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\begin{code}
{-# LANGUAGE NoImplicitPrelude #-}
{-# LANGUAGE RecordWildCards #-}
{-# LANGUAGE FlexibleContexts #-}
{-# LANGUAGE CPP #-}
module Text.RE.Tools.Grep
(
-- Grep
-- $tutorial
grep
, Verbosity(..)
, Line(..)
, grepLines
, grepFilter
, GrepScript
, grepWithScript
, report
, linesMatched
-- * IsRegex
, IsRegex(..)
, SearchReplace(..)
, searchReplaceAll
, searchReplaceFirst
-- * LineNo
, LineNo(..)
, firstLine
, getLineNo
, lineNo
-- * Replace
, module Text.RE.Replace
) where
import qualified Data.ByteString.Lazy.Char8 as LBS
import Prelude.Compat
import Text.Printf
import Text.RE.Replace
import Text.RE.Tools.IsRegex
import Text.RE.ZeInternals.Types.LineNo
\end{code}
\begin{code}
-- | operates a bit like classic @grep@ printing out the lines matched
grep :: IsRegex re LBS.ByteString => Verbosity -> re -> FilePath -> IO ()
grep v rex fp = grepLines rex fp >>= putStr . report v
\end{code}
\begin{code}
-- | specifies whether to return the lines matched or missed
data Verbosity
= LinesMatched
| LinesNotMatched
deriving (Show,Eq,Ord)
\end{code}
\begin{code}
-- | 'grepLines' returns a 'Line' for each line in the file, listing all
-- of the 'Matches' for that line
data Line s =
Line
{ getLineNumber :: LineNo -- ^ the 'LineNo' for this line
, getLineMatches :: Matches s -- ^ all the 'Matches' of the RE on this line
}
deriving (Show)
\end{code}
\begin{code}
-- | returns a 'Line' for each line in the file, enumerating all of the
-- matches for that line
grepLines :: IsRegex re LBS.ByteString
=> re
-> FilePath
-> IO [Line LBS.ByteString]
grepLines rex fp = grepFilter rex <$> LBS.readFile fp
\end{code}
\begin{code}
-- | returns a 'Line' for each line in the argument text, enumerating
-- all of the matches for that line
grepFilter :: IsRegex re s => re -> s -> [Line s]
grepFilter rex = grepWithScript [(rex,mk)] . linesR
where
mk i mtchs = Just $ Line i mtchs
\end{code}
\begin{code}
-- | a GrepScript lists RE-action associations, with the first RE to match
-- a line selecting the action to be executed on each line in the file
type GrepScript re s t = [(re,LineNo -> Matches s -> Maybe t)]
-- | given a list of lines, apply the 'GrepScript' to each line of the file
grepWithScript :: IsRegex re s => GrepScript re s t -> [s] -> [t]
grepWithScript scr = loop firstLine
where
loop _ [] = []
loop i (ln:lns) = seq i $ choose i ln lns scr
choose i _ lns [] = loop (succ i) lns
choose i ln lns ((rex,f):scr') = case f i $ matchMany rex ln of
Nothing -> choose i ln lns scr'
Just t -> t : loop (succ i) lns
-- | generate a grep report from a list of 'Line'
report :: Verbosity -> [Line LBS.ByteString] -> String
report v = unlines . map fmt . linesMatched v
where
fmt Line{..} =
printf "%05d %s" (getLineNo getLineNumber) $
LBS.unpack $ matchesSource getLineMatches
-- | given a 'velocity' flag filter out either the lines matched or not
-- matched
linesMatched :: Verbosity -> [Line s] -> [Line s]
linesMatched v = filter $ f . anyMatches . getLineMatches
where
f = case v of
LinesMatched -> id
LinesNotMatched -> not
\end{code}
\begin{code}
-- $tutorial
-- The Grep toolkit matches REs against each line of a text.
--
-- See the Regex Tools tutorial at http://re-tutorial-tools.regex.uk
\end{code}
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