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| Language.HaLex.RegExp | | Portability | portable | | Stability | provisional | | Maintainer | jas@di.uminho.pt |
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| Description |
Regular Expressions in Haskell.
Code Included in the Lecture Notes on
Language Processing (with a functional flavour).
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| Synopsis |
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| Data type with recursion pattern |
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| data RegExp sy |
| Type of regular expressions. | | Constructors | | Empty | Empty Language | | Epsilon | Empty String | | Literal sy | Literals | | Or (RegExp sy) (RegExp sy) | Disjuncion | | Then (RegExp sy) (RegExp sy) | Sequence | | Star (RegExp sy) | Repetition, possibly zero time | | OneOrMore (RegExp sy) | One or more times (extended RegExp) | | Optional (RegExp sy) | Optional (extended RegExp) |
| | Instances | | Show sy => Show (RegExp sy) | | (Read sy, ??? sy) => Read (RegExp sy) | | (Eq sy, ??? sy) => Eq (RegExp sy) |
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| cataRegExp :: (re, re, re -> re -> re, re -> re, sy -> re, re -> re -> re, re -> re, re -> re) -> RegExp sy -> re |
| Catamorphism induced by the RegExp inductive data type |
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| Matching |
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| matchesRE :: Eq sy => RegExp sy -> [sy] -> Bool |
| Test whether a match can be found for the given regular expression
in the given sequence of characters. The regular expression is
assumed not to contain OneOrMore or Optional. See also matches'. |
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| matches' :: Eq sy => RegExp sy -> [sy] -> Bool |
| Test whether a match can be found for the given regular expression
in the given sequence of characters. The regular expression is
allowed to contain OneOrMore or Optional. |
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| Size |
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| sizeRegExp :: RegExp sy -> Int |
| Compute the size of a regular expression
We define the size of a regular expression as the number of occurrences
of symbols of the alfabeth |
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| Printing |
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| showRE :: Show sy => RegExp sy -> [Char] |
| Print regular expression to String as a catamorphism
A straightforward (catamorphic) show function: it produces too many brackets,
making it diffcicult to read or understand the expression. |
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| Simplification |
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| simplifyRegExp :: Eq sy => RegExp sy -> RegExp sy |
| Simplify regular expressions according to the algebra of regular expressions. |
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| Normalization |
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| extREtoRE :: RegExp sy -> RegExp sy |
| Rewrite extended regular expressions to
plain regular expression. This means that the OneOrMore
and Optional constructors are normalized away. |
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| Produced by Haddock version 0.6 |
