[C++] Add a VisitIntegerType helper

Describe the enhancement requested

In visit_type_inline.h we have a VisitType that dispatches all existing data types to a generic callable (presumably a lambda or template function).

It would be useful to have a similar VisitIntegerType helper that assumes its input is an integer type. This would help implementing helpers for dictionary indices, take indices, etc.

For example this snippet could be reimplemented more tersely using said helper:

arrow/cpp/src/arrow/util/dict_util.cc

Lines 61 to 79 in 154962c

    
           const auto& dict_array_type = internal::checked_cast<const DictionaryType&>(*span.type); 
        
           switch (dict_array_type.index_type()->id()) { 
        
             case Type::UINT8: 
        
               return LogicalNullCount<UInt8Type>(span); 
        
             case Type::INT8: 
        
               return LogicalNullCount<Int8Type>(span); 
        
             case Type::UINT16: 
        
               return LogicalNullCount<UInt16Type>(span); 
        
             case Type::INT16: 
        
               return LogicalNullCount<Int16Type>(span); 
        
             case Type::UINT32: 
        
               return LogicalNullCount<UInt32Type>(span); 
        
             case Type::INT32: 
        
               return LogicalNullCount<Int32Type>(span); 
        
             case Type::UINT64: 
        
               return LogicalNullCount<UInt64Type>(span); 
        
             default: 
        
               return LogicalNullCount<Int64Type>(span); 
        
           }

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@tadeja

@tadeja

And we can similarly want a VisitRunEndType that dispatches over all 3 supported run-end types: INT16, INT32, INT64.

@goel-skd

Also @goel-skd

I can take it along with my current work. Will look at it in a couple of days

take

@VedantRalekar

@VedantRalekar - I am actively working on this.

@goel-skd

@goel-skd Are you still working on this?

Judging by #52469, this would still be useful, for example to reduce:

template <template <typename...> class Checker, typename InType>
Status CheckFloatToIntImpl(const ArraySpan& input, const ArraySpan& output) {
  switch (output.type->id()) {
    case Type::INT8:
      return CheckFloatToIntValues<Checker, InType, Int8Type>(input, output);
    case Type::INT16:
      return CheckFloatToIntValues<Checker, InType, Int16Type>(input, output);
    case Type::INT32:
      return CheckFloatToIntValues<Checker, InType, Int32Type>(input, output);
    case Type::INT64:
      return CheckFloatToIntValues<Checker, InType, Int64Type>(input, output);
    case Type::UINT8:
      return CheckFloatToIntValues<Checker, InType, UInt8Type>(input, output);
    case Type::UINT16:
      return CheckFloatToIntValues<Checker, InType, UInt16Type>(input, output);
    case Type::UINT32:
      return CheckFloatToIntValues<Checker, InType, UInt32Type>(input, output);
    case Type::UINT64:
      return CheckFloatToIntValues<Checker, InType, UInt64Type>(input, output);
    default:
      break;
  }
  DCHECK(false);
  return Status::OK();
}

into something like:

template <template <typename...> class Checker, typename InType>
Status CheckFloatToIntImpl(const ArraySpan& input, const ArraySpan& output) {
  return VisitIntegerType(*output.type, [&]<typename OutType>(OutType*) {
    return CheckFloatToIntValues<Checker, InType, OutType>(input, output);
  });
}

Also cc @taepper

Yes. Will submit a patch soon.

Yes. Will submit a patch soon.

Great, happy to take a look once submitted :)

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[C++] Add a VisitIntegerType helper #50595

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	const auto& dict_array_type = internal::checked_cast<const DictionaryType&>(*span.type);
	switch (dict_array_type.index_type()->id()) {
	case Type::UINT8:
	return LogicalNullCount<UInt8Type>(span);
	case Type::INT8:
	return LogicalNullCount<Int8Type>(span);
	case Type::UINT16:
	return LogicalNullCount<UInt16Type>(span);
	case Type::INT16:
	return LogicalNullCount<Int16Type>(span);
	case Type::UINT32:
	return LogicalNullCount<UInt32Type>(span);
	case Type::INT32:
	return LogicalNullCount<Int32Type>(span);
	case Type::UINT64:
	return LogicalNullCount<UInt64Type>(span);
	default:
	return LogicalNullCount<Int64Type>(span);
	}

[C++] Add a VisitIntegerType helper #50595

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Describe the enhancement requested

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pitrou commented on Jul 22, 2026

pitrou commented on Jul 22, 2026

pitrou commented on Jul 22, 2026

goel-skd commented on Jul 22, 2026

goel-skd commented on Jul 23, 2026

goel-skd commented on Aug 3, 2026

pitrou commented on Oct 27, 2026

goel-skd commented on Oct 27, 2026

taepper commented on Oct 28, 2026

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