From 8cab2461c7f244ac8fabf2c7e61f0753dab68d00 Mon Sep 17 00:00:00 2001
From: =?utf8?q?Hannu=20Niemist=C3=B6?= <hannu.niemisto@semantum.fi>
Date: Mon, 25 Sep 2017 12:41:03 +0300
Subject: [PATCH] Added MMap.getOrCreate

refs #7503

Change-Id: Ibc03b5c51365e4d5c2d2250fbf7265adc298a84a
---
 bundles/org.simantics.scl.runtime/scl/MMap.scl | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/bundles/org.simantics.scl.runtime/scl/MMap.scl b/bundles/org.simantics.scl.runtime/scl/MMap.scl
index 18e5866c0..085728c58 100644
--- a/bundles/org.simantics.scl.runtime/scl/MMap.scl
+++ b/bundles/org.simantics.scl.runtime/scl/MMap.scl
@@ -35,6 +35,15 @@ importJava "java.util.Map" where
     remove :: T a b -> a -> <Proc> (Maybe b)
     clear :: T a b -> <Proc> ()
 
+@inline
+getOrCreate :: T a b -> (a -> <e> b) ->  a -> <Proc,e> b
+getOrCreate m f k = match get m k with
+    Just v -> v
+    Nothing -> do
+        v = f k
+        put m k v
+        v  
+
 @inline
 iter :: (a -> b -> <e> ()) -> T a b -> <e,Proc> ()
 iter f m = MSet.iter (\entry -> f (keyOf entry) (valueOf entry)) (entrySet m)
-- 
2.43.2