Process replacements according to AST depth (fixes #1431)

ShellCheck.cabal

@@ -49,9 +49,10 @@ library
       build-depends:
         semigroups
     build-depends:
+      aeson,
+      array,
       -- GHC 7.6.3 (base 4.6.0.1) is buggy (#1131, #1119) in optimized mode.
       -- Just disable that version entirely to fail fast.
-      aeson,
       base > 4.6.0.1 && < 5,
       bytestring,
       containers >= 0.5,
@@ -91,6 +92,7 @@ executable shellcheck
         semigroups
     build-depends:
       aeson,
+      array,
       base >= 4 && < 5,
       bytestring,
       deepseq >= 1.4.0.0,
@@ -107,6 +109,7 @@ test-suite test-shellcheck
     type: exitcode-stdio-1.0
     build-depends:
       aeson,
+      array,
       base >= 4 && < 5,
       bytestring,
       deepseq >= 1.4.0.0,

src/ShellCheck/Analytics.hs

@@ -250,11 +250,14 @@ replaceStart id params n r =
         new_end = start {
             posColumn = posColumn start + n
         }
+        depth = length $ getPath (parentMap params) (T_EOF id)
     in
     newReplacement {
         repStartPos = start,
         repEndPos = new_end,
-        repString = r
+        repString = r,
+        repPrecedence = depth,
+        repInsertionPoint = InsertAfter
     }
 replaceEnd id params n r =
     let tp = tokenPositions params
@@ -265,11 +268,14 @@ replaceEnd id params n r =
         new_end = end {
             posColumn = posColumn end
         }
+        depth = length $ getPath (parentMap params) (T_EOF id)
     in
     newReplacement {
         repStartPos = new_start,
         repEndPos = new_end,
-        repString = r
+        repString = r,
+        repPrecedence = depth,
+        repInsertionPoint = InsertBefore
     }
 surroundWidth id params s = fixWith [replaceStart id params 0 s, replaceEnd id params 0 s]
 fixWith fixes = newFix { fixReplacements = fixes }
@@ -1676,9 +1682,8 @@ checkSpacefulness params t =
                     "This default assignment may cause DoS due to globbing. Quote it."
             else
                 makeCommentWithFix InfoC (getId token) 2086
-                    "Double quote to prevent globbing and word splitting." (surroundWidth (getId token) params "\"")
+                    "Double quote to prevent globbing and word splitting."
-                -- makeComment InfoC (getId token) 2086
+                        (surroundWidth (getId token) params "\"")
-                --     "Double quote to prevent globbing and word splitting."
 
     writeF _ _ name (DataString SourceExternal) = setSpaces name True >> return []
     writeF _ _ name (DataString SourceInteger) = setSpaces name False >> return []

src/ShellCheck/Fixer.hs

@@ -1,8 +1,33 @@
-module ShellCheck.Fixer (applyFix , replaceMultiLines, Ranged(..)) where
+{-
+    Copyright 2018-2019 Vidar Holen, Ng Zhi An
+
+    This file is part of ShellCheck.
+    https://www.shellcheck.net
+
+    ShellCheck is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    ShellCheck is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+-}
+
+{-# LANGUAGE TemplateHaskell #-}
+module ShellCheck.Fixer (applyFix, mapPositions, Ranged(..), runTests) where
 
 import ShellCheck.Interface
+import Control.Monad.State
+import Data.Array
 import Data.List
 import Data.Semigroup
+import GHC.Exts (sortWith)
+import Test.QuickCheck
 
 -- The Ranged class is used for types that has a start and end position.
 class Ranged a where
@@ -19,6 +44,27 @@ class Ranged a where
     -- Set a new start and end position on a Ranged
     setRange :: (Position, Position) -> a -> a
 
