[openapi-yaml] Prerequisities for Swagger 2 template.

modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/OpenAPIYamlGenerator.java

@@ -18,9 +18,23 @@
 package org.openapitools.codegen.languages;
 
 import org.openapitools.codegen.*;
+import org.openapitools.codegen.templating.mustache.CamelCaseLambda;
+import org.openapitools.codegen.templating.mustache.IndentedLambda;
+import org.openapitools.codegen.templating.mustache.LowercaseLambda;
+import org.openapitools.codegen.templating.mustache.TitlecaseLambda;
+import org.openapitools.codegen.templating.mustache.UppercaseLambda;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
+import com.google.common.collect.ImmutableMap;
+import com.samskivert.mustache.Mustache;
+import com.samskivert.mustache.Template;
+import io.swagger.v3.oas.models.Operation;
+
+import java.io.IOException;
+import java.io.Writer;
+import java.util.ArrayList;
+import java.util.List;
 import java.util.Map;
 
 public class OpenAPIYamlGenerator extends DefaultCodegen implements CodegenConfig {
@@ -61,6 +75,44 @@ public void processOpts() {
         }
         LOGGER.info("Output file [outputFile={}]", outputFile);
         supportingFiles.add(new SupportingFile("openapi.mustache", outputFile));
+
+        addMustacheLambdas(additionalProperties);
+    }
+
+    private void addMustacheLambdas(Map<String, Object> objs) {
+
+        Map<String, Mustache.Lambda> lambdas = new ImmutableMap.Builder<String, Mustache.Lambda>()
+                .put("lowercase", new LowercaseLambda().generator(this))
+                .put("uppercase", new UppercaseLambda())
+                .put("titlecase", new TitlecaseLambda())
+                .put("camelcase", new CamelCaseLambda().generator(this))
+                .put("indented", new IndentedLambda())
+                .put("indented_8", new IndentedLambda(8, " "))
+                .put("indented_12", new IndentedLambda(12, " "))
+                .put("indented_16", new IndentedLambda(16, " "))
+                .put("onchange",  new OnChangeLambda())
+                .build();
+
+        if (objs.containsKey("lambda")) {
+            LOGGER.warn("A property named 'lambda' already exists. Mustache lambdas renamed from 'lambda' to '_lambda'. " +
+                    "You'll likely need to use a custom template, " +
+                    "see https://github.com/OpenAPITools/openapi-generator/blob/master/docs/templating.md. ");
+            objs.put("_lambda", lambdas);
+        } else {
+            objs.put("lambda", lambdas);
+        }
+    }
+
+    /**
+     * Group operations by resourcePath so that operations with same path and
+     * different http method can be rendered one after the other.
+     */
+    @Override
+    public void addOperationToGroup(String tag, String resourcePath, Operation operation, CodegenOperation
+            co, Map<String, List<CodegenOperation>> operations) {
+        List<CodegenOperation> opList = operations.computeIfAbsent(resourcePath,
+                k -> new ArrayList<>());
+        opList.add(co);
     }
 
     @Override
@@ -81,4 +133,24 @@ public String escapeUnsafeCharacters(String input) {
         return input;
     }
 
+    /**
+     * Lambda writes current fragment to the output when it is different than
+     * previous fragment.
+     */
+    public static class OnChangeLambda implements Mustache.Lambda {
+        private static final Logger LOGGER = LoggerFactory.getLogger(OnChangeLambda.class);
+
+        private String lastVal = null;
+
+        @Override
+        public void execute(Template.Fragment frag, Writer out) throws IOException {
+            String curVal = frag.execute();
+            LOGGER.debug("[lastVal={}, curVal={}]", lastVal, curVal);
+            if (curVal != null && !curVal.equals(lastVal)) {
+                out.write(curVal);
+                lastVal = curVal;
+            }
+        }
+    }
+
 }