lib: slightly better journal/time format detection

The Journal, Timelog and Timedot readers' detectors now check
each line in the sample data, not just the first one. I think
the sample data is only about 30 chars right now, but even so
this fixed a format detection issue I was seeing.

hledger-lib/Hledger/Read/JournalReader.hs

@@ -88,9 +88,8 @@ format = "journal"
 -- | Does the given file path and data look like it might be hledger's journal format ?
 detect :: FilePath -> String -> Bool
 detect f s
-  | f /= "-"  = takeExtension f `elem` ['.':format, ".j"]  -- from a file: yes if the extension is .journal or .j
-  -- from stdin: yes if we can see something that looks like a journal entry (digits in column 0 with the next line indented)
-  | otherwise = regexMatches "^[0-9]+.*\n[ \t]+" s
+  | f /= "-"  = takeExtension f `elem` ['.':format, ".j"] -- from a known file name: yes if the extension is this format's name or .j
+  | otherwise = regexMatches "(^|\n)[0-9]+.*\n[ \t]+" s   -- from stdin: yes if we can see something that looks like a journal entry (digits in column 0 with the next line indented)
 
 -- | Parse and post-process a "Journal" from hledger's journal file
 -- format, or give an error.
@@ -275,6 +274,7 @@ includedirectivep = do
        txt <- readFileOrError outerPos filepath
        let inIncluded = show outerPos ++ " in included file " ++ show filename ++ ":\n"
        r <- runParserT journalp outerState filepath txt
+
        case r of
          Right (ju, ctx) -> do
                             u <- combineJournalUpdates [ return $ journalAddFile (filepath,txt)

hledger-lib/Hledger/Read/TimedotReader.hs

@@ -60,9 +60,9 @@ format = "timedot"
 
 -- | Does the given file path and data look like it might contain this format ?
 detect :: FilePath -> String -> Bool
-detect f _s
-  | f /= "-"  = takeExtension f == '.':format  -- from a file: yes if the extension matches the format name
-  | otherwise = False                          -- from stdin: yes if...
+detect f s
+  | f /= "-"  = takeExtension f == '.':format -- from a file: yes if the extension matches the format name
+  | otherwise = regexMatches "(^|\n)[0-9]" s  -- from stdin: yes if we can see a possible timedot day entry (digits in column 0)
 
 -- | Parse and post-process a "Journal" from the timedot format, or give an error.
 parse :: Maybe FilePath -> Bool -> FilePath -> String -> ExceptT String IO Journal

hledger-lib/Hledger/Read/TimelogReader.hs

@@ -51,7 +51,7 @@ import Prelude ()
 import Prelude.Compat
 import Control.Monad (liftM)
 import Control.Monad.Except (ExceptT)
-import Data.List (isPrefixOf, foldl')
+import Data.List (foldl')
 import Data.Maybe (fromMaybe)
 import Test.HUnit
 import Text.Parsec hiding (parse)
@@ -75,8 +75,8 @@ format = "timelog"
 -- | Does the given file path and data look like it might be timeclock.el's timelog format ?
 detect :: FilePath -> String -> Bool
 detect f s
-  | f /= "-"  = takeExtension f == '.':format               -- from a file: yes if the extension is .timelog
-  | otherwise = "i " `isPrefixOf` s || "o " `isPrefixOf` s  -- from stdin: yes if it starts with "i " or "o "
+  | f /= "-"  = takeExtension f == '.':format -- from a known file name: yes if the extension is this format's name
+  | otherwise = regexMatches "(^|\n)[io] " s  -- from stdin: yes if any line starts with "i " or "o "
 
 -- | Parse and post-process a "Journal" from timeclock.el's timelog
 -- format, saving the provided file path and the current time, or give an