| hxt-8.5.4: A collection of tools for processing XML with Haskell. | Source code | Contents | Index

Text.XML.HXT.RelaxNG.XmlSchema.RegexMatch

Portability | portable
Stability | experimental
Maintainer | Uwe Schmidt (uwe@fh-wedel.de)

Description
Convenient functions for W3C XML Schema Regular Expression Matcher. For internals see Text.XML.HXT.RelaxNG.XmlSchema.Regex Grammar can be found under http://www.w3.org/TR/xmlschema11-2/#regexs
Synopsis

matchRE :: String -> String -> Maybe Bool
splitRE :: String -> String -> Maybe (String, String)
sedRE :: (String -> String) -> String -> String -> Maybe String
tokenizeRE :: String -> String -> Maybe [String]
tokenizeRE' :: String -> String -> Maybe [Either String String]
match :: String -> String -> Bool
tokenize :: String -> String -> [String]
tokenize' :: String -> String -> [Either String String]
sed :: (String -> String) -> String -> String -> String
split :: String -> String -> (String, String)
splitRegex :: Regex -> String -> Maybe (String, String)

Documentation

matchRE :: String -> String -> Maybe Bool | Source

match a string with a regular expression

First argument is the regex, second the input string, if the regex is not well formed, `Nothing` is returned, else `Just` the match result

Examples:

     matchRE "x*" "xxx" = Just True
     matchRE "x" "xxx"  = Just False
     matchRE "[" "xxx"  = Nothing

splitRE :: String -> String -> Maybe (String, String) | Source

split a string by taking the longest prefix matching a regular expression

`Nothing` is returned in case of a syntactically wrong regex string or in case there is no matching prefix, else the pair of prefix and rest is returned

examples:

     splitRE "a*b" "abc" = Just ("ab","c")
     splitRE "a*"  "bc"  = Just ("", "bc")
     splitRE "a+"  "bc"  = Nothing
     splitRE "["   "abc" = Nothing

sedRE :: (String -> String) -> String -> String -> Maybe String | Source

sed like editing function

All matching tokens are edited by the 1. argument, the editing function, all other chars remain as they are

examples:

     sedRE (const "b") "a" "xaxax"       = Just "xbxbx"
     sedRE (\ x -> x ++ x) "a" "xax"     = Just "xaax"
     sedRE undefined       "[" undefined = Nothing

tokenizeRE :: String -> String -> Maybe [String] | Source

split a string into tokens (words) by giving a regular expression which all tokens must match

This can be used for simple tokenizers. The words in the result list contain at least one char. All none matching chars are discarded. If the given regex contains syntax errors, `Nothing` is returned

examples:

     tokenizeRE "a*b" ""         = Just []
     tokenizeRE "a*b" "abc"      = Just ["ab"]
     tokenizeRE "a*b" "abaab ab" = Just ["ab","aab","ab"]

     tokenizeRE "[a-z]{2,}|[0-9]{2,}|[0-9]+[.][0-9]+" "ab123 456.7abc"
                                    = Just ["ab","123","456.7","abc"]

     tokenizeRE "[a-z]*|[0-9]{2,}|[0-9]+[.][0-9]+" "cab123 456.7abc"
                                    = Just ["cab","123","456.7","abc"]

     tokenizeRE "[^ \t\n\r]*" "abc def\t\n\rxyz"
                                    = Just ["abc","def","xyz"]

     tokenizeRE "[^ \t\n\r]*"    = words

tokenizeRE' :: String -> String -> Maybe [Either String String] | Source

split a string into tokens and delimierter by giving a regular expression wich all tokens must match

This is a generalisation of the above `tokenizeRE` functions. The none matching char sequences are marked with `Left`, the matching ones are marked with `Right`

If the regular expression contains syntax errors `Nothing` is returned

The following Law holds:

     concat . map (either id id) . fromJust . tokenizeRE' re == id

match :: String -> String -> Bool | Source

convenient function for matchRE syntax errors in R.E. are interpreted as no match found

tokenize :: String -> String -> [String] | Source

convenient function for tokenizeRE a string syntax errors in R.E. result in an empty list

tokenize' :: String -> String -> [Either String String] | Source

convenient function for tokenizeRE' When the regular expression contains errors `[Left input]` is returned, that means tokens are found

sed :: (String -> String) -> String -> String -> String | Source

convenient function for sedRE

When the regular expression contains errors, sed is the identity, else the funtionality is like `sedRE`

     sed undefined "["  == id

split :: String -> String -> (String, String) | Source

convenient function for splitRE syntax errors in R.E. are interpreted as no matching prefix found

splitRegex :: Regex -> String -> Maybe (String, String) | Source

Produced by Haddock version 2.4.2