Check file datestamp before creating PGF file when compiling grammars

When running a command like

	gf -make L_1.gf ... L_n.gf

gf now avoids recreating the target PGF file if it already exists and is
up-to-date. 

gf still reads all required .gfo files, so significant additional speed
improvements are still possible. This could be done by reading .gfo files
more lazily...

src/compiler/GF/Command/Importing.hs

@@ -46,7 +46,7 @@ importSource :: SourceGrammar -> Options -> [FilePath] -> IO SourceGrammar
 importSource src0 opts files = do
   src <- appIOE $ batchCompile opts files
   case src of
-    Ok gr -> return gr
+    Ok (_,_,gr) -> return gr
     Bad msg -> do 
       putStrLn msg
       return src0
@@ -58,7 +58,7 @@ importCF opts files get = do
                Ok gf -> return gf
                Bad s -> error s ---- 
        Ok gr <- appIOE $ compileSourceGrammar opts gf
-       epgf <- appIOE $ link opts (identS (justModuleName (last files) ++ "Abs")) gr
+       epgf <- appIOE $ link opts (identS (justModuleName (last files) ++ "Abs"), (), gr)
        case epgf of
          Ok pgf -> return pgf
          Bad s  -> error s ----

src/compiler/GF/Compile.hs

@@ -1,4 +1,4 @@
-module GF.Compile (batchCompile, link, compileToPGF, compileSourceGrammar) where
+module GF.Compile (batchCompile, link, srcAbsName, compileToPGF, compileSourceGrammar) where
 import Prelude hiding (catch)
 import GF.System.Catch
 
@@ -31,6 +31,7 @@ import System.FilePath
 import qualified Data.Map as Map
 --import qualified Data.Set as Set
 import Data.List(nub)
+import Data.Time(UTCTime)
 import Text.PrettyPrint
 
 import PGF.Optimize
@@ -38,33 +39,33 @@ import PGF
 
 -- | Compiles a number of source files and builds a 'PGF' structure for them.
 compileToPGF :: Options -> [FilePath] -> IOE PGF
-compileToPGF opts fs =
-    do gr <- batchCompile opts fs
-       let name = justModuleName (last fs)
-       link opts (identS name) gr
+compileToPGF opts fs = link opts =<< batchCompile opts fs
 
-link :: Options -> Ident -> SourceGrammar -> IOE PGF
-link opts cnc gr = do
-  let isv = (verbAtLeast opts Normal)
+link :: Options -> (Ident,t,SourceGrammar) -> IOE PGF
+link opts (cnc,_,gr) =
   putPointE Normal opts "linking ... " $ do
-    let abs = err (const cnc) id $ abstractOfConcrete gr cnc
+    let abs = srcAbsName gr cnc
     pgf <- mkCanon2pgf opts gr abs
     probs <- liftIO (maybe (return . defaultProbabilities) readProbabilitiesFromFile (flag optProbsFile opts) pgf)
     when (verbAtLeast opts Normal) $ putStrE "OK"
     return $ setProbabilities probs 
            $ if flag optOptimizePGF opts then optimizePGF pgf else pgf
 
-batchCompile :: Options -> [FilePath] -> IOE SourceGrammar
+srcAbsName gr cnc = err (const cnc) id $ abstractOfConcrete gr cnc
+
+batchCompile :: Options -> [FilePath] -> IOE (Ident,UTCTime,SourceGrammar)
 batchCompile opts files = do
-  (_,gr,_) <- foldM (compileModule opts) emptyCompileEnv files
-  return gr
+  (_,gr,menv) <- foldM (compileModule opts) emptyCompileEnv files
+  let cnc = identS (justModuleName (last files))
+      t = maximum . map fst $ Map.elems menv
+  return (cnc,t,gr)
 
 -- to compile a set of modules, e.g. an old GF or a .cf file
 compileSourceGrammar :: Options -> SourceGrammar -> IOE SourceGrammar
 compileSourceGrammar opts gr = do
   cwd <- liftIO getCurrentDirectory
   (_,gr',_) <- foldM (\env -> compileSourceModule opts cwd env Nothing)
-                     (0,emptySourceGrammar,Map.empty)
+                     emptyCompileEnv
                      (modules gr)
   return gr'
 
