Merge pull request #244 from dmlloyd/pow2

Introduce power-of-two validation methods

constraint/src/main/java/io/smallrye/common/constraint/Assert.java

@@ -455,6 +455,34 @@ public static void checkMaximumParameter(String name, double max, double actual)
             throw Messages.log.paramGreaterThan(name, max);
     }
 
+    /**
+     * Check that the named parameter is zero or a power of two (unsigned).
+     * For a signed check, or to eliminate zero values, use {@link #checkMinimumParameter(String, int, int)}.
+     *
+     * @param name the parameter name
+     * @param actual the actual parameter value
+     * @throws IllegalArgumentException if the actual value is not zero or a power of two
+     */
+    public static void checkPow2Parameter(String name, int actual) throws IllegalArgumentException {
+        checkNotNullParamChecked("name", name);
+        if (actual != 0 && Integer.bitCount(actual) != 1)
+            throw Messages.log.paramNotPow2(name);
+    }
+
+    /**
+     * Check that the named parameter is zero or a power of two (unsigned).
+     * For a signed check, or to eliminate zero values, use {@link #checkMinimumParameter(String, long, long)}.
+     *
+     * @param name the parameter name
+     * @param actual the actual parameter value
+     * @throws IllegalArgumentException if the actual value is not zero or a power of two
+     */
+    public static void checkPow2Parameter(String name, long actual) throws IllegalArgumentException {
+        checkNotNullParamChecked("name", name);
+        if (actual != 0 && Long.bitCount(actual) != 1)
+            throw Messages.log.paramNotPow2(name);
+    }
+
     /**
      * Check that the given offset and length fall completely within the bounds of the given array.
      *

constraint/src/main/java/io/smallrye/common/constraint/Messages.java

@@ -56,4 +56,7 @@ interface Messages {
 
     @Message(id = 13, value = "Method \"%s\" of class \"%s\" is not supported")
     UnsupportedOperationException unsupported(String methodName, String className);
+
+    @Message(id = 14, value = "Parameter '%s' must be a power of two")
+    IllegalArgumentException paramNotPow2(String name);
 }