parse()

template<typename T, typename Tag = parse_as::Default>
constexpr std::expected<T, ParseError> chesscxx::parse(std::string_view str, Tag tag = parse_as::Default{})

Parses an object of type T from a string view, expecting the entire string to be consumed.

Note

This function requires a specialization of Parser<T, const char*, Tag> to be defined. If no such specialization exists, the function is ill-formed and will not compile.

Template Parameters:

• T – The type to be parsed.

• Tag – Optional parsing tag to customize parsing behavior. Defaults to parse_as::Default.

Parameters:

• str – The string view to parse.

• tag – Parsing tag to control specific parsing rules.

Returns:

A std::expected containing the parsed value on success, or a ParseError on failure. Fails with ParseError::kExpectingEndOfString if any unparsed characters remain.

Examples

#include <chesscxx/game.h>
#include <chesscxx/parse.h>
#include <chesscxx/parse_error.h>

#include <print>
#include <string_view>

namespace {
void printErrorOrValue(auto parsed_value) {
  if (parsed_value) {
    std::println("{:fen}", parsed_value.value());
  } else {
    std::println("{}", parsed_value.error());
  }
}

void parseAsPgnAndPrint(std::string_view str) {
  auto parsed_game = chesscxx::parse<chesscxx::Game>(str);
  printErrorOrValue(parsed_game);
}

void parseAsFenAndPrint(std::string_view str) {
  auto parsed_game =
      chesscxx::parse<chesscxx::Game>(str, chesscxx::parse_as::Fen{});
  printErrorOrValue(parsed_game);
}
}  // namespace

auto main() -> int {
  std::println("{}", chesscxx::ParseError::kInvalidRank);
  std::println("{}\n", chesscxx::ParseError::kExpectingEndOfString);

  parseAsFenAndPrint(
      "rnbqkbnr/pppppppp/8/8/4P3/8/PPPP1PPP/RNBQKBNR b KQkq - 0 1");

  parseAsFenAndPrint(
      "rnbqkbnr/pppppppp/8/8/4P3/8/PPPP1PPP/RNBQKBNR b KQkq - 0 1 ");

  parseAsPgnAndPrint(
      "rnbqkbnr/pppppppp/8/8/4P3/8/PPPP1PPP/RNBQKBNR b KQkq e3 0 1");

  parseAsPgnAndPrint(
      "[FEN \"7k/8/6KN/8/7B/8/8/8 w - - 0 1\"]\n"
      "[FEN \"7k/8/6KN/8/7B/8/8/8 w - - 0 1\"]\n"
      "1. Bf6#");

  parseAsPgnAndPrint(
      "[FEN \"7k/8/6KN/8/7B/8/8/8 w - - 0 1\"]\n"
      "1. Bf6#");

  parseAsPgnAndPrint(
      "[]\n"
      "1. b3 e5 2. Bb2 d6 3. e3 Nf6 4. d4 exd4 5. Qxd4 Be7 6. Nf3 O-O 7. Nbd2 "
      "Nc6 8. Qc3 Nd5 9. Qxg7# 1-0");

  parseAsPgnAndPrint(
      "[Result \"1-0\"]\n"
      "1. b3 e5 2. Bb2 d6 3. e3 Nf6 4. d4 exd4 5. Qxd4 Be7 6. Nf3 O-O 7. Nbd2 "
      "Nc6 8. Qc3 Nd5 9. Qxg7# 1-0");
}

Output:

Invalid rank
Expecting end of string

rnbqkbnr/pppppppp/8/8/4P3/8/PPPP1PPP/RNBQKBNR b KQkq - 0 1
Expecting end of string
Invalid file
Duplicated fen tag
7k/8/5BKN/8/8/8/8/8 b - - 1 1
Invalid tag
r1bq1rk1/ppp1bpQp/2np4/3n4/8/1P2PN2/PBPN1PPP/R3KB1R b KQ - 0 9