Github user nickwallen commented on a diff in the pull request:
https://github.com/apache/metron/pull/884#discussion_r159499997
--- Diff:
metron-stellar/stellar-zeppelin/src/main/java/org/apache/metron/stellar/zeppelin/StellarInterpreter.java
---
@@ -0,0 +1,158 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you 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.
+ */
+
+package org.apache.metron.stellar.zeppelin;
+
+import org.apache.commons.lang3.exception.ExceptionUtils;
+import org.apache.metron.stellar.common.shell.DefaultStellarAutoCompleter;
+import org.apache.metron.stellar.common.shell.DefaultStellarShellExecutor;
+import org.apache.metron.stellar.common.shell.StellarAutoCompleter;
+import org.apache.metron.stellar.common.shell.StellarShellExecutor;
+import org.apache.metron.stellar.common.shell.StellarResult;
+import org.apache.metron.stellar.common.utils.ConversionUtils;
+import org.apache.zeppelin.interpreter.Interpreter;
+import org.apache.zeppelin.interpreter.InterpreterContext;
+import org.apache.zeppelin.interpreter.InterpreterResult;
+import org.apache.zeppelin.interpreter.thrift.InterpreterCompletion;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.lang.invoke.MethodHandles;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Optional;
+import java.util.Properties;
+
+import static org.apache.zeppelin.interpreter.InterpreterResult.Code.ERROR;
+import static
org.apache.zeppelin.interpreter.InterpreterResult.Code.SUCCESS;
+import static org.apache.zeppelin.interpreter.InterpreterResult.Type.TEXT;
+
+/**
+ * A Zeppelin Interpreter for Stellar.
+ */
+public class StellarInterpreter extends Interpreter {
+
+ private static final Logger LOG =
LoggerFactory.getLogger(MethodHandles.lookup().lookupClass());
+
+ /**
+ * Executes the Stellar expressions.
+ *
+ * Zeppelin will handle isolation and how the same executor is or is not
used across
+ * multiple notebooks. This is configurable by the user.
+ *
+ * See
https://zeppelin.apache.org/docs/latest/manual/interpreters.html#interpreter-binding-mode.
+ */
+ private StellarShellExecutor executor;
+
+ /**
+ * Handles auto-completion for Stellar expressions.
+ */
+ private StellarAutoCompleter autoCompleter;
+
+ public StellarInterpreter(Properties properties) {
+ super(properties);
+ this.autoCompleter = new DefaultStellarAutoCompleter();
+ }
+
+ public void open() {
+ try {
+ executor = createExecutor();
+
+ } catch (Exception e) {
+ LOG.error("Unable to create a StellarShellExecutor", e);
+ }
+ }
+
+ public void close() {
+ // nothing to do
+ }
+
+ public StellarShellExecutor createExecutor() throws Exception {
+
+ Properties props = getProperty();
+ StellarShellExecutor executor = new DefaultStellarShellExecutor(props,
Optional.empty());
+
+ // register the auto-completer to be notified
+ executor.addSpecialListener((magic) ->
autoCompleter.addCandidateFunction(magic.getCommand()));
+ executor.addFunctionListener((fn) ->
autoCompleter.addCandidateFunction(fn.getName()));
+ executor.addVariableListener((name, val) ->
autoCompleter.addCandidateVariable(name));
+
+ executor.init();
+ return executor;
+ }
+
+ public InterpreterResult interpret(String input, InterpreterContext
context) {
+ InterpreterResult result;
+
+ try {
+ // execute the input
+ StellarResult stellarResult = executor.execute(input);
+
+ if(stellarResult.isSuccess()) {
+ // on success - if no result, use a blank value
+ Object value = stellarResult.getValue().orElse("");
+ String text = ConversionUtils.convert(value, String.class);
+ result = new InterpreterResult(SUCCESS, TEXT, text);
+
+ } else if(stellarResult.isError()) {
+ // on error
+ Throwable e = stellarResult.getException().get();
+ String error = ExceptionUtils.getRootCauseMessage(e);
+ String stack = ExceptionUtils.getStackTrace(e);
+ result = new InterpreterResult(ERROR, TEXT, error +
System.lineSeparator() + stack);
+
+ } else {
+ // should not happen
+ throw new IllegalStateException("Unexpected Stellar result status.
Please file a bug report.");
+ }
+
+ } catch(Throwable t) {
+ // unexpected exception
+ String message = ExceptionUtils.getRootCauseMessage(t);
+ String stack = ExceptionUtils.getStackTrace(t);
+ result = new InterpreterResult(ERROR, TEXT, message +
System.lineSeparator() + stack);
+ }
+
+ return result;
+ }
+
+ public void cancel(InterpreterContext context) {
+ // there is no way to cancel the execution of a Stellar expression
+ }
+
+ public FormType getFormType() {
+ return FormType.SIMPLE;
+ }
+
+ public int getProgress(InterpreterContext context) {
+ // unable to provide progress
+ return 0;
+ }
+
+ @Override
+ public List<InterpreterCompletion> completion(String buf, int cursor) {
--- End diff --
This is where we connect our generic auto-completer that is used across
both REPLs into the auto-complete extension point offered by Zeppelin.
---
