feat: add annotations expression object for thymeleaf

src/main/java/run/halo/app/theme/dialect/HaloExpressionObjectFactory.java

@@ -0,0 +1,40 @@
+package run.halo.app.theme.dialect;
+
+import java.util.Set;
+import org.thymeleaf.context.IExpressionContext;
+import org.thymeleaf.expression.IExpressionObjectFactory;
+import run.halo.app.theme.dialect.expression.Annotations;
+
+/**
+ * Builds the expression objects to be used by Halo dialects.
+ *
+ * @author guqing
+ * @since 2.0.0
+ */
+public class HaloExpressionObjectFactory implements IExpressionObjectFactory {
+
+    public static final String ANNOTATIONS_EXPRESSION_OBJECT_NAME = "annotations";
+
+    protected static final Set<String> ALL_EXPRESSION_OBJECT_NAMES = Set.of(
+        ANNOTATIONS_EXPRESSION_OBJECT_NAME);
+
+    private static final Annotations ANNOTATIONS = new Annotations();
+
+    @Override
+    public Set<String> getAllExpressionObjectNames() {
+        return ALL_EXPRESSION_OBJECT_NAMES;
+    }
+
+    @Override
+    public Object buildObject(IExpressionContext context, String expressionObjectName) {
+        if (ANNOTATIONS_EXPRESSION_OBJECT_NAME.equals(expressionObjectName)) {
+            return ANNOTATIONS;
+        }
+        return null;
+    }
+
+    @Override
+    public boolean isCacheable(String expressionObjectName) {
+        return true;
+    }
+}

src/main/java/run/halo/app/theme/dialect/HaloProcessorDialect.java

@@ -3,6 +3,8 @@
 import java.util.HashSet;
 import java.util.Set;
 import org.thymeleaf.dialect.AbstractProcessorDialect;
+import org.thymeleaf.dialect.IExpressionObjectDialect;
+import org.thymeleaf.expression.IExpressionObjectFactory;
 import org.thymeleaf.processor.IProcessor;
 import org.thymeleaf.standard.StandardDialect;
 
@@ -12,9 +14,13 @@
  * @author guqing
  * @since 2.0.0
  */
-public class HaloProcessorDialect extends AbstractProcessorDialect {
+public class HaloProcessorDialect extends AbstractProcessorDialect implements
+    IExpressionObjectDialect {
     private static final String DIALECT_NAME = "haloThemeProcessorDialect";
 
+    private static final IExpressionObjectFactory HALO_EXPRESSION_OBJECTS_FACTORY =
+        new HaloExpressionObjectFactory();
+
     public HaloProcessorDialect() {
         // We will set this dialect the same "dialect processor" precedence as
         // the Standard Dialect, so that processor executions can interleave.
@@ -31,4 +37,9 @@ public Set<IProcessor> getProcessors(String dialectPrefix) {
         processors.add(new CommentElementTagProcessor(dialectPrefix));
         return processors;
     }
+
+    @Override
+    public IExpressionObjectFactory getExpressionObjectFactory() {
+        return HALO_EXPRESSION_OBJECTS_FACTORY;
+    }
 }

src/main/java/run/halo/app/theme/dialect/expression/Annotations.java

@@ -0,0 +1,65 @@
+package run.halo.app.theme.dialect.expression;
+
+import java.util.Map;
+import org.springframework.lang.NonNull;
+import org.springframework.lang.Nullable;
+import run.halo.app.theme.finders.vo.ExtensionVoOperator;
+
+/**
+ * <p>Expression Object for performing annotations operations inside Halo Extra Expressions.</p>
+ * An object of this class is usually available in variable evaluation expressions with the name
+ * <code>#annotations</code>.
+ *
+ * @author guqing
+ * @since 2.0.2
+ */
+public class Annotations {
+
+    /**
+     * Get annotation value from extension vo.
+     *
+     * @param extension extension vo
+     * @param key the key of annotation
+     * @return annotation value if exists, otherwise null
+     */
+    @Nullable
+    public String get(ExtensionVoOperator extension, String key) {
+        Map<String, String> annotations = extension.getMetadata().getAnnotations();
+        if (annotations == null) {
+            return null;
+        }
+        return annotations.get(key);
+    }
+
+    /**
+     * Returns the value to which the specified key is mapped, or defaultValue if
+     * <code>extension</code> contains no mapping for the key.
+     *
+     * @param extension extension vo
+     * @param key the key of annotation
+     * @return annotation value if exists, otherwise defaultValue
+     */
+    @NonNull
+    public String getOrDefault(ExtensionVoOperator extension, String key, String defaultValue) {
+        Map<String, String> annotations = extension.getMetadata().getAnnotations();
+        if (annotations == null) {
+            return defaultValue;
+        }
+        return annotations.getOrDefault(key, defaultValue);
+    }
+
+    /**
+     * Check if the extension has the specified annotation.
+     *
+     * @param extension extension vo
+     * @param key the key of annotation
+     * @return true if the extension has the specified annotation, otherwise false
+     */
+    public boolean contains(ExtensionVoOperator extension, String key) {
+        Map<String, String> annotations = extension.getMetadata().getAnnotations();
+        if (annotations == null) {
+            return false;
+        }
+        return annotations.containsKey(key);
+    }
+}

