v4: Decorators fixes #442

Author: jknack

handlebars-springmvc/src/main/java/com/github/jknack/handlebars/springmvc/HandlebarsViewResolver.java

@@ -41,6 +41,7 @@
 import org.springframework.web.servlet.view.AbstractTemplateViewResolver;
 import org.springframework.web.servlet.view.AbstractUrlBasedView;
 
+import com.github.jknack.handlebars.Decorator;
 import com.github.jknack.handlebars.Formatter;
 import com.github.jknack.handlebars.Handlebars;
 import com.github.jknack.handlebars.Helper;
@@ -558,4 +559,14 @@ public void setTemplateCache(final TemplateCache templateCache) {
     this.templateCache = templateCache;
   }
 
+  @Override
+  public Decorator decorator(final String name) {
+    return this.registry.decorator(name);
+  }
+
+  @Override
+  public HandlebarsViewResolver registerDecorator(final String name, final Decorator decorator) {
+    registry.registerDecorator(name, decorator);
+    return this;
+  }
 }

handlebars/src/main/antlr4/com/github/jknack/handlebars/internal/HbsLexer.g4

@@ -170,10 +170,6 @@ UNLESS
  : {startToken(start, "^")}? . -> pushMode(VAR)
  ;
 
-START_DECORATOR
- : {startToken(start, "#*")}? . -> pushMode(VAR)
- ;
-
 START_PARTIAL_BLOCK
  : {startToken(start, "#>")}? . -> pushMode(VAR)
  ;
@@ -231,9 +227,20 @@ END
  : {endToken(end)}? . -> mode(DEFAULT_MODE)
  ;
 
-AS: 'as';
+DECORATOR
+  :
+    '*'
+  ;
 
-PIPE: '|';
+AS
+  :
+    'as'
+  ;
+
+PIPE
+  :
+    '|'
+  ;
 
 DOUBLE_STRING
  :

handlebars/src/main/antlr4/com/github/jknack/handlebars/internal/HbsParser.g4

@@ -80,7 +80,7 @@ newline
 
 block
   :
-    startToken = (START_BLOCK|START_DECORATOR) sexpr blockParams? END
+    startToken = START_BLOCK DECORATOR? sexpr blockParams? END
     thenBody=body
     elseBlock*
     END_BLOCK nameEnd=QID END
@@ -131,7 +131,7 @@ ampvar
 
 var
   :
-   START sexpr END
+   START DECORATOR? sexpr END
   ;
 
 delimiters

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

@@ -384,7 +384,9 @@ private static Context root(final Object model) {
     root.extendedContext = new Context(new HashMap<String, Object>());
     root.data = new HashMap<String, Object>();
     root.data.put(PARTIALS, new HashMap<String, Template>());
-    root.data.put(INLINE_PARTIALS, new HashMap<String, Template>());
+    LinkedList<Map<String, Template>> partials = new LinkedList<>();
+    partials.push(new HashMap<String, Template>());
+    root.data.put(INLINE_PARTIALS, partials);
     root.data.put(INVOCATION_STACK, new LinkedList<TemplateSource>());
     root.data.put("root", model);
     return root;
@@ -802,4 +804,18 @@ protected Context newChildContext(final Object model) {
     return new Context(model);
   }
 
+  /**
+   * Creates a new context but keep the <code>data</code> attribute.
+   *
+   * @param context Context to extract the <code>data</code> attribute.
+   * @param model A model/data.
+   * @return A new context.
+   */
+  public static Context copy(final Context context, final Object model) {
+    Context ctx = Context.newContext(model);
+    ctx.data = context.data;
+    ctx.resolver = context.resolver;
+    return ctx;
+  }
+
 }

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

@@ -0,0 +1,23 @@
+package com.github.jknack.handlebars;
+
+import java.io.IOException;
+
+/**
+ * A decorator allows a declarative means to both annotate particular blocks with metadata as
+ * well as to wrap in behaviors when desired, prior to execution.
+ *
+ * @author edgar
+ * @since 4.0.0
+ */
+public interface Decorator {
+
+  /**
+   * Decorate a template with metadata.
+   *
+   * @param fn Decorated template.
+   * @param options Options object.
+   * @throws IOException If something goes wrong.
+   */
+  void apply(Template fn, Options options) throws IOException;
+
+}

