path: root/src/openvic-dataloader/v2script/SimpleGrammar.hpp

#pragma once

#include <openvic-dataloader/NodeLocation.hpp>
#include <openvic-dataloader/v2script/AbstractSyntaxTree.hpp>

#include <lexy/callback.hpp>
#include <lexy/dsl.hpp>
#include <lexy/encoding.hpp>
#include <lexy/input/base.hpp>
#include <lexy/input/buffer.hpp>
#include <lexy/lexeme.hpp>

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

// Grammar Definitions //
/* REQUIREMENTS:
 * DAT-626
 * DAT-627
 * DAT-628
 * DAT-636
 * DAT-641
 * DAT-642
 * DAT-643
 */
namespace ovdl::v2script::grammar {
   template<typename T>
   constexpr auto construct = dsl::construct<T>;
   template<typename T, bool DisableEmpty = false, typename ListType = ast::AssignStatementList>
   constexpr auto construct_list = dsl::construct_list<T, ListType, DisableEmpty>;

   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();
      }
   };

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

   struct ParseOptions {
      /// @brief Makes string parsing avoid string escapes
      bool NoStringEscape;
   };

   static constexpr auto NoStringEscapeOption = ParseOptions { true };
   static constexpr auto StringEscapeOption = ParseOptions { false };

   /* REQUIREMENTS: DAT-630 */
   static constexpr auto whitespace_specifier = lexy::dsl::ascii::blank / lexy::dsl::ascii::newline;
   /* REQUIREMENTS: DAT-631 */
   static constexpr auto comment_specifier = LEXY_LIT("#") >> lexy::dsl::until(lexy::dsl::newline).or_eof();

   static constexpr auto ascii = lexy::dsl::ascii::alpha_digit_underscore / LEXY_ASCII_ONE_OF("+:@%&'-.\\");

   /* REQUIREMENTS:
    * DAT-632
    * DAT-635
    */
   static constexpr auto windows_1252_data_specifier =
      ascii /
      lexy::dsl::lit_b<0x8A> / lexy::dsl::lit_b<0x8C> / lexy::dsl::lit_b<0x8E> /
      lexy::dsl::lit_b<0x92> / lexy::dsl::lit_b<0x97> / lexy::dsl::lit_b<0x9A> / lexy::dsl::lit_b<0x9C> /
      dsl::lit_b_range<0x9E, 0x9F> /
      dsl::lit_b_range<0xC0, 0xD6> /
      dsl::lit_b_range<0xD8, 0xF6> /
      dsl::lit_b_range<0xF8, 0xFF>;

   static constexpr auto windows_1251_data_specifier_additions =
      dsl::lit_b_range<0x80, 0x81> / lexy::dsl::lit_b<0x83> / lexy::dsl::lit_b<0x8D> / lexy::dsl::lit_b<0x8F> /
      lexy::dsl::lit_b<0x90> / lexy::dsl::lit_b<0x9D> / lexy::dsl::lit_b<0x9F> /
      dsl::lit_b_range<0xA1, 0xA3> / lexy::dsl::lit_b<0xA5> / lexy::dsl::lit_b<0xA8> / lexy::dsl::lit_b<0xAA> /
      lexy::dsl::lit_b<0xAF> /
      dsl::lit_b_range<0xB2, 0xB4> / lexy::dsl::lit_b<0xB8> / lexy::dsl::lit_b<0xBA> /
      dsl::lit_b_range<0xBC, 0xBF> /
      lexy::dsl::lit_b<0xD7> / lexy::dsl::lit_b<0xF7>;

   static constexpr auto data_specifier = windows_1252_data_specifier / windows_1251_data_specifier_additions;

   static constexpr auto data_char_class = LEXY_CHAR_CLASS("DataSpecifier", data_specifier);

   static constexpr auto utf_data_specifier = lexy::dsl::unicode::xid_continue / LEXY_ASCII_ONE_OF("+:@%&'-.\\");

   static constexpr auto utf_char_class = LEXY_CHAR_CLASS("DataSpecifier", utf_data_specifier);

   static 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');

   static constexpr auto id = lexy::dsl::identifier(ascii);

   template<ParseOptions Options>
   struct SimpleGrammar {
      struct StatementListBlock;

      struct Identifier : lexy::scan_production<ast::IdentifierValue*>,
                     lexy::token_production {

