Variable expansion in strings and regexes

1 files changed, 40 insertions, 2 deletions

diff --git a/src/Test.hs b/src/Test.hs
index 465b424..d652f9b 100644
--- a/src/Test.hs
+++ b/src/Test.hs
@@ -4,12 +4,21 @@ module Test (
 
     ProcName(..), textProcName, unpackProcName,
     NodeName(..), textNodeName, unpackNodeName,
+
+    MonadEval(..),
+    VarName(..), unpackVarName,
+    StringExpr(..), evalStringExpr,
+    RegexExpr(..), evalRegexExpr,
 ) where
 
+import Control.Monad
+
+import Data.List
 import Data.Text (Text)
 import qualified Data.Text as T
 
 import Text.Regex.TDFA
+import Text.Regex.TDFA.String
 
 import Process
 
@@ -19,8 +28,8 @@ data Test = Test
     }
 
 data TestStep = Spawn ProcName NodeName
-              | Send ProcName Text
-              | Expect ProcName Regex Text
+              | Send ProcName StringExpr
+              | Expect ProcName RegexExpr
               | Wait
 
 newtype NodeName = NodeName Text
@@ -31,3 +40,32 @@ textNodeName (NodeName name) = name
 
 unpackNodeName :: NodeName -> String
 unpackNodeName (NodeName tname) = T.unpack tname
+
+
+class Monad m => MonadEval m where
+  lookupStringVar :: VarName -> m Text
+
+
+data VarName = VarName [Text]
+    deriving (Eq, Ord)
+
+unpackVarName :: VarName -> String
+unpackVarName (VarName name) = concat $ intersperse "." $ map T.unpack name
+
+data StringExpr = StringExpr [Either Text VarName]
+
+evalStringExpr :: MonadEval m => StringExpr -> m Text
+evalStringExpr (StringExpr xs) = fmap T.concat $ forM xs $ \case
+    Left text -> return text
+    Right var -> lookupStringVar var
+
+data RegexExpr = RegexExpr [Either String VarName]
+
+evalRegexExpr :: (MonadFail m, MonadEval m) => RegexExpr -> m Regex
+evalRegexExpr (RegexExpr xs) = do
+    parts <- forM xs $ \case
+        Left str -> return str
+        Right var -> concatMap (\c -> ['\\',c]) . T.unpack <$> lookupStringVar var
+    case compile defaultCompOpt defaultExecOpt $ concat $ concat [["^"], parts, ["$"]] of
+        Left err -> fail err
+        Right re -> return re