diff --git a/Diff.cabal b/Diff.cabal --- a/Diff.cabal +++ b/Diff.cabal @@ -1,39 +1,36 @@ -name: Diff -version: 0.3.0 -synopsis: O(ND) diff algorithm in haskell. -description: Basic implementation of the standard diff algorithm. -category: Algorithms -license: BSD3 -license-file: LICENSE -author: Sterling Clover -maintainer: s.clover@gmail.com -Tested-With: GHC == 6.8.2 -Build-Type: Simple -build-Depends: base -Cabal-Version: >= 1.6 - -flag small-base - -library - if flag(small-base) - build-depends: base >= 3 && <= 6, array - else - build-depends: base < 3 - hs-source-dirs: src - exposed-modules: - Data.Algorithm.Diff, - Data.Algorithm.DiffOutput - ghc-options: -O2 -Wall -funbox-strict-fields - build-depends: pretty - --- test-suite properties --- hs-source-dirs: src, test --- main-is: Test.hs --- type: exitcode-stdio-1.0 - --- build-depends: --- QuickCheck >= 2.4, test-framework >= 0.4, test-framework-quickcheck2 >= 0.2, process, directory - -source-repository head - type: darcs - location: http://patch-tag.com/r/sclv/diff +name: Diff +version: 0.3.1 +synopsis: O(ND) diff algorithm in haskell. +description: Implementation of the standard diff algorithm, and utilities for pretty printing. +category: Algorithms +license: BSD3 +license-file: LICENSE +author: Sterling Clover +maintainer: s.clover@gmail.com +Tested-With: GHC == 7.8.4 +Build-Type: Simple +build-Depends: base +Cabal-Version: >= 1.6 + +flag small-base + +library + build-depends: base >= 3 && <= 6, array, pretty + hs-source-dirs: src + exposed-modules: + Data.Algorithm.Diff, + Data.Algorithm.DiffOutput + Data.Algorithm.DiffContext + ghc-options: -O2 -Wall -funbox-strict-fields + +-- test-suite properties +-- hs-source-dirs: src, test +-- main-is: Test.hs +-- type: exitcode-stdio-1.0 + +-- build-depends: +-- QuickCheck >= 2.4, test-framework >= 0.4, test-framework-quickcheck2 >= 0.2, process, directory + +source-repository head + type: darcs + location: http://hub.darcs.net/sterlingclover/Diff diff --git a/src/Data/Algorithm/Diff.hs b/src/Data/Algorithm/Diff.hs --- a/src/Data/Algorithm/Diff.hs +++ b/src/Data/Algorithm/Diff.hs @@ -38,7 +38,7 @@ data DL = DL {poi :: !Int, poj :: !Int, path::[DI]} deriving (Show, Eq) -instance Ord DL +instance Ord DL where x <= y = if poi x == poi y then poj x > poj y else poi x <= poi y diff --git a/src/Data/Algorithm/DiffContext.hs b/src/Data/Algorithm/DiffContext.hs new file mode 100644 --- /dev/null +++ b/src/Data/Algorithm/DiffContext.hs @@ -0,0 +1,83 @@ +----------------------------------------------------------------------------- +-- | +-- Module : Data.Algorithm.DiffContext +-- Copyright : (c) David Fox (2015) +-- License : BSD 3 Clause +-- Maintainer : s.clover@gmail.com +-- Stability : experimental +-- Portability : portable +-- Author : David Fox (ddssff at the email service from google) +-- +-- Generates a grouped diff with merged runs, and outputs them in the manner of diff -u +----------------------------------------------------------------------------- +module Data.Algorithm.DiffContext + ( getContextDiff + , prettyContextDiff + ) where + +import Data.Algorithm.Diff (Diff(..), getGroupedDiff) +import Data.List (groupBy) +import Data.Monoid ((<>)) +import Text.PrettyPrint (Doc, text, empty, hcat) + +type ContextDiff c = [[Diff [c]]] + +-- | Do a grouped diff and then split up the chunks into runs that +-- contain differences surrounded by N lines of unchanged text. If +-- there is less then 2N+1 lines of unchanged text between two +-- changes, the runs are left merged. +getContextDiff :: Eq a => Int -> [a] -> [a] -> ContextDiff a +getContextDiff context a b = + group $ swap $ trimTail $ trimHead $ concatMap split $ getGroupedDiff a b + where + -- Drop the middle elements of a run of Both if there are more + -- than enough to form the context of the preceding changes and + -- the following changes. + split (Both xs ys) = + case length xs of + n | n > (2 * context) -> [Both (take context xs) (take context ys), Both (drop (n - context) xs) (drop (n - context) ys)] + _ -> [Both xs ys] + split x = [x] + -- If split created a pair of Both runs at the beginning or end + -- of the diff, remove the outermost. + trimHead [] = [] + trimHead [Both _ _] = [] + trimHead [Both _ _, Both _ _] = [] + trimHead (Both _ _ : x@(Both _ _) : more) = x : more + trimHead xs = trimTail xs + trimTail [x@(Both _ _), Both _ _] = [x] + trimTail (x : more) = x : trimTail more + trimTail [] = [] + -- If we see Second before First swap them so that the deletions + -- appear before the additions. + swap (x@(Second _) : y@(First _) : xs) = y : x : swap xs + swap (x : xs) = x : swap xs + swap [] = [] + -- Split the list wherever we see adjacent Both constructors + group xs = + groupBy (\ x y -> not (isBoth x && isBoth y)) xs + where + isBoth (Both _ _) = True + isBoth _ = False + +-- | Pretty print a ContextDiff in the manner of diff -u. +prettyContextDiff :: + Doc -- ^ Document 1 name + -> Doc -- ^ Document 2 name + -> (c -> Doc) -- ^ Element pretty printer + -> ContextDiff c + -> Doc +prettyContextDiff _ _ _ [] = empty +prettyContextDiff old new prettyElem hunks = + hcat . map (<> text "\n") $ (text "--- " <> old : + text "+++ " <> new : + concatMap prettyRun hunks) + where + -- Pretty print a run of adjacent changes + prettyRun hunk = + text "@@" : concatMap prettyChange hunk + + -- Pretty print a single change (e.g. one line of a text file) + prettyChange (Both ts _) = map (\ l -> text " " <> prettyElem l) ts + prettyChange (First ts) = map (\ l -> text "-" <> prettyElem l) ts + prettyChange (Second ts) = map (\ l -> text "+" <> prettyElem l) ts diff --git a/src/Data/Algorithm/DiffOutput.hs b/src/Data/Algorithm/DiffOutput.hs --- a/src/Data/Algorithm/DiffOutput.hs +++ b/src/Data/Algorithm/DiffOutput.hs @@ -11,9 +11,7 @@ -- Generates a string output that is similar to diff normal mode ----------------------------------------------------------------------------- module Data.Algorithm.DiffOutput where - import Data.Algorithm.Diff - import Text.PrettyPrint -- | pretty print the differences. The output is similar to the output of the diff utility