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\begin{code}
{-# LANGUAGE NoImplicitPrelude #-}
{-# LANGUAGE QuasiQuotes #-}
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE RecordWildCards #-}
{-# LANGUAGE FlexibleContexts #-}
{-# LANGUAGE FlexibleInstances #-}
module Text.RE.ZeInternals.Replace
(
-- * REContext and RELocation
REContext(..)
, RELocation(..)
, isTopLocation
-- * replaceAll
, replaceAll
, replaceAllCaptures
, replaceAllCaptures_
, replaceAllCapturesM
-- * replace
, replace
, replaceCaptures
, replaceCaptures_
, replaceCapturesM
-- * expandMacros
, expandMacros
, expandMacros'
-- * templateCaptures
, templateCaptures
-- * Replace and ReplaceMethods
, Replace(..)
, ReplaceMethods(..)
, replaceMethods
) where
import Control.Applicative
import Data.Array
import qualified Data.ByteString.Char8 as B
import qualified Data.ByteString.Lazy.Char8 as LBS
import Data.Char
import qualified Data.Foldable as F
import Data.Functor.Identity
import qualified Data.HashMap.Strict as HM
import Data.Maybe
import Data.Monoid
import qualified Data.Sequence as S
import qualified Data.Text as T
import qualified Data.Text.Encoding as TE
import qualified Data.Text.Lazy as LT
import Prelude.Compat
import Text.RE.REOptions
import Text.RE.ZeInternals.Types.Capture
import Text.RE.ZeInternals.Types.CaptureID
import Text.RE.ZeInternals.Types.Match
import Text.RE.ZeInternals.Types.Matches
import Text.Read
import Text.Regex.TDFA
import Text.Regex.TDFA.Text()
import Text.Regex.TDFA.Text.Lazy()
\end{code}
ReContext and RELocation
------------------------
\begin{code}
-- | @REContext@ specifies which contexts the substitutions should be applied
data REContext
= TOP -- ^ substitutions should be applied to the top-level only,
-- the text that matched the whole RE
| SUB -- ^ substitutions should only be applied to the text
-- captured by bracketed sub-REs
| ALL -- ^ the substitution function should be applied to all
-- captures, the top level and the sub-expression captures
deriving (Show)
-- | the @RELocation@ information passed into the substitution function
-- specifies which sub-expression is being substituted
data RELocation =
RELocation
{ locationMatch :: Int
-- ^ the zero-based, i-th string to be matched,
-- when matching all strings, zero when only the
-- first string is being matched
, locationCapture :: CaptureOrdinal
-- ^ 0, when matching the top-level string
-- matched by the whole RE, 1 for the top-most,
-- left-most redex captured by bracketed
-- sub-REs, etc.
}
deriving (Show)
\end{code}
\begin{code}
-- | True iff the location references a complete match
-- (i.e., not a bracketed capture)
isTopLocation :: RELocation -> Bool
isTopLocation = (==0) . locationCapture
\end{code}
\begin{code}
-- | replace all with a template, $0 for whole text, $1 for first
-- capture, etc.
replaceAll :: Replace a
=> a
-> Matches a
-> a
replaceAll tpl ac = replaceAllCaptures TOP (parseTemplateR tpl) ac
\end{code}
\begin{code}
-- | substitutes using a function that takes the full Match
-- context and returns the same replacement text as the _phi_phi
-- context.
