Add slurp utility function

src/SSG/Djot/Lines.idr

@@ -8,9 +8,9 @@ import Control.Eff
 -- Only for iutils unit tests
 import System
 
---*********************
---* Effect Definition *
---*********************
+--************************
+--*   Effect Definition  *
+--************************
 
 export
 data Lines : Type -> Type where
@@ -19,9 +19,9 @@ data Lines : Type -> Type where
   ||| Take the next line
   Take : Lines (Maybe String)
 
---*********************
---*  Effect Actions   *
---*********************
+--************************
+--*    Effect Actions    *
+--************************
 
 export
 peek : Has Lines fs => Eff fs (Maybe String)
@@ -31,9 +31,29 @@ export
 take : Has Lines fs => Eff fs (Maybe String)
 take = send Take
 
---*********************
---*  Effect Handlers  *
---*********************
+--************************
+--* Extra Effect Actions *
+--************************
+
+||| Take lines until a line matching the given predicate is encountered, dropping the
+||| matching line
+export
+slurp : Has Lines fs => (predicate : String -> Bool) -> Eff fs (List String)
+slurp predicate = do
+  Just line <- peek
+    | _ => pure []
+  if predicate line
+    then do
+      _ <- take
+      pure []
+    else do
+      Just x <- take
+        | _ => pure []
+      map (x ::) (slurp predicate)
+
+--************************
+--*    Effect Handlers   *
+--************************
 
 ||| Split the next line from a string
 nextLine : String -> Maybe (String, String)
@@ -79,9 +99,9 @@ runLines input =
     let (vv, input3) = unLines input2 lns
     in f input3 vv
 
---*********************
---*    Unit Tests     *
---*********************
+--************************
+--*      Unit Tests      *
+--************************
 
 -- @@test runLines Smoke Test
 runLinesSmoke : IO Bool