Added calc and modify functions

src/main/java/rife/bld/extension/propertyfile/Calc.java

@@ -0,0 +1,50 @@
+/*
+ *  Copyright 2023 the original author or authors.
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *   you may not use this file except in compliance with the License.
+ *   You may obtain a copy of the License at
+ *
+ *       https://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+
+package rife.bld.extension.propertyfile;
+
+import java.util.function.IntFunction;
+
+/**
+ * Implements the calculation functions.
+ *
+ * @author <a href="https://github.com/gbevin">Geert Bevin</a>
+ * @author <a href="https://erik.thauvin.net/">Erik C. Thauvin</a>
+ * @since 1.0
+ */
+public final class Calc {
+    public static final IntFunction<Integer> ADD = Calc::add;
+    public static final IntFunction<Integer> SUB = Calc::sub;
+
+    /**
+     * Adds {@code 1} to the value.
+     *
+     * @param v the value
+     */
+    public static Integer add(int v) {
+        return v + 1;
+    }
+
+    /**
+     * Subtracts {@code 1} to the value.
+     *
+     * @param v the value
+     */
+    public static Integer sub(int v) {
+        return v - 1;
+    }
+}
+