replaceAllCaptures :: Replace a
=> REContext
-> (Match a->RELocation->Capture a->Maybe a)
-> Matches a
-> a
\end{code}
\begin{code}
replaceAllCaptures = replaceAllCaptures_ replaceMethods
\end{code}
\begin{code}
-- | replaceAllCaptures_ is like like replaceAllCaptures but takes the
-- Replace methods through the ReplaceMethods argument
replaceAllCaptures_ :: Extract a
=> ReplaceMethods a
-> REContext
-> (Match a->RELocation->Capture a->Maybe a)
-> Matches a
-> a
replaceAllCaptures_ s ctx phi ac =
runIdentity $ replaceAllCapturesM s ctx (lift_phi phi) ac
\end{code}
\begin{code}
-- | replaceAllCapturesM is just a monadically generalised version of
-- replaceAllCaptures_
replaceAllCapturesM :: (Extract a,Monad m)
=> ReplaceMethods a
-> REContext
-> (Match a->RELocation->Capture a->m (Maybe a))
-> Matches a
-> m a
replaceAllCapturesM r ctx phi_ Matches{..} =
replaceCapturesM r ALL phi $ Match matchesSource cnms arr
where
phi _ (RELocation _ i) = case arr_c!i of
Just caps -> phi_ caps . uncurry RELocation $ arr_i ! i
Nothing -> const $ return Nothing
arr_c = listArray bds $
concat $
[ repl (rangeSize $ bounds $ matchArray cs) cs
| cs <- allMatches
]
arr_i = listArray bds j_ks
arr = listArray bds $
[ arr_ ! k
| arr_ <- map matchArray allMatches
, k <- indices arr_
]
bds = (0,CaptureOrdinal $ length j_ks-1)
j_ks =
[ (j,k)
| (j,arr_) <- zip [0..] $ map matchArray allMatches
, k <- indices arr_
]
repl 0 _ = []
repl n x = case ctx of
TOP -> Just x : replicate (n-1) Nothing
SUB -> Nothing : replicate (n-1) (Just x)
ALL -> replicate n $ Just x
cnms = fromMaybe noCaptureNames $ listToMaybe $ map captureNames allMatches
\end{code}
\begin{code}
-- | replace with a template containing $0 for whole text,
-- $1 for first capture, etc.
replace :: Replace a
=> a
-> Match a
-> a
replace tpl c = replaceCaptures TOP (parseTemplateR tpl) c
\end{code}
\begin{code}
-- | substitutes using a function that takes the full Match
-- context and returns the same replacement text as the _phi_phi
-- context.
replaceCaptures :: Replace a
=> REContext
-> (Match a->RELocation->Capture a->Maybe a)
-> Match a
-> a
replaceCaptures = replaceCaptures_ replaceMethods
\end{code}
\begin{code}
-- | replaceCaptures_ is like replaceCaptures but takes the Replace methods
-- through the ReplaceMethods argument
replaceCaptures_ :: Extract a
=> ReplaceMethods a
-> REContext
-> (Match a->RELocation->Capture a->Maybe a)
-> Match a
-> a
replaceCaptures_ s ctx phi caps =
runIdentity $ replaceCapturesM s ctx (lift_phi phi) caps
\end{code}
\begin{code}
-- | replaceCapturesM is just a monadically generalised version of
-- replaceCaptures_
replaceCapturesM :: (Monad m,Extract a)
=> ReplaceMethods a
-> REContext
-> (Match a->RELocation->Capture a->m (Maybe a))
-> Match a
-> m a
replaceCapturesM ReplaceMethods{..} ctx phi_ caps@Match{..} = do
(hay',_) <- foldr sc (return (matchSource,[])) $
zip [0..] $ elems matchArray
return hay'
where
sc (i,cap0) act = do
(hay,ds) <- act
let ndl = capturedText cap
cap = adj hay ds cap0
mb <- phi i cap
case mb of
Nothing -> return (hay,ds)
Just ndl' ->
return
( methodSubst (const ndl') cap
, (captureOffset cap,len'-len) : ds
)
where
len' = methodLength ndl'
