balcmds: elide amounts with 3 or more commodities, unless --no-elide

Multicolumn balance reports showing many commodities tend to become
unreadably wide, especially in tree mode. Now by default we show at
most two commodities, and a count of the rest if there are more than
two. This should help keep reports somewhat readable by default.

hledger-lib/Hledger/Data/Amount.hs

@@ -121,8 +121,10 @@ module Hledger.Data.Amount (
   showMixedAmountDebug,
   showMixedAmountWithoutPrice,
   showMixedAmountOneLineWithoutPrice,
+  showMixedAmountElided,
   cshowMixedAmountWithoutPrice,
   cshowMixedAmountOneLineWithoutPrice,
+  cshowMixedAmountElided,
   showMixedAmountWithZeroCommodity,
   showMixedAmountWithPrecision,
   setMixedAmountPrecision,
@@ -736,6 +738,39 @@ cshowMixedAmountOneLineWithoutPrice m = intercalate ", " $ map cshowAmountWithou
       (Mixed as) = normaliseMixedAmountSquashPricesForDisplay $ stripPrices m
       stripPrices (Mixed as) = Mixed $ map stripprice as where stripprice a = a{aprice=Nothing}
 
+-- | Like showMixedAmountOneLineWithoutPrice, but show at most two commodities,
+-- with a elision indicator if there are more.
+showMixedAmountElided :: MixedAmount -> String
+showMixedAmountElided m = intercalate ", " $ take 2 astrs ++ elisionstr
+  where
+    astrs = map showAmountWithoutPrice as
+      where
+        (Mixed as) = normaliseMixedAmountSquashPricesForDisplay $ stripPrices m
+          where
+            stripPrices (Mixed as) = Mixed $ map stripprice as
+              where
+                stripprice a = a{aprice=Nothing}
+    elisionstr | n > 2     = [show (n - 2) ++ " more.."]
+               | otherwise = []
+      where
+        n = length astrs
+
+-- | Colour version.
+cshowMixedAmountElided :: MixedAmount -> String
+cshowMixedAmountElided m = intercalate ", " $ take 2 astrs ++ elisionstr
+  where
+    astrs = map cshowAmountWithoutPrice as
+      where
+        (Mixed as) = normaliseMixedAmountSquashPricesForDisplay $ stripPrices m
+          where
+            stripPrices (Mixed as) = Mixed $ map stripprice as
+              where
+                stripprice a = a{aprice=Nothing}
+    elisionstr | n > 2     = [show (n - 2) ++ " more.."]
+               | otherwise = []
+      where
+        n = length astrs
+
 -- | Canonicalise a mixed amount's display styles using the provided commodity style map.
 canonicaliseMixedAmount :: M.Map CommoditySymbol AmountStyle -> MixedAmount -> MixedAmount
 canonicaliseMixedAmount styles (Mixed as) = Mixed $ map (canonicaliseAmount styles) as

hledger/Hledger/Cli/Commands/Balance.hs

@@ -629,12 +629,16 @@ balanceReportAsTable opts@ReportOpts{average_, row_total_, balancetype_}
 
 -- | Given a table representing a multi-column balance report (for example,
 -- made using 'balanceReportAsTable'), render it in a format suitable for
--- console output.
+-- console output. Amounts with more than two commodities will be elided
+-- unless --no-elide is used.
 balanceReportTableAsText :: ReportOpts -> Table String String MixedAmount -> String
-balanceReportTableAsText ropts = tableAsText ropts showamt
+balanceReportTableAsText ropts@ReportOpts{..} = tableAsText ropts showamt
   where
-    showamt | color_ ropts = cshowMixedAmountOneLineWithoutPrice
+    showamt
-            | otherwise    =  showMixedAmountOneLineWithoutPrice
+      | no_elide_ && color_ = cshowMixedAmountOneLineWithoutPrice
+      | no_elide_           =  showMixedAmountOneLineWithoutPrice
+      | color_              = cshowMixedAmountElided
+      | otherwise           =  showMixedAmountElided
 
 
 tests_Balance = tests "Balance" [

hledger/Hledger/Cli/Commands/Balance.md

@@ -316,6 +316,17 @@ supported.
 The `--transpose` flag can be used to exchange the rows and columns of
 a multicolumn report.
      
+When showing multicommodity amounts, multicolumn balance reports will
+elide any amounts which have more than two commodities, since
+otherwise columns could get very wide. The `--no-elide` flag disables
+this. Hiding totals with the `-N/--no-total` flag can also help reduce
+the width of multicommodity reports. 
+
+When the report is still too wide, a good workaround is to pipe it
+into `less -RS` (-R for colour, -S to chop long lines). 
+Eg: `hledger bal -D | less -RS`.
+
+
 ### Budget report
 
 With `--budget`, extra columns are displayed showing budget goals for each account and period, if any.

tests/balance/multicommodity.test

@@ -0,0 +1,26 @@
+# 1. In tabular balance reports, amounts with more than two commodities are elided.
+<
+2020-01-01
+  (a)  1A
+  (a)  1B
+  (a)  1C
+  (a)  1D
+
+$ hledger -f- bal -Y
+Balance changes in 2020:
+
+   ||             2020 
+===++==================
+ a || 1A, 1B, 2 more.. 
+---++------------------
+   || 1A, 1B, 2 more.. 
+
+# 2. Unless --no-elide is used.
+$ hledger -f- bal -Y --no-elide
+Balance changes in 2020:
+
+   ||           2020 
+===++================
+ a || 1A, 1B, 1C, 1D 
+---++----------------
+   || 1A, 1B, 1C, 1D