From e4d92d9097033cd32c45f6ea2c4fc60404d3321e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Alexander=20S=C3=B6derberg?=
 <alexander.soderberg@incendo.org>
Date: Sun, 28 Jan 2024 12:01:13 +0100
Subject: [PATCH] feat: allow accessing backing states

---
 .../java/org/incendo/state/EmptyStates.java    |  6 ++++++
 .../java/org/incendo/state/LazyStates.java     |  6 ++++++
 .../main/java/org/incendo/state/States.java    |  8 ++++++++
 .../java/org/incendo/state/StatesImpl.java     | 18 ++++++++++++------
 4 files changed, 32 insertions(+), 6 deletions(-)

diff --git a/state-core/src/main/java/org/incendo/state/EmptyStates.java b/state-core/src/main/java/org/incendo/state/EmptyStates.java
index c05d08a..eb92a30 100644
--- a/state-core/src/main/java/org/incendo/state/EmptyStates.java
+++ b/state-core/src/main/java/org/incendo/state/EmptyStates.java
@@ -23,6 +23,7 @@
 //
 package org.incendo.state;
 
+import java.util.stream.Stream;
 import org.apiguardian.api.API;
 import org.checkerframework.checker.nullness.qual.NonNull;
 
@@ -50,4 +51,9 @@ public boolean empty() {
     public String toString() {
         return "()";
     }
+
+    @Override
+    public @NonNull Stream<S> states() {
+        return Stream.empty();
+    }
 }
diff --git a/state-core/src/main/java/org/incendo/state/LazyStates.java b/state-core/src/main/java/org/incendo/state/LazyStates.java
index ea4db0c..4322743 100644
--- a/state-core/src/main/java/org/incendo/state/LazyStates.java
+++ b/state-core/src/main/java/org/incendo/state/LazyStates.java
@@ -25,6 +25,7 @@
 
 import java.util.Objects;
 import java.util.function.Supplier;
+import java.util.stream.Stream;
 import org.apiguardian.api.API;
 import org.checkerframework.checker.nullness.qual.NonNull;
 
@@ -59,4 +60,9 @@ public boolean contains(final @NonNull S state) {
     public boolean empty() {
         return this.backingStates().empty();
     }
+
+    @Override
+    public @NonNull Stream<S> states() {
+        return this.backingStates().states();
+    }
 }
diff --git a/state-core/src/main/java/org/incendo/state/States.java b/state-core/src/main/java/org/incendo/state/States.java
index 55d01c5..d371945 100644
--- a/state-core/src/main/java/org/incendo/state/States.java
+++ b/state-core/src/main/java/org/incendo/state/States.java
@@ -31,6 +31,7 @@
 import java.util.Objects;
 import java.util.Set;
 import java.util.function.Supplier;
+import java.util.stream.Stream;
 import org.apiguardian.api.API;
 import org.checkerframework.checker.nullness.qual.NonNull;
 
@@ -127,4 +128,11 @@ public interface States<S extends State<S>> {
      * @return {@code true} if this instance contains no states, else {@code false}
      */
     boolean empty();
+
+    /**
+     * Returns a stream of the stateCollection contained in this instance
+     *
+     * @return the stateCollection
+     */
+    @NonNull Stream<S> states();
 }
diff --git a/state-core/src/main/java/org/incendo/state/StatesImpl.java b/state-core/src/main/java/org/incendo/state/StatesImpl.java
index 2997f9c..9dca3e8 100644
--- a/state-core/src/main/java/org/incendo/state/StatesImpl.java
+++ b/state-core/src/main/java/org/incendo/state/StatesImpl.java
@@ -30,15 +30,16 @@
 import java.util.List;
 import java.util.Objects;
 import java.util.stream.Collectors;
+import java.util.stream.Stream;
 import org.apiguardian.api.API;
 import org.checkerframework.checker.nullness.qual.NonNull;
 
 @API(status = API.Status.INTERNAL, since = "1.0.0")
-record StatesImpl<S extends State<S>>(@NonNull Collection<@NonNull S> states) implements States<S> {
+record StatesImpl<S extends State<S>>(@NonNull Collection<@NonNull S> stateCollection) implements States<S> {
 
     @Override
     public boolean contains(final @NonNull S state) {
-        return this.states.contains(state);
+        return this.stateCollection.contains(state);
     }
 
     @Override
@@ -47,22 +48,27 @@ public boolean contains(final @NonNull S state) {
         Objects.requireNonNull(state, "state");
         if (state instanceof Enum<?>) {
             // Special case so that we preserve the EnumSet.
-            final EnumSet enumSet = EnumSet.copyOf((Collection) this.states);
+            final EnumSet enumSet = EnumSet.copyOf((Collection) this.stateCollection);
             enumSet.add(state);
             return new StatesImpl<>(Collections.unmodifiableCollection(enumSet));
         }
-        final List<S> states = new ArrayList<>(this.states);
+        final List<S> states = new ArrayList<>(this.stateCollection);
         states.add(state);
         return new StatesImpl<>(Collections.unmodifiableCollection(states));
     }
 
     @Override
     public String toString() {
-        return this.states.stream().map(S::toString).collect(Collectors.joining(", ", "(", ")"));
+        return this.stateCollection.stream().map(S::toString).collect(Collectors.joining(", ", "(", ")"));
     }
 
     @Override
     public boolean empty() {
-        return this.states.isEmpty();
+        return this.stateCollection.isEmpty();
+    }
+
+    @Override
+    public @NonNull Stream<S> states() {
+        return this.stateCollection.stream();
     }
 }