+-- Tests auto-verify that overlap commutes
+assertOverlap x y = overlap x y && overlap y x
+assertNoOverlap x y = not (overlap x y) && not (overlap y x)
+
+prop_overlap_contiguous = assertNoOverlap
+        (tFromStart 10 12 "foo" 1)
+        (tFromStart 12 14 "bar" 2)
+
+prop_overlap_adjacent_zerowidth = assertNoOverlap
+        (tFromStart 3 3 "foo" 1)
+        (tFromStart 3 3 "bar" 2)
+
+prop_overlap_enclosed = assertOverlap
+        (tFromStart 3 5 "foo" 1)
+        (tFromStart 1 10 "bar" 2)
+
+prop_overlap_partial = assertOverlap
+        (tFromStart 1 5 "foo" 1)
+        (tFromStart 3 7 "bar" 2)
+
+
 instance Ranged PositionedComment where
     start = pcStartPos
     end = pcEndPos
@@ -35,44 +81,60 @@ instance Ranged Replacement where
         repEndPos = e
     }
 
-instance Ranged a => Ranged [a] where
+-- The Monoid instance for Fix merges fixes that do not conflict.
-    start [] = newPosition
+-- TODO: Make an efficient 'mconcat'
-    start xs = (minimum . map start) xs
-    end []   = newPosition
-    end xs   = (maximum . map end) xs
-    setRange (s, e) rs = map (setRange (s, e)) rs
-
-instance Ranged Fix where
-    start = start . fixReplacements
-    end   = end . fixReplacements
-    setRange (s, e) f = f {
-        fixReplacements = setRange (s, e) (fixReplacements f)
-    }
-
--- The Monoid instance for Fix merges replacements that do not overlap.
 instance Monoid Fix where
     mempty = newFix
     mappend = (<>)
 
 instance Semigroup Fix where
-    f1 <> f2 = if overlap f1 f2 then f1 else newFix {
+    f1 <> f2 =
+        -- FIXME: This might need to also discard adjacent zero-width ranges for
+        --        when two fixes change the same AST node, e.g. `foo` -> "$(foo)"
+        if or [ r2 `overlap` r1 | r1 <- fixReplacements f1, r2 <- fixReplacements f2 ]
+        then f1
+        else newFix {
             fixReplacements = fixReplacements f1 ++ fixReplacements f2
-    }
+            }
 
+mapPositions :: (Position -> Position) -> Fix -> Fix
+mapPositions f = adjustFix
+  where
+    adjustReplacement rep =
+        rep {
+            repStartPos = f $ repStartPos rep,
+            repEndPos = f $ repEndPos rep
+        }
+    adjustFix fix =
+        fix {
+            fixReplacements = map adjustReplacement $ fixReplacements fix
+        }
+
+multiToSingleLine :: [Fix] -> Array Int String -> ([Fix], String)
+multiToSingleLine fixes lines =
+    (map (mapPositions adjust) fixes, unlines $ elems lines)
+  where
+    -- A prefix sum tree from line number to column shift.
+    -- FIXME: The tree will be totally unbalanced.
+    shiftTree :: PSTree Int
+    shiftTree =
+        foldl (\t (n,s) -> addPSValue (n+1) (length s + 1) t) newPSTree $
+            assocs lines
+    singleString = unlines $ elems lines
+    adjust pos =
+        pos {
+            posLine = 1,
+            posColumn = (posColumn pos) +
+                (fromIntegral $ getPrefixSum (fromIntegral $ posLine pos) shiftTree)
+        }
+
+-- Apply a fix and return resulting lines.
+-- The number of lines can increase or decrease with no obvious mapping back, so
+-- the function does not return an array.
+applyFix :: Fix -> Array Int String -> [String]
 applyFix fix fileLines =
-    -- apply replacements in sorted order by end position
+    let (adjustedFixes, singleLine) = multiToSingleLine [fix] fileLines
-    let sorted = (removeOverlap . reverse . sort) (fixReplacements fix) in
+    in lines . runFixer $ applyFixes2 adjustedFixes singleLine
-    applyReplacement sorted fileLines
-    where
-        applyReplacement [] s = s
-        applyReplacement (rep:xs) s = applyReplacement xs $ replaceMultiLines rep s
-        -- prereq: list is already sorted by start position
-        removeOverlap [] = []
-        removeOverlap (x:xs) = checkoverlap x xs
-        checkoverlap x [] = x:[]
-        checkoverlap x (y:ys) =
-            if overlap x y then x:(removeOverlap ys) else x:y:(removeOverlap ys)
-
 
