Interface to replace a null or empty value

[YongHeeK]

MWE

/Array::array
[a;b;c
null

currently this give us

[
  {"Array" : ["a","b","c"] }, 
  {"Array" : [] }
]

it will be convinient if we give a option to

[
  {"Array" : ["a","b","c"] }, 
  {"Array" : null}
]

Or more general interface of replace certain value would be desired?

[YongHeeK]

Attribute/A	Attribute/B
var	null
null	var2

currently this give us

[
  {"Attribue" : { "A" : "var", "B": null} },
  {"Attribue" : { "A" : null, "B": "var2"} }
]

it will be convinient if we give a option to

[
  {"Attribue" : { "A" : "var"} },
  {"Attribue" : { "B": "var2"} }
]

[YongHeeK]

"""
    replace_value!(jws::JSONWorksheet, ::Val{T}, cols::Vector)
'Val{T}'별로 지정된 규칙으로 주어진 값을 변환한다 
'drop_empty': 빈 array '[]' 컬럼을 삭제한다
'empty_to_null': 빈 array '[]'를 'null'로 변경
'drop_nullmember': object에서 value가 'null'인 경우 컬럼 삭제
"""
function replace_value!(jws::JSONWorksheet, ::Val{T}, cols::Vector) where T
    @warn "$(sheetnames(jws))에 정의되지 않은 operation $(T)을 시도했습니다"
end

function replace_value!(jws::JSONWorksheet, ::Val{:drop_empty}, cols::Vector)
    @inbounds for row in jws.data
        for p in JSONPointer.Pointer.(cols)
            row[p] = filter(!isempty, row[p])
        end
    end
end
function replace_value!(jws::JSONWorksheet, ::Val{:empty_to_null}, cols::Vector)
    for row in jws.data
        for p in JSONPointer.Pointer.(cols)
            if isempty(row[p])
                row[p] = missing 
            end
        end
    end
end

function replace_value!(jws::JSONWorksheet, ::Val{:drop_nullmember}, cols::Vector)
    for row in jws.data
        for p in JSONPointer.Pointer.(cols)
            if isa(row[p], AbstractDict)
                for (k, v) in row[p]
                    if isnull(v)
                        delete!(row[p], k)
                    end
                end
            end
        end
    end
end