lib: support scientific number notation (#704, #706)

closes simonmichael/hledger#704

hledger-lib/Hledger/Read/Common.hs

@@ -21,6 +21,7 @@ where
 --- * imports
 import Prelude ()
 import Prelude.Compat hiding (readFile)
+import Control.Arrow ((***))
 import Control.Monad.Compat
 import Control.Monad.Except (ExceptT(..), runExceptT, throwError) --, catchError)
 import Control.Monad.State.Strict
@@ -464,10 +465,12 @@ rightsymbolamountp = do
   m <- lift multiplierp
   sign <- lift signp
   rawnum <- lift $ rawnumberp
+  expMod <- lift . option id $ try exponentp
   commodityspaced <- lift $ skipMany' spacenonewline
   c <- lift commoditysymbolp
   suggestedStyle <- getAmountStyle c
-  let (q,prec,mdec,mgrps) = fromRawNumber suggestedStyle (sign == "-") rawnum
+  let (q0,prec0,mdec,mgrps) = fromRawNumber suggestedStyle (sign == "-") rawnum
+      (q, prec) = expMod (q0, prec0)
   p <- priceamountp
   let s = amountstyle{ascommodityside=R, ascommodityspaced=commodityspaced, asprecision=prec, asdecimalpoint=mdec, asdigitgroups=mgrps}
   return $ Amount c q p s m
@@ -572,9 +575,20 @@ numberp suggestedStyle = do
     sign <- signp
     raw <- rawnumberp
     dbg8 "numberp parsed" raw `seq` return ()
-    return $ dbg8 "numberp quantity,precision,mdecimalpoint,mgrps" (fromRawNumber suggestedStyle (sign == "-") raw)
+    let num@(q, prec, decSep, groups) = dbg8 "numberp quantity,precision,mdecimalpoint,mgrps" (fromRawNumber suggestedStyle (sign == "-") raw)
+    option num . try $ do
+        when (isJust groups) $ fail "groups and exponent are not mixable"
+        (q', prec') <- exponentp <*> pure (q, prec)
+        return (q', prec', decSep, groups)
     <?> "numberp"
 
+exponentp :: TextParser m ((Quantity, Int) -> (Quantity, Int))
+exponentp = do
+    char' 'e'
+    exp <- liftM read $ (++) <$> signp <*> some digitChar
+    return $ (* 10^^exp) *** (0 `max`) . (+ (-exp))
+    <?> "exponentp"
+
 fromRawNumber :: Maybe AmountStyle -> Bool -> (Maybe Char, [String], Maybe (Char, String)) -> (Quantity, Int, Maybe Char, Maybe DigitGroupStyle)
 fromRawNumber suggestedStyle negated raw = (quantity, precision, mdecimalpoint, mgrps) where
     -- unpack with a hint if useful

tests/journal/scientific.test

@@ -0,0 +1,98 @@
+# just check
+hledger -f - bal --no-total
+<<<
+D $1,000.00
+
+2018/1/1
+   (a)  2.3
+>>>
+               $2.30  a
+>>>=0
+
+# some basic cases with commodity
+hledger -f - bal --no-total
+<<<
+commodity $1,000.00000000
+
+2018/1/1
+   a  $1.05e2
+   b  $31415926e-7
+   c  $1E+3
+   d
+>>>
+       $105.00000000  a
+         $3.14159260  b
+     $1,000.00000000  c
+    $-1,108.14159260  d
+>>>=0
+
+# some basic cases with commodity
+hledger -f - print --explicit
+<<<
+commodity $1,000.00000000
+
+2018/1/1
+   a  $1.05e2
+   b  $31415926e-7
+   c  $1E+3
+   d
+>>>
+2018/01/01
+    a       $105.00000000
+    b         $3.14159260
+    c     $1,000.00000000
+    d    $-1,108.14159260
+
+>>>=0
+#
+# some basic cases
+hledger -f - bal --no-total
+<<<
+2018/1/1
+   a  1.05e2
+   b  31415926e-7
+   c  1E+3
+   d
+>>>
+         105.0000000  a
+           3.1415926  b
+        1000.0000000  c
+       -1108.1415926  d
+>>>2
+>>>=0
+
+# some strang effect of default
+hledger -f - bal --no-total
+<<<
+D $1,000.00
+
+2018/1/1
+   a  1.050000e2
+   b  31415926e-7
+   c  1E+3
+   d
+>>>
+        $105.0000000  a
+          $3.1415926  b
+      $1,000.0000000  c
+     $-1,108.1415926  d
+>>>2
+>>>=0
+
+# we still should recognize commodities with e
+hledger -f - bal --no-total
+<<<
+2018/1/1
+   (a)  1.00005e
+   (a)  2.00003E
+>>>
+            2.00003E   
+            1.00005e  a
+>>>=0
+
+hledger -f - reg
+<<<
+2018/1/1
+   (a)  1,000.5e-1
+>>>
+>>>=1