 -- A replacement that spans multiple line is applied by:
 -- 1. merging the affected lines into a single string using `unlines`
@@ -111,14 +173,13 @@ replaceMultiLines rep fileLines = -- this can replace doReplace
     in
     xs ++ replacedLines ++ zs
 
--- FIXME: Work correctly with tabs
 -- start and end comes from pos, which is 1 based
--- doReplace 0 0 "1234" "A" -> "A1234" -- technically not valid
+prop_doReplace1 = doReplace 0 0 "1234" "A" == "A1234" -- technically not valid
--- doReplace 1 1 "1234" "A" -> "A1234"
+prop_doReplace2 = doReplace 1 1 "1234" "A" == "A1234"
--- doReplace 1 2 "1234" "A" -> "A234"
+prop_doReplace3 = doReplace 1 2 "1234" "A" == "A234"
--- doReplace 3 3 "1234" "A" -> "12A34"
+prop_doReplace4 = doReplace 3 3 "1234" "A" == "12A34"
--- doReplace 4 4 "1234" "A" -> "123A4"
+prop_doReplace5 = doReplace 4 4 "1234" "A" == "123A4"
--- doReplace 5 5 "1234" "A" -> "1234A"
+prop_doReplace6 = doReplace 5 5 "1234" "A" == "1234A"
 doReplace start end o r =
     let si = fromIntegral (start-1)
         ei = fromIntegral (end-1)
@@ -126,3 +187,207 @@ doReplace start end o r =
         (y, z) = splitAt (ei - si) xs
     in
     x ++ r ++ z
+
+-- Fail if the 'expected' string is not result when applying 'fixes' to 'original'.
+testFixes :: String -> String -> [Fix] -> Bool
+testFixes expected original fixes =
+    actual == expected
+  where
+    actual = runFixer (applyFixes2 fixes original)
+
+
+-- A Fixer allows doing repeated modifications of a string where each
+-- replacement automatically accounts for shifts from previous ones.
+type Fixer a =  State (PSTree Int) a
+
+-- Apply a single replacement using its indices into the original string.
+-- It does not handle multiple lines, all line indices must be 1.
+applyReplacement2 :: Replacement -> String -> Fixer String
+applyReplacement2 rep string = do
+    tree <- get
+    let transform pos = pos + getPrefixSum pos tree
+    let originalPos = (repStartPos rep, repEndPos rep)
+        (oldStart, oldEnd) = tmap (fromInteger . posColumn) originalPos
+        (newStart, newEnd) = tmap transform (oldStart, oldEnd)
+
+    let (l1, l2) = tmap posLine originalPos in
+        when (l1 /= 1 || l2 /= 1) $
+            error "ShellCheck internal error, please report: bad cross-line fix"
+
+    let replacer = repString rep
+    let shift = (length replacer) - (oldEnd - oldStart)
+    let insertionPoint =
+          case repInsertionPoint rep of
+              InsertBefore -> oldStart
+              InsertAfter  -> oldEnd+1
+    put $ addPSValue insertionPoint shift tree
+
+    return $ doReplace newStart newEnd string replacer
+  where
+    tmap f (a,b) = (f a, f b)
+
+-- Apply a list of Replacements in the correct order
+applyReplacements2 :: [Replacement] -> String -> Fixer String
+applyReplacements2 reps str =
+    foldM (flip applyReplacement2) str $
+        reverse $ sortWith repPrecedence reps
+
+-- Apply all fixes with replacements in the correct order
+applyFixes2 :: [Fix] -> String -> Fixer String
+applyFixes2 fixes = applyReplacements2 (concatMap fixReplacements fixes)
+
+-- Get the final value of a Fixer.
+runFixer :: Fixer a -> a
+runFixer f = evalState f newPSTree
+
+
+
+-- A Prefix Sum Tree that lets you look up the sum of values at and below an index.
+-- It's implemented essentially as a Fenwick tree without the bit-based balancing.
+-- The last Num is the sum of the left branch plus current element.
+data PSTree n = PSBranch n (PSTree n) (PSTree n) n | PSLeaf
+    deriving (Show)
+
+newPSTree :: Num n => PSTree n
+newPSTree = PSLeaf
+
+-- Get the sum of values whose keys are <= 'target'
+getPrefixSum :: (Ord n, Num n) => n -> PSTree n -> n
+getPrefixSum = f 0
+  where
+    f sum _ PSLeaf = sum
+    f sum target (PSBranch pivot left right cumulative) =
+        case () of
+            _ | target < pivot -> f sum target left