len = methodLength ndl
adj hay ds cap =
Capture
{ captureSource = hay
, capturedText = before len $ after off0 hay
, captureOffset = off0
, captureLength = len
}
where
len = len0 + sum
[ delta
| (off,delta) <- ds
, off < off0 + len0
]
len0 = captureLength cap
off0 = captureOffset cap
phi i cap = case ctx of
TOP | i/=0 -> return Nothing
SUB | i==0 ->return Nothing
_ ->
case not $ hasCaptured cap of
True -> return Nothing
False -> phi_ caps (RELocation 0 i) cap
\end{code}
expandMacros
------------
\begin{code}
-- | expand all of the @{..} macros in the RE in the argument String
-- according to the Macros argument, preprocessing the RE String
-- according to the Mode argument (used internally)
expandMacros :: (r->String) -> Macros r -> String -> String
expandMacros x_src hm s =
case HM.null hm of
True -> s
False -> expandMacros' (fmap x_src . flip HM.lookup hm) s
\end{code}
\begin{code}
-- | expand the @{..} macos in the argument string using the given
-- function
expandMacros' :: (MacroID->Maybe String) -> String -> String
expandMacros' lu = fixpoint e_m
where
e_m re_s = replaceAllCaptures TOP phi $ re_s $=~ "@(@|\\{([^{}]+)\\})"
where
phi mtch _ cap = case txt == "@@" of
True -> Just "@"
False -> Just $ fromMaybe txt $ lu ide
where
txt = capturedText cap
ide = MacroID $ capturedText $ capture c2 mtch
c2 = IsCaptureOrdinal $ CaptureOrdinal 2
\end{code}
\begin{code}
lift_phi :: Monad m
=> (Match a->RELocation->Capture a->Maybe a)
-> (Match a->RELocation->Capture a->m (Maybe a))
lift_phi phi_ = phi
where
phi caps' loc' cap' = return $ phi_ caps' loc' cap'
\end{code}
templateCaptures
----------------
\begin{code}
-- | list all of the CaptureID references in the replace template in
-- the second argument
templateCaptures :: ( Replace a
, RegexContext Regex a (Matches a)
, RegexMaker Regex CompOption ExecOption String
)
=> (a->String)
-> a
-> [CaptureID]
templateCaptures unpack tpl =
[ cid
| mtch <- allMatches $ scan_template tpl
, Right cid <- [parse_template_capture unpack mtch]
]
-- | parse a Match generated by acan_template, returning @Left "$")
-- iff the capture reference is an escaped @$@ (i.e., @$$@)
parse_template_capture :: (a->String) -> Match a -> Either a CaptureID
parse_template_capture unpack t_mtch = case t_mtch !$? c2 of
Just cap -> case readMaybe stg of
Nothing -> Right $ IsCaptureName $ CaptureName $ T.pack stg
Just cn -> Right $ IsCaptureOrdinal $ CaptureOrdinal cn
where
stg = unpack $ capturedText cap
Nothing -> case s == "$" of
True -> Left t
False -> Right $ IsCaptureOrdinal $ CaptureOrdinal $ read s
where
s = unpack t
t = capturedText $ capture c1 t_mtch
c1 = IsCaptureOrdinal $ CaptureOrdinal 1
c2 = IsCaptureOrdinal $ CaptureOrdinal 2
-- | scan a replacement template, returning a Match for each capture
-- reference in the template (like $1, ${foo})
scan_template :: ( Replace a
, RegexContext Regex a (Matches a)
, RegexMaker Regex CompOption ExecOption String
)
=> a
-> Matches a
scan_template tpl = tpl $=~ "\\$(\\$|[0-9]|\\{([^{}]+)\\})"
\end{code}
Replace and ReplaceMethods
--------------------------
\begin{code}
-- | Replace provides the missing needed to replace the matched
-- text in a @Replace a => Match a@.
