GF shell: fix a parsing problem with the cc command

This patch fixes a problem introduced last year when the GF shell was
refactored to allow more commands to be treated uniformly and be part
of pipes. The cc command was one of those commands, but unfortunately this
introduced a parsing problem, e.g.

	> cc "last"
	constant not found: last

	> cc "last"++"year"
	command not parsed: cc "last"++"year"

This happened because the generic command line parser in
GF.Command.{Abstract,Parse} assumes that all commands have an argument of
type PGF.Expr. Commands that expect other types of arguments have to
use PGF.showExpr combined with other conversion to the argument type they
expect. The cc command excpets a GF.Grammar.Term, and unfortunately not 
all terms survice the roundtrip through PGF.Expr, in part because of
an additional hack to allow strings to be roundtripped through PGF.Expr
without adding superfluous double quotes.

To solve the problem, this patch

 + makes room for arguments of type Term in the Argument type in
   GF.Command.Abstract.
   
 + makes a special case for the cc command in GF.Command.Parse, by
   calling the partial parser 'runPartial pTerm' recently added in
   GF.Grammar.Lexer and GF.Grammar.Parser. Care was taken so that
   that "|" and ";" can be used both inside terms and as separators between
   commands in the shell, e.g. things like the following now work:

       > cc ("a"|"b") | ps -lexcode
       variants { "a" ; "b" }

 + introduces a type CommandArgument that replaces [Expr] as the
   type of values passed between commands in pipes. It has room for
   values of type [Expr], [String] and Term, thus eliminating the need
   to roundtrip through the Expr type all the time.
   The hack to avoid adding superfluous quotes when strings are
   roundtripped through Expr has been left in place for now,
   but can probably be removed.
   

7 files changed, 97 insertions, 54 deletions

diff --git a/src/compiler/GF/Command/Abstract.hs b/src/compiler/GF/Command/Abstract.hs
index 0a664d1ca..25760e41f 100644
--- a/src/compiler/GF/Command/Abstract.hs
+++ b/src/compiler/GF/Command/Abstract.hs
@@ -1,6 +1,7 @@
-module GF.Command.Abstract(module GF.Command.Abstract,Expr,showExpr) where
+module GF.Command.Abstract(module GF.Command.Abstract,Expr,showExpr,Term) where
 
 import PGF(CId,mkCId,Expr,showExpr)
+import GF.Grammar.Grammar(Term)
 
 type Ident = String
 
@@ -25,6 +26,7 @@ data Value
 
 data Argument
   = AExpr Expr
+  | ATerm Term
   | ANoArg
   | AMacro Ident
   deriving (Eq,Ord,Show)
diff --git a/src/compiler/GF/Command/CommandInfo.hs b/src/compiler/GF/Command/CommandInfo.hs
index 7d68f9221..b0b5869c3 100644
--- a/src/compiler/GF/Command/CommandInfo.hs
+++ b/src/compiler/GF/Command/CommandInfo.hs
@@ -1,10 +1,13 @@
 module GF.Command.CommandInfo where
-import GF.Command.Abstract(Option,Expr)
+import GF.Command.Abstract(Option,Expr,Term)
+import GF.Text.Pretty(render)
+import GF.Grammar.Printer() -- instance Pretty Term
+import GF.Grammar.Macros(string2term)
 import qualified PGF as H(showExpr)
 import qualified PGF.Internal as H(Literal(LStr),Expr(ELit)) ----
 
 data CommandInfo m = CommandInfo {
-  exec     :: [Option] -> [Expr] -> m CommandOutput,
+  exec     :: [Option] -> CommandArguments -> m CommandOutput,
   synopsis :: String,
   syntax   :: String,
   explanation :: String,
@@ -35,26 +38,46 @@ class Monad m => TypeCheckArg m where typeCheckArg :: Expr -> m Expr
 
 --------------------------------------------------------------------------------
 
-newtype CommandOutput  = Piped {fromPipe :: ([Expr],String)} ---- errors, etc
+data CommandArguments = Exprs [Expr] | Strings [String] | Term Term
+
+newtype CommandOutput = Piped (CommandArguments,String) ---- errors, etc
 