+            _ | target > pivot -> f (sum+cumulative) target right
+            _ -> sum+cumulative
+
+-- Add a value to the Prefix Sum tree at the given index.
+-- Values accumulate: addPSValue 42 2 . addPSValue 42 3 == addPSValue 42 5
+addPSValue :: (Ord n, Num n) => n -> n -> PSTree n -> PSTree n
+addPSValue key value tree = if value == 0 then tree else f tree
+  where
+    f PSLeaf = PSBranch key PSLeaf PSLeaf value
+    f (PSBranch pivot left right sum) =
+        case () of
+            _ | key < pivot -> PSBranch pivot (f left) right (sum + value)
+            _ | key > pivot -> PSBranch pivot left (f right) sum
+            _ -> PSBranch pivot left right (sum + value)
+
+prop_pstreeSumsCorrectly kvs targets =
+  let
+    -- Trivial O(n * m) implementation
+    dumbPrefixSums :: [(Int, Int)] -> [Int] -> [Int]
+    dumbPrefixSums kvs targets =
+        let prefixSum target = sum . map snd . filter (\(k,v) -> k <= target) $ kvs
+        in map prefixSum targets
+    -- PSTree O(n * log m) implementation
+    smartPrefixSums :: [(Int, Int)] -> [Int] -> [Int]
+    smartPrefixSums kvs targets =
+        let tree = foldl (\tree (pos, shift) -> addPSValue pos shift tree) PSLeaf kvs
+        in map (\x -> getPrefixSum x tree) targets
+  in smartPrefixSums kvs targets == dumbPrefixSums kvs targets
+
+
+-- Semi-convenient functions for constructing tests.
+testFix :: [Replacement] -> Fix
+testFix list = newFix {
+        fixReplacements = list
+    }
+
+tFromStart :: Int -> Int -> String -> Int -> Replacement
+tFromStart start end repl order =
+    newReplacement {
+        repStartPos = newPosition {
+            posLine = 1,
+            posColumn = fromIntegral start
+        },
+        repEndPos = newPosition {
+            posLine = 1,
+            posColumn = fromIntegral end
+        },
+        repString = repl,
+        repPrecedence = order,
+        repInsertionPoint = InsertAfter
+    }
+
+tFromEnd start end repl order =
+    (tFromStart start end repl order) {
+        repInsertionPoint = InsertBefore
+    }
+
+prop_simpleFix1 = testFixes "hello world" "hell world" [
+    testFix [
+        tFromEnd 5 5 "o" 1
+    ]]
+
+prop_anchorsLeft = testFixes "-->foobar<--" "--><--" [
+    testFix [
+        tFromStart 4 4 "foo" 1,
+        tFromStart 4 4 "bar" 2
+    ]]
+
+prop_anchorsRight = testFixes "-->foobar<--" "--><--" [
+    testFix [
+        tFromEnd 4 4 "bar" 1,
+        tFromEnd 4 4 "foo" 2
+    ]]
+
+prop_anchorsBoth1 = testFixes "-->foobar<--" "--><--" [
+    testFix [
+        tFromStart 4 4 "bar" 2,
+        tFromEnd 4 4 "foo" 1
+    ]]
+
+prop_anchorsBoth2 = testFixes "-->foobar<--" "--><--" [
+    testFix [
+        tFromEnd 4 4 "foo" 2,
+        tFromStart 4 4 "bar" 1
+    ]]
+
+prop_composeFixes1 = testFixes "cd \"$1\" || exit" "cd $1" [
+    testFix [
+        tFromStart 4 4 "\"" 10,
+        tFromEnd   6 6 "\"" 10
+    ],
+    testFix [
+        tFromEnd 6 6 " || exit" 5
+    ]]
+
+prop_composeFixes2 = testFixes "$(\"$1\")" "`$1`" [
+    testFix [
+        tFromStart 1 2 "$(" 5,
+        tFromEnd   4 5 ")" 5
+    ],
+    testFix [
+        tFromStart 2 2 "\"" 10,
+        tFromEnd 4 4 "\"" 10
+    ]]
+
+prop_composeFixes3 = testFixes "(x)[x]" "xx" [
+    testFix [
+        tFromStart 1 1 "(" 4,
+        tFromEnd   2 2 ")" 3,
+        tFromStart 2 2 "[" 2,
+        tFromEnd   3 3 "]" 1
+    ]]
+
+prop_composeFixes4 = testFixes "(x)[x]" "xx" [
+    testFix [
+        tFromStart 1 1 "(" 4,
+        tFromStart 2 2 "[" 3,
+        tFromEnd   2 2 ")" 2,
+        tFromEnd   3 3 "]" 1
+    ]]
+
+prop_composeFixes5 = testFixes "\"$(x)\"" "`x`" [
+    testFix [
+        tFromStart 1 2 "$(" 2,
+        tFromEnd   3 4 ")"  2,
+        tFromStart 1 1 "\"" 1,
+        tFromEnd   4 4 "\"" 1
+    ]]
+
+
+return []
+runTests = $quickCheckAll

