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Text.Regex.Base.Context

Portability | non-portable (MPTC+FD)
Stability | experimental
Maintainer | libraries@haskell.org, textregexlazy@personal.mightyreason.com

Description

This is a module of instances of `RegexContext`. Nothing else is exported. These work for all the front ends and backends interchangably. These instances are important because they provide the different results that can be gotten from a match or matchM operation (often via the `=~` and `=~~` operators). The name is Context because they are context dependent: use them in a context that expects an Int and you get a count of matches, use them in a Bool context and get True if there is a match, etc.

    type MatchArray = Array Int (MatchOffset, MatchLength)
    type MatchText source = Array Int (source, (MatchOffset, MatchLength))

These are for the first match:

(`RegexLike a b => RegexContext a b Bool` ) : Whether there is any match or not

(`RegexLike a b => RegexContext a b ()` ) : Useful using `=~~` in a monad, since failure to match is via `fail`

(`RegexLike a b => RegexContext a b (MatchOffset,MatchLength)` ) : This returns the initial index and length of the whole match. Starting at (-1) indicates failure to match.

(`RegexLike a b => RegexContext a b b` ) : This returns the text of the whole match. It will return `empty` from `Extract` if there is no match. These are defined in other modules, but documented here for convenience.

(`RegexLike a b => RegexContext a b MatchArray` ) : Where each sub-part the match starts and its length. Starting at (-1) indicates unused.

(`RegexLike a b => RegexContext a b (Array Int b)` ) : The text of each sub-part of the match. Unused matches are `empty` (defined via `Extract`)

(`RegexLike a b => RegexContext a b (b, MatchText b, b)` ) : The text before the match, the details of the match, and the text after the match

(`RegexLike a b => RegexContext a b (b, b, b)` ) : The text before the match, the text of the match, the text after the match

(`RegexLike a b => RegexContext a b (b, b, b, [b])` ) : The text before the match, the text of the match, the text after the match, and the text of the 1st and higher sub-parts of the match. This is the same return value as used in Text.Regex.

(`RegexLike a b => RegexContext a b (MatchResult b)` ) : The `MatchResult` structure for the match.

These instances are for all the matches (non-overlapping):

(`RegexLike a b => RegexContext a b Int` ) : The number of matches

These instances similar to the single match ones above, but in a List:

(`RegexLike a b => RegexContext a b [(MatchOffset, MatchLength)]` ) :

(`RegexLike a b => RegexContext a b [b]` ) : As a policy, I chose [b] to be the list of whole text of each match.

(`RegexLike a b => RegexContext a b [MatchArray]` ) :

(`RegexLike a b => RegexContext a b [Array Int b]` ) :

(`RegexLike a b => RegexContext a b [MatchText b]` ) :

(`RegexLike a b => RegexContext a b [[b]]` ) : This is the list of the list of the text of the sub-part of each match. Unused matches are `empty` (defined via `Extract`)

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