Status ParseLine()

in cpp/src/arrow/csv/parser.cc [276:465]

• 160 lines of code
• 41 McCabe index (conditional complexity)

  Status ParseLine(ValueDescWriter* values_writer, DataWriter* parsed_writer,
                   const char* data, const char* data_end, bool is_final,
                   const char** out_data, const BulkFilter& bulk_filter) {
    int32_t num_cols = 0;
    char c;
    const auto start = data;

    DCHECK_GT(data_end, data);

    auto FinishField = [&]() { values_writer->FinishField(parsed_writer); };

    values_writer->BeginLine();
    parsed_writer->BeginLine();

    // The parsing state machine

    // Special case empty lines: do we start with a newline separator?
    c = *data;
    if (ARROW_PREDICT_FALSE(IsControlChar(c))) {
      if (c == '\r') {
        data++;
        if (data < data_end && *data == '\n') {
          data++;
        }
        goto EmptyLine;
      }
      if (c == '\n') {
        data++;
        goto EmptyLine;
      }
    }

  FieldStart:
    // At the start of a field
    if (*data == options_.delimiter) {
      // Empty cells are very common in some files, shortcut them
      values_writer->StartField(false /* quoted */);
      FinishField();
      ++data;
      ++num_cols;
      if (ARROW_PREDICT_FALSE(data == data_end)) {
        goto AbortLine;
      }
      goto FieldStart;
    }

    // Quoting is only recognized at start of field
    if (SpecializedOptions::quoting &&
        ARROW_PREDICT_FALSE(*data == options_.quote_char)) {
      ++data;
      values_writer->StartField(true /* quoted */);
      goto InQuotedField;
    } else {
      values_writer->StartField(false /* quoted */);
      goto InField;
    }

  InField:
    // Inside a non-quoted part of a field
    if (UseBulkFilter) {
      const char* bulk_end = RunBulkFilter(parsed_writer, data, data_end, bulk_filter);
      if (ARROW_PREDICT_FALSE(bulk_end == nullptr)) {
        if (is_final) {
          data = data_end;
        }
        goto AbortLine;
      }
      data = bulk_end;
    } else {
      if (ARROW_PREDICT_FALSE(data == data_end)) {
        goto AbortLine;
      }
    }

    c = *data++;
    if (SpecializedOptions::escaping && ARROW_PREDICT_FALSE(c == options_.escape_char)) {
      if (ARROW_PREDICT_FALSE(data == data_end)) {
        goto AbortLine;
      }
      c = *data++;
      parsed_writer->PushFieldChar(c);
      goto InField;
    }
    if (ARROW_PREDICT_FALSE(c == options_.delimiter)) {
      goto FieldEnd;
    }
    if (ARROW_PREDICT_FALSE(IsControlChar(c))) {
      if (c == '\r') {
        // In the middle of a newline separator?
        if (ARROW_PREDICT_TRUE(data < data_end) && *data == '\n') {
          data++;
        }
        goto LineEnd;
      }
      if (c == '\n') {
        goto LineEnd;
      }
    }
    parsed_writer->PushFieldChar(c);
    goto InField;

  InQuotedField:
    // Inside a quoted part of a field
    if (UseBulkFilter) {
      const char* bulk_end = RunBulkFilter(parsed_writer, data, data_end, bulk_filter);
      if (ARROW_PREDICT_FALSE(bulk_end == nullptr)) {
        if (is_final) {
          data = data_end;
        }
        goto AbortLine;
      }
      data = bulk_end;
    } else {
      if (ARROW_PREDICT_FALSE(data == data_end)) {
        goto AbortLine;
      }
    }
    c = *data++;
    if (SpecializedOptions::escaping && ARROW_PREDICT_FALSE(c == options_.escape_char)) {
      if (ARROW_PREDICT_FALSE(data == data_end)) {
        goto AbortLine;
      }
      c = *data++;
      parsed_writer->PushFieldChar(c);
      goto InQuotedField;
    }
    if (ARROW_PREDICT_FALSE(c == options_.quote_char)) {
      if (options_.double_quote && ARROW_PREDICT_TRUE(data < data_end) &&
          ARROW_PREDICT_FALSE(*data == options_.quote_char)) {
        // Double-quoting
        ++data;
      } else {
        // End of single-quoting
        goto InField;
      }
    }
    parsed_writer->PushFieldChar(c);
    goto InQuotedField;

  FieldEnd:
    // At the end of a field
    FinishField();
    ++num_cols;
    if (ARROW_PREDICT_FALSE(data == data_end)) {
      goto AbortLine;
    }
    goto FieldStart;

  LineEnd:
    // At the end of line
    FinishField();
    ++num_cols;
    if (ARROW_PREDICT_FALSE(num_cols != batch_.num_cols_)) {
      if (batch_.num_cols_ == -1) {
        batch_.num_cols_ = num_cols;
      } else {
        return HandleInvalidRow(values_writer, parsed_writer, start, data, num_cols,
                                out_data);
      }
    }
    ++batch_.num_rows_;
    *out_data = data;
    return Status::OK();

  AbortLine:
    // Not a full line except perhaps if in final block
    if (is_final) {
      goto LineEnd;
    }
    // Truncated line at end of block, rewind parsed state
    values_writer->RollbackLine();
    parsed_writer->RollbackLine();
    return Status::OK();

  EmptyLine:
    if (!options_.ignore_empty_lines) {
      if (batch_.num_cols_ == -1) {
        // Consider as single value
        batch_.num_cols_ = 1;
      }
      // Record as row of empty (null?) values
      while (num_cols++ < batch_.num_cols_) {
        values_writer->StartField(false /* quoted */);
        FinishField();
      }
      ++batch_.num_rows_;
    }
    *out_data = data;
    return Status::OK();
  }