src/ShellCheck/Formatter/Format.hs

@@ -22,6 +22,7 @@ module ShellCheck.Formatter.Format where
 import ShellCheck.Data
 import ShellCheck.Interface
 import ShellCheck.Fixer
+import Data.Array
 
 -- A formatter that carries along an arbitrary piece of data
 data Formatter = Formatter {
@@ -51,11 +52,12 @@ severityText pc =
 makeNonVirtual comments contents =
     map fix comments
   where
-    ls = lines contents
+    list = lines contents
-    fix c =  realign c ls
+    arr = listArray (1, length list) list
+    fix c =  realign c arr
 
 -- Realign a Ranged from a tabstop of 8 to 1
-realign :: Ranged a => a -> [String] -> a
+realign :: Ranged a => a -> Array Int String -> a
 realign range ls =
     let startColumn = realignColumn lineNo colNo range
         endColumn = realignColumn endLineNo endColNo range
@@ -65,7 +67,7 @@ realign range ls =
   where
     realignColumn lineNo colNo c =
       if lineNo c > 0 && lineNo c <= fromIntegral (length ls)
-      then real (ls !! fromIntegral (lineNo c - 1)) 0 0 (colNo c)
+      then real (ls ! fromIntegral (lineNo c)) 0 0 (colNo c)
       else colNo c
     real _ r v target | target <= v = r
     -- hit this case at the end of line, and if we don't hit the target

src/ShellCheck/Formatter/TTY.hs

@@ -24,6 +24,7 @@ import ShellCheck.Interface
 import ShellCheck.Formatter.Format
 
 import Control.Monad
+import Data.Array
 import Data.Foldable
 import Data.Ord
 import Data.IORef
@@ -37,6 +38,8 @@ wikiLink = "https://www.shellcheck.net/wiki/"
 
