexy::dsl::unicode::character;
   constexpr auto utf_control = lexy::dsl::unicode::control;

   constexpr auto escaped_symbols = lexy::symbol_table<char> //
                               .map<'"'>('"')
                               .map<'\''>('\'')
                               .map<'\\'>('\\')
                               .map<'/'>('/')
                               .map<'b'>('\b')
                               .map<'f'>('\f')
                               .map<'n'>('\n')
                               .map<'r'>('\r')
                               .map<'t'>('\t');

   constexpr auto escaped_quote = lexy::symbol_table<char> //
                              .map<'"'>('"');

   constexpr auto escaped_newline = lexy::symbol_table<char> //
                               .map<'n'>('\n');

   template<ParseOptions Options>
   struct CsvGrammar {
      struct StringValue : lexy::scan_production<std::string>,
                      lexy::token_production {

         template<typename Context, typename Reader>
         static constexpr scan_result scan(lexy::rule_scanner<Context, Reader>& scanner, detail::IsFileParseState auto& state) {
            using encoding = typename Reader::encoding;

            constexpr auto rule = [] {
               // Arbitrary code points
               auto c = [] {
                  if constexpr (std::same_as<encoding, lexy::default_encoding> || std::same_as<encoding, lexy::byte_encoding>) {
                     return ansi_character - ansi_control;
                  } else {
                     return utf_character - utf_control;
                  }
               }();

               auto back_escape = lexy::dsl::backslash_escape //
                                 .symbol<escaped_symbols>();

               auto quote_escape = lexy::dsl::escape(lexy::dsl::lit_c<'"'>) //
                                 .template symbol<escaped_quote>();

               return lexy::dsl::delimited(lexy::dsl::lit_c<'"'>, lexy::dsl::not_followed_by(lexy::dsl::lit_c<'"'>, lexy::dsl::lit_c<'"'>))(c, back_escape, quote_escape);
            }();

            lexy::scan_result<std::string> str_result = scanner.template parse<std::string>(rule);
            if (!scanner || !str_result)
               return lexy::scan_failed;
            return str_result.value();
         }

         static constexpr auto rule = lexy::dsl::peek(lexy::dsl::lit_c<'"'>) >> lexy::dsl::scan;

         static constexpr auto value = convert_as_string<Options, std::string> >> lexy::forward<std::string>;
      };

      struct PlainValue : lexy::scan_production<std::string>,
                     lexy::token_production {

         template<auto character>
         static constexpr auto _escape_check = character - (lexy::dsl::lit_b<Options.SepChar> / lexy::dsl::ascii::newline);

         struct Backslash {
            static constexpr auto rule = LEXY_LIT("\\n");
            static constexpr auto value = lexy::constant('\n');
         };

         template<typename Context, typename Reader>
         static constexpr scan_result scan(lexy::rule_scanner<Context, Reader>& scanner, detail::IsFileParseState auto& state) {
            using encoding = typename Reader::encoding;

            constexpr auto rule = [] {
               constexpr auto character = [] {
                  if constexpr (std::same_as<encoding, lexy::default_encoding> || std::same_as<encoding, lexy::byte_encoding>) {
                     return ansi_character;
                  } else {
                     return utf_character;
                  }
               }();

               if constexpr (Options.SupportStrings) {
                  return lexy::dsl::identifier(character - (lexy::dsl::lit_b<Options.SepChar> / lexy::dsl::ascii::newline));
               } else {
                  constexpr auto backslash = lexy::dsl::lit_b<'\\'>;

                  constexpr auto escape_check_char = _escape_check<character>;
                  constexpr auto escape_rule = lexy::dsl::p<Backslash>;

                  return lexy::dsl::list(
                     lexy::dsl::identifier(escape_check_char - backslash) |
                     escape_rule |
                     lexy::dsl::capture(escape_check_char) //
                  );
               }
            }();

            if constexpr (Options.SupportStrings) {
               auto lexeme_result = scanner.template parse<lexy::lexeme<Reader>>(rule);
               if (!scanner || !lexeme_result)
                  return lexy::scan_failed;
               return std::string { lexeme_result.value().begin(), lexeme_result.value().end() };
            } else {
               lexy::scan_result<std::string> str_result = scanner.template parse<std::string>(rule);
               if (!scanner || !str_result)
                  return lexy::scan_failed;
               return str_result.value();
            }
         }

