refactor: remove TupleLike

* Directly transform VIATRA tuples into Refinery tuples, since creating
  the additional wrapper object doesn't save any memory.
* Adds static arity Tuple3 and Tuple4 implementations to be more
  aligned with VIATRA internals and save memory for queries with up to
  4 parameters.
* Makes sure no new objects are allocated (for varargs handling) when a
  static arity tuple is hashed.

9 files changed, 184 insertions, 76 deletions

diff --git a/subprojects/store/src/main/java/tools/refinery/store/tuple/Tuple.java b/subprojects/store/src/main/java/tools/refinery/store/tuple/Tuple.java
index bf844c6d..51e2895a 100644
--- a/subprojects/store/src/main/java/tools/refinery/store/tuple/Tuple.java
+++ b/subprojects/store/src/main/java/tools/refinery/store/tuple/Tuple.java
@@ -1,28 +1,37 @@
 package tools.refinery.store.tuple;
 
-public sealed interface Tuple extends TupleLike permits Tuple0, Tuple1, Tuple2, TupleN {
-        @Override
-        default Tuple toTuple() {
-                return this;
-        }
+public sealed interface Tuple permits Tuple0, Tuple1, Tuple2, Tuple3, Tuple4, TupleN {
+        int getSize();
+
+        int get(int element);
 
-        static Tuple of() {
+        static Tuple0 of() {
                 return Tuple0.INSTANCE;
         }
 
-        static Tuple of(int value) {
+        static Tuple1 of(int value) {
                 return Tuple1.Cache.INSTANCE.getOrCreate(value);
         }
 
-        static Tuple of(int value1, int value2) {
+        static Tuple2 of(int value1, int value2) {
                 return new Tuple2(value1, value2);
         }
 
+        static Tuple3 of(int value1, int value2, int value3) {
+                return new Tuple3(value1, value2, value3);
+        }
+
+        static Tuple4 of(int value1, int value2, int value3, int value4) {
+                return new Tuple4(value1, value2, value3, value4);
+        }
+
         static Tuple of(int... values) {
                 return switch (values.length) {
                         case 0 -> of();
                         case 1 -> of(values[0]);
                         case 2 -> of(values[0], values[1]);
+                        case 3 -> of(values[0], values[1], values[2]);
+                        case 4 -> of(values[0], values[1], values[2], values[3]);
                         default -> new TupleN(values);
                 };
         }
diff --git a/subprojects/store/src/main/java/tools/refinery/store/tuple/Tuple0.java b/subprojects/store/src/main/java/tools/refinery/store/tuple/Tuple0.java
index 8eea5c3a..266e2cca 100644
--- a/subprojects/store/src/main/java/tools/refinery/store/tuple/Tuple0.java
+++ b/subprojects/store/src/main/java/tools/refinery/store/tuple/Tuple0.java
@@ -1,7 +1,13 @@
 package tools.refinery.store.tuple;
 
-public record Tuple0() implements Tuple {
-        public static Tuple0 INSTANCE = new Tuple0();
+import static tools.refinery.store.tuple.TupleConstants.TUPLE_BEGIN;
+import static tools.refinery.store.tuple.TupleConstants.TUPLE_END;
+
+public final class Tuple0 implements Tuple {
+        public static final Tuple0 INSTANCE = new Tuple0();
+
+        private Tuple0() {
+        }
 
         @Override
         public int getSize() {
@@ -14,12 +20,7 @@ public record Tuple0() implements Tuple {
         }
 
         @Override
-        public int[] toArray() {
-                return new int[]{};
-        }
-
-        @Override
         public String toString() {
-                return "[]";
+                return TUPLE_BEGIN + TUPLE_END;
         }
 }
diff --git a/subprojects/store/src/main/java/tools/refinery/store/tuple/Tuple1.java b/subprojects/store/src/main/java/tools/refinery/store/tuple/Tuple1.java
index 07380966..bdcc47b5 100644
--- a/subprojects/store/src/main/java/tools/refinery/store/tuple/Tuple1.java
+++ b/subprojects/store/src/main/java/tools/refinery/store/tuple/Tuple1.java
@@ -4,7 +4,20 @@ import tools.refinery.store.model.TupleHashProvider;
 
 import java.util.Arrays;
 
-public record Tuple1(int value0) implements Tuple {
+import static tools.refinery.store.tuple.TupleConstants.TUPLE_BEGIN;
+import static tools.refinery.store.tuple.TupleConstants.TUPLE_END;
+
+public final class Tuple1 implements Tuple {
+        private final int value0;
+
+        private Tuple1(int value0) {
+                this.value0 = value0;
+        }
+
+        public int value0() {
+                return value0;
+        }
+
         @Override
         public int getSize() {
                 return 1;
@@ -19,13 +32,21 @@ public record Tuple1(int value0) implements Tuple {
         }
 
         @Override
-        public int[] toArray() {
-                return new int[]{value0};
+        public String toString() {
+                return TUPLE_BEGIN + value0 + TUPLE_END;
         }
 
