hledger/Parse.hs

{-
Here's the ledger 2.5 grammar:
"The ledger file format is quite simple, but also very flexible. It supports
many options, though typically the user can ignore most of them. They are
summarized below.  The initial character of each line determines what the
line means, and how it should be interpreted. Allowable initial characters
are:

NUMBER      A line beginning with a number denotes an entry. It may be followed by any
            number of lines, each beginning with whitespace, to denote the entry’s account
            transactions. The format of the first line is:

                    DATE[=EDATE] [*|!] [(CODE)] DESC

            If ‘*’ appears after the date (with optional effective date), it indicates the entry
            is “cleared”, which can mean whatever the user wants it t omean. If ‘!’ appears
            after the date, it indicates d the entry is “pending”; i.e., tentatively cleared from
            the user’s point of view, but not yet actually cleared. If a ‘CODE’ appears in
            parentheses, it may be used to indicate a check number, or the type of the
            transaction. Following these is the payee, or a description of the transaction.
            The format of each following transaction is:

                      ACCOUNT     AMOUNT    [; NOTE]

            The ‘ACCOUNT’ may be surrounded by parentheses if it is a virtual
            transactions, or square brackets if it is a virtual transactions that must
            balance. The ‘AMOUNT’ can be followed by a per-unit transaction cost,
            by specifying ‘ AMOUNT’, or a complete transaction cost with ‘@ AMOUNT’.
            Lastly, the ‘NOTE’ may specify an actual and/or effective date for the
            transaction by using the syntax ‘[ACTUAL_DATE]’ or ‘[=EFFECTIVE_DATE]’ or
            ‘[ACTUAL_DATE=EFFECtIVE_DATE]’.

=           An automated entry. A value expression must appear after the equal sign.
            After this initial line there should be a set of one or more transactions, just as
            if it were normal entry. If the amounts of the transactions have no commodity,
            they will be applied as modifiers to whichever real transaction is matched by
            the value expression.
 
~           A period entry. A period expression must appear after the tilde.
            After this initial line there should be a set of one or more transactions, just as
            if it were normal entry.


!           A line beginning with an exclamation mark denotes a command directive. It
            must be immediately followed by the command word. The supported commands
            are:

           ‘!include’
                        Include the stated ledger file.
           ‘!account’
                        The account name is given is taken to be the parent of all transac-
                        tions that follow, until ‘!end’ is seen.
           ‘!end’       Ends an account block.
 
;          A line beginning with a colon indicates a comment, and is ignored.
 
Y          If a line begins with a capital Y, it denotes the year used for all subsequent
           entries that give a date without a year. The year should appear immediately
           after the Y, for example: ‘Y2004’. This is useful at the beginning of a file, to
           specify the year for that file. If all entries specify a year, however, this command
           has no effect.
           
 
P          Specifies a historical price for a commodity. These are usually found in a pricing
           history file (see the ‘-Q’ option). The syntax is:

                  P DATE SYMBOL PRICE

N SYMBOL   Indicates that pricing information is to be ignored for a given symbol, nor will
           quotes ever be downloaded for that symbol. Useful with a home currency, such
           as the dollar ($). It is recommended that these pricing options be set in the price
           database file, which defaults to ‘~/.pricedb’. The syntax for this command is:

                  N SYMBOL

        
D AMOUNT   Specifies the default commodity to use, by specifying an amount in the expected
           format. The entry command will use this commodity as the default when none
           other can be determined. This command may be used multiple times, to set
           the default flags for different commodities; whichever is seen last is used as the
           default commodity. For example, to set US dollars as the default commodity,
           while also setting the thousands flag and decimal flag for that commodity, use:

                  D $1,000.00

C AMOUNT1 = AMOUNT2
           Specifies a commodity conversion, where the first amount is given to be equiv-
           alent to the second amount. The first amount should use the decimal precision
           desired during reporting:

                  C 1.00 Kb = 1024 bytes

i, o, b, h
           These four relate to timeclock support, which permits ledger to read timelog
           files. See the timeclock’s documentation for more info on the syntax of its
           timelog files."
-}
-- parsec example: http://pandoc.googlecode.com/svn/trunk/src/Text/Pandoc/Readers/RST.hs

module Parse where

import Text.ParserCombinators.Parsec
import qualified Text.ParserCombinators.Parsec.Token as P
import Text.ParserCombinators.Parsec.Language