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

            std::basic_string<char_type> value_result;

            auto content_begin = scanner.position();
            do {
               if constexpr (std::same_as<encoding, lexy::default_encoding> || std::same_as<encoding, lexy::byte_encoding>) {
                  if (lexy::scan_result<lexy::lexeme<Reader>> ascii_result; scanner.branch(ascii_result, lexy::dsl::identifier(ascii))) {
                     if (!scanner.peek(data_char_class)) {
                        if (ascii_result.value().size() == 0) {
                           return lexy::scan_failed;
                        }

                        auto value = state.ast().intern(ascii_result.value());
                        return state.ast().template create<ast::IdentifierValue>(ovdl::NodeLocation::make_from(content_begin, scanner.position()), value);
                     }

                     value_result.append(ascii_result.value().begin(), ascii_result.value().end());
                     continue;
                  }

                  char_type char_array[] { *scanner.position(), char_type {} };
                  auto input = lexy::range_input(&char_array[0], &char_array[1]);
                  auto reader = input.reader();
                  convert::map_value val = convert::try_parse_map(state.encoding(), reader);

                  if (val.is_invalid()) {
                     ConvertErrorHandler::on_invalid_character(state, reader);
                     continue;
                  }

                  if (!val.is_pass()) {
                     // non-pass characters are not valid ascii and are mapped to utf8 values
                     value_result.append(val._value);
                     scanner.parse(data_char_class);
                  } else {
                     break;
                  }
               } else {
                  auto lexeme_result = scanner.template parse<lexy::lexeme<Reader>>(lexy::dsl::identifier(utf_char_class));
                  if (lexeme_result) {
                     if (lexeme_result.value().size() == 0) {
                        return lexy::scan_failed;
                     }

                     auto value = state.ast().intern(lexeme_result.value());
                     return state.ast().template create<ast::IdentifierValue>(ovdl::NodeLocation::make_from(content_begin, scanner.position()), value);
                  }
               }
            } while (scanner);
            auto content_end = scanner.position();

            if (value_result.empty()) {
               return lexy::scan_failed;
            }

            auto value = state.ast().intern(value_result);
            return state.ast().template create<ast::IdentifierValue>(ovdl::NodeLocation::make_from(content_begin, content_end), value);
         }

         static constexpr auto rule = dsl::peek(data_char_class, utf_char_class) >> lexy::dsl::scan;
      };

      /* REQUIREMENTS:
       * DAT-633
       * DAT-634
       */
      struct StringExpression : lexy::scan_production<ast::StringValue*>,
                          lexy::token_production {

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

            constexpr auto rule = [] {
               if constexpr (Options.NoStringEscape) {
                  auto c = [] {
                     if constexpr (std::same_as<encoding, lexy::default_encoding> || std::same_as<encoding, lexy::byte_encoding>) {
                        return dsl::lit_b_range<0x01, 0xFF>;
                     } else {
                        return lexy::dsl::unicode::character;
                     }
                  }();
                  return lexy::dsl::quoted(c);
               } else {
                  // Arbitrary code points that aren't control characters.
                  auto c = [] {
                     if constexpr (std::same_as<encoding, lexy::default_encoding> || std::same_as<encoding, lexy::byte_encoding>) {
                        return dsl::lit_b_range<0x20, 0xFF> - lexy::dsl::ascii::control;
                     } else {
                        return -lexy::dsl::unicode::control;
                     }
                  }();

