Add escaping functions (fixes #37)

iconnect · Mar 5, 2017 · e1d229a · e1d229a
1 parent 68ae0ca
commit e1d229a
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Showing 8 changed files with 166 additions and 40 deletions.
diff --git a/Text/RE/Internal/EscapeREString.hs b/Text/RE/Internal/EscapeREString.hs
@@ -0,0 +1,21 @@
+module Text.RE.Internal.EscapeREString where
+
+escapeREString :: String -> String
+escapeREString = foldr esc []
+  where
+    esc c t | isMetaChar c = '\\' : c : t
+            | otherwise    = c : t
+
+isMetaChar :: Char -> Bool
+isMetaChar c = case c of
+  '*' -> True
+  '?' -> True
+  '+' -> True
+  '[' -> True
+  ']' -> True
+  '{' -> True
+  '}' -> True
+  '$' -> True
+  '^' -> True
+  '.' -> True
+  _   -> False
diff --git a/Text/RE/PCRE/RE.hs b/Text/RE/PCRE/RE.hs
@@ -42,6 +42,8 @@ module Text.RE.PCRE.RE
   , defaultOptions
   , unpackSimpleRegexOptions
   , compileRegex
+  , escape
+  , escapeREString
   ) where
 
 import           Data.Bits
@@ -50,6 +52,7 @@ import           Language.Haskell.TH
 import           Language.Haskell.TH.Quote
 import           Prelude.Compat
 import           Text.RE
+import           Text.RE.Internal.EscapeREString
 import           Text.RE.Internal.NamedCaptures
 import           Text.RE.Internal.PreludeMacros
 import           Text.RE.Internal.QQ
@@ -243,3 +246,6 @@ preludeSources = preludeMacroSources PCRE
 
 preludeSource :: PreludeMacro -> String
 preludeSource = preludeMacroSource PCRE
+
+escape :: (String->String) -> String -> RE
+escape f = unsafeCompileRegex () . f . escapeREString
diff --git a/Text/RE/TDFA/RE.hs b/Text/RE/TDFA/RE.hs
@@ -42,13 +42,16 @@ module Text.RE.TDFA.RE
   , preludeSource
   , unpackSimpleRegexOptions
   , compileRegex
+  , escape
+  , escapeREString
   ) where
 
 import           Data.Functor.Identity
 import           Language.Haskell.TH
 import           Language.Haskell.TH.Quote
 import           Prelude.Compat
 import           Text.RE
+import           Text.RE.Internal.EscapeREString
 import           Text.RE.Internal.NamedCaptures
 import           Text.RE.Internal.PreludeMacros
 import           Text.RE.Internal.QQ
@@ -239,3 +242,6 @@ preludeSources = preludeMacroSources TDFA
 
 preludeSource :: PreludeMacro -> String
 preludeSource = preludeMacroSource TDFA
+
+escape :: (String->String) -> String -> RE
+escape f = unsafeCompileRegex () . f . escapeREString