 -- An arbitrary Ord thing to order warnings
 type Ranking = (Char, Severity, Integer)
+-- Ansi coloring function
+type ColorFunc = (String -> String -> String)
 
 format :: FormatterOptions -> IO Formatter
 format options = do
@@ -119,59 +122,66 @@ outputForFile color sys comments = do
     let fileName = sourceFile (head comments)
     result <- (siReadFile sys) fileName
     let contents = either (const "") id result
-    let fileLines = lines contents
+    let fileLinesList = lines contents
-    let lineCount = fromIntegral $ length fileLines
+    let lineCount = length fileLinesList
+    let fileLines = listArray (1, lineCount) fileLinesList
     let groups = groupWith lineNo comments
     mapM_ (\commentsForLine -> do
-        let lineNum = lineNo (head commentsForLine)
+        let lineNum = fromIntegral $ lineNo (head commentsForLine)
         let line = if lineNum < 1 || lineNum > lineCount
                         then ""
-                        else fileLines !! fromIntegral (lineNum - 1)
+                        else fileLines ! fromIntegral lineNum
         putStrLn ""
         putStrLn $ color "message" $
            "In " ++ fileName ++" line " ++ show lineNum ++ ":"
         putStrLn (color "source" line)
         mapM_ (\c -> putStrLn (color (severityText c) $ cuteIndent c)) commentsForLine
         putStrLn ""
-        showFixedString color comments lineNum fileLines
+        showFixedString color commentsForLine (fromIntegral lineNum) fileLines
       ) groups
 
-hasApplicableFix lineNum comment = fromMaybe False $ do
+-- Pick out only the lines necessary to show a fix in action
-    replacements <- fixReplacements <$> pcFix comment
+sliceFile :: Fix -> Array Int String -> (Fix, Array Int String)
-    guard $ all (\c -> onSameLine (repStartPos c) && onSameLine (repEndPos c)) replacements
+sliceFile fix lines =
-    return True
+    (mapPositions adjust fix, sliceLines lines)
   where
-    onSameLine pos = posLine pos == lineNum
+    (minLine, maxLine) =
+        foldl (\(mm, mx) pos -> ((min mm $ fromIntegral $ posLine pos), (max mx $ fromIntegral $ posLine pos)))
+                (maxBound, minBound) $
+            concatMap (\x -> [repStartPos x, repEndPos x]) $ fixReplacements fix
+    sliceLines :: Array Int String -> Array Int String
+    sliceLines = ixmap (1, maxLine - minLine + 1) (\x -> x + minLine - 1)
+    adjust pos =
+        pos {
+            posLine = posLine pos - (fromIntegral minLine) + 1
+        }
 
--- FIXME: Work correctly with multiple replacements
+showFixedString :: ColorFunc -> [PositionedComment] -> Int -> Array Int String -> IO ()
 showFixedString color comments lineNum fileLines =
-    let line = fileLines !! fromIntegral (lineNum - 1) in
+    let line = fileLines ! fromIntegral lineNum in
-    -- need to check overlaps
+    case mapMaybe pcFix comments of
-    case filter (hasApplicableFix lineNum) comments of
         [] -> return ()
-        -- all the fixes are single-line only, but there could be multiple
+        fixes -> do
-        -- fixes for that single line. We can fold the fixes (which removes
+            -- Folding automatically removes overlap
-        -- overlaps), and apply it as a single fix with multiple replacements.
+            let mergedFix = realignFix $ fold fixes
-        applicableComments -> do
+            -- We show the complete, associated fixes, whether or not it includes this and/or unrelated lines.
-            let mergedFix = (realignFix . fold . catMaybes . (map pcFix)) applicableComments
+            let (excerptFix, excerpt) = sliceFile mergedFix fileLines
             -- in the spirit of error prone
             putStrLn $ color "message" "Did you mean: "
-            putStrLn $ unlines $ fixedString mergedFix fileLines
+            putStrLn $ unlines $ fixedString excerptFix excerpt
         where
+            -- FIXME: This should be handled by Fixer
             realignFix f = f { fixReplacements = map fix (fixReplacements f) }
             fix r = realign r fileLines
 