         static constexpr auto rule =
            dsl::peek(
               _escape_check<ansi_character>,
               _escape_check<utf_character>) >>
            lexy::dsl::scan;

         static constexpr auto value = convert_as_string<Options, std::string> >> lexy::forward<std::string>;
      };

      struct Value {
         static constexpr auto rule = [] {
            if constexpr (Options.SupportStrings) {
               return lexy::dsl::p<StringValue> | lexy::dsl::p<PlainValue>;
            } else {
               return lexy::dsl::p<PlainValue>;
            }
         }();
         static constexpr auto value = lexy::forward<std::string>;
      };

      struct SepConst {
         static constexpr auto rule = lexy::dsl::lit_b<Options.SepChar>;
         static constexpr auto value = lexy::constant(1);
      };

      struct Seperator {
         static constexpr auto rule = lexy::dsl::list(lexy::dsl::p<SepConst>);
         static constexpr auto value = lexy::count;
      };

      struct LineEnd {
         static constexpr auto rule = lexy::dsl::list(lexy::dsl::p<Value>, lexy::dsl::trailing_sep(lexy::dsl::p<Seperator>));
         static constexpr auto value = lexy::fold_inplace<ovdl::csv::LineObject>(
            std::initializer_list<ovdl::csv::LineObject::value_type> {},
            [](ovdl::csv::LineObject& result, std::size_t&& arg) {
               // Count seperators, adds to previous value, making it a position
               using position_type = ovdl::csv::LineObject::position_type;
               result.emplace_back(static_cast<position_type>(arg + result.back().first), "");
            },
            [](ovdl::csv::LineObject& result, std::string&& arg) {
               if (result.empty()) {
                  result.emplace_back(0u, LEXY_MOV(arg));
               } else {
                  auto& [pos, value] = result.back();
                  value = LEXY_MOV(arg);
               }
            });
      };

      struct Line {
         static constexpr auto suffix_setter(ovdl::csv::LineObject& line) {
            auto& [position, value] = line.back();
            if (value.empty()) {
               line.set_suffix_end(position);
               line.pop_back();
            } else {
               line.set_suffix_end(position + 1);
            }
         };

         static constexpr auto rule = lexy::dsl::p<LineEnd> | lexy::dsl::p<Seperator> >> lexy::dsl::opt(lexy::dsl::p<LineEnd>);
         static constexpr auto value =
            lexy::callback<ovdl::csv::LineObject>(
               [](ovdl::csv::LineObject&& line) {
                  suffix_setter(line);
                  return LEXY_MOV(line);
               },
               [](std::size_t prefix_count, ovdl::csv::LineObject&& line) {
                  line.set_prefix_end(prefix_count);
                  // position needs to be adjusted to prefix
                  for (auto& [position, value] : line) {
                     position += prefix_count;
                  }
                  suffix_setter(line);
                  return LEXY_MOV(line);
               },
               [](std::size_t suffix_count, lexy::nullopt = {}) {
                  return ovdl::csv::LineObject(0, {}, suffix_count + 1);
               });
      };
   };

   template<ParseOptions Options>
   struct File {
      static constexpr auto rule = lexy::dsl::terminator(lexy::dsl::eof).opt_list(lexy::dsl::p<typename CsvGrammar<Options>::Line> | lexy::dsl::newline);

      static constexpr auto value = lexy::as_list<std::vector<ovdl::csv::LineObject>>;
   };

   using CommaFile = File<ParseOptions { ',', false, '$' }>;
   using ColonFile = File<ParseOptions { ':', false, '$' }>;
   using SemiColonFile = File<ParseOptions { ';', false, '$' }>;
   using TabFile = File<ParseOptions { '\t', false, '$' }>;
   using BarFile = File<ParseOptions { '|', false, '$' }>;

   namespace strings {
      using CommaFile = File<ParseOptions { ',', true, '$' }>;
      using ColonFile = File<ParseOptions { ':', true, '$' }>;
      using SemiColonFile = File<ParseOptions { ';', true, '$' }>;
      using TabFile = File<ParseOptions { '\t', true, '$' }>;
      using BarFile = File<ParseOptions { '|', true, '$' }>;
   }
}