Hi, all, Here's my question: I thought, for grins, I'd try to turn some log output into a dependency graph (using GraphViz's dot(1)). I'm having difficulty forcing my stateful paradigm into a functional one, so I need some help. If I was to do this with an imperative (stateful) language, I'd build a set of edges (or a map to a frequency count, really, since I'll use freq > 1 to add some output text noting the repeated occurrences), and then dump out the set elements to a text file that would look something like this fragment: a -> q q -> d d -> e [color=red] d -> f [color=red My big problem now is that if I process a subtree that looks like: a b c d b d e my current plan is to proces the first b-c-d subtree and then process the b-d-e subtree, *BUT* I need to pass the updated edge set to the second processing call, which is pretty stateful. Do I need to just bite the bullet and find some succinct way to do that, or is my entire approach just wrong, stuck in my stateful mindset? My (awful) code looks like this: -- Emit to stdout a series of dot(1) edges specifying dependencies.-- "A -> B" means "A depends on B".---- Build with 'ghc dependency-graph.hs'-- -- Input is a text file containing lines as follows:-- (some indentation) (some extraneous text) (file-A) in (some directory)-- (some extra indentation) (some extraneous text) (file-B) in (some directory)-- (some indentation matching the first line above) (some extraneous text) (file-C) in (some directory)---- This means that file-A depends on file-B, but neither file-A nor file-B depend on file-C.---- Sample:-- Helios.MigrationTool.Common.AssemblyUtils.GetAssemblyList() Information: 0 : Processing SXA.Compass.Config.ViewModel.dll in C:\Program Files (x86)\Allscripts Sunrise\Clinical Manager Client\7.2.5575.0\-- Helios.MigrationTool.Common.AssemblyUtils.GetAssemblyList() Information: 0 : Adding C:\Program Files (x86)\Allscripts Sunrise\Clinical Manager Client\7.2.5575.0\SXA.Compass.Config.ViewModel.dll (IsPresent=true) to assemblyList at beginning of GetAssemblyListEx()-- Helios.MigrationTool.Common.AssemblyUtils.GetAssemblyList() Information: 0 : Processing SXA.Compass.Config.Utils.dll in C:\Program Files (x86)\Allscripts Sunrise\Clinical Manager Client\7.2.5575.0\---- (Need to skip the line containing "Adding", and only process the ones containing "Processing".)-- -- Algorithm:-- Read first line, parse, remember indentation-- Repeat for other lines, but if indentation increases, store pair A -> B in hashset.-- At end, dump out hashset. -- import Debug.Trace-- import System.Environment-- import System.Console.GetOpt-- import Data.Maybe (fromMaybe)-- import Data.List.Splitimport Prelude -- hiding (readFile) -- Because we want the System.IO.Strict version-- import System.IO (hPutStr, hPutStrLn, stderr)-- import System.IO.Strict-- import Control.Monad-- import System.Directory-- import System.FilePathimport Text.Regex.TDFA-- import Text.Regex.TDFA.String-- import Text.Printf -- import qualified Data.Map.Lazy as Mapimport qualified Data.Map.Strict as Map ---------------------------------------------------------------- Test Datal1 = " Helios.MigrationTool.Common.AssemblyUtils.GetAssemblyList() Information: 0 : Processing SXA.Compass.Config.ViewModel.dll\tin C:\\Program Files (x86)\\Allscripts Sunrise\\Clinical Manager Client\\7.2.5575.0\\"l2 = " Helios.MigrationTool.Common.AssemblyUtils.GetAssemblyList() Information: 0 : Adding C:\\Program Files (x86)\\Allscripts Sunrise\\Clinical Manager Client\\7.2.5575.0\\SXA.Compass.Config.ViewModel.dll\t(IsPresent=true)\tto assemblyList at beginning of GetAssemblyListEx()"l3 = " Helios.MigrationTool.Common.AssemblyUtils.GetAssemblyList() Information: 0 : Processing SXA.Compass.Config.Utils.dll\tin C:\\Program Files (x86)\\Allscripts Sunrise\\Clinical Manager Client\\7.2.5575.0\\"---------------------------------------------------------------- Test Data Ends-- See http://stackoverflow.com/q/32149354/370611-- toRegex = makeRegexOpts defaultCompOpt{multiline=False} defaultExecOpt -- Escape parens?-- initialFillerRegex :: String-- initialFillerRegex = "Helios.MigrationTool.Common.AssemblyUtils.GetAssemblyList\\(\\) Information: 0 : Processing" -- Regex matching (marking) a line to be processed-- valuableLineRegex :: String-- valuableLineRegex = "\\bProcessing\\b" -- |Regex matching line to be parsedparseLineRegex :: StringparseLineRegex = "^(.* Information: 0 : Processing )([^ ]*)[ \t]+in (.*)" -- 3subexpressions main :: IO()main = do logContents <- getContents putStrLn $ unlines $ fst $ edges (parseIndent $ lines logContents) Map.empty ------------------------------------------------------------------ |Parses out the leading indentation of the given String into a string of spaces and the rest of the lineparseIndent :: String -> (String,String)parseIndent s = ((fourth $ (s =~ "^( *)(.