LineNumberAttribute readLineNumberAttribute()

in folly/experimental/symbolizer/DwarfLineNumberVM.cpp [59:178]
113 lines of code
23 McCabe index (conditional complexity)

LineNumberAttribute readLineNumberAttribute(
    bool is64Bit,
    folly::StringPiece& format,
    folly::StringPiece& entries,
    folly::StringPiece debugStr,
    folly::StringPiece debugLineStr) {
  uint64_t contentTypeCode = readULEB(format);
  uint64_t formCode = readULEB(format);
  boost::variant<uint64_t, folly::StringPiece> attrValue;

  switch (contentTypeCode) {
    case DW_LNCT_path: {
      switch (formCode) {
        case DW_FORM_string:
          attrValue = readNullTerminated(entries);
          break;
        case DW_FORM_line_strp: {
          auto off = readOffset(entries, is64Bit);
          attrValue = getStringFromStringSection(debugLineStr, off);
        } break;
        case DW_FORM_strp:
          attrValue = getStringFromStringSection(
              debugStr, readOffset(entries, is64Bit));
          break;
        case DW_FORM_strp_sup:
          FOLLY_SAFE_CHECK(false, "Unexpected DW_FORM_strp_sup");
          break;
        default:
          FOLLY_SAFE_CHECK(
              false, "Unexpected form for DW_LNCT_path: ", formCode);
          break;
      }
    } break;

    case DW_LNCT_directory_index: {
      switch (formCode) {
        case DW_FORM_data1:
          attrValue = read<uint8_t>(entries);
          break;
        case DW_FORM_data2:
          attrValue = read<uint16_t>(entries);
          break;
        case DW_FORM_udata:
          attrValue = readULEB(entries);
          break;
        default:
          FOLLY_SAFE_CHECK(
              false, "Unexpected form for DW_LNCT_directory_index: ", formCode);
          break;
      }
    } break;

    case DW_LNCT_timestamp: {
      switch (formCode) {
        case DW_FORM_udata:
          attrValue = readULEB(entries);
          break;
        case DW_FORM_data4:
          attrValue = read<uint32_t>(entries);
          break;
        case DW_FORM_data8:
          attrValue = read<uint64_t>(entries);
          break;
        case DW_FORM_block:
          attrValue = readBytes(entries, readULEB(entries));
          break;
        default:
          FOLLY_SAFE_CHECK(
              false, "Unexpected form for DW_LNCT_timestamp: ", formCode);
      }
    } break;

    case DW_LNCT_size: {
      switch (formCode) {
        case DW_FORM_udata:
          attrValue = readULEB(entries);
          break;
        case DW_FORM_data1:
          attrValue = read<uint8_t>(entries);
          break;
        case DW_FORM_data2:
          attrValue = read<uint16_t>(entries);
          break;
        case DW_FORM_data4:
          attrValue = read<uint32_t>(entries);
          break;
        case DW_FORM_data8:
          attrValue = read<uint64_t>(entries);
          break;
        default:
          FOLLY_SAFE_CHECK(
              false, "Unexpected form for DW_LNCT_size: ", formCode);
          break;
      }
    } break;

    case DW_LNCT_MD5: {
      switch (formCode) {
        case DW_FORM_data16:
          attrValue = readBytes(entries, 16);
          break;
        default:
          FOLLY_SAFE_CHECK(
              false, "Unexpected form for DW_LNCT_MD5: ", formCode);
          break;
      }
    } break;

    default:
      // TODO: skip over vendor data as specified by the form instead.
      FOLLY_SAFE_CHECK(
          false, "Unexpected vendor content type code: ", contentTypeCode);
      break;
  }
  return {
      .contentTypeCode = contentTypeCode,
      .formCode = formCode,
      .attrValue = attrValue,
  };
}