lib/Hcompta/Lib/Regex.hs

   1 {-# LANGUAGE DeriveDataTypeable #-}
   2 {-# LANGUAGE FlexibleContexts #-}
   3 {-# LANGUAGE FlexibleInstances #-}
   4 {-# LANGUAGE StandaloneDeriving #-}
   5 {-# LANGUAGE TypeSynonymInstances #-}
   6 {-# OPTIONS_GHC -fno-warn-orphans #-}
   7 module Hcompta.Lib.Regex where
   8
   9 import qualified Data.Array
  10 import           Data.Data ()
  11 import qualified Data.Char
  12 import qualified Data.List
  13 import qualified Text.Regex.TDFA as R
  14 import qualified Text.Regex.TDFA.Text ()
  15 import           Text.Regex.TDFA.Common as R
  16 import qualified Text.Regex.TDFA.IntArrTrieSet as R.IntArrTrieSet
  17 import           Data.Typeable ()
  18 import           Data.Text (Text)
  19
  20 -- * The 'Regex' type
  21
  22 type Regex       = R.Regex
  23 type Replacement = String
  24
  25 -- * Constructors
  26
  27 -- | Parse the given 'String' to a 'Regex'.
  28 of_String :: String -> R.Regex
  29 of_String = R.makeRegex
  30
  31 instance Read R.Regex where
  32         readsPrec _ s = [(R.makeRegex s, "")]
  33 instance Show R.Regex where
  34         show _ = "Regex"
  35 -- instance Eq Regex where
  36 --      _x == _y = True
  37 deriving instance Eq a => Eq (R.IntArrTrieSet.TrieSet a)
  38 deriving instance Eq R.CompOption
  39 deriving instance Eq R.DFA
  40 deriving instance Eq R.DT
  41 deriving instance Eq R.ExecOption
  42 deriving instance Eq R.GroupInfo
  43 deriving instance Eq R.Instructions
  44 deriving instance Eq R.Transition
  45 instance Eq (R.Position -> R.OrbitTransformer) where
  46         _x == _y = True
  47 deriving instance Eq R.Regex
  48
  49 -- | Parse the given 'String' to a 'R.Regex' (monadic version).
  50 of_StringM :: Monad m => String -> m R.Regex
  51 of_StringM = R.makeRegexM
  52
  53 -- * Matchers
  54
  55 match :: R.Regex -> Text -> Bool
  56 match = R.match
  57
  58 -- | Synonym to Text.R.Regex.TDFA.'Text.R.Regex.TDFA.=~'.
  59 (=~) :: ( R.RegexMaker R.Regex R.CompOption R.ExecOption source
  60         , R.RegexContext R.Regex source1 target )
  61      => source1 -> source -> target
  62 (=~) = (R.=~)
  63
  64 -- | Synonym to Text.R.Regex.TDFA.'Text.R.Regex.TDFA.=~~'.
  65 (=~~) :: ( R.RegexMaker R.Regex R.CompOption R.ExecOption source
  66          , R.RegexContext R.Regex source1 target,Monad m )
  67       => source1 -> source -> m target
  68 (=~~) = (R.=~~)
  69
  70 -- * Replacers
  71
  72 replace :: R.Regex -> Replacement -> String -> String
  73 replace re repl s =
  74         Data.List.foldl (replace_match repl) s
  75         (reverse $ R.match re s :: [R.MatchText String])
  76
  77 replace_match :: Replacement -> String -> R.MatchText String -> String
  78 replace_match replacement s match_groups =
  79         concat [prev, repl, next]
  80         where
  81                 ((_, (ofs, len)):_) = Data.Array.elems match_groups
  82                         -- NOTE: groups should have 0-based indexes,
  83                         --       and there should always be at least one,
  84                         --       since this is a match.
  85                 (prev, next') = Data.List.splitAt ofs s
  86                 next = Data.List.drop len next'
  87                 repl = replace_all (of_String "\\\\[0-9]+") (replace_backref match_groups) replacement
  88
  89 replace_backref :: R.MatchText String -> String -> String
  90 replace_backref match_groups ('\\':s@(_:_))
  91         | Data.List.all Data.Char.isDigit s =
  92                 case read s of
  93                  n | Data.List.elem n $ Data.Array.indices match_groups -> fst ((Data.Array.!) match_groups n)
  94                  _ -> error $ concat ["no match group exists for backreference \"\\", s, "\""]
  95 replace_backref _ s =
  96         error $ concat $ ["replace_backref called on non-numeric-backref \"", s, "\""]
  97
  98 replace_all :: R.Regex -> (String -> String) -> String -> String
  99 replace_all re f s =
 100         concat (reverse $ remaining:done)
 101         where
 102                 (_ind, remaining, done) = Data.List.foldl' go (0, s, []) $ R.getAllMatches $ R.match re s
 103                 go (ind, prev_ok_next, repl) (ofs, len) =
 104                         let (prev, ok_next) = Data.List.splitAt (ofs - ind) prev_ok_next
 105                             (ok, next)      = Data.List.splitAt len ok_next in
 106                         ( ofs + len
 107                         , next
 108                         , f ok : prev : repl
 109                         )