Extracts info about the processed file to be later used by the header detection/manipulation functions.

Adds given header at position specified by the FileInfo. Does nothing if any header is already present, use replaceHeader if you need to override it.

Drops header at position specified by the FileInfo from the given text. Does nothing if no header is present.

Replaces existing header at position specified by the FileInfo in the given text. Basically combines addHeader with dropHeader. If no header is present, then the given one is added to the text.

Finds header position in given text, where position is represented by line number of first and last line of the header (numbered from zero). Based on the HeaderSyntax specified in given HeaderConfig, this function delegates its work to either findBlockHeader or findLineHeader.

>>> :set -XFlexibleContexts
>>> :set -XTypeFamilies
>>> let hc = HeaderConfig ["hs"] 0 0 [] [] (BlockComment "{-" "-}")
>>> findHeader hc "foo\nbar\n{- HEADER -}\nbaz"
Just (2,2)

Finds header in the form of multi-line comment syntax, which is delimited with starting and ending pattern.

>>> findBlockHeader "{-" "-}" ["", "{- HEADER -}", "", ""] 0
Just (1,1)

Finds header in the form of single-line comment syntax, which is delimited with the prefix pattern.

>>> findLineHeader "--" ["", "a", "-- first", "-- second", "foo"] 0
Just (2,3)

Finds very first line that matches the given regex (numbered from zero).

>>> import Headroom.Data.Regex (re)
>>> :set -XQuasiQuotes
>>> firstMatching [[re|^foo|]] ["some text", "foo bar", "foo baz", "last"]
Just 1

Finds very last line that matches the given regex (numbered from zero).

>>> import Headroom.Data.Regex (re)
>>> :set -XQuasiQuotes
>>> lastMatching [[re|^foo|]] ["some text", "foo bar", "foo baz", "last"]
Just 2

Splits input lines into three parts:

1. list of all lines located before the very last occurence of one of the conditions from the first condition list
2. list of all lines between the first and last lists
3. list of all lines located after the very first occurence of one of the conditions from the second condition list

If both first and second patterns are empty, then all lines are returned in the middle list.

>>> import Headroom.Data.Regex (re)
>>> :set -XQuasiQuotes

>>> splitInput [[re|->|]] [[re|<-|]] "text\n->\nRESULT\n<-\nfoo"
(["text","->"],["RESULT"],["<-","foo"])

>>> splitInput [] [[re|<-|]] "text\n->\nRESULT\n<-\nfoo"
([],["text","->","RESULT"],["<-","foo"])

>>> splitInput [] [] "one\ntwo"
([],["one","two"],[])