Adding lambda support

Author: fjtirado

experimental/lambda/src/main/java/io/serverlessworkflow/impl/expressions/JavaExpressionFactory.java

@@ -22,6 +22,7 @@
 import io.serverlessworkflow.impl.WorkflowModelFactory;
 import java.util.function.BiFunction;
 import java.util.function.BiPredicate;
+import java.util.function.Function;
 
 public class JavaExpressionFactory implements ExpressionFactory {
 
@@ -42,15 +43,17 @@ public Expression buildExpression(String expression) {
 
   @Override
   public WorkflowFilter buildFilter(String expr, Object value) {
-    if (value instanceof BiPredicate pred) {
+    if (value instanceof Function func) {
+      return (w, t, n) -> modelFactory.fromAny(func.apply(n.asJavaObject()));
+    } else if (value instanceof BiPredicate pred) {
       return (w, t, n) -> modelFactory.from(pred.test(w, t));
     } else if (value instanceof BiFunction func) {
       return (w, t, n) -> modelFactory.fromAny(func.apply(w, t));
     } else if (value instanceof WorkflowFilter filter) {
       return filter;
+    } else {
+      return (w, t, n) -> modelFactory.fromAny(value);
     }
-    throw new UnsupportedOperationException(
-        "Unsupported value " + value + "+ of type " + value.getClass());
   }
 
   @Override

experimental/lambda/src/main/java/io/serverlessworkflow/impl/expressions/JavaModelFactory.java

@@ -27,8 +27,7 @@ public class JavaModelFactory implements WorkflowModelFactory {
 
   @Override
   public WorkflowModel combine(Map<String, WorkflowModel> workflowVariables) {
-    // TODO Auto-generated method stub
-    return null;
+    return new JavaModel(workflowVariables);
   }
 
   @Override

experimental/lambda/src/test/java/io/serverless/workflow/impl/LambdaTest.java

@@ -0,0 +1,77 @@
+/*
+ * Copyright 2020-Present The Serverless Workflow Specification Authors
+ *
+ * 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.
+ */
+package io.serverless.workflow.impl;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import io.serverlessworkflow.api.types.Document;
+import io.serverlessworkflow.api.types.Output;
+import io.serverlessworkflow.api.types.OutputAsExpresssions;
+import io.serverlessworkflow.api.types.Set;
+import io.serverlessworkflow.api.types.SetTask;
+import io.serverlessworkflow.api.types.SetTaskConfiguration;
+import io.serverlessworkflow.api.types.Task;
+import io.serverlessworkflow.api.types.TaskItem;
+import io.serverlessworkflow.api.types.Workflow;
+import io.serverlessworkflow.impl.WorkflowApplication;
+import java.util.List;
+import java.util.Map;
+import java.util.concurrent.ExecutionException;
+import org.junit.jupiter.api.Test;
+
+class LambdaTest {
+
+  @Test
+  void testSimpleExpression() throws InterruptedException, ExecutionException {
+
+    try (WorkflowApplication app = WorkflowApplication.builder().build()) {
+      Workflow workflow =
+          new Workflow()
+              .withDocument(
+                  new Document().withNamespace("test").withName("test").withVersion("1.0"))
+              .withDo(
+                  List.of(
+                      new TaskItem(
+                          "javierito",
+                          new Task()
+                              .withSetTask(
+                                  new SetTask()
+                                      .withSet(
+                                          new Set()
+                                              .withSetTaskConfiguration(
+                                                  new SetTaskConfiguration()
+                                                      .withAdditionalProperty("name", "Francisco")))
+                                      .withOutput(
+                                          new Output()
+                                              .withAs(
+                                                  new OutputAsExpresssions()
+                                                      .withFunction(this::addJavierito)))))));
+      assertThat(
+              app.workflowDefinition(workflow)
+                  .instance(Map.of())
+                  .start()
+                  .get()
+                  .asMap()
+                  .map(m -> m.get("name"))
+                  .orElseThrow())
+          .isEqualTo("Francisco Javierito");
+    }
+  }
+
+  private Map<String, Object> addJavierito(Map<String, Object> map) {
+    return Map.of("name", map.get("name") + " Javierito");
+  }
+}

experimental/types/src/main/java/io/serverlessworkflow/api/types/OutputAsExpresssions.java

@@ -0,0 +1,26 @@
+/*
+ * Copyright 2020-Present The Serverless Workflow Specification Authors
+ *
+ * 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.
+ */
+package io.serverlessworkflow.api.types;
+
+import java.util.function.Function;
+
+public class OutputAsExpresssions extends OutputAs {
+
+  public <T, V> OutputAs withFunction(Function<T, V> value) {
+    setObject(value);
+    return this;
+  }
+}

impl/core/src/main/java/io/serverlessworkflow/impl/executors/ForkExecutor.java

@@ -26,6 +26,7 @@
 import io.serverlessworkflow.impl.executors.RegularTaskExecutor.RegularTaskExecutorBuilder;
 import io.serverlessworkflow.impl.resources.ResourceLoader;
 import java.util.HashMap;
+import java.util.LinkedHashMap;
 import java.util.Map;
 import java.util.Map.Entry;
 import java.util.Optional;
@@ -108,6 +109,11 @@ private WorkflowModel combine(WorkflowContext context, Map<String, TaskContext>
             .application()
             .modelFactory()
             .combine(
-                sortedStream.collect(Collectors.toMap(Entry::getKey, e -> e.getValue().output())));
+                sortedStream.collect(
+                    Collectors.toMap(
+                        Entry::getKey,
+                        e -> e.getValue().output(),
+                        (x, y) -> y,
+                        LinkedHashMap::new)));
   }
 }