         @Override
-        public String toString() {
-                return "[" + value0 + "]";
+        public boolean equals(Object o) {
+                if (this == o) return true;
+                if (o == null || getClass() != o.getClass()) return false;
+                Tuple1 tuple1 = (Tuple1) o;
+                return value0 == tuple1.value0;
+        }
+
+        @Override
+        public int hashCode() {
+                return 31 + value0;
         }
 
         /**
diff --git a/subprojects/store/src/main/java/tools/refinery/store/tuple/Tuple2.java b/subprojects/store/src/main/java/tools/refinery/store/tuple/Tuple2.java
index 0836a32d..fc0fbd8e 100644
--- a/subprojects/store/src/main/java/tools/refinery/store/tuple/Tuple2.java
+++ b/subprojects/store/src/main/java/tools/refinery/store/tuple/Tuple2.java
@@ -1,5 +1,7 @@
 package tools.refinery.store.tuple;
 
+import static tools.refinery.store.tuple.TupleConstants.*;
+
 public record Tuple2(int value0, int value1) implements Tuple {
         @Override
         public int getSize() {
@@ -16,12 +18,22 @@ public record Tuple2(int value0, int value1) implements Tuple {
         }
 
         @Override
-        public int[] toArray() {
-                return new int[]{value0, value1};
+        public String toString() {
+                return TUPLE_BEGIN + value0 + TUPLE_SEPARATOR + value1 + TUPLE_END;
         }
 
         @Override
-        public String toString() {
-                return "[" + value0 + ", " + value1 + "]";
+        public boolean equals(Object o) {
+                if (this == o) return true;
+                if (o == null || getClass() != o.getClass()) return false;
+                Tuple2 tuple2 = (Tuple2) o;
+                return value0 == tuple2.value0 && value1 == tuple2.value1;
+        }
+
+        @Override
+        public int hashCode() {
+                int hash = 31 + value0;
+                hash = 31 * hash + value1;
+                return hash;
         }
 }
diff --git a/subprojects/store/src/main/java/tools/refinery/store/tuple/Tuple3.java b/subprojects/store/src/main/java/tools/refinery/store/tuple/Tuple3.java
new file mode 100644
index 00000000..a6ec17b0
--- /dev/null
+++ b/subprojects/store/src/main/java/tools/refinery/store/tuple/Tuple3.java
@@ -0,0 +1,41 @@
+package tools.refinery.store.tuple;
+
+import static tools.refinery.store.tuple.TupleConstants.*;
+
+public record Tuple3(int value0, int value1, int value2) implements Tuple {
+        @Override
+        public int getSize() {
+                return 3;
+        }
+
+        @Override
+        public int get(int element) {
+                return switch (element) {
+                        case 0 -> value0;
+                        case 1 -> value1;
+                        case 2 -> value2;
+                        default -> throw new ArrayIndexOutOfBoundsException(element);
+                };
+        }
+
+        @Override
+        public String toString() {
+                return TUPLE_BEGIN + value0 + TUPLE_SEPARATOR + value1 + TUPLE_SEPARATOR + value2 + TUPLE_END;
+        }
+
+        @Override
+        public boolean equals(Object o) {
+                if (this == o) return true;
+                if (o == null || getClass() != o.getClass()) return false;
+                Tuple3 tuple3 = (Tuple3) o;
+                return value0 == tuple3.value0 && value1 == tuple3.value1 && value2 == tuple3.value2;
+        }
+
+        @Override
+        public int hashCode() {
+                int hash = 31 + value0;
+                hash = 31 * hash + value1;
+                hash = 31 * hash + value2;
+                return hash;
+        }
+}
diff --git a/subprojects/store/src/main/java/tools/refinery/store/tuple/Tuple4.java b/subprojects/store/src/main/java/tools/refinery/store/tuple/Tuple4.java
new file mode 100644
index 00000000..66cef32b
--- /dev/null
+++ b/subprojects/store/src/main/java/tools/refinery/store/tuple/Tuple4.java
@@ -0,0 +1,44 @@
+package tools.refinery.store.tuple;
+
+import static tools.refinery.store.tuple.TupleConstants.*;
+
+public record Tuple4(int value0, int value1, int value2, int value3) implements Tuple {
+        @Override
+        public int getSize() {
+                return 4;
+        }
+
+        @Override
+        public int get(int element) {
+                return switch (element) {
+                        case 0 -> value0;
+                        case 1 -> value1;
+                        case 2 -> value2;
+                        case 3 -> value3;
+                        default -> throw new ArrayIndexOutOfBoundsException(element);
+                };
+        }
+
+        @Override
+        public String toString() {
+                return TUPLE_BEGIN + value0 + TUPLE_SEPARATOR + value1 + TUPLE_SEPARATOR + value2 + TUPLE_SEPARATOR + value3 +
+                                TUPLE_END;
+        }
+
+        @Override
+        public boolean equals(Object o) {
+                if (this == o) return true;
+                if (o == null || getClass() != o.getClass()) return false;
+                Tuple4 tuple4 = (Tuple4) o;
+                return value0 == tuple4.value0 && value1 == tuple4.value1 && value2 == tuple4.value2 && value3 == tuple4.value3;
+        }
+
+        @Override
+        public int hashCode() {
+                int hash = 31 + value0;
+                hash = 31 * hash + value1;
+                hash = 31 * hash + value2;
+                hash = 31 * hash + value3;
+                return hash;
+        }
+}
diff --git a/subprojects/store/src/main/java/tools/refinery/store/tuple/TupleConstants.java b/subprojects/store/src/main/java/tools/refinery/store/tuple/TupleConstants.java
new file mode 100644
index 00000000..3d95a655
--- /dev/null
+++ b/subprojects/store/src/main/java/tools/refinery/store/tuple/TupleConstants.java
@@ -0,0 +1,12 @@
+package tools.refinery.store.tuple;
+
+final class TupleConstants {
+        public static final int MAX_STATIC_ARITY_TUPLE_SIZE = 4;
+        public static final String TUPLE_BEGIN = "[";
+        public static final String TUPLE_SEPARATOR = ", ";
+        public static final String TUPLE_END = "]";
+
+        private TupleConstants() {
+                throw new IllegalArgumentException("This is a static utility class an should not instantiated directly");
+        }
+}
diff --git a/subprojects/store/src/main/java/tools/refinery/store/tuple/TupleLike.java b/subprojects/store/src/main/java/tools/refinery/store/tuple/TupleLike.java
deleted file mode 100644
index 953ea9f8..00000000
--- a/subprojects/store/src/main/java/tools/refinery/store/tuple/TupleLike.java
+++ /dev/null
@@ -1,35 +0,0 @@
-package tools.refinery.store.tuple;
-
-import java.util.stream.Collectors;
-import java.util.stream.IntStream;
-
-public interface TupleLike {
-        int getSize();
-
-        int get(int element);
-
-        default int[] toArray() {
-                int size = getSize();
-                var array = new int[size];
-                for (int i = 0; i < size; i++) {
-                        array[i] = get(i);
-                }
-                return array;
-        }
-
-        default Tuple toTuple() {
-                return switch (getSize()) {
-                        case 0 -> Tuple.of();
-                        case 1 -> Tuple.of(get(0));
-                        case 2 -> Tuple.of(get(0), get(1));
-                        default -> Tuple.of(toArray());
-                };
-        }
-
-        static String toString(TupleLike tuple) {
-                var valuesString = IntStream.range(0, tuple.getSize())
-                                .mapToObj(i -> Integer.toString(tuple.get(i)))
-                                .collect(Collectors.joining(", "));
-                return "[" + valuesString + "]";
-        }
-}
diff --git a/subprojects/store/src/main/java/tools/refinery/store/tuple/TupleN.java b/subprojects/store/src/main/java/tools/refinery/store/tuple/TupleN.java
index c3aed847..512bab49 100644
--- a/subprojects/store/src/main/java/tools/refinery/store/tuple/TupleN.java
+++ b/subprojects/store/src/main/java/tools/refinery/store/tuple/TupleN.java
@@ -1,13 +1,18 @@
 package tools.refinery.store.tuple;
 
