From: Hannu Niemistö <hannu.niemisto@semantum.fi>
Date: Wed, 25 Apr 2018 12:03:16 +0000 (+0300)
Subject: New method to Prelude: indexSet
X-Git-Tag: v1.43.0~136^2~487
X-Git-Url: https://gerrit.simantics.org/r/gitweb?a=commitdiff_plain;h=e65cd7676f6e843e34a8501afc57f56cbc8602d3;p=simantics%2Fplatform.git

New method to Prelude: indexSet

Change-Id: I06affe3386f014ae098c31416503fd941f3c7d36
---

diff --git a/bundles/org.simantics.scl.runtime/scl/Prelude.scl b/bundles/org.simantics.scl.runtime/scl/Prelude.scl
index d5d278828..32582affa 100644
--- a/bundles/org.simantics.scl.runtime/scl/Prelude.scl
+++ b/bundles/org.simantics.scl.runtime/scl/Prelude.scl
@@ -1965,6 +1965,11 @@ importJava "org.simantics.scl.runtime.Lists" where
     """
     index :: [(a,b)] -> a -> Maybe b
     
+    """
+    Given a list of elements, the function produces its characteristic function.
+    """
+    indexSet :: [a] -> a -> Boolean
+    
     """
     Given a list of values and a function computing a key for each value, the function produces a function that finds a value
     effeciently for the given key.
diff --git a/bundles/org.simantics.scl.runtime/src/org/simantics/scl/runtime/Lists.java b/bundles/org.simantics.scl.runtime/src/org/simantics/scl/runtime/Lists.java
index 5259ce631..99c19d6b9 100644
--- a/bundles/org.simantics.scl.runtime/src/org/simantics/scl/runtime/Lists.java
+++ b/bundles/org.simantics.scl.runtime/src/org/simantics/scl/runtime/Lists.java
@@ -240,7 +240,19 @@ public class Lists {
             }
         };
     }
-    
+
+    public static Function indexSet(List<Object> l) {
+        THashSet set = new THashSet(l.size());
+        for(Object obj : l)
+            set.add(obj);
+        return new FunctionImpl1<Object,Object>() {
+            @Override
+            public Object apply(Object p0) {
+                return set.contains(p0);
+            }
+        };
+    }
+
     public static Function indexBy(Function f, List l) {
         THashMap map = new THashMap(l.size());
         for(Object o : l)