try to simplify FilterPatterns a bit

Ledger.hs

@@ -62,31 +62,37 @@ cacheLedger pats l =
     in
       Ledger l' ant amap lprecision
 
--- | filter entries by description and whether any transactions match account patterns
+-- | keep only entries whose description matches one of the
+-- | description patterns, if any, and which have at least one
+-- | transaction matching one of the account patterns, if any.
+-- | No description or account patterns implies match all.
 filterLedgerEntries :: FilterPatterns -> LedgerFile -> LedgerFile
 filterLedgerEntries (acctpat,descpat) (LedgerFile ms ps es f) = 
-    LedgerFile ms ps (filter matchdesc $ filter (any matchtxn . etransactions) es) f
+    LedgerFile ms ps filteredentries f
     where
-      matchtxn t = case matchRegex (wilddefault acctpat) (taccount t) of
+      filteredentries :: [LedgerEntry]
+      filteredentries = (filter matchdesc $ filter (any matchtxn . etransactions) es)
+      matchtxn :: LedgerTransaction -> Bool
+      matchtxn t = case matchRegex acctpat (taccount t) of
                      Nothing -> False
                      otherwise -> True
-      matchdesc e = case matchRegex (wilddefault descpat) (edescription e) of
+      matchdesc :: LedgerEntry -> Bool
+      matchdesc e = case matchRegex descpat (edescription e) of
                       Nothing -> False
                       otherwise -> True
 
--- | filter transactions in each ledger entry by account patterns
--- this may unbalance entries
+-- | in each ledger entry, filter out transactions which do not match
+-- | the account patterns, if any.  (Entries are no longer balanced
+-- | after this.)
 filterLedgerTransactions :: FilterPatterns -> LedgerFile -> LedgerFile
 filterLedgerTransactions (acctpat,descpat) (LedgerFile ms ps es f) = 
     LedgerFile ms ps (map filterentrytxns es) f
     where
       filterentrytxns l@(LedgerEntry _ _ _ _ _ ts _) = l{etransactions=filter matchtxn ts}
-      matchtxn t = case matchRegex (wilddefault acctpat) (taccount t) of
+      matchtxn t = case matchRegex acctpat (taccount t) of
                      Nothing -> False
                      otherwise -> True
 
-wilddefault = fromMaybe (mkRegex ".*")
-
 accountnames :: Ledger -> [AccountName]
 accountnames l = flatten $ accountnametree l
 

Options.hs

@@ -72,17 +72,20 @@ tildeExpand ('~':'/':xs) =  getHomeDirectory >>= return . (++ ('/':xs))
 tildeExpand xs           =  return xs
 -- -- courtesy of allberry_b
 
--- | ledger pattern args are 0 or more account patterns optionally followed
--- by -- and 0 or more description patterns
+-- | ledger pattern arguments are: 0 or more account patterns
+-- | optionally followed by -- and 0 or more description patterns.
+-- | Here we convert the arguments, if any, to FilterPatterns,
+-- | which is a pair of maybe regexps.
 parsePatternArgs :: [String] -> FilterPatterns
-parsePatternArgs args = argpats as ds' 
+parsePatternArgs args = (regexFor as, regexFor ds')
     where (as, ds) = break (=="--") args
           ds' = dropWhile (=="--") ds
 
-argpats :: [String] -> [String] -> FilterPatterns
-argpats as ds = (regexify as, regexify ds)
-    where
-      regexify :: [String] -> Maybe Regex
-      regexify [] = Nothing
-      regexify ss = Just $ mkRegex $ "(" ++ (unwords $ intersperse "|" ss) ++ ")"
+-- | convert a list of strings to a regular expression matching any of them,
+-- | or a wildcard if there are none.
+regexFor :: [String] -> Regex
+regexFor [] = wildcard
+regexFor ss = mkRegex $ "(" ++ (unwords $ intersperse "|" ss) ++ ")"
 
+wildcard :: Regex
+wildcard = mkRegex ".*"

Tests.hs

@@ -284,7 +284,7 @@ ledger7 = LedgerFile
           ]
           ""
 
-l7 = cacheLedger (argpats [] []) ledger7
+l7 = cacheLedger (parsePatternArgs []) ledger7
 
 timelogentry1_str  = "i 2007/03/11 16:19:00 hledger\n"
 timelogentry1 = TimeLogEntry 'i' "2007/03/11 16:19:00" "hledger"
@@ -375,7 +375,7 @@ test_ledgerAccountNames =
     (rawLedgerAccountNames ledger7)
 
 test_cacheLedger =
-    assertEqual' 15 (length $ Map.keys $ accounts $ cacheLedger (argpats [] []) ledger7)
+    assertEqual' 15 (length $ Map.keys $ accounts $ cacheLedger (parsePatternArgs []) ledger7)
 
 test_showLedgerAccounts = 
     assertEqual' 4 (length $ lines $ showLedgerAccounts l7 1)

Types.hs

@@ -6,8 +6,8 @@ where
 import Utils
 import qualified Data.Map as Map
 
--- | account and description-matching patterns
-type FilterPatterns = (Maybe Regex, Maybe Regex)
+-- | account and description-matching patterns, see 'Options.parsePatternArgs'.
+type FilterPatterns = (Regex, Regex)
                        
 type Date = String
 

hledger.hs

@@ -98,25 +98,28 @@ balance opts pats = do
               where 
                 showsubs = (ShowSubs `elem` opts)
                 depth = case (pats, showsubs) of
-                          ((Nothing,_), False) -> 1
+                          -- when there are no account patterns and no -s,
+                          -- show only to depth 1. (This was clearer and more
+                          -- correct when FilterPatterns used maybe.)
+                          ((wildcard,_), False) -> 1
                           otherwise  -> 9999
 
 -- helpers for interacting in ghci
 
 -- | return a Ledger parsed from the file your LEDGER environment variable
--- points to or (WARNING:) an empty one if there was a problem.
+-- points to or (WARNING) an empty one if there was a problem.
 myledger :: IO Ledger
 myledger = do
   parsed <- ledgerFilePath [] >>= parseLedgerFile
   let ledgerfile = either (\_ -> LedgerFile [] [] [] "") id parsed
-  return $ cacheLedger (argpats [] []) ledgerfile
+  return $ cacheLedger (parsePatternArgs []) ledgerfile
 
 -- | return a Ledger parsed from the given file path
 ledgerfromfile :: String -> IO Ledger
 ledgerfromfile f = do
   parsed <- ledgerFilePath [File f] >>= parseLedgerFile
   let ledgerfile = either (\_ -> LedgerFile [] [] [] "") id parsed
-  return $ cacheLedger (argpats [] []) ledgerfile
+  return $ cacheLedger (parsePatternArgs []) ledgerfile
 
 accountnamed :: AccountName -> IO Account
 accountnamed a = myledger >>= (return . fromMaybe nullacct . Map.lookup a . accounts)