Move TemplateEngine into FreeMarker implementation

codegen/smithy-codegen-core/src/main/java/software/amazon/smithy/codegen/core/DefaultDataTemplateEngine.java

@@ -21,24 +21,9 @@
 import software.amazon.smithy.utils.SmithyBuilder;
 
 /**
- * Creates a template engine that always injects default values
- * into the data model.
- *
- * <p>Default values can be overridden per/template by passing in a
- * different value in the data model when rendering templates.
- *
- * <pre>
- * {@code
- * TemplateEngine myEngine = createMyTemplateEngine();
- * TemplateEngine wrappedEngine = DefaultDataTemplateEngine.builder()
- *         .delegate(myEngine)
- *         .put("foo", "baz")
- *         .put("hello", true)
- *         .build();
- * assert(wrappedEngine.renderString("{{ foo }}") == "baz");
- * }
- * </pre>
+ * This is deprecated and will be removed in 0.10.0.
  */
+@Deprecated
 public final class DefaultDataTemplateEngine implements TemplateEngine {
     private final TemplateEngine delegate;
     private final Map<String, Object> defaultContext;
@@ -72,6 +57,7 @@ private Map<String, Object> merge(Map<String, Object> map) {
     /**
      * Builds a new DefaultDataTemplateEngine.
      */
+    @Deprecated
     public static final class Builder {
         private TemplateEngine delegate;
         private final Map<String, Object> defaultContext = new HashMap<>();

codegen/smithy-codegen-core/src/main/java/software/amazon/smithy/codegen/core/TemplateEngine.java

@@ -21,38 +21,19 @@
 import java.util.Map;
 
 /**
- * Abstraction to renderFile templates using a data model.
+ * This is deprecated and will be removed in 0.10.0.
  */
 @FunctionalInterface
+@Deprecated
 public interface TemplateEngine {
-    /**
-     * Writes a template to the given writer.
-     *
-     * @param templatePath Loaded template to render.
-     * @param out Writer to write to.
-     * @param dataModel Data model to apply to the template.
-     */
     void write(String templatePath, Writer out, Map<String, Object> dataModel);
 
-    /**
-     * Renders a template loaded from the given path and returns the result.
-     *
-     * @param templatePath Path to a template to load.
-     * @param dataModel Data model to apply to the template.
-     * @return Returns the rendered text of the template.
-     */
     default String render(String templatePath, Map<String, Object> dataModel) {
         StringWriter writer = new StringWriter();
         write(templatePath, writer, dataModel);
         return writer.toString();
     }
 
-    /**
-     * Renders a template loaded from the given path and returns the result.
-     *
-     * @param templatePath Path to a template to load.
-     * @return Returns the rendered text of the template.
-     */
     default String render(String templatePath) {
         return render(templatePath, Collections.emptyMap());
     }

codegen/smithy-codegen-freemarker/src/main/java/software/amazon/smithy/codegen/freemarker/FreeMarkerEngine.java

@@ -23,15 +23,16 @@
 import freemarker.template.TemplateHashModel;
 import freemarker.template.TemplateModel;
 import java.io.IOException;
+import java.io.StringWriter;
 import java.io.Writer;
+import java.util.Collections;
 import java.util.HashMap;
 import java.util.Iterator;
 import java.util.List;
 import java.util.Map;
 import java.util.Optional;
 import java.util.stream.Stream;
 import software.amazon.smithy.codegen.core.CodegenException;
-import software.amazon.smithy.codegen.core.DefaultDataTemplateEngine;
 import software.amazon.smithy.codegen.core.TemplateEngine;
 import software.amazon.smithy.model.node.ArrayNode;
 import software.amazon.smithy.model.node.BooleanNode;
@@ -49,13 +50,24 @@
  * @see <a href="https://freemarker.apache.org/">FreeMarker</a>
  */
 public final class FreeMarkerEngine implements TemplateEngine {
+
     private final Configuration freeMarkerConfig;
+    private final Map<String, Object> defaultContext;
 
