imp:print:beancount: conversion improvements

- omit balance assertions
- replace more currency symbols, and match within symbols like C$
- do more account validation, and error if conversion is too hard
- backslash-escape double quotes and backslashes in payee and note

hledger-lib/Hledger/Data/AccountName.hs

@@ -73,6 +73,7 @@ import Text.DocLayout (realLength)
 
 import Hledger.Data.Types
 import Hledger.Utils
+import Data.Char (isDigit, isLetter)
 
 -- $setup
 -- >>> :set -XOverloadedStrings
@@ -349,18 +350,46 @@ accountNameToAccountOnlyRegexCI a = toRegexCI' $ "^" <> escapeName a <> "$" -- P
 --isAccountRegex s = take 1 s == "^" && take 5 (reverse s) == ")$|:("
 
 type BeancountAccountName = AccountName
+type BeancountAccountNameComponent = AccountName
 
 -- Convert a hledger account name to a valid Beancount account name.
--- It capitalises each part, and if the first part is not one of
--- Assets, Liabilities, Equity, Income, Expenses, it prepends Equity:.
+-- It replaces non-supported characters with @-@ (warning: in extreme cases
+-- separate accounts could end up with the same name), and it capitalises 
+-- each account name part. It also checks that the first part is one of 
+-- Assets, Liabilities, Equity, Income, or Expenses, and if not it raises an error.
+-- Account aliases (eg --alias) should be used to set these required
+-- top-level account names if needed.
 accountNameToBeancount :: AccountName -> BeancountAccountName
 accountNameToBeancount a =
   -- https://beancount.github.io/docs/beancount_language_syntax.html#accounts
   accountNameFromComponents $
-  case map textCapitalise $ accountNameComponents a of
-    [] -> []
-    c:cs | c `elem` beancountTopLevelAccounts -> c:cs
-    cs -> "Equity" : cs
+  case map (accountNameComponentToBeancount a) $ accountNameComponents a of
+    c:_ | c `notElem` beancountTopLevelAccounts -> error' e
+      where
+        e = T.unpack $ T.unlines [
+          beancountAccountErrorMessage a,
+          "For Beancount output, all top-level accounts must be (or be aliased to) one of",
+          T.intercalate ", " beancountTopLevelAccounts <> "."
+          ]
+    cs -> cs
+
+accountNameComponentToBeancount :: AccountName -> AccountName -> BeancountAccountNameComponent
+accountNameComponentToBeancount acct part =
+  case T.uncons part of
+    Just (c,_) | not $ isLetter c -> error' e
+      where
+        e = unlines [
+          T.unpack $ beancountAccountErrorMessage acct,
+          "For Beancount output, each account name part must begin with a letter."
+          ]
+    _ -> textCapitalise part'
+      where part' = T.map (\c -> if isBeancountAccountChar c then c else '-') part
+
+beancountAccountErrorMessage :: AccountName -> Text
+beancountAccountErrorMessage a = "Could not convert \"" <> a <> "\" to a Beancount account name."
+
+isBeancountAccountChar :: Char -> Bool
+isBeancountAccountChar c = c `elem` ("-:"::[Char]) || isLetter c || isDigit c
 
 beancountTopLevelAccounts = ["Assets", "Liabilities", "Equity", "Income", "Expenses"]
 

hledger-lib/Hledger/Data/Posting.hs

@@ -342,10 +342,9 @@ postingAsLinesBeancount elideamount acctwidth amtwidth p =
                        render [ textCell BottomLeft statusandaccount
                               , textCell BottomLeft "  "
                               , Cell BottomLeft [pad amt]
-                              , Cell BottomLeft [assertion]
                               , textCell BottomLeft samelinecomment
                               ]
-                    | (amt,assertion) <- shownAmountsAssertions]
+                    | (amt,_assertion) <- shownAmountsAssertions]
     render = renderRow def{tableBorders=False, borderSpaces=False} . Group NoLine . map Header
     pad amt = WideBuilder (TB.fromText $ T.replicate w " ") w <> amt
       where w = max 12 amtwidth - wbWidth amt  -- min. 12 for backwards compatibility
@@ -384,13 +383,17 @@ type BeancountAmount = Amount
 
