Create a new field for internal, unresolved storage

handlebars/src/main/java/com/github/jknack/handlebars/Context.java

@@ -75,6 +75,7 @@ protected BlockParam(final Context parent, final Map<String, Object> hash) {
       this.extendedContext.resolver = parent.resolver;
       this.parent = parent;
       this.data = parent.data;
+      this.internalData = parent.internalData;
       this.resolver = parent.resolver;
     }
 
@@ -152,6 +153,7 @@ protected PartialCtx(final Context parent, final Object model, final Map<String,
       this.extendedContext.extendedContext = new Context(Collections.emptyMap());
       this.parent = parent;
       this.data = parent.data;
+      this.internalData = parent.internalData;
       this.resolver = parent.resolver;
     }
 
@@ -432,6 +434,11 @@ public Object eval(final ValueResolver resolver, final Context context, final Ob
    */
   protected Map<String, Object> data;
 
+  /**
+   * Functions similarly to data, but not resolved during rendering.
+   */
+  protected Map<String, Object> internalData;
+
   /**
    * Additional, data can be stored here.
    */
@@ -470,6 +477,7 @@ private static Context root(final Object model) {
     root.data.put(INLINE_PARTIALS, partials);
     root.data.put(INVOCATION_STACK, new LinkedList<TemplateSource>());
     root.data.put("root", model);
+    root.internalData = new HashMap<>();
     return root;
   }
 
@@ -535,6 +543,41 @@ public Context data(final Map<String, ?> attributes) {
     return this;
   }
 
+  /**
+   * Read the attribute from the internal data storage.
+   *
+   * @param name The attribute's name.
+   * @param <T> Data type.
+   * @return The attribute value or null.
+   */
+  @SuppressWarnings("unchecked")
+  public <T> T internalData(final String name) {
+    return (T) internalData.get(name);
+  }
+
+  /**
+   * Set an attribute in the internal data storage.
+   *
+   * @param name The attribute's name. Required.
+   * @param value The attribute's value. Required.
+   * @return This context.
+   */
+  public Context internalData(final String name, final Object value) {
+    internalData.put(name, value);
+    return this;
+  }
+
+  /**
+   * Store the map in the internal data storage.
+   *
+   * @param attributes The attributes to add. Required.
+   * @return This context.
+   */
+  public Context internalData(final Map<String, ?> attributes) {
+    internalData.putAll(attributes);
+    return this;
+  }
+
   /**
    * Resolved as '.' or 'this' inside templates.
    *
@@ -692,6 +735,9 @@ public void destroy() {
       if (data != null) {
         data.clear();
       }
+      if (internalData != null) {
+        internalData.clear();
+      }
     }
     if (extendedContext != null) {
       extendedContext.destroy();
@@ -790,6 +836,7 @@ private Context newChild(final Object model) {
     child.setResolver(this.resolver);
     child.parent = this;
     child.data = this.data;
+    child.internalData = this.internalData;
     return child;
   }
 
@@ -813,6 +860,7 @@ protected Context newChildContext(final Object model) {
   public static Context copy(final Context context, final Object model) {
     Context ctx = Context.newContext(model);
     ctx.data = context.data;
+    ctx.internalData = context.internalData;
     ctx.resolver = context.resolver;
     return ctx;
   }

handlebars/src/test/java/com/github/jknack/handlebars/InternalDataTest.java

@@ -0,0 +1,61 @@
+package com.github.jknack.handlebars;
+
+import com.github.jknack.handlebars.context.FieldValueResolver;
+import com.github.jknack.handlebars.context.JavaBeanValueResolver;
+import com.github.jknack.handlebars.context.MapValueResolver;
+import com.github.jknack.handlebars.context.MethodValueResolver;
+import java.io.IOException;
+
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNull;
+
+public class InternalDataTest extends AbstractTest {
+
+  @Override
+  protected Handlebars newHandlebars() {
+    Handlebars handlebars = new Handlebars();
+    handlebars.registerHelper("printFooAndBar", (context, options) ->
+            String.format("%s %s", options.context.data("foo"), options.context.internalData("bar")));
+    return handlebars;
+  }
+
+  @Override
+  protected Object configureContext(final Object model) {
+    return Context.newBuilder(model)
+        .resolver(
+                MapValueResolver.INSTANCE,
+                JavaBeanValueResolver.INSTANCE,
+                FieldValueResolver.INSTANCE,
+                MethodValueResolver.INSTANCE)
+        .build()
+        .data("foo", "foo")
+        .internalData("bar", "bar");
+  }
+
+  @Test
+  public void dataAvailableForRendering() throws IOException {
+    shouldCompileTo("{{foo}}", "", "foo");
+    assertEquals("foo", ((Context)configureContext("")).get("foo"));
+  }
+
+  @Test
+  public void internalDataNotAvailableForRendering() throws IOException {
+    shouldCompileTo("{{bar}}", "", "");
+    shouldCompileTo("{{./bar}}", "", "");
+    shouldCompileTo("{{../bar}}", "", "");
+    shouldCompileTo("{{.././bar}}", "", "");
+    shouldCompileTo("{{this.bar}}", "", "");
+    shouldCompileTo("{{internalData}}", "", "");
+    shouldCompileTo("{{internalData.bar}}", "", "");
+    shouldCompileTo("{{this.internalData}}", "", "");
+    shouldCompileTo("{{this.internalData.bar}}", "", "");
+    assertNull(((Context)configureContext("")).get("bar"));
+  }
+
+  @Test
+  public void helperAbleToAccessInternalData() throws IOException {
+    shouldCompileTo("{{printFooAndBar}}", "", "foo bar");
+  }
+}