Extend Metadata interface

legend-pure-runtime/legend-pure-runtime-java-engine-compiled/src/main/java/org/finos/legend/pure/runtime/java/compiled/execution/CompiledProcessorSupport.java

@@ -60,7 +60,6 @@
 import org.finos.legend.pure.runtime.java.compiled.metadata.Metadata;
 import org.finos.legend.pure.runtime.java.compiled.metadata.MetadataAccessor;
 import org.finos.legend.pure.runtime.java.compiled.metadata.MetadataHolder;
-import org.finos.legend.pure.runtime.java.compiled.metadata.MetadataPelt;
 
 import java.lang.reflect.Method;
 
@@ -287,9 +286,9 @@ public CoreInstance newGenericType(SourceInformation sourceInformation, CoreInst
     @Override
     public CoreInstance package_getByUserPath(String path)
     {
-        if (this.metadata instanceof MetadataPelt)
+        if (this.metadata.supportsElementByPath())
         {
-            return ((MetadataPelt) this.metadata).getElementByPath(path);
+            return this.metadata.getElementByPath(path);
         }
 
         // Check top level elements
@@ -370,9 +369,9 @@ public CoreInstance package_getByUserPath(String path)
     @Override
     public CoreInstance repository_getTopLevel(String name)
     {
-        if ((this.metadata instanceof MetadataPelt) && GraphTools.isTopLevelName(name))
+        if (this.metadata.supportsElementByPath() && GraphTools.isTopLevelName(name))
         {
-            return ((MetadataPelt) this.metadata).getElementByPath(name);
+            return this.metadata.getElementByPath(name);
         }
 
         if (M3Paths.Root.equals(name))
@@ -505,8 +504,8 @@ public CoreInstance getClassifier(CoreInstance instance)
     {
         if (instance instanceof ValCoreInstance)
         {
-            return (this.metadata instanceof MetadataPelt) ?
-                   ((MetadataPelt) this.metadata).getElementByPath(((ValCoreInstance) instance).getType()) :
+            return this.metadata.supportsElementByPath() ?
+                   this.metadata.getElementByPath(((ValCoreInstance) instance).getType()) :
                    this.metadataAccessor.getPrimitiveType(((ValCoreInstance) instance).getType());
         }
 
@@ -549,21 +548,17 @@ public boolean type_subTypeOf(CoreInstance type, CoreInstance possibleSuperType)
     @Override
     public CoreInstance type_BottomType()
     {
-        if (this.metadata instanceof MetadataPelt)
-        {
-            return ((MetadataPelt) this.metadata).getElementByPath(M3Paths.Nil);
-        }
-        return this.metadataAccessor.getBottomType();
+        return this.metadata.supportsElementByPath() ?
+               this.metadata.getElementByPath(M3Paths.Nil) :
+               this.metadataAccessor.getBottomType();
     }
 
     @Override
     public CoreInstance type_TopType()
     {
-        if (this.metadata instanceof MetadataPelt)
-        {
-            return ((MetadataPelt) this.metadata).getElementByPath(M3Paths.Any);
-        }
-        return this.metadataAccessor.getTopType();
+        return this.metadata.supportsElementByPath() ?
+               this.metadata.getElementByPath(M3Paths.Any) :
+               this.metadataAccessor.getTopType();
     }
 
     public Metadata getMetadata()

legend-pure-runtime/legend-pure-runtime-java-engine-compiled/src/main/java/org/finos/legend/pure/runtime/java/compiled/metadata/Metadata.java

@@ -36,4 +36,59 @@ default RichIterable<CoreInstance> getClassifierInstances(String classifier)
     }
 
     CoreInstance getEnum(String enumerationName, String enumName);
+
+    /**
+     * <p>Return whether the metadata supports accessing an element by its package path.</p>
+     *
+     * <p>If true, then {@link #hasElement} and {@link #getElementByPath} can be used to access elements by their
+     * package path. Otherwise, those methods will throw {@link UnsupportedOperationException}.</p>
+     * 
+     * @return whether element by path is supported
+     * @see #hasElement
+     * @see #getElementByPath
+     */
+    default boolean supportsElementByPath()
+    {
+        return false;
+    }
+
+    /**
+     * <p>Return whether the metadata has an element with the given package path.</p>
+     *
+     * <p>For a given path, {@link #getElementByPath} will return the element if and only if this method returns true.
+     * Otherwise, it will return null.</p>
+     *
+     * <p>Use {@link #supportsElementByPath} to check if the method is supported on this metadata instance. If not,
+     * an {@link UnsupportedOperationException} will be thrown.</p>
+     *
+     * @param path package path
+     * @return whether there is an element with the given path
+     * @throws UnsupportedOperationException if element by path access is not supported
+     * @see #supportsElementByPath
+     * @see #getElementByPath
+     */
+    default boolean hasElement(String path)
+    {
+        return getElementByPath(path) != null;
+    }
+
+    /**
+     * <p>Get an element by its package path. Returns null if there is no such element</p>
+     *
+     * <p>This method will return the element if and only if {@link #hasElement} returns true. Otherwise, it will return
+     * null.</p>
+     *
+     * <p>Use {@link #supportsElementByPath} to check if the method is supported on this metadata instance. If not,
+     * an {@link UnsupportedOperationException} will be thrown.</p>
+     *
+     * @param path package path of the element
+     * @return element with the given path, or null if there is no such element
+     * @throws UnsupportedOperationException if element by path access is not supported
+     * @see #supportsElementByPath
+     * @see #hasElement
+     */
+    default CoreInstance getElementByPath(String path)
+    {
+        throw new UnsupportedOperationException(getClass().getName() + " does not support element by path");
+    }
 }

legend-pure-runtime/legend-pure-runtime-java-engine-compiled/src/main/java/org/finos/legend/pure/runtime/java/compiled/metadata/MetadataPelt.java

@@ -141,23 +141,19 @@ public CoreInstance getInstance(String id)
         return this.instanceCache.getIfAbsentPutWithKey(id, this.refIdResolver::resolveReference);
     }
 
-    /**
-     * Return whether the metadata has an element with the given package path.
-     *
-     * @param path package path
-     * @return whether there is an element with the given path
-     */
+    @Override
+    public boolean supportsElementByPath()
+    {
+        return true;
+    }
+
+    @Override
     public boolean hasElement(String path)
     {
         return this.elementLoader.elementExists(path);
     }
 
-    /**
-     * Get an element by its package path. Returns null if there is no such element.
-     *
-     * @param path package path of the element
-     * @return element with the given path, or null if there is no such element
-     */
+    @Override
     public CoreInstance getElementByPath(String path)
     {
         return this.elementLoader.loadElement(path);