text-markup

This library provides a data structure for associating arbitrary metadata ("markup") with subsequences of text. The motivation for this library is to provide a tool for mapping text attributes to text sequences in terminal applications where we may want to perform many such mappings by searching text with regular expressions or using parsers to do syntax highlighting.

The main interface to the library is through three functions:

• toMarkup - convert a Text into a Markup a,
• markRegion - mark a region of the Text with a metadata value of type a, and
• fromMarkup - recover the subsequences of the text with accompanying metadata.

For example,

> let m = toMarkup (T.pack "some@email.com 192.168.1.1 http://google.com/") Nothing
> fromMarkup $ markRegion 27 18 (Just "url")
             $ markRegion 15 11 (Just "ipv4")
             $ markRegion 0 14 (Just "e-mail") m
[ ("some@email.com"    , Just "e-mail")
, (" "                 , Nothing)
, ("192.168.1.1"       , Just "ipv4")
, (" "                 , Nothing)
, ("http://google.com/", Just "url")
]

Applying the same markup to adjacent regions results in a merge:

> let m = toMarkup (T.pack "foobar") Nothing
> fromMarkup $ markRegion 0 3 (Just "token") m
[("foo",Just "token"),("bar",Nothing)]
> fromMarkup $ markRegion 3 3 (Just "token")
             $ markRegion 0 3 (Just "token") m
[("foobar",Just "token")]