 -- ** Converting command output
-fromStrings ss         = Piped (map stringAsExpr ss, unlines ss)
-fromExprs   es         = Piped (es,unlines (map (H.showExpr []) es))
-fromString  s          = Piped ([stringAsExpr s], s)
-pipeWithMessage es msg = Piped (es,msg)
-pipeMessage msg        = Piped ([],msg)
-pipeExprs   es         = Piped (es,[]) -- only used in emptyCommandInfo
-void                   = Piped ([],"")
+fromStrings ss         = Piped (Strings ss, unlines ss)
+fromExprs   es         = Piped (Exprs es,unlines (map (H.showExpr []) es))
+fromString  s          = Piped (Strings [s], s)
+pipeWithMessage es msg = Piped (Exprs es,msg)
+pipeMessage msg        = Piped (Exprs [],msg)
+pipeExprs   es         = Piped (Exprs es,[]) -- only used in emptyCommandInfo
+void                   = Piped (Exprs [],"")
 
 stringAsExpr = H.ELit . H.LStr -- should be a pattern macro
 
 -- ** Converting command input
 
-toStrings = map showAsString
+toStrings args =
+    case args of
+      Strings ss -> ss
+      Exprs es -> zipWith showAsString (True:repeat False) es
+      Term t -> [render t]
   where
-    showAsString t = case t of
-      H.ELit (H.LStr s) -> s
-      _ -> "\n" ++ H.showExpr [] t ---newline needed in other cases than the first
+    showAsString first t =
+      case t of
+        H.ELit (H.LStr s) -> s
+        _ -> ['\n'|not first] ++
+             H.showExpr [] t ---newline needed in other cases than the first
+
+toExprs args =
+  case args of
+    Exprs es -> es
+    Strings ss -> map stringAsExpr ss
+    Term t -> [stringAsExpr (render t)]
+
+toTerm args =
+  case args of
+    Term t -> t
+    Strings ss -> string2term $ unwords ss -- hmm
+    Exprs es -> string2term $ unwords $ map (H.showExpr []) es -- hmm
 
