{-
    BNF Converter: Java 1.5 Compositional Vistor generator
    Copyright (C) 2006 Bjorn Bringert
    Based on CFtoVisitSkel.hs, Copyright (C) 2004-2006  Michael Pellauer

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
-}

module BNFC.Backend.Java.CFtoComposVisitor (cf2ComposVisitor) where

import BNFC.CF
import BNFC.Backend.Java.CFtoJavaAbs15 (typename)
import BNFC.Utils ((+++), (++++))
import BNFC.Backend.Common.NamedVariables
import Data.List
import Data.Char(toLower, toUpper, isDigit)

cf2ComposVisitor :: String -> String -> CF -> String
cf2ComposVisitor packageBase packageAbsyn cf =
  concat [
    header,
    concatMap (prData packageAbsyn user) groups,
    "}"]
  where
    user = fst (unzip (tokenPragmas cf))
    groups = [ g | g@(c,_) <- fixCoercions (ruleGroupsInternals cf), not (isList c) ]
    is = map (prInterface packageAbsyn) groups
    header = unlines [
      "package" +++ packageBase ++ ";",
      "import" +++ packageAbsyn ++ ".*;",
      "/** BNFC-Generated Composition Visitor",
      "*/",
      "",
      "public class ComposVisitor<A> implements",
      concat $ intersperse ",\n" $ map ("  "++) is,
      "{"
      ]


prInterface :: String -> (Cat, [Rule]) -> String
prInterface packageAbsyn (cat, rules) =
    q ++ ".Visitor<" ++ q ++ ",A>"
  where q = packageAbsyn ++ "." ++ identCat cat

commaList :: [String] -> String
commaList = concat . intersperse ", "

--Traverses a category based on its type.
prData :: String -> [UserDef] -> (Cat, [Rule]) -> String
prData packageAbsyn user (cat, rules) =
    unlines [
             "/* " ++ identCat cat ++ " */",
	     concatMap (prRule packageAbsyn user cat) rules
	    ]
--traverses a standard rule.
prRule :: String -> [UserDef] -> Cat -> Rule -> String
prRule packageAbsyn user cat (Rule fun _ cats)
    | not (isCoercion fun || isDefinedRule fun) = unlines
  [
   "    public " ++ identCat cat ++ " visit(" ++ cls ++ " p, A arg)",
   "    {",
   unlines (map ("      "++) visitVars),
   "      return new " ++ cls ++ "(" ++ commaList children ++ ");",
   "    }"
  ]
   where
    cats' = if allTerms cats
        then []
    	else [ (c,v) |
	       (Left c, Left v) <- zip cats (fixOnes (numVars [] cats)), c /= InternalCat ]
    cls = packageAbsyn ++ "." ++ fun
    allTerms [] = True
    allTerms ((Left z):zs) = False
    allTerms (z:zs) = allTerms zs
    children = map snd cats'
    visitVars = concatMap (uncurry (prCat user)) cats'
prRule  _ _ _ _ = ""

--Traverses a class's instance variables.
prCat :: [UserDef]
      -> Cat       -- ^ Variable category
      -> String    -- ^ Variable name
      -> [String]  -- ^ Code for visiting the variable
prCat user cat nt
    | isBasicType user varType || (isList cat && isBasicType user et) = [decl var]
    | isList cat = listAccept
    | otherwise = [decl (var ++ ".accept(this, arg)")]
      where
      var = "p." ++ nt
      varType = typename (identCat (normCat cat)) user
      accept = var ++ ".accept(this, arg);"
      et = typename (show$normCatOfList cat) user
      decl v = varType +++ nt +++ "=" +++ v ++ ";"
      listAccept = [decl ("new"+++varType++"()"),
                    "for (" ++ et ++ " x : " ++ var ++ ") {",
                    "  " ++ nt ++ ".add(x.accept(this,arg));",
	            "}"]

--Just checks if something is a basic or user-defined type.
isBasicType :: [UserDef] -> String -> Bool
isBasicType user v = v `elem` (map show user ++ ["Integer","Character","String","Double"])