                  // Escape sequences start with a backlash.
                  // They either map one of the symbols,
                  // or a Unicode code point of the form uXXXX.
                  auto escape = lexy::dsl::backslash_escape //
                                .symbol<escaped_symbols>();
                  return lexy::dsl::quoted(c, escape);
               }
            }();

            auto begin = scanner.position();
            lexy::scan_result<std::string> str_result;
            scanner.parse(str_result, rule);
            if (!scanner || !str_result)
               return lexy::scan_failed;
            auto end = scanner.position();
            auto str = str_result.value();
            auto value = state.ast().intern(str.data(), str.size());
            return state.ast().template create<ast::StringValue>(ovdl::NodeLocation::make_from(begin, end), value);
         }

         static constexpr auto rule = lexy::dsl::peek(lexy::dsl::quoted.open()) >> lexy::dsl::scan;
         static constexpr auto value = convert_as_string<std::string> >> lexy::forward<ast::StringValue*>;
      };

      /* REQUIREMENTS: DAT-638 */
      struct ValueExpression {
         static constexpr auto rule = lexy::dsl::p<Identifier> | lexy::dsl::p<StringExpression>;
         static constexpr auto value = lexy::forward<ast::Value*>;
      };

      struct SimpleAssignmentStatement {
         static constexpr auto rule = [] {
            auto right_brace = lexy::dsl::lit_c<'}'>;

            auto value_expression = lexy::dsl::p<ValueExpression>;
            auto statement_list_expression = lexy::dsl::recurse_branch<StatementListBlock>;

            auto rhs_recover = lexy::dsl::recover(value_expression, statement_list_expression).limit(right_brace);
            auto rhs_try = lexy::dsl::try_(value_expression | statement_list_expression, rhs_recover);

            auto identifier =
               dsl::p<Identifier> >>
               (lexy::dsl::equal_sign >> rhs_try);

            auto recover = lexy::dsl::recover(identifier).limit(right_brace);
            return lexy::dsl::try_(identifier, recover);
         }();

         static constexpr auto value = construct<ast::AssignStatement>;
      };

      /* REQUIREMENTS: DAT-639 */
      struct AssignmentStatement {
         static constexpr auto rule = [] {
            auto right_brace = lexy::dsl::lit_c<'}'>;

            auto value_expression = lexy::dsl::p<ValueExpression>;
            auto statement_list_expression = lexy::dsl::recurse_branch<StatementListBlock>;

            auto rhs_recover = lexy::dsl::recover(value_expression, statement_list_expression).limit(right_brace);
            auto rhs_try = lexy::dsl::try_(value_expression | statement_list_expression, rhs_recover);

            auto identifier =
               dsl::p<Identifier> >>
               (lexy::dsl::equal_sign >>
                     rhs_try |
                  lexy::dsl::else_ >> lexy::dsl::return_);

            auto string_expression = dsl::p<StringExpression>;
            auto statement_list = lexy::dsl::recurse_branch<StatementListBlock>;

            return identifier | string_expression | statement_list;
         }();

         static constexpr auto value = dsl::callback<ast::Statement*>(
            [](detail::IsParseState auto& state, const char* pos, ast::IdentifierValue* name, ast::Value* initializer) -> ast::AssignStatement* {
               return state.ast().template create<ast::AssignStatement>(pos, name, initializer);
            },
            [](detail::IsParseState auto& state, bool&, const char* pos, ast::IdentifierValue* name, ast::Value* initializer) {
               return state.ast().template create<ast::AssignStatement>(pos, name, initializer);
            },
            [](detail::IsParseState auto& state, bool&, bool&, const char* pos, ast::IdentifierValue* name, ast::Value* initializer) {
               return state.ast().template create<ast::AssignStatement>(pos, name, initializer);
            },
            [](detail::IsParseState auto& state, bool&, bool&, const char* pos, ast::Value* name) {
               return state.ast().template create<ast::ValueStatement>(pos, name);
            },
            [](detail::IsParseState auto& state, const char* pos, ast::Value* left, lexy::nullopt = {}) {
               return state.ast().template create<ast::ValueStatement>(pos, left);
            },
            [](detail::IsParseState auto& state, bool&, const char* pos, ast::Value* left, lexy::nullopt = {}) {
               return state.ast().template create<ast::ValueStatement>(pos, left);
            },
            [](detail::IsParseState auto& state, ast::Value* left) -> ast::ValueStatement* {
               if (left == nullptr) { // May no longer be neccessary
                  return nullptr;
               }
               return state.ast().template create<ast::ValueStatement>(state.ast().location_of(left), left);
            },
            [](detail::IsParseState auto& state, bool&, ast::Value* left) -> ast::ValueStatement* {
               if (left == nullptr) { // May no longer be neccessary
                  return nullptr;
               }
               return state.ast().template create<ast::ValueStatement>(state.ast().location_of(left), left);
            });
      };