 -- ** Creating documentation
 
diff --git a/src/compiler/GF/Command/Commands.hs b/src/compiler/GF/Command/Commands.hs
index adea48857..feaeb0f33 100644
--- a/src/compiler/GF/Command/Commands.hs
+++ b/src/compiler/GF/Command/Commands.hs
@@ -61,7 +61,8 @@ pgfCommands = Map.fromList [
        "by the view flag. The target format is png, unless overridden by the",
        "flag -format. Results from multiple trees are combined to pdf with convert (ImageMagick)."
        ],
-     exec = getEnv $ \ opts es (Env pgf mos) -> do
+     exec = getEnv $ \ opts arg (Env pgf mos) -> do
+         let es = toExprs arg
          let langs = optLangs pgf opts
          if isOpt "giza" opts
            then do
@@ -182,11 +183,11 @@ pgfCommands = Map.fromList [
        ("depth","the maximum generation depth"),
        ("probs", "file with biased probabilities (format 'f 0.4' one by line)")
        ],
-     exec = getEnv $ \ opts xs (Env pgf mos) -> do
+     exec = getEnv $ \ opts arg (Env pgf mos) -> do
        pgf <- optProbs opts (optRestricted opts pgf)
        gen <- newStdGen
        let dp = valIntOpts "depth" 4 opts
-       let ts  = case mexp xs of
+       let ts  = case mexp (toExprs arg) of
                    Just ex -> generateRandomFromDepth gen pgf ex (Just dp)
                    Nothing -> generateRandomDepth     gen pgf (optType pgf opts) (Just dp)
        returnFromExprs $ take (optNum opts) ts
@@ -212,10 +213,10 @@ pgfCommands = Map.fromList [
        mkEx "gt -cat=NP -depth=2    -- trees in the category NP to depth 2",
        mkEx "gt (AdjCN ? (UseN ?))  -- trees of form (AdjCN ? (UseN ?))"
        ],
-     exec = getEnv $ \ opts xs (Env pgf mos) -> do
+     exec = getEnv $ \ opts arg (Env pgf mos) -> do
        let pgfr = optRestricted opts pgf
        let dp = valIntOpts "depth" 4 opts
-       let ts = case mexp xs of
+       let ts = case mexp (toExprs arg) of
                   Just ex -> generateFromDepth pgfr ex (Just dp)
                   Nothing -> generateAllDepth pgfr (optType pgf opts) (Just dp)
        returnFromExprs $ take (optNumInf opts) ts
@@ -266,7 +267,7 @@ pgfCommands = Map.fromList [
        mkEx "gr -lang=LangHin -cat=Cl | l -table -to_devanagari -- hindi table",
        mkEx "l -unlexer=\"LangAra=to_arabic LangHin=to_devanagari\" -- different unlexers"
        ],
-     exec = getEnv $ \ opts ts (Env pgf mos) -> return . fromStrings $ optLins pgf opts ts,
+     exec = getEnv $ \ opts ts (Env pgf mos) -> return . fromStrings . optLins pgf opts $ toExprs ts,
      options = [
        ("all",    "show all forms and variants, one by line (cf. l -list)"),
        ("bracket","show tree structure with brackets and paths to nodes"),
@@ -291,7 +292,7 @@ pgfCommands = Map.fromList [
      examples = [
        mkEx "l -lang=LangSwe,LangNor -chunks ? a b (? c d)"
        ],
-     exec = getEnv $ \ opts ts (Env pgf mos) -> return . fromStrings $ optLins pgf (opts ++ [OOpt "chunks"]) ts,
+     exec = getEnv $ \ opts ts (Env pgf mos) -> return . fromStrings $ optLins pgf (opts ++ [OOpt "chunks"]) (toExprs ts),
      options = [
        ("treebank","show the tree and tag linearizations with language names")
        ] ++ stringOpOptions,
@@ -332,11 +333,11 @@ pgfCommands = Map.fromList [
      longname = "morpho_quiz",
      synopsis = "start a morphology quiz",
      syntax   = "mq (-cat=CAT)? (-probs=FILE)? TREE?",
-     exec = getEnv $ \ opts xs (Env pgf mos) -> do
+     exec = getEnv $ \ opts arg (Env pgf mos) -> do
          let lang = optLang pgf opts
          let typ  = optType pgf opts
          pgf <- optProbs opts pgf
-         let mt = mexp xs
+         let mt = mexp (toExprs arg)
          restricted $ morphologyQuiz mt pgf lang typ
          return void,
      flags = [
@@ -427,8 +428,8 @@ pgfCommands = Map.fromList [
        mkEx "pt -compute (plus one two)                               -- compute value",
        mkEx "p \"4 dogs love 5 cats\" | pt -transfer=digits2numeral | l -- four...five..."
        ],
-     exec = getEnv $ \ opts ts (Env pgf mos) ->
-            returnFromExprs . takeOptNum opts $ treeOps pgf opts ts,
+     exec = getEnv $ \ opts arg (Env pgf mos) ->
+            returnFromExprs . takeOptNum opts . treeOps pgf opts $ toExprs arg,
      options = treeOpOptions undefined{-pgf-},
      flags = [("number","take at most this many trees")] ++ treeOpFlags undefined{-pgf-}
      }),
@@ -481,7 +482,8 @@ pgfCommands = Map.fromList [
        "by the file given by flag -probs=FILE, where each line has the form",
        "'function probability', e.g. 'youPol_Pron  0.01'."
        ],
-     exec = getEnv $ \ opts ts (Env pgf mos) -> do
+     exec = getEnv $ \ opts arg (Env pgf mos) -> do
+         let ts = toExprs arg
          pgf <- optProbs opts pgf
          let tds = rankTreesByProbs pgf ts
          if isOpt "v" opts
@@ -503,11 +505,11 @@ pgfCommands = Map.fromList [
      longname = "translation_quiz",
      syntax   = "tq -from=LANG -to=LANG (-cat=CAT)? (-probs=FILE)? TREE?",
      synopsis = "start a translation quiz",
-     exec = getEnv $ \ opts xs (Env pgf mos) -> do
+     exec = getEnv $ \ opts arg (Env pgf mos) -> do
          let from = optLangFlag "from" pgf opts
          let to   = optLangFlag "to" pgf opts
          let typ  = optType pgf opts
-         let mt   = mexp xs
+         let mt   = mexp (toExprs arg)
          pgf <- optProbs opts pgf
          restricted $ translationQuiz mt pgf from to typ
          return void,
@@ -542,7 +544,8 @@ pgfCommands = Map.fromList [
        "flag -format. Results from multiple trees are combined to pdf with convert (ImageMagick).",
        "See also 'vp -showdep' for another visualization of dependencies." 
        ],
-     exec = getEnv $ \ opts es (Env pgf mos) -> do
+     exec = getEnv $ \ opts arg (Env pgf mos) -> do
+         let es = toExprs arg
          let debug = isOpt "v" opts
          let file = valStrOpts "file" "" opts
          let outp = valStrOpts "output" "dot" opts
@@ -552,7 +555,7 @@ pgfCommands = Map.fromList [
          let lang = optLang pgf opts
          let grphs = map (graphvizDependencyTree outp debug mlab Nothing pgf lang) es
          if isOpt "conll2latex" opts
-           then return $ fromString $ conlls2latexDoc $ stanzas $ unlines $ toStrings es
+           then return $ fromString $ conlls2latexDoc $ stanzas $ unlines $ toStrings arg
            else if isFlag "view" opts && valStrOpts "output" "" opts == "latex"
              then do
                let view = optViewGraph opts
@@ -596,7 +599,8 @@ pgfCommands = Map.fromList [
        "by the view flag. The target format is png, unless overridden by the",
        "flag -format. Results from multiple trees are combined to pdf with convert (ImageMagick)."
        ],
-     exec = getEnv $ \ opts es (Env pgf mos) -> do
+     exec = getEnv $ \ opts arg (Env pgf mos) -> do
+         let es = toExprs arg
          let lang = optLang pgf opts
          let gvOptions = GraphvizOptions {noLeaves = isOpt "noleaves" opts && not (isOpt "showleaves" opts),
                                           noFun = isOpt "nofun" opts || not (isOpt "showfun" opts),
@@ -661,7 +665,8 @@ pgfCommands = Map.fromList [
        "flag -format. Results from multiple trees are combined to pdf with convert (ImageMagick).",
        "With option -mk, use for showing library style function names of form 'mkC'."
        ],
-     exec = getEnv $ \ opts es (Env pgf mos) ->
+     exec = getEnv $ \ opts arg (Env pgf mos) ->
+      let es = toExprs arg in
        if isOpt "mk" opts
        then return $ fromString $ unlines $ map (tree2mk pgf) es
        else if isOpt "api" opts
@@ -707,7 +712,7 @@ pgfCommands = Map.fromList [
        "metavariables and the type of the expression."
        ],
      exec = getEnv $ \ opts arg (Env pgf mos) -> do
-       case arg of
+       case toExprs arg of
          [EFun id] -> case Map.lookup id (funs (abstract pgf)) of
                         Just fd -> do putStrLn $ render (ppFun id fd)
                                       let (_,_,_,prob) = fd
@@ -748,7 +753,10 @@ pgfCommands = Map.fromList [
 