 import java.util.Arrays;
+import java.util.stream.Collectors;
 
-public record TupleN(int[] values) implements Tuple {
-        static final int CUSTOM_TUPLE_SIZE = 2;
+import static tools.refinery.store.tuple.TupleConstants.*;
 
-        public TupleN(int[] values) {
-                if (values.length < CUSTOM_TUPLE_SIZE)
-                        throw new IllegalArgumentException();
+public final class TupleN implements Tuple {
+        private final int[] values;
+
+        TupleN(int[] values) {
+                if (values.length < MAX_STATIC_ARITY_TUPLE_SIZE) {
+                        throw new IllegalArgumentException("Tuples of size at most %d must use static arity Tuple classes"
+                                        .formatted(MAX_STATIC_ARITY_TUPLE_SIZE));
+                }
                 this.values = Arrays.copyOf(values, values.length);
         }
 
@@ -22,18 +27,11 @@ public record TupleN(int[] values) implements Tuple {
         }
 
         @Override
-        public int[] toArray() {
-                return values;
-        }
-
-        @Override
         public String toString() {
-                return TupleLike.toString(this);
-        }
-
-        @Override
-        public int hashCode() {
-                return Arrays.hashCode(values);
+                var valuesString = Arrays.stream(values)
+                                .mapToObj(Integer::toString)
+                                .collect(Collectors.joining(TUPLE_SEPARATOR));
+                return TUPLE_BEGIN + valuesString + TUPLE_END;
         }
 
         @Override
@@ -47,4 +45,9 @@ public record TupleN(int[] values) implements Tuple {
                 TupleN other = (TupleN) obj;
                 return Arrays.equals(values, other.values);
         }
+
+        @Override
+        public int hashCode() {
+                return Arrays.hashCode(values);
+        }
 }