-fixedString :: Fix -> [String] -> [String]
+fixedString :: Fix -> Array Int String -> [String]
 fixedString fix fileLines =
     case (fixReplacements fix) of
         [] -> []
         reps ->
             -- applyReplacement returns the full update file, we really only care about the changed lines
             -- so we calculate overlapping lines using replacements
-            drop start $ take end $ applyFix fix fileLines
+            applyFix fix fileLines
-            where
-                start = (fromIntegral $ minimum $ map (posLine . repStartPos) reps) - 1
-                end = fromIntegral $ maximum $ map (posLine . repEndPos) reps
 
 cuteIndent :: PositionedComment -> String
 cuteIndent comment =
@@ -187,6 +197,7 @@ cuteIndent comment =
 
 code num = "SC" ++ show num
 
+getColorFunc :: ColorOption -> IO ColorFunc
 getColorFunc colorOption = do
     term <- hIsTerminalDevice stdout
     let windows = "mingw" `isPrefixOf` os

src/ShellCheck/Interface.hs

@@ -52,7 +52,8 @@ module ShellCheck.Interface
     , newComment
     , Fix(fixReplacements)
     , newFix
-    , Replacement(repStartPos, repEndPos, repString)
+    , InsertionPoint(InsertBefore, InsertAfter)
+    , Replacement(repStartPos, repEndPos, repString, repPrecedence, repInsertionPoint)
     , newReplacement
     ) where
 
@@ -209,16 +210,25 @@ newComment = Comment {
 data Replacement = Replacement {
     repStartPos :: Position,
     repEndPos :: Position,
-    repString :: String
+    repString :: String,
+    -- Order in which the replacements should happen: highest precedence first.
+    repPrecedence :: Int,
+    -- Whether to insert immediately before or immediately after the specified region.
+    repInsertionPoint :: InsertionPoint
 } deriving (Show, Eq, Generic, NFData)
 
+data InsertionPoint = InsertBefore | InsertAfter
+    deriving (Show, Eq, Generic, NFData)
+
 instance Ord Replacement where
     compare r1 r2 = (repStartPos r1) `compare` (repStartPos r2)
 
 newReplacement = Replacement {
     repStartPos = newPosition,
     repEndPos = newPosition,
-    repString = ""
+    repString = "",
+    repPrecedence = 1,
+    repInsertionPoint = InsertAfter
 }
 
 data Fix = Fix {

test/shellcheck.hs

@@ -2,22 +2,24 @@ module Main where
 
 import Control.Monad
 import System.Exit
-import qualified ShellCheck.Checker
 import qualified ShellCheck.Analytics
 import qualified ShellCheck.AnalyzerLib
-import qualified ShellCheck.Parser
+import qualified ShellCheck.Checker
 import qualified ShellCheck.Checks.Commands
 import qualified ShellCheck.Checks.ShellSupport
+import qualified ShellCheck.Fixer
+import qualified ShellCheck.Parser
 
 main = do
     putStrLn "Running ShellCheck tests..."
     results <- sequence [
-        ShellCheck.Checker.runTests,
+        ShellCheck.Analytics.runTests
-        ShellCheck.Checks.Commands.runTests,
+        ,ShellCheck.AnalyzerLib.runTests
-        ShellCheck.Checks.ShellSupport.runTests,
+        ,ShellCheck.Checker.runTests
-        ShellCheck.Analytics.runTests,
+        ,ShellCheck.Checks.Commands.runTests
-        ShellCheck.AnalyzerLib.runTests,
+        ,ShellCheck.Checks.ShellSupport.runTests
-        ShellCheck.Parser.runTests
+        ,ShellCheck.Fixer.runTests
+        ,ShellCheck.Parser.runTests
       ]
     if and results
       then exitSuccess