GROOVY-11306: Provide left/right shift operators for BitSet

src/main/java/org/codehaus/groovy/runtime/DefaultGroovyMethods.java

diff --git a/src/main/java/org/codehaus/groovy/runtime/DefaultGroovyMethods.java b/src/main/java/org/codehaus/groovy/runtime/DefaultGroovyMethods.java
index 424bcdb..1f78e16 100644
--- a/src/main/java/org/codehaus/groovy/runtime/DefaultGroovyMethods.java
+++ b/src/main/java/org/codehaus/groovy/runtime/DefaultGroovyMethods.java
@@ -8561,6 +8561,26 @@
         return NumberMath.leftShift(self, operand);
     }
 
+    /**
+     * Implementation of the left shift operator for BitSets,
+     * returning a new BitSet and leaving the original unchanged.
+     * The {@code intValue()} is taken for the shift distance for non-integer operands.
+     *
+     * @param self    a BitSet
+     * @param operand the shift distance by which to shift the BitSet left
+     * @return the resulting BitSet
+     * @since 5.0.0
+     */
+    public static BitSet leftShift(BitSet self, Number operand) {
+        BitSet result = new BitSet(self.size());
+        final int limit = self.size() - 1;
+        self.stream().forEach(i -> {
+            if (i < limit)
+                result.set(i + operand.intValue());
+        });
+        return result;
+    }
+
     //--------------------------------------------------------------------------
     // max
 
@@ -11397,6 +11417,23 @@
         return NumberMath.rightShift(self, operand);
     }
 
+    /**
+     * Implementation of the right shift operator for BitSets,
+     * returning a new BitSet and leaving the original unchanged.
+     * The {@code intValue()} is taken for the shift distance for non-integer operands.
+     *
+     * @param self    a BitSet
+     * @param operand the shift distance by which to right shift the BitSet
+     * @return the resulting BitSet
+     * @since 5.0.0
+     */
+    public static BitSet rightShift(BitSet self, Number operand) {
+        boolean carry = self.get(self.size() - 1);
+        BitSet result = self.get(operand.intValue(), Math.max(operand.intValue(), self.length()));
+        result.set(self.size() - 1, carry);
+        return result;
+    }
+
     //--------------------------------------------------------------------------
     // rightShiftUnsigned
 
@@ -11413,6 +11450,21 @@
         return NumberMath.rightShiftUnsigned(self, operand);
     }
 
+    /**
+     * Implementation of the right shift (unsigned) operator for BitSets,
+     * returning a new BitSet and leaving the original unchanged.
+     * The {@code intValue()} is taken for the shift distance for non-integer operands.
+     *
+     * @param self    a BitSet
+     * @param operand the shift distance by which to right shift (unsigned) the BitSet
+     * @return the resulting BitSet
+     * @since 5.0.0
+     */
+    public static BitSet rightShiftUnsigned(BitSet self, Number operand) {
+        return self.get(operand.intValue(), Math.max(operand.intValue(), self.length()));
+    }
+
+
     //--------------------------------------------------------------------------
     // round
 

src/test/groovy/BitSetTest.groovy

diff --git a/src/test/groovy/BitSetTest.groovy b/src/test/groovy/BitSetTest.groovy
index 9910fca..25a7192 100644
--- a/src/test/groovy/BitSetTest.groovy
+++ b/src/test/groovy/BitSetTest.groovy
@@ -162,6 +162,24 @@
         assertBitFalse b, 3
     }
 
+    void testLeftShift() {
+        def testCases = [
+            [1, -12L],
+            [3, 271],
+            [1, (Long.MAX_VALUE/2 - 10).longValue()],
+            [1, (Long.MAX_VALUE/2 + 10).longValue()]
+        ]
+        testCases.each { int operand, long value ->
+            def a = BitSet.valueOf(value)
+            def b = BitSet.valueOf(value << operand)
+            def c = BitSet.valueOf(value >> operand)
+            def d = BitSet.valueOf(value >>> operand)
+            assert b == a << operand
+            assert c == a >> operand
+            assert d == a >>> operand
+        }
+    }
+
     private assertBitTrue(bitset, index) {
         assertTrue  'index ' + index + ' should have been true',  bitset[index]
     }