common.hpp

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/*
 
Copyright 2025 Matthew Tolman
 
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
 
   http://www.apache.org/licenses/LICENSE-2.0
 
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
 
*/
 
#ifndef MTCORE_CSV_COMMON_HPP
#define MTCORE_CSV_COMMON_HPP
 
#include "mtcore/colls/optional.hpp"
 
namespace mtcore::csv {
  static constexpr u64 chunkSize = 64;
 
  enum class ReadErrorCode {
    INTERNAL_LIMIT_REACHED,
    UNEXPECTED_EOF,
    INVALID_LINE_ENDING,
    QUOTE_PREMATURELY_TERMINATED,
    UNEXPECTED_QUOTE,
 
    END_OF_FILE,
    ALLOCATION_FAILED,
    SIZE_EXCEEDED,
  };
 
  struct ReadError {
    ReadErrorCode code;
    size_t pos;
 
    bool operator==(const ReadError &o) const { return code == o.code && pos == o.pos; }
 
    bool operator==(const ReadErrorCode &o) const { return code == o; }
 
    bool operator!=(const ReadError &o) const { return !(*this == o); }
 
    bool operator!=(const ReadErrorCode &o) const { return !(*this == o); }
 
    static const ReadError END_OF_FILE;
    static const ReadError ALLOCATION_FAILED;
    static const ReadError SIZE_EXCEEDED;
 
    template<WriterImpl WI>
    Result<size_t, typename io::Writer<WI>::ErrType> fmt(io::Writer<WI> &writer, const io::FormatOptions &) {
      const char *codeStr = "";
      switch (code) {
        case ReadErrorCode::INTERNAL_LIMIT_REACHED:
          codeStr = "INTERNAL_LIMIT_REACHED";
          break;
        case ReadErrorCode::UNEXPECTED_EOF:
          codeStr = "UNEXPECTED_EOF";
          break;
        case ReadErrorCode::INVALID_LINE_ENDING:
          codeStr = "INVALID_LINE_ENDING";
          break;
        case ReadErrorCode::QUOTE_PREMATURELY_TERMINATED:
          codeStr = "QUOTE_PREMATURELY_TERMINATED";
          break;
        case ReadErrorCode::UNEXPECTED_QUOTE:
          codeStr = "UNEXPECTED_QUOTE";
          break;
        case ReadErrorCode::END_OF_FILE:
          codeStr = "END_OF_FILE";
          break;
        case ReadErrorCode::ALLOCATION_FAILED:
          codeStr = "ALLOCATION_FAILED";
          break;
        case ReadErrorCode::SIZE_EXCEEDED:
          codeStr = "SIZE_EXCEEDED";
          break;
      }
 
      return io::print(writer, "ReadError\\{{}, {}\\}", codeStr, pos);
    }
  };

  struct Options {
    Optional<char> cr        = '\r';
    char lf                  = '\n';
    char quote               = '"';
    char sep                 = ',';
    size_t internalIterLimit = 65536;
 
    [[nodiscard]] bool valid() const;
  };
 
  namespace common {
    [[nodiscard]] u64 quoted_regions(u64 m);
 
    Slice<const char> unquote_quoted(Slice<const char> data, Options opts);
 
    template<WriterImpl WI>
    Result<size_t, typename io::Writer<WI>::ErrType> decode(io::Writer<WI> &writer, Slice<const char> field,
                                                            const Options options = {}) {
      ensure(options.valid());
      const auto quote = options.quote;
      if (field.len < 2 || field[0] != quote) {
        return writer.write_all(field);
      }
 
      const auto data = unquote_quoted(field, options);
      Optional<char> nextChar;
      Optional<char> curChar;
      size_t ni      = 1;
      size_t written = 0;
 
      if (0 < data.len) {
        curChar = data[0];
        if (1 < data.len) {
          nextChar = data[1];
        }
      }
 
      char c;
      while (curChar.copy_if_present(c)) {
        mtdefer {
          ni++;
          curChar = nextChar;
          if (ni < data.len) {
            nextChar = data[ni];
          }
          else {
            nextChar = nullopt;
          }
        };
 
        if (c != quote) {
          if (auto r = writer.write(c); r.is_error()) {
            return r.error();
          }
          ++written;
          continue;
        }
 
        if (nextChar == quote) {
          mtdefer {
            ni += 1;
            curChar = nextChar;
            if (ni < data.len) {
              nextChar = data[ni];
            }
            else {
              nextChar = nullopt;
            }
          };
 
          if (auto r = writer.write(c); r.is_error()) {
            return r.error();
          }
          ++written;
        }
      }
 
      return success(written);
    }
  }  // namespace common
 
  [[nodiscard]] u64 bit_match_64(char ch, Slice<const char> s);
}  // namespace mtcore::csv
 
#endif  // MTCORE_CSV_COMMON_HPP