tags: add --values flag

hledger/Hledger/Cli/Commands/Tags.hs

@@ -9,13 +9,16 @@ where
 
 import Data.List
 import qualified Data.Text as T
+import qualified Data.Text.IO as T
 import Safe
+import System.Console.CmdArgs.Explicit as C
 import Hledger
 import Hledger.Cli.CliOptions
 
 tagsmode = hledgerCommandMode
   $(embedFileRelative "Hledger/Cli/Commands/Tags.txt")
-  [] -- [flagNone ["strict"] (setboolopt "strict") "makes date comparing strict"] --
+  [flagNone ["values"] (setboolopt "values") "list tag values instead of tag names"
+  ]
   [generalflagsgroup1]
   hiddenflags
   ([], Just $ argsFlag "[TAGREGEX [QUERY...]]")
@@ -24,12 +27,15 @@ tags CliOpts{rawopts_=rawopts,reportopts_=ropts} j = do
   d <- getCurrentDay
   let
     args      = listofstringopt "args" rawopts
-    mtagpats  = headMay args
+    mtagpat   = headMay args
     queryargs = drop 1 args
+    values    = boolopt "values" rawopts
     q = queryFromOpts d $ ropts{query_ = unwords queryargs}
     txns = filter (q `matchesTransaction`) $ jtxns $ journalSelectingAmountFromOpts ropts j
-    tags =
+    tagsorvalues =
       nub $ sort $
-      (maybe id (filter . regexMatchesCI) mtagpats) $
-      map (T.unpack . fst) $ concatMap transactionAllTags txns
-  mapM_ putStrLn tags
+      [if values then v else t
+      | (t,v) <- concatMap transactionAllTags txns
+      , maybe True (`regexMatchesCI` T.unpack t) mtagpat
+      ]
+  mapM_ T.putStrLn tagsorvalues

hledger/Hledger/Cli/Commands/Tags.md

@@ -2,10 +2,6 @@ tags\
 List all the tag names used in the journal. With a TAGREGEX argument,
 only tag names matching the regular expression (case insensitive) are shown. 
 With QUERY arguments, only transactions matching the query are considered.
+With --values flag, the tags' unique values are listed instead.
 
 _FLAGS_
-
-There's no direct way to list a tag's values, but there is an indirect way:
---pivot converts a tag's values to accounts, which you can list, like this:
-
-    hledger --pivot SOMETAG accounts --used

tests/tags.test

@@ -0,0 +1,28 @@
+# tags command
+
+2000/1/1    ; ttag:foo
+  (a)    1  ; ptag:bar
+
+2000/1/2    ; ttag2:foo
+  (a)    1  ; ptag:qux
+
+# 1. list all tags
+$ hledger -f - tags
+ptag
+ttag
+ttag2
+
+# 2. list tag names matching a regex
+$ hledger -f - tags ttag
+ttag
+ttag2
+
+# 3. list tag values
+$ hledger -f - tags --values
+bar
+foo
+qux
+
+# 4. list values of tags matching a regex from transactions matching a query
+$ hledger -f - tags --values ptag date:2000/1/1
+bar