Text.Regex.XMLSchema.Generic.Matching

hxt-regex-xmlschema-9.2.0.3: A regular expression library for W3C XML Schema regular expressions

Copyright | Copyright (C) 2014- Uwe Schmidt
License | MIT
Maintainer | Uwe Schmidt <uwe@fh-wedel.de>
Stability | stable
Portability | portable
Safe Haskell | Safe
Language | Haskell2010

Text.Regex.XMLSchema.Generic.Matching

Description

Convenient functions for W3C XML Schema Regular Expression Matcher. For internals see `Regex`

Grammar can be found under http://www.w3.org/TR/xmlschema11-2/#regexs

Synopsis

- grep :: StringLike s => s -> [s] -> [s]
- grepExt :: StringLike s => s -> [s] -> [s]
- grepRE :: StringLike s => GenRegex s -> [s] -> [s]
- grepREwithLineNum :: StringLike s => GenRegex s -> [s] -> [(Int, s)]
- match :: StringLike s => s -> s -> Bool
- matchExt :: StringLike s => s -> s -> Bool
- matchSubex :: StringLike s => s -> s -> [(s, s)]
- sed :: StringLike s => (s -> s) -> s -> s -> s
- sedExt :: StringLike s => (s -> s) -> s -> s -> s
- split :: StringLike s => s -> s -> (s, s)
- splitExt :: StringLike s => s -> s -> (s, s)
- splitSubex :: StringLike s => s -> s -> ([(s, s)], s)
- tokenize :: StringLike s => s -> s -> [s]
- tokenizeExt :: StringLike s => s -> s -> [s]
- tokenize' :: StringLike s => s -> s -> [Either s s]
- tokenizeExt' :: StringLike s => s -> s -> [Either s s]
- tokenizeSubex :: StringLike s => s -> s -> [(s, s)]
- matchRE :: StringLike s => GenRegex s -> s -> Bool
- matchSubexRE :: StringLike s => GenRegex s -> s -> [(s, s)]
- sedRE :: StringLike s => (s -> s) -> GenRegex s -> s -> s
- splitRE :: StringLike s => GenRegex s -> s -> Maybe (s, s)
- splitSubexRE :: StringLike s => GenRegex s -> s -> Maybe ([(s, s)], s)
- tokenizeRE :: StringLike s => GenRegex s -> s -> [s]
- tokenizeRE' :: StringLike s => GenRegex s -> s -> [Either s s]
- tokenizeSubexRE :: StringLike s => GenRegex s -> s -> [(s, s)]

# Documentation

grep :: StringLike s => s -> [s] -> [s] #

grep like filter for lists of strings

The regular expression may be prefixed with the usual context spec "^" for start of string, and "\<" for start of word. and suffixed with "$" for end of text and "\>" end of word. Word chars are defined by the multi char escape sequence "\w"

Examples

    grep "a"    ["_a_", "_a", "a_", "a", "_"]      => ["_a_", "_a", "a_", "a"]
    grep "^a"   ["_a_", "_a", "a_", "a", "_"]      => ["a_", "a"]
    grep "a$"   ["_a_", "_a", "a_", "a", "_"]      => ["_a", "a"]
    grep "^a$"  ["_a_", "_a", "a_", "a", "_"]      => ["a"]
    grep "\\<a" ["x a b", " ax ", " xa ", "xab"]   => ["x a b", " ax "]
    grep "a\\>" ["x a b", " ax ", " xa ", "xab"]   => ["x a b", " xa "]

grepExt :: StringLike s => s -> [s] -> [s] #

grep with extended regular expressions

grepRE :: StringLike s => GenRegex s -> [s] -> [s] #

grep with already prepared Regex (ususally with `parseContextRegex`)

grepREwithLineNum :: StringLike s => GenRegex s -> [s] -> [(Int, s)] #

grep with Regex and line numbers

match :: StringLike s => s -> s -> Bool #

convenient function for `matchRE`

Examples:

    match "x*" "xxx" = True
    match "x" "xxx"  = False
    match "[" "xxx"  = False

matchExt :: StringLike s => s -> s -> Bool #

match with extended regular expressions

matchSubex :: StringLike s => s -> s -> [(s, s)] #

convenient function for `matchRE`

Examples:

    matchSubex "({1}x*)"                 "xxx"      = [("1","xxx")]
    matchSubex "({1}x*)"                 "y"        = []
    matchSubex "({w}[0-9]+)x({h}[0-9]+)" "800x600"  = [("w","800"),("h","600")]
    matchSubex "[" "xxx"                            = []

sed :: StringLike s => (s -> s) -> s -> s -> s #

convenient function for `sedRE`

examples:

    sed (const "b") "a" "xaxax"       = "xbxbx"
    sed (\ x -> x ++ x) "a" "xax"     = "xaax"
    sed undefined       "[" "xxx"     = "xxx"

sedExt :: StringLike s => (s -> s) -> s -> s -> s #

split :: StringLike s => s -> s -> (s, s) #

convenient function for `splitRE`

examples:

    split "a*b" "abc" = ("ab","c")
    split "a*"  "bc"  = ("", "bc")    -- "a*" matches ""
    split "a+"  "bc"  = ("", "bc")    -- "a+" does not match, no split
    split "["   "abc" = ("", "abc")   -- "["  syntax error, no split

