Stackbuste test:

aol · Aug 8, 2017 · 50b2bfa · 50b2bfa
1 parent 2200285
commit 50b2bfa
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Showing 3 changed files with 104 additions and 26 deletions.
diff --git a/cyclops-vavr/src/main/java/cyclops/companion/vavr/Streams.java b/cyclops-vavr/src/main/java/cyclops/companion/vavr/Streams.java
@@ -1,5 +1,6 @@
 package cyclops.companion.vavr;
 
+import cyclops.control.*;
 import cyclops.monads.VavrWitness.queue;
 import cyclops.monads.VavrWitness.tryType;
 import io.vavr.Lazy;
@@ -9,10 +10,6 @@
 import com.aol.cyclops.vavr.hkt.*;
 import cyclops.companion.CompletableFutures;
 import cyclops.companion.Optionals;
-import cyclops.control.Eval;
-import cyclops.control.Maybe;
-import cyclops.control.Reader;
-import cyclops.control.Xor;
 import cyclops.conversion.vavr.FromCyclopsReact;
 import cyclops.monads.*;
 import cyclops.monads.VavrWitness.*;
@@ -39,6 +36,7 @@
 import cyclops.typeclasses.monad.*;
 import io.vavr.collection.List;
 import io.vavr.collection.Stream;
+import io.vavr.control.Try;
 import lombok.experimental.UtilityClass;
 import org.jooq.lambda.tuple.Tuple2;
 
@@ -72,13 +70,20 @@ public static  <T,R> Stream<R> tailRec(T initial, Function<? super T, ? extends
         boolean newValue[] = {true};
         for(;;){
 
-            next = next.flatMap(e -> e.fold(s -> {
-                        newValue[0]=true;
-                        return fn.apply(s); },
-                    p -> {
-                        newValue[0]=false;
-                        return Stream.of(e);
-                    }));
+            Stream<Either<T, R>> rebuild = Stream.of();
+            for(Either<T,R> e : next){
+                Stream<? extends Either<T, R>> r = e.fold(s -> {
+                            newValue[0] = true;
+
+                            return fn.apply(s);
+                        },
+                        p -> {
+                            newValue[0] = false;
+                            return Stream.of(e);
+                        });
+                rebuild = Stream.concat(rebuild,r);
+            }
+            next = rebuild;
             if(!newValue[0])
                 break;
 
@@ -92,13 +97,21 @@ public static  <T,R> Stream<R> tailRecXor(T initial, Function<? super T, ? exten
         boolean newValue[] = {true};
         for(;;){
 
-            next = next.flatMap(e -> e.visit(s -> {
-                        newValue[0]=true;
-                        return fn.apply(s); },
-                    p -> {
-                        newValue[0]=false;
-                        return Stream.of(e);
-                    }));
+            Stream<Xor<T, R>> rebuild = Stream.of();
+            for(Xor<T,R> e : next){
+                Stream<? extends Xor<T, R>> r = e.visit(s -> {
+                            newValue[0] = true;
+
+                            return fn.apply(s);
+                        },
+                        p -> {
+                            newValue[0] = false;
+                            return Stream.of(e);
+                        });
+                rebuild = Stream.concat(rebuild,r);
+            }
+
+            next = rebuild;
             if(!newValue[0])
                 break;
 
@@ -114,18 +127,20 @@ public static <T,R> R foldRightUnsafe(Stream<T> stream,R identity, BiFunction<?
             return fn.apply(stream.head(),foldRight(stream.tail(),identity,fn));
     }
 
-    public static <T,R> R foldRight(Stream<T> stream,R identity, BiFunction<? super T, ? super R, ? extends R> fn){
-        return foldRightRec(stream,Eval.now(identity),(a,b)-> b.map(b2->fn.apply(a,b2))).get();
-    }
-    private static <T,R> Eval<R> foldRightRec(Stream<T> stream,Eval<R> identity, BiFunction<? super T, ? super Eval<R>, ? extends Eval<R>> fn){
+    public static <T,R> R foldRight(Stream<T> stream,R identity, BiFunction<? super T, ? super R, ? extends R> p){
+        class Step{
+            public Trampoline<R> loop(Stream<T> s, Function<? super R, ? extends Trampoline<R>> fn){
+                   if (s.isEmpty())
+                       return fn.apply(identity);
+                   return Trampoline.more(()->loop(s.tail(), rem -> Trampoline.more(() -> fn.apply(p.apply(s.head(), rem)))));
 
-        if(stream.isEmpty())
-            return identity;
-        else
-            return identity.flatMap(i-> fn.apply(stream.head(), foldRightRec(stream.tail(), identity, fn)));
+            }
+        }
+        return new Step().loop(stream,i->Trampoline.done(i)).result();
     }
 
 
+
     public static <T> AnyMSeq<stream,T> anyM(Stream<T> option) {
         return AnyM.ofSeq(option, stream.INSTANCE);
     }

diff --git a/cyclops-vavr/src/test/java/cyclops/MonadRecTest.java b/cyclops-vavr/src/test/java/cyclops/MonadRecTest.java
@@ -0,0 +1,39 @@
+package cyclops;
+
+import com.aol.cyclops.vavr.hkt.ListKind;
+import com.aol.cyclops2.hkt.Higher;
+import cyclops.async.Future;
+
+import cyclops.companion.vavr.Lists;
+import cyclops.companion.vavr.Streams;
+import cyclops.control.Xor;
+import cyclops.monads.VavrWitness;
+import cyclops.monads.VavrWitness.list;
+import cyclops.monads.VavrWitness.stream;
+import cyclops.stream.ReactiveSeq;
+import cyclops.typeclasses.monad.MonadRec;
+import io.vavr.collection.List;
+import io.vavr.collection.Stream;
+import org.junit.Test;
+
+import java.util.Optional;
+
+import static org.hamcrest.Matchers.equalTo;
+import static org.junit.Assert.assertThat;
+
+
+public class MonadRecTest {
+
+    @Test
+    public void listTest(){
+        MonadRec<list> mr = Lists.Instances.monadRec();
+        List<Integer> l = Lists.tailRecXor(0, i -> i < 100_000 ? List.of(Xor.secondary(i + 1)) : List.of(Xor.primary(i + 1)));
+        assertThat(l,equalTo(List.of(100_001)));
+    }
+    @Test
+    public void streamTest(){
+        MonadRec<stream> mr = Streams.Instances.monadRec();
+        Stream<Integer> l = Streams.tailRecXor(0, i -> i < 100_000 ? Stream.of(Xor.secondary(i + 1)) : Stream.of(Xor.primary(i + 1)));
+        assertThat(l,equalTo(Stream.of(100_001)));
+    }
+}
diff --git a/cyclops-vavr/src/test/java/cyclops/StreamsTest.java b/cyclops-vavr/src/test/java/cyclops/StreamsTest.java
@@ -0,0 +1,24 @@
+package cyclops;
+
+import cyclops.companion.vavr.Streams;
+import io.vavr.collection.Stream;
+import org.junit.Test;
+
+
+import static org.hamcrest.Matchers.equalTo;
+import static org.junit.Assert.assertThat;
+
+/**
+ * Created by johnmcclean on 08/08/2017.
+ */
+public class StreamsTest {
+
+    @Test
+    public void simpleFoldRight(){
+        assertThat(Streams.foldRight(Stream.of(1,2,3),0,(a,b)->a+b),equalTo(6));
+    }
+    @Test
+    public void stackBuster(){
+        assertThat(Streams.foldRight(Stream.range(0,100_000),0,(a,b)->a+b),equalTo(704982704));
+    }
+}