 -- | Do some best effort adjustments to make an amount that renders
 -- in a way that Beancount can read: forces the commodity symbol to the right,
--- converts $ to USD.
+-- converts a few currency symbols to names, capitalises all letters.
 amountToBeancount :: Amount -> BeancountAmount
 amountToBeancount a@Amount{acommodity=c,astyle=s,aprice=mp} = a{acommodity=c', astyle=s', aprice=mp'}
   -- https://beancount.github.io/docs/beancount_language_syntax.html#commodities-currencies
   where
-    c' | c=="$"    = "USD"
-       | otherwise = c
+    c' = T.toUpper $
+      T.replace "$" "USD" $
+      T.replace "€" "EUR" $
+      T.replace "¥" "JPY" $
+      T.replace "£" "GBP" $
+      c
     s' = s{ascommodityside=R, ascommodityspaced=True}
     mp' = costToBeancount <$> mp
       where

hledger-lib/Hledger/Data/Transaction.hs

@@ -193,11 +193,11 @@ showTransactionBeancount t =
     (payee,note) =
       case payeeAndNoteFromDescription' $ tdescription t of
         ("","") -> ("",      ""      )
-        (p ,"") -> (wrapq p, wrapq "")
         ("",n ) -> (""     , wrapq n )
+        (p ,"") -> (wrapq p, wrapq "")
         (p ,n ) -> (wrapq p, wrapq n )
       where
-        wrapq = wrap " \"" "\""
+        wrapq = wrap " \"" "\"" . escapeDoubleQuotes . escapeBackslash
     tags = T.concat $ map ((" #"<>).fst) $ ttags t
     (samelinecomment, newlinecomments) =
       case renderCommentLines (tcomment t) of []   -> ("",[])

hledger-lib/Hledger/Utils/Text.hs

@@ -19,6 +19,7 @@ module Hledger.Utils.Text
   -- quotechars,
   -- whitespacechars,
   escapeDoubleQuotes,
+  escapeBackslash,
   -- escapeSingleQuotes,
   -- escapeQuotes,
   -- words',
@@ -139,6 +140,9 @@ whitespacechars = " \t\n\r"
 escapeDoubleQuotes :: T.Text -> T.Text
 escapeDoubleQuotes = T.replace "\"" "\\\""
 
+escapeBackslash :: T.Text -> T.Text
+escapeBackslash = T.replace "\\" "\\\\"
+
 -- escapeSingleQuotes :: T.Text -> T.Text
 -- escapeSingleQuotes = T.replace "'" "\'"
 

hledger/Hledger/Cli/Commands/Print.md

@@ -118,17 +118,26 @@ The output formats supported are
 `txt`, `beancount`, `csv`, `tsv`, `json` and `sql`.
 
 *Experimental:*
-The `beancount` format tries to produce Beancount-compatible output.
-It is very basic and may require additional manual fixups:
+The `beancount` format tries to produce Beancount-compatible output, as follows:
 
 - Transaction and postings with unmarked status are converted to cleared (`*`) status.
-- Transactions' payee and note are wrapped in double quotes.
+- Transactions' payee and note are backslash-escaped and double-quote-escaped and wrapped in double quotes.
 - Transaction tags are copied to Beancount #tag format.
-- Account name parts are capitalised, and if the first account name part 
-  is not one of Assets, Liabilities, Equity, Income, or Expenses, "Equity:" is prepended.
-- The `$` commodity symbol is converted to `USD`.
+- Commodity symbols are converted to upper case, and a small number of currency symbols
+  like `$` are converted to the corresponding currency names.
+- Account name parts are capitalised and unsupported characters are replaced with `-`.
+  If an account name part does not begin with a letter, or if the first part
+  is not Assets, Liabilities, Equity, Income, or Expenses, an error is raised.
+  (Use `--alias` options to bring your accounts into compliance.)
 - An `open` directive is generated for each account used, on the earliest transaction date.
 
+Some limitations:
+
+- Balance assertions are removed.
+- Balance assignments become missing amounts.
+- Virtual and balanced virtual postings become regular postings.
+- Directives are not converted.
+
 Here's an example of print's CSV output:
 
 ```shell