Comparator reference

generator/src/main/java/org/sudu/protogen/generator/message/MessageGenerator.java

@@ -1,9 +1,6 @@
 package org.sudu.protogen.generator.message;
 
-import com.squareup.javapoet.ClassName;
-import com.squareup.javapoet.FieldSpec;
-import com.squareup.javapoet.ParameterSpec;
-import com.squareup.javapoet.TypeSpec;
+import com.squareup.javapoet.*;
 import org.jetbrains.annotations.NotNull;
 import org.sudu.protogen.generator.GenerationContext;
 import org.sudu.protogen.generator.field.FieldGenerator;
@@ -42,6 +39,9 @@ public TypeSpec generate() {
         TypeSpec.Builder typeBuilder = getRecordBuilder(fields);
 
         boolean annotateNotNull = msgDescriptor.getContainingFile().doUseNullabilityAnnotation(false);
+        msgDescriptor.getComparatorReference().ifPresent(
+                comparator -> addComparable(typeBuilder, comparator)
+        );
 
         return typeBuilder
                 .multiLineRecord(true)
@@ -52,6 +52,21 @@ public TypeSpec generate() {
                 .build();
     }
 
+    private void addComparable(TypeSpec.Builder typeBuilder, String comparator) {
+        ClassName type = generatedType();
+        typeBuilder.addSuperinterface(ParameterizedTypeName.get(ClassName.get(Comparable.class), type));
+        ParameterSpec methodParameter = ParameterSpec.builder(type, "rhs").build();
+        typeBuilder.addMethod(
+                MethodSpec.methodBuilder("compareTo")
+                        .addModifiers(Modifier.PUBLIC)
+                        .returns(TypeName.INT)
+                        .addParameter(methodParameter)
+                        .addAnnotation(ClassName.get(Override.class))
+                        .addStatement("return $L.compare(this, $N)", comparator, methodParameter)
+                        .build()
+        );
+    }
+
     private TypeSpec.Builder getRecordBuilder(List<FieldSpec> fields) {
         List<ParameterSpec> parameters = fields.stream()
                 .map(Poem::fieldToParameter)

generator/src/main/java/org/sudu/protogen/protobuf/Message.java

@@ -26,5 +26,7 @@ public final boolean isUnfolded() {
      */
     public abstract boolean isMap();
 
+    public abstract Optional<String> getComparatorReference();
+
     protected abstract Optional<Boolean> getUnfoldOption();
 }

generator/src/main/java/org/sudu/protogen/protoc/adaptor/Message.java

@@ -92,4 +92,9 @@ public boolean equals(Object o) {
     public int hashCode() {
         return Objects.hash(descriptor);
     }
+
+    @Override
+    public Optional<String> getComparatorReference() {
+        return Options.wrapExtension(descriptor.getOptions(), protogen.Options.messageComparator);
+    }
 }

generator/src/test/java/org/sudu/protogen/protobuf/MessageMock.java

@@ -181,6 +181,11 @@ public void setUnfoldOption(Optional<Boolean> unfoldOption) {
         this.unfoldOption = unfoldOption;
     }
 
+    @Override
+    public Optional<String> getComparatorReference() {
+        return Optional.empty();
+    }
+
     @Override
     public String toString() {
         return "MessageMock{" +

options/src/main/proto/protogen/options.proto

@@ -55,6 +55,11 @@ extend google.protobuf.MessageOptions {
    * Ex: option (protogen.custom_class) = "org.sudu.api.computeengine.BatchInfo";
    */
   string custom_class = 5104;
+  /*
+   * Allows to implement Comparable using specified comparator.
+   * Ex: option (protogen.message_comparator) = "org.sudu.api.console.types.ConsoleComparators.INSTANCE_ID";
+   */
+  string message_comparator = 5105;
 }
 
 extend google.protobuf.EnumOptions {

tests/src/test/java/org/sudu/protogen/test/comparatorRef/ComparatorReferenceTest.java

@@ -0,0 +1,20 @@
+package org.sudu.protogen.test.comparatorRef;
+
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+
+public class ComparatorReferenceTest {
+
+    @Test
+    public void Person_should_compare_correctly() {
+        Person anton20 = new Person("Anton", 20);
+        Person anton25 = new Person("Anton", 25);
+        Person lena20 = new Person("Lena", 20);
+
+        Assertions.assertTrue(anton20.compareTo(anton25) < 0);
+        Assertions.assertTrue(anton20.compareTo(anton20) == 0);
+        Assertions.assertTrue(lena20.compareTo(anton25) > 0);
+        Assertions.assertTrue(lena20.compareTo(anton20) > 0);
+        Assertions.assertTrue(anton20.compareTo(lena20) < 0);
+    }
+}

tests/src/test/java/org/sudu/protogen/test/comparatorRef/TestComparators.java

@@ -0,0 +1,8 @@
+package org.sudu.protogen.test.comparatorRef;
+
+import java.util.Comparator;
+
+public class TestComparators {
+
+    public static final Comparator<Person> PERSON_COMPARATOR = Comparator.comparing(Person::name).thenComparing(Person::age);
+}

tests/src/test/proto/comparatorRef.proto

@@ -0,0 +1,16 @@
+syntax = "proto3";
+
+package org.sudu.protogen.test.comparatorRef;
+
+import "google/protobuf/empty.proto";
+import "protogen/options.proto";
+
+option java_multiple_files = true;
+option (.protogen.enable) = true;
+
+message GrpcPerson {
+  string name = 1;
+  int32 age = 2;
+
+  option (.protogen.message_comparator) = "org.sudu.protogen.test.comparatorRef.TestComparators.PERSON_COMPARATOR";
+}