diff options
| -rw-r--r-- | Day7/app/Main.hs | 31 |
1 files changed, 27 insertions, 4 deletions
diff --git a/Day7/app/Main.hs b/Day7/app/Main.hs index 8956791..fa1d522 100644 --- a/Day7/app/Main.hs +++ b/Day7/app/Main.hs @@ -49,12 +49,35 @@ stripTrailingNewline [] = [] stripTrailingNewline (a:as) = a:stripTrailingNewline as buildDirectoryFromCommands :: [Command] -> Directory -buildDirectoryFromCommands = error "unimplemented" +buildDirectoryFromCommands = snd . foldl applyCommandToDirectory (Path [], Directory "/" [] []) applyCommandToDirectory :: (Path, Directory) -> Command -> (Path, Directory) -applyCommandToDirectory (oldPath, oldDir) CdRoot = (Path [], oldDir) -applyCommandToDirectory (oldPath, oldDir) CdUp = (fst . popDirectory $ oldPath, oldDir) --- todo: other arms +applyCommandToDirectory (oldPath, dir) CdRoot = (Path [], dir) +applyCommandToDirectory (oldPath, dir) CdUp = (fst . popDirectory $ oldPath, dir) +applyCommandToDirectory (oldPath, dir) (Cd subDir) = (pushDirectory oldPath subDir, dir) +applyCommandToDirectory (path, oldDir) (Ls contents) = (path, addContentsToDirectory path oldDir $ parseLsOutput contents) + +addContentsToDirectory :: Path -> Directory -> ([Directory], [File]) -> Directory +addContentsToDirectory (Path []) (Directory name dirs files) (newDirs, newFiles) = Directory name (newDirs ++ dirs) (newFiles ++ files) +addContentsToDirectory (Path p) (Directory name dirs files) n = Directory name (addContentsToDirectory (Path $ init p) subDir n:otherSubDirs) files + where (subDir, otherSubDirs) = getSubDir $ break (\(Directory name _ _) -> name == lp) dirs + getSubDir (a, b:bs) = (b, a ++ bs) + getSubDir (a, []) = error "Cannot descend into an unknown subdirectory." + lp = last p + + +data DirOrFile = Dir Directory | Fil File +parseLsOutput :: String -> ([Directory], [File]) +parseLsOutput = foldl appendLsLine ([],[]) . map parseLsLine . lines + where appendLsLine (dirs, files) (Dir d) = (d:dirs, files) + appendLsLine (dirs, files) (Fil f) = (dirs, f:files) + +parseLsLine :: String -> DirOrFile +parseLsLine ('d':'i':'r':' ':dn) = Dir $ Directory dn [] [] +parseLsLine fileSizeAndName = Fil $ File nn (read sz) + where (sz,nn) = verifyWordCount $ words fileSizeAndName + verifyWordCount [a,b] = (a,b) -- could use literal [sz,nn] pattern instead, but that doesn't give a nice error message. This does. + verifyWordCount _ = error "Wrong number of words in ls file entry." solveDay7Parts :: Directory -> (Int, Int) solveDay7Parts = error "unimplemented"
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