The DLMReader package uses informat to call a special type of functions on raw text before parsing its values. This gives a flexible feature to DLMReader and enables it to handle messy delimited files.

The package is shipped with some pre-registered informats which are listed (new informats may be added to future releases) below:

  • STRIP!: Remove leading and trailing blanks
  • COMMA!: Remove $, and ,(thousands separators) from the numbers
  • COMMAX!: Treat , as decimal point, and removes , and . (thousands separators) from numbers
  • NA!: Treat NA, na, Na, nA as missing
  • BOOL!: Convert any form of True and False to 1 and 0, respectively
  • ACC!: Treat numbers in parentheses (Accounting format) as negative values, i.e. it replaces ( with - and ) with blank.
  • COMPRESS!: Remove all blanks (0x20)

Users can define their own informats, which is basically a function with one positional argument. The function must accept a special mutable string and returns its modified value (or returns a subset of it). To use the new defined function as informat, user must register it by calling the register_informat function.

Note that if the function definition is changed, DLMReader uses the new definition and user MUST re-register it to avoid extra allocation.

Supported string manipulation functions

The function used for informat must accept a special mutable string type and return it. Thus, user must only modify the input argument in-place. Currently, few string manipulation functions are optimised for this purpose - For small to medium size files, user can use any other functions, which support working with AbstractString, for manipulating the input argument: (in the following paragraph x is referring to the positional argument of the user defined informat)

  • isequal: User can use isequal to check if the input function or a sub-string of it is equal to a string.
  • setindex!: To assign a string to the input argument, use setindex!(x, "newtext") syntax. If the length of new text is smaller than x, it will be padded with blank (0x20), if it is longer than x it will be truncated.
  • replace!: User can use replace! to replace part of the input argument. For instance replace!(x, "12"=>"21") replace every occurrence of "12" with "21". Note that shorter replacing text will be padded with blank and longer ones will be truncated.
  • occursin: occursin("text", x) determines whether the first argument is a substring of the second.
    • User can use regular expressions too, i.e. occursin(r::Regex, x)
  • contains: contains(x, "text") determines whether the second argument is a substring of the first.
    • User can use regular expressions too, i.e. contains(x, r::Regex)
  • findfirst: User can search for the first occurrence of the index of a regular expression pattern via the allocation free function findfirst, i.e. findfirst(r::Regex, x)
  • findnext: User can search for the next occurrence of the index of a regular expression pattern vai the allocation free function findnext, i.e. findnext(r::Regex, x, i)
  • remove!: It removes some text (replace it with blanks) from the input argument. It can removes a String constant or a sequence of string location provided as a range, e.g.
    • remove!(x, "text")
    • remove!(x, 2:4)

Users can test the new defined informats by calling DLMReader.test(f, text) where f is the user defined informat and text is a given string.