imp: Add ' as possible digit separator

It is used for Swiss Francs: CHF 1'000.

hledger-lib/Hledger/Read/Common.hs

@@ -1077,6 +1077,8 @@ disambiguateNumber msuggestedStyle (AmbiguousNumber grp1 sep grp2) =
 -- Left (AmbiguousNumber "1" ',' "000")
 -- >>> parseTest rawnumberp "1 000"
 -- Right (WithSeparators ' ' ["1","000"] Nothing)
+-- >>> parseTest rawnumberp "1'000"
+-- Right (WithSeparators '\'' ["1","000"] Nothing)
 --
 rawnumberp :: TextParser m (Either AmbiguousNumber RawNumber)
 rawnumberp = label "number" $ do
@@ -1142,7 +1144,7 @@ rawnumberp = label "number" $ do
  pure $ NoSeparators grp1 (Just (decPt, mempty))
 
 isDigitSeparatorChar :: Char -> Bool
-isDigitSeparatorChar c = isDecimalMark c || c == ' '
+isDigitSeparatorChar c = isDecimalMark c || c == ' ' || c == '\''
 
 -- | Some kinds of number literal we might parse.
 data RawNumber

hledger/hledger.m4.md

@@ -1184,10 +1184,11 @@ A *decimal mark* can be written as a period or a comma:
 
 In the integer part of the quantity (left of the decimal mark), groups
 of digits can optionally be separated by a *digit group mark* - a
-space, comma, or period (different from the decimal mark):
+space, comma, single quote, or period (different from the decimal mark):
 
   $1,000,000.00
   EUR 2.000.000,00
+  CHF 2'000'000.00
  INR 9,99,99,999.00
   1 000 000.9455
 
@@ -2192,9 +2193,10 @@ by 0 or more decimal digits.
 
 A few more examples:
 ```journal
-# number formats for $, EUR, INR and the no-symbol commodity:
+# number formats for $, EUR, CHF, INR and the no-symbol commodity:
 commodity $1,000.00
 commodity EUR 1.000,00
+commodity CHF 1'000.00
 commodity INR 9,99,99,999.0
 commodity 1 000 000.
 ```

hledger/test/journal/numbers.test

@@ -234,3 +234,16 @@ Balance changes in 2021:
 ===++===================================
  a || -0.12345678901234567890123456 EUR 
 >>>=0
+
+# 19. number begins with a separator char
+hledger bal -f -
+<<<
+commodity 1'000.00 CHF
+
+2017/1/1
+ a 1000 CHF
+ b -1000 CHF
+>>>
+ 1'000.00 CHF a
+ -1'000.00 CHF b
+>>>=0