      /* REQUIREMENTS: DAT-640 */
      struct StatementListBlock {
         static constexpr auto rule = [] {
            auto right_brace = lexy::dsl::lit_c<'}'>;

            auto assign_statement = lexy::dsl::recurse_branch<AssignmentStatement>;

            auto assign_try = lexy::dsl::try_(assign_statement, lexy::dsl::nullopt);
            auto assign_opt = lexy::dsl::opt(lexy::dsl::list(assign_try));

            auto curly_bracket = dsl::curly_bracketed(assign_opt + lexy::dsl::opt(lexy::dsl::semicolon));

            return curly_bracket;
         }();

         static constexpr auto value =
            lexy::as_list<ast::StatementList> >>
            dsl::callback<ast::ListValue*>(
               [](detail::IsParseState auto& state, const char* begin, auto&& list, const char* end) {
                  if constexpr (std::is_same_v<std::decay_t<decltype(list)>, lexy::nullopt>) {
                     return state.ast().template create<ast::ListValue>(ovdl::NodeLocation::make_from(begin, end));
                  } else {
                     return state.ast().template create<ast::ListValue>(ovdl::NodeLocation::make_from(begin, end), LEXY_MOV(list));
                  }
               },
               [](detail::IsParseState auto& state, const char* begin, auto&& list, auto&& semicolon, const char* end) {
                  if constexpr (std::is_same_v<std::decay_t<decltype(list)>, lexy::nullopt>) {
                     return state.ast().template create<ast::ListValue>(ovdl::NodeLocation::make_from(begin, end));
                  } else {
                     return state.ast().template create<ast::ListValue>(ovdl::NodeLocation::make_from(begin, end), LEXY_MOV(list));
                  }
               });
      };
   };

   template<ParseOptions Options>
   using StringExpression = typename SimpleGrammar<Options>::StringExpression;

   template<ParseOptions Options>
   using Identifier = typename SimpleGrammar<Options>::Identifier;

   template<ParseOptions Options>
   using SAssignStatement = typename SimpleGrammar<Options>::SimpleAssignmentStatement;

   template<ovdl::detail::string_literal Keyword, auto Production, auto Value = dsl::default_kw_value<ast::IdentifierValue, Keyword>>
   using keyword_rule = dsl::keyword_rule<
      id,
      ast::AssignStatement,
      Keyword, Production, Value>;

   template<ovdl::detail::string_literal Keyword, auto Production, auto Value = dsl::default_kw_value<ast::IdentifierValue, Keyword>>
   using fkeyword_rule = dsl::fkeyword_rule<
      id,
      ast::AssignStatement,
      Keyword, Production, Value>;

   template<ParseOptions Options>
   struct BasicFile {
      // Allow arbitrary spaces between individual tokens.
      static constexpr auto whitespace = whitespace_specifier | comment_specifier;

      static constexpr auto rule = lexy::dsl::position(
         lexy::dsl::terminator(lexy::dsl::eof)
            .opt_list(lexy::dsl::p<typename SimpleGrammar<Options>::AssignmentStatement>));

      static constexpr auto value = lexy::as_list<ast::StatementList> >> construct<ast::FileTree>;
   };

   using File = BasicFile<NoStringEscapeOption>;
}