class (Show a,Eq a,Ord a,Extract a,Monoid a) => Replace a where
-- | length function for a
lengthR :: a -> Int
-- | inject String into a
packR :: String -> a
-- | project a onto a String
unpackR :: a -> String
-- | inject into Text
textifyR :: a -> T.Text
-- | project Text onto a
detextifyR :: T.Text -> a
-- | split into lines
linesR :: a -> [a]
-- | concatenate a list of lines
unlinesR :: [a] -> a
-- | append a newline
appendNewlineR :: a -> a
-- | apply a substitution function to a Capture
substR :: (a->a) -> Capture a -> a
-- | convert a template containing $0, $1, etc., in the first
-- argument, into a 'phi' replacement function for use with
-- replaceAllCaptures and replaceCaptures
parseTemplateR :: a -> Match a -> RELocation -> Capture a -> Maybe a
textifyR = T.pack . unpackR
detextifyR = packR . T.unpack
appendNewlineR = (<> packR "\n")
substR f m@Capture{..} =
capturePrefix m <> f capturedText <> captureSuffix m
\end{code}
\begin{code}
-- | a selction of the Replace methods can be encapsulated with ReplaceMethods
-- for the higher-order replacement functions
data ReplaceMethods a =
ReplaceMethods
{ methodLength :: a -> Int
, methodSubst :: (a->a) -> Capture a -> a
}
-- | replaceMethods encapsulates ReplaceMethods a from a Replace a context
replaceMethods :: Replace a => ReplaceMethods a
replaceMethods =
ReplaceMethods
{ methodLength = lengthR
, methodSubst = substR
}
\end{code}
The Replace Instances
---------------------
\begin{code}
instance Replace [Char] where
lengthR = length
packR = id
unpackR = id
textifyR = T.pack
detextifyR = T.unpack
linesR = lines
unlinesR = unlines
appendNewlineR = (<>"\n")
parseTemplateR = parseTemplateR' id
instance Replace B.ByteString where
lengthR = B.length
packR = B.pack
unpackR = B.unpack
textifyR = TE.decodeUtf8
detextifyR = TE.encodeUtf8
linesR = B.lines
unlinesR = B.unlines
appendNewlineR = (<>"\n")
parseTemplateR = parseTemplateR' B.unpack
instance Replace LBS.ByteString where
lengthR = fromEnum . LBS.length
packR = LBS.pack
unpackR = LBS.unpack
textifyR = TE.decodeUtf8 . LBS.toStrict
linesR = LBS.lines
unlinesR = LBS.unlines
detextifyR = LBS.fromStrict . TE.encodeUtf8
appendNewlineR = (<>"\n")
parseTemplateR = parseTemplateR' LBS.unpack
instance Replace (S.Seq Char) where
lengthR = S.length
packR = S.fromList
unpackR = F.toList
linesR = map packR . lines . unpackR
unlinesR = packR . unlines . map unpackR
parseTemplateR = parseTemplateR' F.toList
instance Replace T.Text where
lengthR = T.length
packR = T.pack
unpackR = T.unpack
textifyR = id
detextifyR = id
linesR = T.lines
unlinesR = T.unlines
appendNewlineR = (<>"\n")
parseTemplateR = parseTemplateR' T.unpack
instance Replace LT.Text where
lengthR = fromEnum . LT.length
packR = LT.pack
unpackR = LT.unpack
textifyR = LT.toStrict
detextifyR = LT.fromStrict
linesR = LT.lines
unlinesR = LT.unlines
appendNewlineR = (<>"\n")
parseTemplateR = parseTemplateR' LT.unpack
\end{code}
Parsing Replace Templates
-------------------------
\begin{code}
-- | parse the replacement template in second argument, substititing
-- the capture references with corresponding captures from the Match
-- in the third argument (the result of a single match of the RE
-- against the input text to be matched); Nothing is returned if the
-- inputs are not well formed (currently all inputs are well formed)
parseTemplateR' :: ( Replace a
, RegexContext Regex a (Matches a)
, RegexMaker Regex CompOption ExecOption String
)
=> (a->String)
-> a
-> Match a
-> RELocation
-> Capture a
-> Maybe a
parseTemplateR' unpack tpl mtch _ _ =
Just $ replaceAllCaptures TOP phi $ scan_template tpl
where
phi t_mtch _ _ = either Just this $ parse_template_capture unpack t_mtch
this cid = capturedText <$> mtch !$? cid
\end{code}
Helpers
-------
\begin{code}
fixpoint :: (Eq a) => (a->a) -> a -> a
fixpoint f = chk . iterate f
where
chk (x:x':_) | x==x' = x
chk xs = chk $ tail xs
\end{code}
\begin{code}
($=~) :: ( RegexContext Regex source target
, RegexMaker Regex CompOption ExecOption String
)
=> source -> String -> target
($=~) = (=~)
\end{code}