Added Mask renderer

README.md

@@ -37,6 +37,7 @@ This project provides a collection of useful template renderers.
 | Renderer                                                                                                            | Description                                                      |
 |:--------------------------------------------------------------------------------------------------------------------|:-----------------------------------------------------------------|
 | [rife.render.formatCreditcard](https://github.com/rife2/rife2-template-renderers/wiki/rife.render.FormatCreditCard) | Formats a template credit card number value to the last 4 digits |
+| [rife.render.Mask](https://github.com/rife2/rife2-template-renderers/wiki/rife.render.Mask)                         | Masks characters of a template value                             |
 | [rife.render.Normalize](https://github.com/rife2/rife2-template-renderers/wiki/rife.render.Normalize)               | Normalizes a template value for inclusion in a URL path          |
 | [rife.render.QrCode](https://github.com/rife2/rife2-template-renderers/wiki/rife.render.QrCode)                     | Generates an SVG QR Code from a template value                   |
 | [rife.render.ShortenUrl](https://github.com/rife2/rife2-template-renderers/wiki/rife.render.ShortenUrl)             | Shortens a template value URL                                    |

lib/src/main/java/rife/render/Mask.java

@@ -0,0 +1,63 @@
+/*
+ *  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.render;
+
+import rife.template.Template;
+import rife.template.ValueRenderer;
+
+import java.io.IOException;
+import java.io.StringReader;
+import java.util.Properties;
+
+/**
+ * <p>Masks characters of a template value.
+ *
+ * <p>Usage:</p>
+ *
+ * <pre>
+ *   &lt;!--v render:rife.render.Mask:valueId/--&gt;
+ *   {{v render:rife.render.Mask:valueId/}}
+ * </pre>
+ *
+ * @author <a href="https://erik.thauvin.net/">Erik C. Thauvin</a>
+ * @see <a href="https://github.com/rife2/rife2-template-renderers/wiki/rife.render.Mask">rife.render.Mask</a>
+ * @since 1.0
+ */
+public class Mask implements ValueRenderer {
+    /**
+     * {@inheritDoc}
+     */
+    @Override
+    public String render(Template template, String valueId, String differentiator) {
+        var mask = "*";
+        var unmasked = 0;
+        var fromStart = false;
+        if (template.hasDefaultValue(valueId)) {
+            var properties = new Properties();
+            try {
+                properties.load(new StringReader(template.getDefaultValue(valueId)));
+                mask = properties.getProperty("mask", mask);
+                unmasked = Integer.parseInt(properties.getProperty("unmasked", "0"));
+                fromStart = "true".equalsIgnoreCase(properties.getProperty("fromStart", "false"));
+            } catch (IOException | NumberFormatException ignore) {
+                // do nothing
+            }
+        }
+        return RenderUtils.mask(template.getValueOrAttribute(differentiator), mask, unmasked, fromStart);
+    }
+}

lib/src/main/java/rife/render/Normalize.java

@@ -21,7 +21,7 @@ import rife.template.Template;
 import rife.template.ValueRenderer;
 
 /**
- * <p>Normalizes a template value for inclusion in URL path.</p>
+ * <p>Normalizes a template value for inclusion in a URL path.</p>
  *
  * <p>Usage:</p>
  *

lib/src/main/java/rife/render/RenderUtils.java

@@ -84,7 +84,6 @@ public final class RenderUtils {
     /**
      * Returns the last 4 digits a credit card number. The number must satisfy the Luhn algorithm.
      * Non-digits are stripped from the number.
-     * Th
      *
      * @param src the credit card number
      * @return the last 4 digits of the credit card number or empty
@@ -124,6 +123,32 @@ public final class RenderUtils {
         return "";
     }
 
+    /**
+     * Masks characters in a String.
+     *
+     * @param src       the source String.
+     * @param mask      the String to mask characters with
+     * @param unmasked  the number of characters to leave unmasked
+     * @param fromStart to unmask characters from the start of the String
+     * @return the masked String
+     */
+    public static String mask(String src, String mask, int unmasked, boolean fromStart) {
+        var len = src.length();
+        var buff = new StringBuilder(len);
+        if (unmasked > 0 && unmasked < len) {
+            if (fromStart) {
+                buff.append(src, 0, unmasked);
+            }
+            buff.append(mask.repeat(len - unmasked));
+            if (!fromStart) {
+                buff.append(src.substring(len - unmasked));
+            }
+        } else {
+            buff.append(mask.repeat(len));
+        }
+        return buff.toString();
+    }
+
     /**
      * Normalizes a String for inclusion in a URL path.
      *

lib/src/test/java/rife/render/TestFormat.java

@@ -36,6 +36,24 @@ class TestFormat {
         assertThat(t.getContent()).isEmpty();
     }
 
+    @Test
+    void testMask() {
+        var t = TemplateFactory.HTML.get("mask");
+        var foo = "374380141731053";
+        t.setAttribute(TestCase.FOO, foo);
+        assertThat(t.getContent()).as("mask.html").isEqualTo("3743•••••••••••");
+
+        t = TemplateFactory.TXT.get("mask");
+        t.setAttribute(TestCase.FOO, foo);
+        assertThat(t.getContent()).as("mask.txt").isEqualTo("***************");
+
+        assertThat(RenderUtils.mask(foo, "?", 4, false)).as("mask=?")
+                .isEqualTo("???????????1053");
+
+        assertThat(RenderUtils.mask(foo, "-", 22, false)).as("unmasked=22")
+                .isEqualTo("---------------");
+    }
+
     @Test
     void testNormalize() {
         var t = TemplateFactory.HTML.get("normalize");

lib/src/test/resources/templates/mask.html

@@ -0,0 +1,5 @@
+<!--v render:rife.render.Mask:foo-->
+mask=•
+unmasked=4
+fromStart=true
+        <!--/v-->

lib/src/test/resources/templates/mask.txt

@@ -0,0 +1 @@
+{{v render:rife.render.Mask:foo/}}