-{-# OPTIONS -cpp #-}
-----------------------------------------------------------------------------
-- |
-- Module : Text.Regex
--
-- Maintainer : libraries@haskell.org
-- Stability : experimental
--- Portability : non-portable (only on platforms that provide a regex lib)
+-- Portability : portable
--
-- Regular expression matching. Uses the POSIX regular expression
-- interface in "Text.Regex.Posix".
--
-----------------------------------------------------------------------------
-#include "config.h"
module Text.Regex (
-- * Regular expressions
Regex,
-#if !defined(__HUGS__) || defined(HAVE_REGEX_H)
mkRegex,
mkRegexWithOpts,
matchRegex,
- matchRegexAll
-#endif
+ matchRegexAll,
+ subRegex,
+ splitRegex
) where
import Prelude
import Text.Regex.Posix ( Regex )
import System.IO.Unsafe
-#if !defined(__HUGS__) || defined(HAVE_REGEX_H)
-- | Makes a regular expression with the default options (multi-line,
-- case-sensitive). The syntax of regular expressions is
-- otherwise that of @egrep@ (i.e. POSIX \"extended\" regular
mkRegex s = unsafePerformIO (RE.regcomp s RE.regExtended)
-- | Makes a regular expression, where the multi-line and
--- case-sensitve options can be changed from the default settings.
+-- case-sensitive options can be changed from the default settings.
mkRegexWithOpts
:: String -- ^ The regular expression to compile
-> Bool -- ^ 'True' @\<=>@ @\'^\'@ and @\'$\'@ match the beginning and
matchRegexAll p str = unsafePerformIO (RE.regexec p str)
-#endif
+{- | Replaces every occurance of the given regexp with the replacement string.
+
+In the replacement string, @\"\\1\"@ refers to the first substring;
+@\"\\2\"@ to the second, etc; and @\"\\0\"@ to the entire match.
+@\"\\\\\\\\\"@ will insert a literal backslash.
+
+-}
+subRegex :: Regex -- ^ Search pattern
+ -> String -- ^ Input string
+ -> String -- ^ Replacement text
+ -> String -- ^ Output string
+subRegex _ "" _ = ""
+subRegex regexp inp repl =
+ let bre = mkRegex "\\\\(\\\\||[0-9]+)"
+ lookup _ [] _ = []
+ lookup [] _ _ = []
+ lookup match repl groups =
+ case matchRegexAll bre repl of
+ Nothing -> repl
+ Just (lead, _, trail, bgroups) ->
+ let newval = if (head bgroups) == "\\"
+ then "\\"
+ else let index = (read (head bgroups)) - 1
+ in
+ if index == -1
+ then match
+ else groups !! index
+ in
+ lead ++ newval ++ lookup match trail groups
+ in
+ case matchRegexAll regexp inp of
+ Nothing -> inp
+ Just (lead, match, trail, groups) ->
+ lead ++ lookup match repl groups ++ (subRegex regexp trail repl)
+
+{- | Splits a string based on a regular expression. The regular expression
+should identify one delimiter.
+-}
+
+splitRegex :: Regex -> String -> [String]
+splitRegex _ [] = []
+splitRegex delim str =
+ case matchRegexAll delim str of
+ Nothing -> [str]
+ Just (firstline, _, remainder, _) ->
+ if remainder == ""
+ then firstline : [] : []
+ else firstline : splitRegex delim remainder