StringToPascal.luau

StringToPascal.luau

--!strict

type function _safeIs(input: any, isType: any)
    if typeof(input) ~= "userdata" then return false end

    local is = input.is
    if not is then return false end
    return is(input, isType)
end

type function _arrayToUnion(arr: { any })
    local arrLength = #arr
    return if arrLength == 0 then types.never elseif arrLength == 1 then arr[1] else types.unionof(table.unpack(arr))
end

type function _arrayToIntersection(arr: { any })
    local arrLength = #arr
    return if arrLength == 0 then types.never elseif arrLength == 1 then arr[1] else types.intersectionof(table.unpack(arr))
end

type function _tableMap(input: { any }, fn: (item: any, idx: number) -> ...any)
    local output = table.create(#input)
    for idx, item in input do output[idx] = fn(item, idx) end
    return output
end

type function _safeValue(input: any)
    if _safeIs(input, "singleton") then return input:value() end
    return input
end

type function _toPascal(input: string)
    return types.singleton(string.upper(string.sub(input, 1, 1))..string.sub(input, 2, -1))
end

export type function StringToPascal(input: string)
    if _safeIs(input, "union") then return _arrayToUnion(_tableMap(input:components(), StringToPascal)) end
    if _safeIs(input, "intersection") then return _arrayToIntersection(_tableMap(input:components(), StringToPascal)) end

    input = _safeValue(input)
    if typeof(input) ~= "string" then return input end

    return _toPascal(input)
end

return nil