Haskell Hierarchical Libraries (regex-posix package)Source codeContentsIndex
Text.Regex.Posix.String
Portabilitynon-portable (regex-base needs MPTC+FD)
Stabilityexperimental
Maintainerlibraries@haskell.org, textregexlazy@personal.mightyreason.com
Contents
Types
Miscellaneous
Medium level API functions
Compilation options
Execution options
Description

This provides String instances for RegexMaker and RegexLike based on Text.Regex.Posix.Wrap, and a (RegexContext Regex String String) instance.

To use these instance, you would normally import Text.Regex.Posix. You only need to import this module to use the medium level API of the compile, regexec, and execute functions. All of these report error by returning Left values instead of undefined or error or fail.

Synopsis
data Regex
MatchOffset
MatchLength
data ReturnCode
type WrapError = (ReturnCode, String)
unusedOffset :: Int
compile :: CompOption -> ExecOption -> String -> IO (Either WrapError Regex)
regexec :: Regex -> String -> IO (Either WrapError (Maybe (String, String, String, [String])))
execute :: Regex -> String -> IO (Either WrapError (Maybe (Array Int (MatchOffset, MatchLength))))
newtype CompOption = CompOption CInt
compBlank :: CompOption
compExtended :: CompOption
compIgnoreCase :: CompOption
compNoSub :: CompOption
compNewline :: CompOption
newtype ExecOption = ExecOption CInt
execBlank :: ExecOption
execNotBOL :: ExecOption
execNotEOL :: ExecOption
Types
data Regex
A compiled regular expression.
show/hide Instances
MatchOffset
MatchLength
data ReturnCode

ReturnCode is an enumerated CInt, corresponding to the error codes from man 3 regex:

  • retBadbr (REG_BADBR) invalid repetition count(s) in { }
  • retBadpat (REG_BADPAT) invalid regular expression
  • retBadrpt (REG_BADRPT) ?, *, or + operand invalid
  • retEcollate (REG_ECOLLATE) invalid collating element
  • retEctype (REG_ECTYPE) invalid character class
  • retEescape (REG_EESCAPE) \ applied to unescapable character
  • retEsubreg (REG_ESUBREG) invalid backreference number
  • retEbrack (REG_EBRACK) brackets [ ] not balanced
  • retEparen (REG_EPAREN) parentheses ( ) not balanced
  • retEbrace (REG_EBRACE) braces { } not balanced
  • retErange (REG_ERANGE) invalid character range in [ ]
  • retEspace (REG_ESPACE) ran out of memory
  • retNoMatch (REG_NOMATCH) The regexec() function failed to match
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type WrapError = (ReturnCode, String)
The return code will be retOk when it is the Haskell wrapper and not the underlying library generating the error message.
Miscellaneous
unusedOffset :: Int
Medium level API functions
compile
:: CompOptionFlags (summed together)
-> ExecOptionFlags (summed together)
-> StringThe regular expression to compile (ASCII only, no null bytes)
-> IO (Either WrapError Regex)Returns: the compiled regular expression
regexec
:: RegexCompiled regular expression
-> StringString to match against
-> IO (Either WrapError (Maybe (String, String, String, [String])))

Returns: Nothing if the regex did not match the string, or: 

   Just (everything before match,
         matched portion,
         everything after match,
         subexpression matches)
Matches a regular expression against a string
execute
:: RegexCompiled regular expression
-> StringString to match against
-> IO (Either WrapError (Maybe (Array Int (MatchOffset, MatchLength))))

Returns: Nothing if the regex did not match the string, or: 

   Just (array of offset length pairs)
Matches a regular expression against a string
Compilation options
newtype CompOption

A bitmapped CInt containing options for compilation of regular expressions. Option values (and their man 3 regcomp names) are

  • compBlank which is a completely zero value for all the flags. This is also the blankCompOpt value.
  • compExtended (REG_EXTENDED) which can be set to use extended instead of basic regular expressions. This is set in the defaultCompOpt value.
  • compNewline (REG_NEWLINE) turns on newline sensitivity: The dot (.) and inverted set [^ ] never match newline, and ^ and $ anchors do match after and before newlines. This is set in the defaultCompOpt value.
  • compIgnoreCase (REG_ICASE) which can be set to match ignoring upper and lower distinctions.
  • compNoSub (REG_NOSUB) which turns off all information from matching except whether a match exists.
Constructors
CompOption CInt
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compBlank :: CompOption
A completely zero value for all the flags. This is also the blankCompOpt value.
compExtended :: CompOption
compIgnoreCase :: CompOption
compNoSub :: CompOption
compNewline :: CompOption
Execution options
newtype ExecOption

A bitmapped CInt containing options for execution of compiled regular expressions. Option values (and their man 3 regexec names) are

  • execBlank which is a complete zero value for all the flags. This is the blankExecOpt value.
  • execNotBOL (REG_NOTBOL) can be set to prevent ^ from matching at the start of the input.
  • execNotEOL (REG_NOTEOL) can be set to prevent $ from matching at the end of the input (before the terminating NUL).
Constructors
ExecOption CInt
show/hide Instances
execBlank :: ExecOption
A completely zero value for all the flags. This is also the blankExecOpt value.
execNotBOL :: ExecOption
execNotEOL :: ExecOption
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