    fromParse opts = foldr (joinPiped . fromParse1 opts) void
 
-   joinPiped (Piped (es1,ms1)) (Piped (es2,ms2)) = Piped (es1++es2,ms1+++-ms2)
+   joinPiped (Piped (es1,ms1)) (Piped (es2,ms2)) = Piped (jA es1 es2,ms1+++-ms2)
+     where
+       jA (Exprs es1) (Exprs es2) = Exprs (es1++es2)
+       -- ^ fromParse1 always output Exprs
 
    fromParse1 opts (s,(po,bs))
      | isOpt "bracket" opts = pipeMessage (showBracketedString bs)
diff --git a/src/compiler/GF/Command/CommonCommands.hs b/src/compiler/GF/Command/CommonCommands.hs
index 0dce8e894..0cafad531 100644
--- a/src/compiler/GF/Command/CommonCommands.hs
+++ b/src/compiler/GF/Command/CommonCommands.hs
@@ -179,7 +179,7 @@ commonCommands = fmap (mapCommandExec liftSIO) $ Map.fromList [
      longname = "to_trie",
      syntax = "to_trie",
      synopsis = "combine a list of trees into a trie",
-     exec = \ _ ts -> return . fromString $ trie ts
+     exec = \ _ -> return . fromString . trie . toExprs
     }),
   ("ut", emptyCommandInfo {
      longname = "unicode_table",
diff --git a/src/compiler/GF/Command/Help.hs b/src/compiler/GF/Command/Help.hs
index 2a736088d..eb50c6d35 100644
--- a/src/compiler/GF/Command/Help.hs
+++ b/src/compiler/GF/Command/Help.hs
@@ -1,6 +1,6 @@
 module GF.Command.Help where
 import GF.Command.Messages
-import GF.Command.Abstract(isOpt,getCommandOp,showExpr)
+import GF.Command.Abstract(isOpt,getCommandOp)
 import GF.Command.CommandInfo
 