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

@@ -1192,4 +1192,15 @@ public static void error(final String message) {
     logger.error(message);
   }
 
+  @Override
+  public Decorator decorator(final String name) {
+    return registry.decorator(name);
+  }
+
+  @Override
+  public Handlebars registerDecorator(final String name, final Decorator decorator) {
+    registry.registerDecorator(name, decorator);
+    return this;
+  }
+
 }

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

@@ -136,7 +136,9 @@ public interface HelperRegistry {
    * </ul>
    *
    * Only static methods will be registered as helpers.
-   * <p>Enums are supported too</p>
+   * <p>
+   * Enums are supported too
+   * </p>
    *
    * @param helperSource The helper source. Enums are supported. Required.
    * @return This handlebars object.
@@ -297,9 +299,28 @@ HelperRegistry registerHelpers(String filename, InputStream source)
    *
    * @param filename The file name (just for debugging purpose). Required.
    * @param source The JavaScript source. Required.
-   * @return This handlebars object.
+   * @return This registry.
    * @throws Exception If the JavaScript helpers can't be registered.
    */
   HelperRegistry registerHelpers(String filename, String source) throws Exception;
 
+  /**
+   * Find a decorator by name.
+   *
+   * @param name A decorator's name.
+   * @return A decorator or <code>null</code>.
+   * @since 4.0.0
+   */
+  Decorator decorator(String name);
+
+  /**
+   * Register a decorator and make it accessible via {@link #decorator(String)}.
+   *
+   * @param name A decorator's name. Required.
+   * @param decorator A decorator. Required.
+   * @return This registry.
+   * @since 4.0.0
+   */
+  HelperRegistry registerDecorator(String name, Decorator decorator);
+
 }

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

@@ -31,6 +31,11 @@ public enum TagType {
    */
   VAR,
 
+  /**
+   * A var decorator tag, like: <code>{{*name}}</code>.
+   */
+  STAR_VAR,
+
   /**
    * All variables are HTML escaped by default. If you want to return unescaped HTML, use the
    * triple mustache: <code>{{{@literal &}name}}</code>.
@@ -65,6 +70,16 @@ public enum TagType {
     public boolean inline() {
       return false;
     }
+  },
+
+  /**
+   * Like {{#* decorator}}success{{/decorator}}.
+   */
+  START_SECTION {
+    @Override
+    public boolean inline() {
+      return false;
+    }
   };
 
   /**

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

@@ -59,6 +59,14 @@ public void apply(final Object context, final Writer writer)
         throws IOException {
     }
 
+    @Override
+    public void before(final Context context, final Writer writer) throws IOException {
+    }
+
+    @Override
+    public void after(final Context context, final Writer writer) throws IOException {
+    }
+
     @Override
     public String toJavaScript() {
       return "";
@@ -71,7 +79,7 @@ public String filename() {
 
     @Override
     public int[] position() {
-      return new int[] {0, 0};
+      return new int[]{0, 0 };
     }
 
     @SuppressWarnings({"rawtypes", "unchecked" })
@@ -135,6 +143,24 @@ public List<String> collectReferenceParameters() {
    */
   void apply(Context context, Writer writer) throws IOException;
 
+  /**
+   * Notify that template is going to be processed.
+   *
+   * @param context The context object. Required.
+   * @param writer The writer object. Required.
+   * @throws IOException If a resource cannot be loaded.
+   */
+  void before(Context context, Writer writer) throws IOException;
+
+  /**
+   * Notify that template has been processed.
+   *
+   * @param context The context object. Required.
+   * @param writer The writer object. Required.
+   * @throws IOException If a resource cannot be loaded.
+   */
+  void after(Context context, Writer writer) throws IOException;
+
   /**
    * Merge the template tree using the given context.
    *

handlebars/src/main/java/com/github/jknack/handlebars/helper/DefaultHelperRegistry.java

@@ -47,6 +47,7 @@
 import java.util.Map.Entry;
 import java.util.Set;
 