     /**
      * @param freeMarkerConfig FreeMarker configuration.
      */
     public FreeMarkerEngine(Configuration freeMarkerConfig) {
+        this(freeMarkerConfig, Collections.emptyMap());
+    }
+
+    /**
+     * @param freeMarkerConfig FreeMarker configuration.
+     * @param defaultContext Default context to pass to each template.
+     */
+    public FreeMarkerEngine(Configuration freeMarkerConfig, Map<String, Object> defaultContext) {
         this.freeMarkerConfig = freeMarkerConfig;
+        this.defaultContext = defaultContext;
     }
 
     /**
@@ -71,21 +83,53 @@ public static Builder builder() {
         return new Builder();
     }
 
-    @Override
+    /**
+     * Writes a template to the given writer.
+     *
+     * @param templatePath Loaded template to render.
+     * @param out Writer to write to.
+     * @param dataModel Data model to apply to the template.
+     */
     public void write(String templatePath, Writer out, Map<String, Object> dataModel) {
         try {
+            Map<String, Object> merged = new HashMap<>(defaultContext);
+            merged.putAll(dataModel);
             Template template = freeMarkerConfig.getTemplate(templatePath);
-            template.process(dataModel, out);
+            template.process(merged, out);
         } catch (IOException | TemplateException e) {
             throw new CodegenException(String.format(
                     "Error evaluating FreeMarker template [%s]: %s", templatePath, e.getMessage()), e);
         }
     }
 
+    /**
+     * Renders a template loaded from the given path and returns the result.
+     *
+     * @param templatePath Path to a template to load.
+     * @param dataModel Data model to apply to the template.
+     * @return Returns the rendered text of the template.
+     */
+    public String render(String templatePath, Map<String, Object> dataModel) {
+        StringWriter writer = new StringWriter();
+        write(templatePath, writer, dataModel);
+        return writer.toString();
+    }
+
+    /**
+     * Renders a template loaded from the given path and returns the result.
+     *
+     * @param templatePath Path to a template to load.
+     * @return Returns the rendered text of the template.
+     */
+    public String render(String templatePath) {
+        return render(templatePath, Collections.emptyMap());
+    }
+
     /**
      * Builds a new FreeMarker template engine.
      */
-    public static final class Builder implements SmithyBuilder<TemplateEngine> {
+    public static final class Builder implements SmithyBuilder<FreeMarkerEngine> {
+
         private Configuration config;
         private boolean disableObjectWrapper;
         private boolean disableHelpers;
@@ -95,7 +139,7 @@ public static final class Builder implements SmithyBuilder<TemplateEngine> {
         private final Map<String, Object> defaultProperties = new HashMap<>();
 
         @Override
-        public TemplateEngine build() {
+        public FreeMarkerEngine build() {
             if (config == null) {
                 config = new Configuration(Configuration.VERSION_2_3_28);
             }
@@ -123,10 +167,7 @@ public TemplateEngine build() {
                 putDefaultProperty("CaseUtils", loadUtilsIntoTemplateModel(CaseUtils.class));
             }
 
-            return DefaultDataTemplateEngine.builder()
-                    .putAll(defaultProperties)
-                    .delegate(new FreeMarkerEngine(config))
-                    .build();
+            return new FreeMarkerEngine(config, defaultProperties);
         }
 
         /**

codegen/smithy-codegen-freemarker/src/test/java/software/amazon/smithy/codegen/freemarker/FreeMarkerEngineTest.java

@@ -8,14 +8,13 @@
 import java.util.Optional;
 import java.util.stream.Stream;
 import org.junit.jupiter.api.Test;
-import software.amazon.smithy.codegen.core.TemplateEngine;
 import software.amazon.smithy.model.node.Node;
 import software.amazon.smithy.utils.MapUtils;
 
 public class FreeMarkerEngineTest {
     @Test
     public void rendersTemplatesWithObjectWrapper() {
-        TemplateEngine engine = FreeMarkerEngine.builder()
+        FreeMarkerEngine engine = FreeMarkerEngine.builder()
                 .classLoader(getClass())
                 .build();
         Map<String, Object> properties = new HashMap<>();
@@ -34,7 +33,7 @@ public void rendersTemplatesWithObjectWrapper() {
 
     @Test
     public void rendersTemplatesWithUtils() {
-        TemplateEngine engine = FreeMarkerEngine.builder()
+        FreeMarkerEngine engine = FreeMarkerEngine.builder()
                 .classLoader(getClass().getClassLoader())
                 .putDefaultProperty("snake", "snake_man")
                 .build();