Freemarker based code generation

pom.xml

@@ -132,9 +132,9 @@
       <version>${project.version}</version>
     </dependency>
     <dependency>
-      <groupId>com.squareup</groupId>
-      <artifactId>javapoet</artifactId>
-      <version>1.11.1</version>
+      <groupId>org.freemarker</groupId>
+      <artifactId>freemarker</artifactId>
+      <version>2.3.31</version>
     </dependency>
     <dependency>
       <groupId>ch.qos.logback</groupId>

src/main/java/io/vlingo/xoom/schemata/codegen/CodeGenerator.java

@@ -0,0 +1,45 @@
+package io.vlingo.xoom.schemata.codegen;
+
+import freemarker.template.*;
+import io.vlingo.xoom.codegen.CodeGenerationException;
+import io.vlingo.xoom.common.Outcome;
+import io.vlingo.xoom.common.Success;
+import io.vlingo.xoom.schemata.errors.SchemataBusinessException;
+
+import java.io.IOException;
+import java.io.StringWriter;
+import java.io.Writer;
+import java.util.Locale;
+
+import static freemarker.template.Configuration.DEFAULT_INCOMPATIBLE_IMPROVEMENTS;
+
+public class CodeGenerator {
+
+    private final Configuration configuration;
+
+    public CodeGenerator() {
+        DefaultObjectWrapper objectWrapper = new DefaultObjectWrapper(DEFAULT_INCOMPATIBLE_IMPROVEMENTS);
+        objectWrapper.setExposeFields(true);
+        this.configuration = new Configuration(DEFAULT_INCOMPATIBLE_IMPROVEMENTS);
+        configuration.setClassForTemplateLoading(CodeGenerator.class, "/");
+        configuration.setDefaultEncoding("UTF-8");
+        configuration.setLocale(Locale.US);
+        configuration.setTemplateExceptionHandler(TemplateExceptionHandler.RETHROW_HANDLER);
+        configuration.setObjectWrapper(objectWrapper);
+    }
+
+    public void generateWith(String language, String templateName, Object templateArgs, Writer output) throws IOException, TemplateException {
+        Template template = configuration.getTemplate("/codegen/" + language + "/" + templateName + ".ftl");
+        template.process(templateArgs, output);
+    }
+
+    public Outcome<SchemataBusinessException, String> generateWith(String language, String templateName, Object templateArgs) {
+        StringWriter result = new StringWriter();
+        try{
+            generateWith(language, templateName, templateArgs, result);
+        }catch (IOException | TemplateException e) {
+            throw new CodeGenerationException(e);
+        }
+        return Success.of(result.toString());
+    }
+}