import Types

-- see sample data in Tests.hs 

-- set up token parsers, though we're not using these heavily yet
ledgerLanguageDef = LanguageDef {
   commentStart   = ""
   , commentEnd     = ""
   , commentLine    = ";"
   , nestedComments = False
   , identStart     = letter <|> char '_'
   , identLetter    = alphaNum <|> oneOf "_':"
   , opStart        = opLetter emptyDef
   , opLetter       = oneOf "!#$%&*+./<=>?@\\^|-~"
   , reservedOpNames= []
   , reservedNames  = []
   , caseSensitive  = False
   }
lexer      = P.makeTokenParser ledgerLanguageDef
whiteSpace = P.whiteSpace lexer
lexeme     = P.lexeme lexer
symbol     = P.symbol lexer
natural    = P.natural lexer
parens     = P.parens lexer
semi       = P.semi lexer
identifier = P.identifier lexer
reserved   = P.reserved lexer
reservedOp = P.reservedOp lexer

-- ledger file parsers

ledger :: Parser Ledger
ledger = do
  ledgernondatalines
  -- for now these must come first, unlike ledger
  modifier_entries <- many ledgermodifierentry
  periodic_entries <- many ledgerperiodicentry
  --
  entries <- (many ledgerentry) <?> "entry"
  eof
  return (Ledger modifier_entries periodic_entries entries)

ledgernondatalines :: Parser [String]
ledgernondatalines = many (ledgerdirective <|> ledgercomment <|> do {whiteSpace1; return []})

ledgercomment :: Parser String
ledgercomment = char ';' >> restofline <?> "comment"

ledgerdirective :: Parser String
ledgerdirective = char '!' >> restofline <?> "directive"

ledgermodifierentry :: Parser ModifierEntry
ledgermodifierentry = do
  char '=' <?> "entry"
  many spacenonewline
  valueexpr <- restofline
  transactions <- ledgertransactions
  ledgernondatalines
  return (ModifierEntry valueexpr transactions)

ledgerperiodicentry :: Parser PeriodicEntry
ledgerperiodicentry = do
  char '~' <?> "entry"
  many spacenonewline
  periodexpr <- restofline
  transactions <- ledgertransactions
  ledgernondatalines
  return (PeriodicEntry periodexpr transactions)

ledgerentry :: Parser Entry
ledgerentry = do
  date <- ledgerdate
  status <- ledgerstatus
  code <- ledgercode
  description <- anyChar `manyTill` ledgereol
  transactions <- ledgertransactions
  ledgernondatalines
  return (Entry date status code description transactions)

ledgerdate :: Parser String
ledgerdate = do date <- many1 (digit <|> char '/'); many1 spacenonewline; return date

ledgerstatus :: Parser Bool
ledgerstatus = try (do { char '*'; many1 spacenonewline; return True } ) <|> return False

ledgercode :: Parser String
ledgercode = try (do { char '('; code <- anyChar `manyTill` char ')'; many1 spacenonewline; return code } ) <|> return ""

ledgertransactions :: Parser [Transaction]
ledgertransactions = (ledgertransaction <?> "transaction") `manyTill` (newline <?> "blank line")
                     -- => unlike ledger, we need to end the file with a blank line

ledgertransaction :: Parser Transaction
ledgertransaction = do
  many1 spacenonewline
  account <- ledgeraccount <?> "account"
  amount <- ledgeramount <?> "amount"
  many spacenonewline
  ledgereol
  many ledgercomment
  return (Transaction account amount)

-- account names may have single spaces in them, and are terminated by two or more spaces
ledgeraccount :: Parser String
ledgeraccount = many1 (alphaNum <|> char ':' <|> try (do {spacenonewline; do {notFollowedBy spacenonewline; return ' '}}))

ledgeramount :: Parser Amount
ledgeramount = try (do
                      many1 spacenonewline
                      currency <- many (noneOf "-.0123456789\n") <?> "currency"
                      quantity <- many1 (oneOf "-.0123456789") <?> "quantity"
                      return (Amount currency (read quantity))
                   ) <|> 
                    return (Amount "" 0)

ledgereol :: Parser String
ledgereol = ledgercomment <|> do {newline; return []}

spacenonewline :: Parser Char
spacenonewline = satisfy (\c -> c `elem` " \v\f\t")

restofline :: Parser String
restofline = anyChar `manyTill` newline

whiteSpace1 :: Parser ()
whiteSpace1 = do space; whiteSpace


-- ok, what can we do with it ?

printParseResult r =
    case r of
      Left err -> do putStr "ledger parse error at "; print err
      Right x  -> do print x

parseLedgerFile :: IO String -> IO (Either ParseError Ledger)
parseLedgerFile filepath = do
  f <- filepath
  parseFromFile ledger f >>= return