splitExt :: StringLike s => s -> s -> (s, s) #

split with extended syntax

splitSubex :: StringLike s => s -> s -> ([(s, s)], s) #

convenient function for `splitSubex`, uses extended syntax

examples:

    splitSubex "({1}a*)b"  "abc" = ([("1","a")],"c")
    splitSubex "({2}a*)"   "bc"  = ([("2","")], "bc")
    splitSubex "({1}a|b)+" "abc" = ([("1","a"),("1","b")],"c")        -- subex 1 matches 2 times

    splitSubex ".*({x}a*)" "aa"  = ([("x",""),("x","a"),("x","aa")],"")
                                                                      -- nondeterminism: 3 matches for a*

    splitSubex "({1}do)|({2}[a-z]+)" "do you know"
                                   = ([("1","do"),("2","do")]," you know")
                                                                      -- nondeterminism: 2 matches for do

    splitSubex "({1}do){|}({2}[a-z]+)" "do you know"
                                   = ([("1","do")]," you know")
                                                                      -- no nondeterminism with {|}: 1. match for do

    splitSubex "({1}a+)"   "bcd" = ([], "bcd")                        -- no match
    splitSubex "["         "abc" = ([], "abc")                        -- syntax error

tokenize :: StringLike s => s -> s -> [s] #

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

Convenient function for `tokenizeRE`

This can be used for simple tokenizers. It is recommended to use regular expressions where the empty word does not match. Else there will appear a lot of probably useless empty tokens in the output. All none matching chars are discarded. If the given regex contains syntax errors, `Nothing` is returned

examples:

    tokenize "a" "aabba"      = ["a","a","a"]
    tokenize "a*" "aaaba"     = ["aaa","a"]
    tokenize "a*" "bbb"       = ["","",""]
    tokenize "a+" "bbb"       = []

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

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

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

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

    tokenize ".*"   "\nabc\n123\n\nxyz\n"
                              = ["","abc","123","","xyz"]

    tokenize ".*"             = lines

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

tokenizeExt :: StringLike s => s -> s -> [s] #

tokenize with extended syntax

tokenize' :: StringLike s => s -> s -> [Either s s] #

convenient function for `tokenizeRE'`

When the regular expression parses as Zero, `[Left input]` is returned, that means no tokens are found

tokenizeExt' :: StringLike s => s -> s -> [Either s s] #

tokenizeSubex :: StringLike s => s -> s -> [(s, s)] #

convenient function for `tokenizeSubexRE` a string

examples:

    tokenizeSubex "({name}[a-z]+)|({num}[0-9]{2,})|({real}[0-9]+[.][0-9]+)"
                    "cab123 456.7abc"
                                     = [("name","cab")
                                       ,("num","123")
                                       ,("real","456.7")
                                       ,("name","abc")]

    tokenizeSubex "({real}({n}[0-9]+)([.]({f}[0-9]+))?)"
                    "12.34"          = [("real","12.34")
                                       ,("n","12")
                                       ,("f","34")]

    tokenizeSubex "({real}({n}[0-9]+)([.]({f}[0-9]+))?)"
                     "12 34"         = [("real","12"),("n","12")
                                       ,("real","34"),("n","34")]

    tokenizeSubex "({real}({n}[0-9]+)(([.]({f}[0-9]+))|({f})))"
                     "12 34.56"      = [("real","12"),("n","12"),("f","")
                                       ,("real","34.56"),("n","34"),("f","56")]

matchRE :: StringLike s => GenRegex s -> s -> Bool #

match a string with a regular expression

matchSubexRE :: StringLike s => GenRegex s -> s -> [(s, s)] #

match a string with a regular expression and extract subexpression matches

sedRE :: StringLike s => (s -> s) -> GenRegex s -> s -> s #

sed like editing function

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

splitRE :: StringLike s => GenRegex s -> s -> Maybe (s, s) #

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

`Nothing` is returned in case there is no matching prefix, else the pair of prefix and rest is returned

splitSubexRE :: StringLike s => GenRegex s -> s -> Maybe ([(s, s)], s) #

split a string by removing the longest prefix matching a regular expression and then return the list of subexpressions found in the matching part

`Nothing` is returned in case of no matching prefix, else the list of pairs of labels and submatches and the rest is returned

tokenizeRE :: StringLike s => GenRegex s -> s -> [s] #

The function, that does the real work for `tokenize`

tokenizeRE' :: StringLike s => GenRegex s -> s -> [Either s s] #

split a string into tokens and delimierter by giving a regular expression which 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) . tokenizeRE' re == id

tokenizeSubexRE :: StringLike s => GenRegex s -> s -> [(s, s)] #

split a string into tokens (pair of labels and words) by giving a regular expression containing labeled subexpressions.

This function should not be called with regular expressions without any labeled subexpressions. This does not make sense, because the result list will always be empty.

Result is the list of matching subexpressions This can be used for simple tokenizers. At least one char is consumed by parsing a token. The pairs in the result list contain the matching substrings. All none matching chars are discarded. If the given regex contains syntax errors, `Nothing` is returned