feat(script-engine): add Python script engine

pom.xml

@@ -76,6 +76,7 @@
         <ver.log4j1>1.2.17</ver.log4j1>
         <ver.graalvm>23.1.1</ver.graalvm>
         <ver.graalvm-js>23.1.1</ver.graalvm-js>
+        <ver.graalvm-py>23.1.1</ver.graalvm-py>
     </properties>
 
     <dependencies>
@@ -92,6 +93,14 @@
             <type>pom</type>
         </dependency>
 
+        <dependency>
+            <groupId>org.graalvm.polyglot</groupId>
+            <artifactId>python</artifactId>
+            <version>${ver.graalvm-py}</version>
+            <scope>runtime</scope>
+            <type>pom</type>
+        </dependency>
+
         <dependency>
             <groupId>org.apache.jena</groupId>
             <artifactId>jena-arq</artifactId>

src/main/java/org/topbraid/shacl/py/GraalPyScriptEngine.java

@@ -0,0 +1,71 @@
+package org.topbraid.shacl.py;
+
+import org.apache.jena.query.QuerySolution;
+import org.apache.jena.rdf.model.Resource;
+import org.graalvm.polyglot.Context;
+
+import javax.script.ScriptException;
+
+/**
+ * @author Ashley Caselli
+ */
+public class GraalPyScriptEngine extends PyScriptEngineImpl {
+
+    private Context context;
+
+    public GraalPyScriptEngine() {
+        initEngine();
+        // TODO implement
+    }
+
+    @Override
+    public void initEngine() {
+        this.context = Context.newBuilder()
+                .option("engine.WarnInterpreterOnly", "false")
+                .build();
+        if (this.context == null) {
+            throw new RuntimeException("GraalVM not found in the current context");
+        }
+    }
+
+    @Override
+    public Object eval(String expr) throws ScriptException {
+        return context.eval("python", expr);
+    }
+
+    @Override
+    public void executeLibraries(Resource exec) throws Exception {
+        // TODO implement
+    }
+
+    @Override
+    public void executeScriptFromURL(String url) throws Exception {
+        // TODO implement
+    }
+
+    @Override
+    public Object get(String varName) {
+        return context.getBindings("python").getMember(varName);
+    }
+
+    @Override
+    public Object invokeFunction(String functionName, QuerySolution bindings) throws ScriptException, NoSuchMethodException {
+        return null;
+        // TODO implement
+    }
+
+    public final Context getContext() {
+        return context;
+    }
+
+    @Override
+    public Object invokeFunctionOrdered(String functionName, Object[] args) throws ScriptException, NoSuchMethodException {
+        return context.getBindings("python").getMember(functionName).execute(args);
+    }
+
+    @Override
+    public void put(String varName, Object value) {
+        context.getBindings("python").putMember(varName, value);
+    }
+
+}

src/main/java/org/topbraid/shacl/py/PyScriptEngine.java

@@ -0,0 +1,46 @@
+/*
+ *  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
+ *
+ *      http://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.
+ *
+ *  See the NOTICE file distributed with this work for additional
+ *  information regarding copyright ownership.
+ */
+package org.topbraid.shacl.py;
+
+import org.apache.jena.query.QuerySolution;
+import org.apache.jena.rdf.model.Resource;
+
+import javax.script.ScriptException;
+
+/**
+ * Abstraction layer between TopBraid and the Python API.
+ *
+ * @author Ashley Caselli
+ */
+public interface PyScriptEngine {
+
+    void initEngine();
+
+    Object eval(String expr) throws ScriptException;
+
+    void executeLibraries(Resource exec) throws Exception;
+
+    void executeScriptFromURL(String url) throws Exception;
+
+    Object get(String varName);
+
+    Object invokeFunction(String functionName, QuerySolution bindings) throws ScriptException, NoSuchMethodException;
+
+    Object invokeFunctionOrdered(String functionName, Object[] args) throws ScriptException, NoSuchMethodException;
+
+    void put(String varName, Object value);
+}

src/main/java/org/topbraid/shacl/py/PyScriptEngineFactory.java

@@ -0,0 +1,22 @@
+package org.topbraid.shacl.py;
+
+public class PyScriptEngineFactory {
+
+    private static PyScriptEngineFactory singleton = new PyScriptEngineFactory();
+
+    public static PyScriptEngineFactory get() {
+        return singleton;
+    }
+
+    public static void set(PyScriptEngineFactory value) {
+        PyScriptEngineFactory.singleton = value;
+    }
+
+    public PyScriptEngine createScriptEngine(final String engineName) {
+        if (engineName.equals("Graal")) {
+            return new GraalPyScriptEngine();
+        }
+        return null;
+    }
+
+}

src/main/java/org/topbraid/shacl/py/PyScriptEngineImpl.java

@@ -0,0 +1,39 @@
+package org.topbraid.shacl.py;
+
+import org.apache.jena.query.QuerySolution;
+import org.apache.jena.rdf.model.Resource;
+
+import javax.script.ScriptException;
+
+public abstract class PyScriptEngineImpl implements PyScriptEngine {
+    @Override
+    public abstract void initEngine();
+
+    @Override
+    public abstract Object eval(String expr) throws ScriptException;
+
+    @Override
+    public void executeLibraries(Resource exec) throws Exception {
+        // TODO implement
+    }
+
+    @Override
+    public void executeScriptFromURL(String url) throws Exception {
+        // TODO implement
+    }
+
+    @Override
+    public abstract Object get(String varName);
+
+    @Override
+    public Object invokeFunction(String functionName, QuerySolution bindings) throws ScriptException, NoSuchMethodException {
+        return null;
+        // TODO implement
+    }
+
+    @Override
+    public abstract Object invokeFunctionOrdered(String functionName, Object[] args) throws ScriptException, NoSuchMethodException;
+
+    @Override
+    public abstract void put(String varName, Object value);
+}

src/test/java/org/topbraid/shacl/TestGraalPyScriptEngine.java

@@ -0,0 +1,22 @@
+package org.topbraid.shacl;
+
+import org.graalvm.polyglot.Value;
+import org.junit.Test;
+import org.topbraid.shacl.py.PyScriptEngine;
+import org.topbraid.shacl.py.PyScriptEngineFactory;
+
+import javax.script.ScriptException;
+import java.util.Objects;
+
+public class TestGraalPyScriptEngine {
+
+    @Test
+    public void testEngine() throws ScriptException {
+        PyScriptEngine engine = PyScriptEngineFactory.get().createScriptEngine("Graal");
+        Value value = (Value) engine.eval("[1,2,42,4]");
+        int element = value.getArrayElement(2).asInt();
+        assert Objects.equals(element, 42);
+        // TODO add test with TermFactory
+    }
+
+}