src/main/java/run/halo/app/theme/finders/vo/CategoryTreeVo.java

@@ -20,7 +20,7 @@
 @Builder
 @ToString
 @EqualsAndHashCode
-public class CategoryTreeVo implements VisualizableTreeNode<CategoryTreeVo> {
+public class CategoryTreeVo implements VisualizableTreeNode<CategoryTreeVo>, ExtensionVoOperator {
 
     private MetadataOperator metadata;
 

src/main/java/run/halo/app/theme/finders/vo/CategoryVo.java

@@ -15,7 +15,7 @@
 @Value
 @Builder
 @EqualsAndHashCode
-public class CategoryVo {
+public class CategoryVo implements ExtensionVoOperator {
 
     MetadataOperator metadata;
 

src/main/java/run/halo/app/theme/finders/vo/CommentVo.java

@@ -18,7 +18,7 @@
 @Value
 @Builder
 @EqualsAndHashCode
-public class CommentVo {
+public class CommentVo implements ExtensionVoOperator {
 
     @Schema(required = true)
     MetadataOperator metadata;

src/main/java/run/halo/app/theme/finders/vo/ExtensionVoOperator.java

@@ -0,0 +1,16 @@
+package run.halo.app.theme.finders.vo;
+
+import org.springframework.lang.NonNull;
+import run.halo.app.extension.MetadataOperator;
+
+/**
+ * An operator for extension value object.
+ *
+ * @author guqing
+ * @since 2.0.0
+ */
+public interface ExtensionVoOperator {
+
+    @NonNull
+    MetadataOperator getMetadata();
+}

src/main/java/run/halo/app/theme/finders/vo/ListedPostVo.java

@@ -19,7 +19,7 @@
 @SuperBuilder
 @ToString
 @EqualsAndHashCode
-public class ListedPostVo {
+public class ListedPostVo implements ExtensionVoOperator {
 
     private MetadataOperator metadata;
 

src/main/java/run/halo/app/theme/finders/vo/ListedSinglePageVo.java

@@ -19,7 +19,7 @@
 @SuperBuilder
 @ToString
 @EqualsAndHashCode
-public class ListedSinglePageVo {
+public class ListedSinglePageVo implements ExtensionVoOperator {
 
     private MetadataOperator metadata;
 

src/main/java/run/halo/app/theme/finders/vo/MenuItemVo.java

@@ -17,7 +17,7 @@
 @Data
 @ToString
 @Builder
-public class MenuItemVo implements VisualizableTreeNode<MenuItemVo> {
+public class MenuItemVo implements VisualizableTreeNode<MenuItemVo>, ExtensionVoOperator {
 
     MetadataOperator metadata;
 

src/main/java/run/halo/app/theme/finders/vo/MenuVo.java

@@ -18,7 +18,7 @@
 @Value
 @ToString
 @Builder
-public class MenuVo {
+public class MenuVo implements ExtensionVoOperator {
 
     MetadataOperator metadata;
 

src/main/java/run/halo/app/theme/finders/vo/ReplyVo.java

@@ -20,7 +20,7 @@
 @Builder
 @ToString
 @EqualsAndHashCode
-public class ReplyVo {
+public class ReplyVo implements ExtensionVoOperator {
 
     @Schema(required = true)
     MetadataOperator metadata;

src/main/java/run/halo/app/theme/finders/vo/TagVo.java

@@ -10,7 +10,7 @@
  */
 @Value
 @Builder
-public class TagVo {
+public class TagVo implements ExtensionVoOperator {
 
     MetadataOperator metadata;
 

src/main/java/run/halo/app/theme/finders/vo/ThemeVo.java

@@ -17,7 +17,7 @@
 @Value
 @Builder
 @ToString
-public class ThemeVo {
+public class ThemeVo implements ExtensionVoOperator {
 
     MetadataOperator metadata;
 

src/main/java/run/halo/app/theme/finders/vo/UserVo.java

@@ -10,7 +10,7 @@
 
 @Value
 @Builder
-public class UserVo {
+public class UserVo implements ExtensionVoOperator {
     MetadataOperator metadata;
 
     User.UserSpec spec;