Method applyMap

bolt/expression/CastExpr.cpp:80–181

  }()

VectorPtr CastExpr::applyMap(
    const SelectivityVector& rows,
    const MapVector* input,
    exec::EvalCtx& context,
    const MapType& fromType,
    const MapType& toType) {
  // Cast input keys/values vector to output keys/values vector using their
  // element selectivity vector

  // Initialize nested rows
  auto mapKeys = input->mapKeys();
  auto mapValues = input->mapValues();

  SelectivityVector nestedRows;
  BufferPtr elementToTopLevelRows;
  if (fromType.keyType() != toType.keyType() ||
      fromType.valueType() != toType.valueType()) {
    nestedRows = functions::toElementRows(mapKeys->size(), rows, input);
    elementToTopLevelRows = functions::getElementToTopLevelRows(
        mapKeys->size(), rows, input, context.pool());
  }

  ErrorVectorPtr oldErrors;
  context.swapErrors(oldErrors);

  // Cast keys
  VectorPtr newMapKeys;
  if (fromType.keyType() == toType.keyType()) {
    newMapKeys = input->mapKeys();
  } else {
    {
      ScopedVarSetter holder(&inTopLevel, false);
      apply(
          nestedRows,
          mapKeys,
          context,
          fromType.keyType(),
          toType.keyType(),
          newMapKeys);
    }
  }

  // Cast values
  VectorPtr newMapValues;
  if (fromType.valueType() == toType.valueType()) {
    newMapValues = mapValues;
  } else {
    {
      ScopedVarSetter holder(&inTopLevel, false);
      apply(
          nestedRows,
          mapValues,
          context,
          fromType.valueType(),
          toType.valueType(),
          newMapValues);
    }
  }