feat: Add equals and hashCode implementations for Arity.

src/main/java/cz/jirutka/rsql/parser/ast/Arity.java

@@ -47,6 +47,25 @@ public interface Arity {
      */
     int max();
 
+    /**
+     * Compares this object with the specified object for equality. Two objects are considered equal if they represent
+     * the same Arity, meaning their min and max are equal.
+     *
+     * @param o The object to be compared for equality with this object.
+     * @return {@code true} if the specified object is equal to this object; {@code false} otherwise.
+     */
+    @Override
+    boolean equals(Object o);
+
+    /**
+     * Returns the hash code value for this object. The hash code is computed based on the properties of the object and
+     * ensures that equal objects have the same hash code.
+     *
+     * @return The hash code value for this object.
+     */
+    @Override
+    int hashCode();
+
     /**
      * Creates arity with given {@code min} and {@code max}.
      *

src/main/java/cz/jirutka/rsql/parser/ast/DynamicArity.java

@@ -52,4 +52,19 @@ public int min() {
     public int max() {
         return max;
     }
+
+    @Override
+    public boolean equals(Object o) {
+        if (!(o instanceof Arity)) {
+            return false;
+        }
+
+        Arity that = (Arity) o;
+        return min == that.min() && max == that.max();
+    }
+
+    @Override
+    public int hashCode() {
+        return Integer.hashCode(min) + (31 * Integer.hashCode(max));
+    }
 }

src/main/java/cz/jirutka/rsql/parser/ast/NAry.java

@@ -44,4 +44,19 @@ public int min() {
     public int max() {
         return n;
     }
+
+    @Override
+    public boolean equals(Object o) {
+        if (!(o instanceof Arity)) {
+            return false;
+        }
+
+        Arity that = (Arity) o;
+        return n == that.min() && n == that.max();
+    }
+
+    @Override
+    public int hashCode() {
+        return Integer.hashCode(n);
+    }
 }

src/test/groovy/cz/jirutka/rsql/parser/ast/DynamicAritySpec.groovy

@@ -1,5 +1,6 @@
 package cz.jirutka.rsql.parser.ast
 
+import nl.jqno.equalsverifier.EqualsVerifier
 import spock.lang.Specification
 
 class DynamicAritySpec extends Specification {
@@ -30,4 +31,21 @@ class DynamicAritySpec extends Specification {
         actual.min() == min
         actual.max() == max
     }
+
+    def 'Should be equal with n-ary'() {
+        expect:
+        //noinspection GrEqualsBetweenInconvertibleTypes
+        new DynamicArity(0, 0) == new NAry(0)
+    }
+
+    def 'Should not be equal with n-ary'() {
+        expect:
+        //noinspection GrEqualsBetweenInconvertibleTypes
+        new DynamicArity(0, 0) != new NAry(1)
+    }
+
+    def 'Should implement equals and hashCode'() {
+        expect:
+        EqualsVerifier.forClass(DynamicArity).verify()
+    }
 }

src/test/groovy/cz/jirutka/rsql/parser/ast/NArySpec.groovy

@@ -1,5 +1,6 @@
 package cz.jirutka.rsql.parser.ast
 
+import nl.jqno.equalsverifier.EqualsVerifier
 import spock.lang.Specification
 
 class NArySpec extends Specification {
@@ -23,4 +24,24 @@ class NArySpec extends Specification {
         where:
         n << [0, 1, 2, 32]
     }
+
+    def 'Should be equal with dynamic arity'() {
+        expect:
+        //noinspection GrEqualsBetweenInconvertibleTypes
+        new NAry(0) == new DynamicArity(0, 0)
+    }
+
+    def 'Should be not equal with dynamic arity'() {
+        expect:
+        //noinspection GrEqualsBetweenInconvertibleTypes
+        new NAry(0) != a
+
+        where:
+        a << [new DynamicArity(0, 1), new DynamicArity(1, 1)]
+    }
+
+    def 'Should implement equals and hashCode'() {
+        expect:
+        EqualsVerifier.forClass(NAry).verify()
+    }
 }