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| Text.Regex.Base.RegexLike | | Portability | non-portable (MPTC+FD) | | Stability | experimental | | Maintainer | libraries@haskell.org, textregexlazy@personal.mightyreason.com |
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| Description |
Classes and instances for Regex matching.
All the classes are declared here, and some common type aliases, and
the MatchResult data type.
The only instances here are for Extract String and Extract ByteString.
There are no data values. The RegexContext instances are in
Text.Regex.Base.Context, except for ones which run afoul of a
repeated variable (RegexContext regex a a), which are defined in each
modules' String and ByteString modules.
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| Synopsis |
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| Type aliases
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| type MatchOffset = Int |
| 0 based index from start of source, or (-1) for unused
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| type MatchLength = Int |
| non-negative length of a match
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| type MatchArray = Array Int (MatchOffset, MatchLength) |
| 0 based array, with 0th index indicating the full match. If the
full match location is not available, represent as (0,0).
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| type MatchText source = Array Int (source, (MatchOffset, MatchLength)) |
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| Data types
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| data MatchResult a |
| This is the same as the type from JRegex.
| | Constructors | | MR | | | mrBefore :: a | | | mrMatch :: a | | | mrAfter :: a | | | mrSubList :: [a] | | | mrSubs :: (Array Int a) | |
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|  Instances | |
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| Classes
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| class RegexOptions regex compOpt execOpt | regex -> compOpt execOpt, compOpt -> regex execOpt, execOpt -> regex compOpt where |
| Rather than carry them around spearately, the options for how to
execute a regex are kept as part of the regex. There are two types
of options. Those that can only be specified at compilation time
and never changed are CompOpt. Those that can be changed later and
affect how matching is performed are ExecOpt. The actually types
for these depend on the backend.
| | | Methods | | blankCompOpt | | :: compOpt | no options set at all in the backend
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| | | blankExecOpt | | :: execOpt | no options set at all in the backend
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| | | defaultCompOpt | | :: compOpt | reasonable options (extended,caseSensitive,multiline regex)
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| | | defaultExecOpt | | :: execOpt | reasonable options (extended,caseSensitive,multiline regex)
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| | | setExecOpts :: execOpt -> regex -> regex | | forget old flags and use new ones
| | | getExecOpts :: regex -> execOpt | | retrieve the current flags
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| class RegexOptions regex compOpt execOpt => RegexMaker regex compOpt execOpt source | regex -> compOpt execOpt, compOpt -> regex execOpt, execOpt -> regex compOpt where |
RegexMaker captures the creation of the compiled regular
expression from a source type and an option type. makeRegexM and
makeRegexM report parse error using MonadError, usually (Either
String regex).
The makeRegex function has a default implementation that depends
on makeRegexOpts and used defaultCompOpt and defaultExecOpt.
Similarly for makeRegexM and makeRegexOptsM.
There are also default implementaions for makeRegexOpts and
makeRegexOptsM in terms of each other. So a minimal instance
definition needs to only define one of these, hopefully
makeRegexOptsM.
| | | Methods | | makeRegex :: source -> regex | | make using the defaultCompOpt and defaultExecOpt
| | | makeRegexOpts :: compOpt -> execOpt -> source -> regex | | Specify your own options
| | | makeRegexM :: Monad m => source -> m regex | | make using the defaultCompOpt and defaultExecOpt, reporting errors with fail
| | | makeRegexOptsM :: Monad m => compOpt -> execOpt -> source -> m regex | | Specify your own options, reporting errors with fail
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| class Extract source => RegexLike regex source where |
RegexLike is parametrized on a regular expression type and a
source type to run the matching on.
There are default implementations: matchTest and matchOnceText use
matchOnce; matchCount and matchAllText use matchAll. matchOnce uses
matchOnceText and matchAll uses matchAllText. So a minimal complete
instance need to provide at least (matchOnce or matchOnceText) and
(matchAll or matchAllText). Additional definitions are often
provided where they will increase efficiency.
[ c | let notVowel = makeRegex "[^aeiou]" :: Regex, c <- ['a'..'z'], matchTest notVowel [c] ]
"bcdfghjklmnpqrstvwxyz"
The strictness of these functions is instance dependent.
| | | Methods | | matchOnce :: regex -> source -> Maybe MatchArray | | This returns the first match in the source (it checks the whole
source, not just at the start). This returns an array of
(offset,length) index pairs for the match and captured
substrings. The offset is 0-based. A (-1) for an offset means a
failure to match. The lower bound of the array is 0, and the 0th
element is the (offset,length) for the whole match.
| | | matchAll :: regex -> source -> [MatchArray] | | matchAll returns a list of matches. The matches are in order
and do not overlap. If any match succeeds but has 0 length then
this will be the last match in the list.
| | | matchCount :: regex -> source -> Int | | matchCount returns the number of non-overlapping matches
returned by matchAll.
| | | matchTest :: regex -> source -> Bool | | matchTest return True if there is a match somewhere in the
source (it checks the whole source not just at the start).
| | | matchAllText :: regex -> source -> [MatchText source] | | This is matchAll with the actual subsections of the source
instead of just the (offset,length) information.
| | | matchOnceText :: regex -> source -> Maybe (source, MatchText source, source) | | This can return a tuple of three items: the source before the
match, an array of the match and captured substrings (with their
indices), and the source after the match.
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| class RegexLike regex source => RegexContext regex source target where |
RegexContext is the polymorphic interface to do matching. Since
target is polymorphic you may need to suply the type explicitly
in contexts where it cannot be inferred.
The monadic matchM version uses fail to report when the regex
has no match in source. Two examples:
Here the contest Bool is inferred:
[ c | let notVowel = makeRegex "[^aeiou]" :: Regex, c <- ['a'..'z'], match notVowel [c] ]
"bcdfghjklmnpqrstvwxyz"
Here the context '[String]' must be supplied:
let notVowel = (makeRegex "[^aeiou]" :: Regex )
in do { c <- ['a'..'z'] ; matchM notVowel [c] } :: [String]
["b","c","d","f","g","h","j","k","l","m","n","p","q","r","s","t","v","w","x","y","z"]
| | | Methods | | match :: regex -> source -> target | | | matchM :: Monad m => regex -> source -> m target |
| | | Instances | |
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| class Extract source where |
| Extract allows for indexing operations on String or ByteString.
| | | Methods | | before :: Int -> source -> source | | before is a renamed take
| | | after :: Int -> source -> source | | after is a renamed drop
| | | empty :: source | | For when there is no match, this can construct an empty data value
| | | extract :: (Int, Int) -> source -> source | | extract takes an offset and length and has a default
implementation of extract (off,len) source = before len (after
off source)
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| | | Instances | |
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| Produced by Haddock version 0.8 |