src/main/java/io/vlingo/xoom/schemata/codegen/SchemaTypeArguments.java

@@ -0,0 +1,91 @@
+package io.vlingo.xoom.schemata.codegen;
+
+import io.vlingo.xoom.schemata.codegen.ast.FieldDefinition;
+import io.vlingo.xoom.schemata.codegen.ast.types.BasicArrayType;
+import io.vlingo.xoom.schemata.codegen.ast.types.TypeDefinition;
+import io.vlingo.xoom.schemata.codegen.ast.values.ListValue;
+import io.vlingo.xoom.schemata.codegen.ast.values.SingleValue;
+import io.vlingo.xoom.schemata.codegen.ast.values.Value;
+import io.vlingo.xoom.schemata.model.Category;
+
+import java.util.List;
+import java.util.stream.Collectors;
+
+public class SchemaTypeArguments {
+
+    public final String namespace;
+    public final String version;
+    public final List<Property> properties;
+    public final Category type;
+    public final String typeName;
+    public final boolean createDefaultConstructor;
+    public final boolean createRequiredArgsConstructor;
+
+    public SchemaTypeArguments(String language, String fqdn, String version, TypeDefinition node) {
+        this.namespace = extractNamespace(fqdn);
+        this.type = node.category;
+        this.typeName = node.typeName;
+        this.version = version;
+        this.properties = extractProperties(language, node);
+        this.createDefaultConstructor = properties.stream()
+                .filter(property -> !property.name.equals("eventType"))
+                .filter(property -> !property.name.equals("eventVersion"))
+                .filter(property -> !property.name.equals("occurredOn"))
+                .allMatch(property -> property.value != null);
+        this.createRequiredArgsConstructor = properties.stream()
+                .anyMatch(property -> !property.name.equals("eventType")
+                                        && !property.name.equals("eventVersion")
+                                        && !property.name.equals("occurredOn"));
+    }
+
+    public static class Property {
+        public final String type;
+        public final boolean array;
+        public final String name;
+        public final Object value;
+
+        public Property(String type, boolean array, String name, Object value) {
+            this.type = type;
+            this.array = array;
+            this.name = name;
+            this.value = value;
+        }
+
+        @Override
+        public String toString() {
+            return "Property{" +
+                    "type='" + type + '\'' +
+                    ", array=" + array +
+                    ", name='" + name + '\'' +
+                    ", value=" + value +
+                    '}';
+        }
+    }
+
+    private String extractNamespace(String fqdn) {
+        int i = fqdn.indexOf(':', fqdn.indexOf(':') + 1) + 1;
+        int j = fqdn.indexOf(':', i);
+        return fqdn.substring(i, j) + ".events";
+    }
+
+    private List<Property> extractProperties(String language, TypeDefinition root) {
+        TypeMap typeMap = TypeMap.valueOf(language);
+        return root.children.stream()
+                .map(node -> (FieldDefinition) node)
+                .map(node -> {
+                    String type = typeMap.typeOf(node.type.name());
+                    boolean array = node.type instanceof BasicArrayType;
+                    Object defaultValue = array
+                            ? node.defaultValue
+                                    .filter(value -> value instanceof ListValue)
+                                    .map(value -> (ListValue<List<SingleValue>>)value)
+                                    .map(listValue -> listValue.value.stream()
+                                                                    .map(Value::value)
+                                                                    .collect(Collectors.toList()))
+                                    .orElse(null)
+                            : node.defaultValue.map(Value::value).orElse(null);
+                    return new Property(type, array, node.name, defaultValue);
+                })
+                .collect(Collectors.toList());
+    }
+}

src/main/java/io/vlingo/xoom/schemata/codegen/TypeDefinitionCompiler.java

@@ -10,8 +10,6 @@
 import io.vlingo.xoom.actors.Stage;
 import io.vlingo.xoom.common.Completes;
 import io.vlingo.xoom.common.Outcome;
-import io.vlingo.xoom.schemata.codegen.backend.Backend;
-import io.vlingo.xoom.schemata.codegen.backend.java.JavaBackend;
 import io.vlingo.xoom.schemata.codegen.parser.AntlrTypeParser;
 import io.vlingo.xoom.schemata.codegen.parser.TypeParser;
 import io.vlingo.xoom.schemata.codegen.processor.Processor;
@@ -50,29 +48,27 @@ public static TypeDefinitionCompiler compilerFor(final Stage stage, final String
    * @return TypeDefinitionCompiler
    */
   public static TypeDefinitionCompiler newCompilerFor(final Stage stage, final String language) {
-    switch (language) {
-    case "java":
-      return forBackend(stage, new JavaBackend());
-    default:
+    if (!language.equals("java") && !language.equals("csharp")){
       throw new IllegalArgumentException("Unsupported language: " + language);
     }
+    return forBackend(stage, language);
   }
 
   /**
    * Answer a new {@code TypeDefinitionCompiler} for a given language {@code backendType}.
    * @param stage the Stage in which to create the compiler actor
-   * @param backend the language backend
+   * @param language the backend language
    * @return TypeDefinitionCompiler
    */
-  static TypeDefinitionCompiler forBackend(final Stage stage, Backend backend) {
+  static TypeDefinitionCompiler forBackend(final Stage stage, String language) {
     final TypeParser typeParser =  new AntlrTypeParser();
     final TypeResolver typeResolver = StorageProvider.instance().typeResolverQueries;
 
     return new TypeDefinitionCompilerActor(typeParser,
             Arrays.asList(
                     stage.actorFor(Processor.class, ComputableTypeProcessor.class),
                     stage.actorFor(Processor.class, TypeResolverProcessor.class, typeResolver)
-            ), backend);
+            ), language);
   }
 