 import GF.Data.Operations((++++))
@@ -75,13 +75,13 @@ helpCommand allCommands =
        ("license","show copyright and license information"),
        ("t2t","output help in txt2tags format")
        ],
-     exec = \opts ts ->
+     exec = \opts args ->
        let
-        msg = case ts of
+        msg = case toStrings args of
           _ | isOpt "changes" opts -> changesMsg
           _ | isOpt "coding" opts -> codingMsg
           _ | isOpt "license" opts -> licenseMsg
-          [t] -> let co = getCommandOp (showExpr [] t) in
+          [s] -> let co = getCommandOp s in
                  case Map.lookup co allCommands of
                    Just info -> commandHelp' opts True (co,info)
                    _ -> "command not found"
diff --git a/src/compiler/GF/Command/Interpreter.hs b/src/compiler/GF/Command/Interpreter.hs
index abd06c3a1..bcb15d238 100644
--- a/src/compiler/GF/Command/Interpreter.hs
+++ b/src/compiler/GF/Command/Interpreter.hs
@@ -33,29 +33,31 @@ interpretPipe env cs = do
      putStrLnE s
      return ()
   where
-   intercs [] treess = return treess
-   intercs (c:cs) (Piped (trees,_)) = interc c trees >>= intercs cs
+   intercs [] args = return args
+   intercs (c:cs) (Piped (args,_)) = interc c args >>= intercs cs
 
-   interc comm@(Command co opts arg) es =
+   interc comm@(Command co opts arg) args =
      case co of
        '%':f -> case Map.lookup f (commandmacros env) of
          Just css ->
-           do es <- getCommandTrees env False arg es
-              mapM_ (interpretPipe env) (appLine es css)
+           do args <- getCommandTrees env False arg args
+              mapM_ (interpretPipe env) (appLine args css)
               return void
          Nothing  -> do
            putStrLnE $ "command macro " ++ co ++ " not interpreted"
            return void
-       _ -> interpret env es comm
+       _ -> interpret env args comm
 
    appLine = map . map . appCommand
 
 -- | macro definition applications: replace ?i by (exps !! i)
-appCommand :: [Expr] -> Command -> Command
-appCommand xs c@(Command i os arg) = case arg of
+appCommand :: CommandArguments -> Command -> Command
+appCommand args c@(Command i os arg) = case arg of
   AExpr e -> Command i os (AExpr (app e))
   _       -> c
  where
+  xs = toExprs args
+
   app e = case e of
     EAbs b x e -> EAbs b x (app e)
     EApp e1 e2 -> EApp (app e1) (app e2)
@@ -97,14 +99,15 @@ checkOpts info opts =
     os  -> fail $ "options not interpreted: " ++ unwords os
 
 --getCommandTrees :: CommandEnv -> Bool -> Argument -> [Expr] -> Either String [Expr]
-getCommandTrees env needsTypeCheck a es =
+getCommandTrees env needsTypeCheck a args =
   case a of
     AMacro m -> case Map.lookup m (expmacros env) of
                   Just e -> one e
-                  _      -> return [] -- report error?
+                  _      -> return (Exprs []) -- report error?
     AExpr e -> if needsTypeCheck
                then one =<< typeCheckArg e
                else one e
-    ANoArg  -> return es  -- use piped
+    ATerm t -> return (Term t)
+    ANoArg  -> return args  -- use piped
   where
-    one e = return [e] -- ignore piped
+    one e = return (Exprs [e]) -- ignore piped
diff --git a/src/compiler/GF/Command/Parse.hs b/src/compiler/GF/Command/Parse.hs
index 0967f30e9..9ead12e7e 100644
--- a/src/compiler/GF/Command/Parse.hs
+++ b/src/compiler/GF/Command/Parse.hs
@@ -1,6 +1,7 @@
 module GF.Command.Parse(readCommandLine, pCommand) where
 
 import PGF(pExpr,pIdent)
+import GF.Grammar.Parser(runPartial,pTerm)
 import GF.Command.Abstract
 
 import Data.Char(isDigit,isSpace)
@@ -21,10 +22,10 @@ pCommandLine =
 pPipe = sepBy1 (skipSpaces >> pCommand) (skipSpaces >> char '|')
 
 pCommand = (do
-  cmd  <- pIdent <++ (char '%' >> pIdent >>= return . ('%':))
+  cmd  <- pIdent <++ (char '%' >> fmap ('%':) pIdent)
   skipSpaces
   opts <- sepBy pOption skipSpaces
-  arg  <- pArgument
+  arg  <- if getCommandOp cmd == "cc" then pArgTerm else pArgument
   return (Command cmd opts arg)
   )
     <++ (do
@@ -55,6 +56,12 @@ pArgument =
               <++
     (skipSpaces >> char '%' >> fmap AMacro pIdent))
 
+pArgTerm = ATerm `fmap` readS_to_P sTerm
+  where
+    sTerm s = case runPartial pTerm s of
+                Right (s,t) -> [(t,s)]
+                _ -> []
+
 pSystemCommand =
     (char '"' >> (manyTill (pEsc <++ get) (char '"')))
       <++