+import com.github.jknack.handlebars.Decorator;
 import com.github.jknack.handlebars.Handlebars;
 import com.github.jknack.handlebars.Helper;
 import com.github.jknack.handlebars.HelperRegistry;
@@ -64,8 +65,10 @@ public class DefaultHelperRegistry implements HelperRegistry {
   /**
    * The helper registry.
    */
-  private final Map<String, Helper<?>> helpers =
-      new HashMap<String, Helper<?>>();
+  private final Map<String, Helper<?>> helpers = new HashMap<String, Helper<?>>();
+
+  /** Decorators. */
+  private final Map<String, Decorator> decorators = new HashMap<>();
 
   /**
    * A Handlebars.js implementation.
@@ -222,7 +225,27 @@ private static void registerBuiltinsHelpers(final HelperRegistry registry) {
     registry.registerHelper("i18n", I18nHelper.i18n);
     registry.registerHelper("i18nJs", I18nHelper.i18nJs);
     registry.registerHelper(LookupHelper.NAME, LookupHelper.INSTANCE);
-    registry.registerHelper("inline", InlineHelper.INSTANCE);
+
+    // decorator
+    registry.registerDecorator("inline", InlineDecorator.INSTANCE);
+  }
+
+  @Override
+  public Decorator decorator(final String name) {
+    notEmpty(name, "A decorator's name is required.");
+    return decorators.get(name);
+  }
+
+  @Override
+  public HelperRegistry registerDecorator(final String name, final Decorator decorator) {
+    notEmpty(name, "A decorator's name is required.");
+    notNull(decorator, "A decorator is required.");
+
+    Decorator old = decorators.put(name, decorator);
+    if (old != null) {
+      Handlebars.warn("Decorator '%s' has been replaced by '%s'", name, decorator);
+    }
+    return this;
   }
 
 }

handlebars/src/main/java/com/github/jknack/handlebars/helper/InlineDecorator.java

@@ -1,15 +1,16 @@
 package com.github.jknack.handlebars.helper;
 
 import java.io.IOException;
+import java.util.Deque;
 import java.util.Map;
 
 import com.github.jknack.handlebars.Context;
-import com.github.jknack.handlebars.Helper;
+import com.github.jknack.handlebars.Decorator;
 import com.github.jknack.handlebars.Options;
+import com.github.jknack.handlebars.Template;
 
 /**
- * Inline partials are implemented via helpers (not decorators like in handlebars.js). Decorators
- * are not supported in handlebars.java.
+ * Inline partials via {@link Decorator} API.
  *
  * <pre>
  * {{#*inline \"myPartial\"}}success{{/inline}}{{> myPartial}}
@@ -18,18 +19,17 @@
  * @author edgar
  * @since 4.0.0
  */
-public class InlineHelper implements Helper<String> {
+public class InlineDecorator implements Decorator {
 
   /**
    * A singleton instance of this helper.
    */
-  public static final Helper<String> INSTANCE = new InlineHelper();
+  public static final Decorator INSTANCE = new InlineDecorator();
 
   @Override
-  public CharSequence apply(final String path, final Options options) throws IOException {
-    Map<String, Object> partials = options.data(Context.INLINE_PARTIALS);
-    partials.put(path, options.fn);
-    return null;
+  public void apply(final Template fn, final Options options) throws IOException {
+    Deque<Map<String, Template>> partials = options.data(Context.INLINE_PARTIALS);
+    partials.getLast().put((String) options.param(0), options.fn);
   }
 
 }

handlebars/src/main/java/com/github/jknack/handlebars/internal/BaseTemplate.java

@@ -121,6 +121,7 @@ public String apply(final Context context) throws IOException {
   public void apply(final Context context, final Writer writer)
       throws IOException {
     try {
+      before(context, writer);
       merge(context, writer);
     } catch (HandlebarsException ex) {
       throw ex;
@@ -136,6 +137,8 @@ public void apply(final Context context, final Writer writer)
       // Override the stack-trace
       hex.setStackTrace(ex.getStackTrace());
       throw hex;
+    } finally {
+      after(context, writer);
     }
   }
 
@@ -152,6 +155,14 @@ private static Context wrap(final Object candidate) {
     return Context.newContext(candidate);
   }
 
+  @Override
+  public void before(final Context context, final Writer writer) throws IOException {
+  }
+
+  @Override
+  public void after(final Context context, final Writer writer) throws IOException {
+  }
+
   /**
    * Merge a child template into the writer.
    *