*)" :: (String,String,String,[String]))) !! 0, (fourth $ (s =~ "^( *)(.*)" :: (String,String,String,[String]))) !! 1) ------------------------------------------------------------------ |Returns a list of strings describing edges in the form "a -> b /* comment */"edges :: [(String,String)] -- ^ Input tuples: (indent, restOfString) -> Map.Map String Int -- ^ Map of edges in form "a -> b" with a count of the number of times that edge occurs -> [String] -- ^ Output list of edge descriptions in form "a -> b optionalExtraText" edges [] edgeSet = (edgeDump $ Map.assocs edgeSet, 0) edges (lastLine:[]) edgeSet = (edgeDump $ Map.assocs edgeSet, 1) edges (fstLogLine:sndLogLine:[]) edgeSet = let fstFields = (snd fstLogLine) =~ parseLineRegex :: (String,String,String,[String]) sndFields = (snd sndLogLine) =~ parseLineRegex :: (String,String,String,[String]) in if length (fourth fstFields) == 0 then error ("Unmatched: " ++ (first fstFields)) -- First line must always match else if length (fourth sndFields) == 0 -- "Adding", not "Processing" then edges (fstLogLine:[]) edgeSet -- Skip useless line else if indentLength fstLogLine >= indentLength sndLogLine then edges (sndLogLine:[]) edgeSet -- Can't be an edge from first to second line; drop first line and keep going. else edges (sndLogLine:[]) (Map.insertWith (+) ((fullName fstFields) ++ (fullName sndFields)) 1) edges (fstLogLine:sndLogLine:thdLogLine:logLines) edgeSet = let fstFields = (snd fstLogLine) =~ parseLineRegex :: (String,String,String,[String]) sndFields = (snd sndLogLine) =~ parseLineRegex :: (String,String,String,[String]) thdFields = (snd thdLogLine) =~ parseLineRegex :: (String,String,String,[String]) in if length (fourth fstFields) == 0 then error ("Unmatched: " ++ (first fstFields)) -- First line must always match else if length (fourth sndFields) == 0 -- "Adding", not "Processing" then edges (fstLogLine:thdLogLine:logLines) edgeSet -- Skip useless line else if indentLength fstLogLine >= indentLength sndLogLine then [] -- Stop processing at outdent else -- Looking one of: -- 1 -- 2 -- process 1 -> 2, then process 2.. as subtree -- 3 -- Need to process as subtree rooted at 2, then drop subtree (zero or more lines at same level as 3) -- or -- 1 -- 2 -- processs, then drop this line (process 2.. as empty subtree?) -- 3 -- or -- 1 -- 2 -- process, then drop this line (drop entire subtree rooted at 1) (same as above, drop empty subtree? (2)) -- 3 -- or -- 1 -- 2 -- same as above? Drop empty subtree rooted at 2 -- 3 edges (sndLogLine:thdLogLine:logLines) (Map.insertWith (+) ((fullName fstFields) ++ (fullName sndFields)) 1) -- now what? I need to pass the UPDATED edgeSet on to the next call, after the subtree rooted at 2 is dropped. then edges (sndLogLine:logLines) edgeSet -- Can't be an edge from first to second line; drop first line and keep going. else edges (sndLogLine:(takeWhile (increasingIndent $ length $ fst fstLogLine) logLines)) (Map.insertWith (+) ((fullName fstFields) ++ (fullName sndFields)) 1) else ((fst $ edges (sndLogLine:logLines) edgeSet) ++ (fst $ edges (fstLogLine:(drop (snd $ edges (sndLogLine:logLines) edgeSet) -- # of lines processed logLines)) edgeSet), (snd $ edges (sndLogLine:logLines) edgeSet) + (snd $ edges (fstLogLine:(drop (snd $ edges (sndLogLine:logLines) edgeSet) -- # of lines processed logLines)) edgeSet) ) ----------------------------------------------------------------fullname :: (String,String,String,[String]) -> Stringfullname (_,_,_,[_,fileName,directoryName]) = directoryName ++ fileName ------------------------------------------------------------------ |Edges from the first line to all following linesedgesFrom :: String -- ^ First line -> [String] -- ^ Following lines -> Map.Map String Int -- ^ Set of edges built so far -> [String]edgesFrom a b c = [] ------------------------------------------------------------------ |Return length of indent or errorindentLength :: (String,String,String,[String]) -- ^ Regex match context -> Int -- ^ Length of indentindentLength (prefix,_,_,[]) = error $ "Not matched: " ++ prefixindentLength (_,_,_,subexprs) = length $ subexprs !! 0 ------------------------------------------------------------------ |Returns a list of edges, possibly with comments indicating occurrence counts > 1edgeDump :: [(String,Int)] -- ^ List of (edge,count) tuples -> [String] -- ^ List of edges, possibly w/commentsedgeDump [] = []edgeDump ((edge,count):rest) | count <= 1 = edge:(edgeDump rest) | otherwise = (edge ++ " /* " ++ (show count) ++ " occurrences */"):(edgeDump rest) ----------------------------------------------------------------first :: (a,b,c,d) -> afirst (x,_,_,_) = x fourth :: (a,b,c,d) -> dfourth (_,_,_,x) = x