   /**

src/main/java/io/vlingo/xoom/schemata/codegen/TypeDefinitionCompilerActor.java

@@ -10,7 +10,7 @@
 import io.vlingo.xoom.common.Completes;
 import io.vlingo.xoom.common.Outcome;
 import io.vlingo.xoom.schemata.codegen.ast.Node;
-import io.vlingo.xoom.schemata.codegen.backend.Backend;
+import io.vlingo.xoom.schemata.codegen.ast.types.TypeDefinition;
 import io.vlingo.xoom.schemata.codegen.parser.TypeParser;
 import io.vlingo.xoom.schemata.codegen.processor.Processor;
 import io.vlingo.xoom.schemata.errors.SchemataBusinessException;
@@ -22,20 +22,21 @@
 public class TypeDefinitionCompilerActor implements TypeDefinitionCompiler, TypeDefinitionMiddleware {
     private final TypeParser parser;
     private final List<Processor> processors;
-    private final Backend backend;
+    private final String language;
+    private final CodeGenerator codeGenerator = new CodeGenerator();
 
-    public TypeDefinitionCompilerActor(final TypeParser parser, final List<Processor> processors, final Backend backend) {
+    public TypeDefinitionCompilerActor(final TypeParser parser, final List<Processor> processors, final String language) {
         this.parser = parser;
         this.processors = processors;
-        this.backend = backend;
+        this.language = language;
     }
 
     @Override
     public Completes<Outcome<SchemataBusinessException, String>> compile(final InputStream typeDefinition, final String fullyQualifiedTypeName, final String version) {
         return Completes.withSuccess(
                 parser.parseTypeDefinition(typeDefinition, fullyQualifiedTypeName)
                     .andThen(node -> this.process(fullyQualifiedTypeName).apply(node))
-                    .andThenTo(node -> backend.generateOutput(node, version))
+                    .andThenTo(node -> codeGenerator.generateWith(language, "SchemaType", new SchemaTypeArguments(language, fullyQualifiedTypeName, version, (TypeDefinition) node)))
                     .otherwiseFail(ex -> ex)
                 );
     }

src/main/java/io/vlingo/xoom/schemata/codegen/TypeMap.java

@@ -0,0 +1,59 @@
+package io.vlingo.xoom.schemata.codegen;
+
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.Map;
+
+public enum TypeMap {
+
+    java(ofMapEntries(
+            "boolean", "boolean",
+            "byte", "byte",
+            "char", "char",
+            "short", "short",
+            "int", "int",
+            "long", "long",
+            "float", "float",
+            "double", "double",
+            "string", "String",
+            "type", "String",
+            "version", "int",
+            "timestamp", "long"
+    )),
+    csharp(ofMapEntries(
+            "boolean", "bool",
+            "byte", "byte",
+            "char", "char",
+            "short", "short",
+            "int", "int",
+            "long", "long",
+            "float", "float",
+            "double", "double",
+            "type", "string",
+            "version", "int",
+            "timestamp", "long"
+    ));
+
+    final Map<String, String> types;
+
+    TypeMap(Map<String, String> types) {
+        this.types = Collections.unmodifiableMap(types);
+    }
+
+    public String typeOf(String type){
+        return types.getOrDefault(type, type);
+    }
+
+    private static Map<String, String> ofMapEntries(String ... entries) {
+        if (entries.length % 2 != 0){
+            throw new IllegalArgumentException("parameters must even");
+        }
+        Map<String, String> result = new HashMap<>();
+        for (int i=0; i<entries.length-1; i+=2){
+            String key = entries[i];
+            String val = entries[i+1];
+            result.put(key, val);
+        }
+        return result;
+    }
+}