@@ -84,9 +85,6 @@ warnOut opts warnings
          then '\n':warnings
          else warnings
 
--- | the environment
-type CompileEnv = (Int,SourceGrammar,ModEnv)
-
 -- | compile with one module as starting point
 -- command-line options override options (marked by --#) in the file
 -- As for path: if it is read from file, the file path is prepended to each name.
@@ -238,6 +236,9 @@ writeGFO opts file mo = do
 
 --reverseModules (MGrammar ms) = MGrammar $ reverse ms
 
+-- | The environment
+type CompileEnv = (Int,SourceGrammar,ModEnv)
+
 emptyCompileEnv :: CompileEnv
 emptyCompileEnv = (0,emptySourceGrammar,Map.empty)
 

src/compiler/GFC.hs

@@ -10,7 +10,7 @@ import GF.Compile
 import GF.Compile.Export
 
 import GF.Grammar.CF ---- should this be on a deeper level? AR 15/10/2008
-import GF.Infra.Ident(identS)
+import GF.Infra.Ident(identS,showIdent)
 
 import GF.Infra.UseIO
 import GF.Infra.Option
@@ -45,13 +45,19 @@ mainGFC opts fs = do
 
 compileSourceFiles :: Options -> [FilePath] -> IOE ()
 compileSourceFiles opts fs = 
-    do gr <- batchCompile opts fs
-       let cnc = justModuleName (last fs)
+    do cnc_gr@(cnc,t_src,gr) <- batchCompile opts fs
        unless (flag optStopAfterPhase opts == Compile) $
-              do pgf <- link opts (identS cnc) gr
-                 writePGF opts pgf
-                 writeByteCode opts pgf
-                 writeOutputs opts pgf
+              do let abs = showIdent (srcAbsName gr cnc)
+                     pgfFile = grammarName' opts abs<.>"pgf"
+                 t_pgf <- if outputJustPGF opts
+                          then maybeIO $ getModificationTime pgfFile
+                          else return Nothing
+                 if t_pgf >= Just t_src
+                   then putIfVerb opts $ pgfFile ++ " is up-to-date."
+                   else do pgf <- link opts cnc_gr
+                           writePGF opts pgf
+                           writeByteCode opts pgf
+                           writeOutputs opts pgf
 
 compileCFFiles :: Options -> [FilePath] -> IOE ()
 compileCFFiles opts fs = 
@@ -59,13 +65,13 @@ compileCFFiles opts fs =
        let cnc = justModuleName (last fs)
        gr <- compileSourceGrammar opts =<< getCF cnc s
        unless (flag optStopAfterPhase opts == Compile) $
-              do pgf <- link opts (identS cnc) gr
+              do pgf <- link opts (identS cnc, (), gr)
                  writePGF opts pgf
                  writeOutputs opts pgf
 
 unionPGFFiles :: Options -> [FilePath] -> IOE ()
 unionPGFFiles opts fs =
-    if null (outputFormats opts)
+    if outputJustPGF opts
     then maybe doIt checkFirst (flag optName opts)
     else doIt
   where
@@ -97,6 +103,7 @@ writeOutputs opts pgf = do
                    (name,str) <- exportPGF opts fmt pgf]
 
 outputFormats opts = [fmt | fmt <- flag optOutputFormats opts, fmt/=FmtByteCode]
+outputJustPGF opts = null (flag optOutputFormats opts) && not (flag optSplitPGF opts)
 
 writeByteCode :: Options -> PGF -> IOE ()
 writeByteCode opts pgf
@@ -132,7 +139,9 @@ writePGF opts pgf
                                putPointE Normal opts ("Writing " ++ outfile ++ "...") $ liftIO $ encodeFile outfile pgf
 
 grammarName :: Options -> PGF -> String
-grammarName opts pgf = fromMaybe (showCId (absname pgf)) (flag optName opts)
+grammarName opts pgf = --fromMaybe (showCId (absname pgf)) (flag optName opts)
+                       grammarName' opts (showCId (absname pgf))
+grammarName' opts abs = fromMaybe abs (flag optName opts)
 
 writeOutput :: Options -> FilePath-> String -> IOE ()
 writeOutput opts file str =