Import hs-plugins cvs

examples/shell/shell/API.hs

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+module API where
+
+-- the interface between the app and the plugin
+data Interface = Interface { function :: String -> String }
+
+-- default values for the interface
+plugin :: Interface
+plugin = Interface { function = id }

examples/shell/shell/Main.hs

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+--
+-- a simple shell for loading plugins and evaluating their functions
+-- 
+
+import Plugins
+import API
+
+import Data.Either
+import Data.Char
+import Control.Monad            ( when )
+import System.Console.Readline  ( readline )
+import System.Exit              ( ExitCode(..), exitWith )
+
+
+source = "Plugin.hs"
+stub   = "Plugin.stub"
+
+sym = "resource"
+
+main = do
+        status <- makeWith source stub []
+        p <- case status of
+                MakeFailure e -> mapM_ putStrLn e >> error "failed to compile"
+                MakeSuccess _ obj -> do
+                        m_v <- load obj ["."] [] sym
+                        case m_v of
+                                LoadSuccess m v -> return (m,v)
+                                LoadFailure e   -> do mapM_ putStrLn e
+                                                      error "failed to load"
+        shell p
+
+    where
+        shell p@(m,v) = do 
+
+            s <- readline "> "
+            cmd <- case s of 
+                Nothing   -> exitWith ExitSuccess
+                Just ":q" -> exitWith ExitSuccess
+                Just s    -> return (chomp s)
+
+            status <- makeWith source stub []   
+            case status of 
+                MakeFailure e -> do 
+                    mapM_ putStrLn e
+                    shell p     -- print error and back to prompt
+
+                MakeSuccess NotReq o ->  do
+                    p' <- eval cmd p
+                    shell p'    -- eval str again
+
+                MakeSuccess ReComp o -> do
+                    m_v' <- reload m sym
+                    case m_v' of
+                        LoadFailure e    -> mapM_ putStrLn e >> error "failed to load"
+                        LoadSuccess _ v' -> do
+                                let p' = (m,v')
+                                p'' <- eval cmd p'
+                                shell p''
+
+--
+-- shell commands
+--
+eval "" p = return p
+
+eval ":clear" p = do
+        let loop i = when (i < 40) (do putStr "\n" ; loop $! i+1)
+        loop 0
+        return p
+
+eval ":?"  p     = do
+        putStrLn$"\":?\"\n"       ++
+                 "\":quit\"\n"    ++
+                 "\":clear\"\n"   ++
+                 "\"foo\""
+        return p
+
+eval s (m,v) = putStrLn ((function v) s) >> return (m,v)
+
+--
+-- strip trailing whitespace
+--
+chomp :: String -> String
+chomp [] = []
+chomp s | isSpace (last s) = chomp $! init s
+        | otherwise        = s

examples/shell/shell/Makefile

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+TOP=../../..
+include ../../eval.mk

examples/shell/shell/Plugin.hs

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+
+resource = plugin { 
+        function = map toUpper
+}
+

examples/shell/shell/Plugin.stub

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+--
+-- this is a "stub" file, containing default syntax we don't
+-- want the user to have to write
+--
+-- for example, it constrains the module name and force the API to be
+-- imported
+
+module Plugin ( resource ) where
+
+import API
+import Data.Char
+import Data.List
+
+-- this is a default definition of 'resource'. it will be overridden
+-- by anything the user writes. useful for default values
+
+resource :: Interface
+resource = plugin
+

examples/shell/shell/README

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+$ make
+$ ./a.out 
+Compiling plugin ... done
+Loading package base ... linking ... done
+Loading objects API Plugin ... done
+> ?
+"?"
+"quit"
+"clear"
+"filter foo"
+> filter adf adsf
+fsda fda
+> filter asd faSDFADSF
+FSDAFDSaf dsa
+
+-- at this point I edit the plugin and save the source
+
+> filter asfdaSDFASD
+Compiling plugin ... done
+Reloading Plugin ... done
+DSAFDSADFSA
+
+-- it compiled and reloaded it for me. nice.

examples/shell/simple/Main.hs

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+import Plugins
+import StringProcessorAPI
+import System.Console.Readline
+import System.Exit
+
+source = "Plugin.hs"
+stub   = "Plugin.stub"
+symbol = "resource"
+
+main = do s <- makeWith source stub []
+          o <- case s of
+                MakeSuccess _ obj -> do
+                        ls <- load obj ["."] [] symbol
+                        case ls of LoadSuccess m v -> return (m,v)
+                                   LoadFailure err -> error "load failed"
+                MakeFailure e -> mapM_ putStrLn e >> error "compile failed"
+          shell o
+
+shell o@(m,plugin) = do 
+        s <- readline "> "
+        cmd <- case s of 
+                Nothing          -> exitWith ExitSuccess
+                Just (':':'q':_) -> exitWith ExitSuccess
+                Just s           -> addHistory s >> return s
+
+        s  <- makeWith source stub []   -- maybe recompile the source
+        o' <- case s of
+                MakeSuccess ReComp o -> do 
+                        ls <- reload m symbol
+                        case ls of LoadSuccess m' v' -> return (m',v')
+                                   LoadFailure err   -> error "reload failed"
+                MakeSuccess NotReq _ -> return o
+                MakeFailure e -> mapM_ putStrLn e >> shell o
+        eval cmd o'
+        shell o'
+
+eval ":?" _ = putStrLn ":?\n:q\n<string>"
+
+eval s (_,plugin) = let fn = (stringProcessor plugin) in putStrLn (fn s)
+
+

examples/shell/simple/Makefile

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+OBJS=StringProcessorAPI.o
+TOP=../../..
+include ../../eval.mk
+
+#all:
+#	@echo test disabled

examples/shell/simple/Plugin.hs

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+import Char
+
+resource = plugin { 
+        stringProcessor = map toUpper
+}

examples/shell/simple/Plugin.stub

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+--
+-- this is a "stub" file, containing default syntax we don't
+-- want the user to have to write
+--
+-- for example, it constrains the module name and force the API to be
+-- imported
+
+module Plugin ( resource ) where
+
+import StringProcessorAPI
+import Data.Char
+import Data.List
+
+-- this is a default definition of 'resource'. it will be overridden
+-- by anything the user writes. useful for default values
+
+resource :: Interface
+resource = plugin
+

examples/shell/simple/README

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+$ make
+$ ./a.out 
+Compiling plugin ... done
+Loading package base ... linking ... done
+Loading objects API Plugin ... done
+> ?
+"?"
+"quit"
+"clear"
+"filter foo"
+> filter adf adsf
+fsda fda
+> filter asd faSDFADSF
+FSDAFDSaf dsa
+
+-- at this point I edit the plugin and save the source
+
+> filter asfdaSDFASD
+Compiling plugin ... done
+Reloading Plugin ... done
+DSAFDSADFSA
+
+-- it compiled and reloaded it for me. nice.

examples/shell/simple/StringProcessorAPI.hs

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+module StringProcessorAPI where
+
+data Interface = Interface { 
+        stringProcessor :: String -> String 
+}
+
+plugin :: Interface
+plugin = Interface { stringProcessor = id }