[ggj][nestedsig] feat: add support for nested method sigs (aip.dev/4232) (#626)

* fix: fix dep ordering in Bazel dedupe rules

* feat: add a basic trie

* fix: add hashCode() and equals() to Field

* fix: add equals() and hashCode() for MethodArgument

* feat: add a TriFunction

* feat: add DFS traversal to Trie

* feat: add support for nested method sigs (aip.dev/4232)

Author: miraleung

src/main/java/com/google/api/generator/gapic/composer/BUILD.bazel

@@ -23,6 +23,7 @@ java_library(
         "//src/main/java/com/google/api/generator/gapic/composer/utils",
         "//src/main/java/com/google/api/generator/gapic/model",
         "//src/main/java/com/google/api/generator/gapic/utils",
+        "//src/main/java/com/google/api/generator/util",
         "@com_google_api_api_common//jar",
         "@com_google_api_gax_java//gax",
         "@com_google_api_gax_java//gax-grpc:gax_grpc",

src/main/java/com/google/api/generator/gapic/composer/ServiceClientClassComposer.java

@@ -68,6 +68,8 @@
 import com.google.api.generator.gapic.model.MethodArgument;
 import com.google.api.generator.gapic.model.Service;
 import com.google.api.generator.gapic.utils.JavaStyle;
+import com.google.api.generator.util.TriFunction;
+import com.google.api.generator.util.Trie;
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.base.Preconditions;
 import com.google.common.base.Strings;
@@ -84,6 +86,7 @@
 import java.util.Map;
 import java.util.Objects;
 import java.util.concurrent.TimeUnit;
+import java.util.function.BiFunction;
 import java.util.function.Function;
 import java.util.stream.Collectors;
 import javax.annotation.Generated;
@@ -1336,23 +1339,68 @@ private static ClassDefinition createNestedRpcFixedSizeCollectionClass(
   static Expr createRequestBuilderExpr(
       Method method, List<MethodArgument> signature, TypeStore typeStore) {
     TypeNode methodInputType = method.inputType();
-    MethodInvocationExpr newBuilderExpr =
+    Expr newBuilderExpr =
         MethodInvocationExpr.builder()
             .setMethodName("newBuilder")
             .setStaticReferenceType(methodInputType)
             .build();
-    for (MethodArgument argument : signature) {
-      newBuilderExpr = buildNestedSetterInvocationExpr(argument, newBuilderExpr);
+    // Maintain the args' order of appearance for better determinism.
+    List<Field> rootFields = new ArrayList<>();
+    Map<Field, Trie<Field>> rootFieldToTrie = new HashMap<>();
+    for (MethodArgument arg : signature) {
+      Field rootField = arg.nestedFields().isEmpty() ? arg.field() : arg.nestedFields().get(0);
+      if (!rootFields.contains(rootField)) {
+        rootFields.add(rootField);
+      }
+      Trie<Field> updatedTrie =
+          rootFieldToTrie.containsKey(rootField) ? rootFieldToTrie.get(rootField) : new Trie();
+      List<Field> nestedFieldsWithChild = new ArrayList<>(arg.nestedFields());
+      nestedFieldsWithChild.add(arg.field());
+      updatedTrie.insert(nestedFieldsWithChild);
+      rootFieldToTrie.put(rootField, updatedTrie);
     }
 
-    MethodInvocationExpr builderExpr =
-        MethodInvocationExpr.builder()
-            .setMethodName("build")
-            .setExprReferenceExpr(newBuilderExpr)
-            .setReturnType(methodInputType)
-            .build();
+    Function<Field, Expr> parentPreprocFn =
+        field ->
+            (Expr)
+                MethodInvocationExpr.builder()
+                    .setStaticReferenceType(field.type())
+                    .setMethodName("newBuilder")
+                    .build();
+    TriFunction<Field, Expr, Expr, Expr> parentPostprocFn =
+        (field, baseRefExpr, leafProcessedExpr) -> {
+          boolean isRootNode = field == null;
+          return isRootNode
+              ? leafProcessedExpr
+              : MethodInvocationExpr.builder()
+                  .setExprReferenceExpr(baseRefExpr)
+                  .setMethodName(String.format("set%s", JavaStyle.toUpperCamelCase(field.name())))
+                  .setArguments(
+                      MethodInvocationExpr.builder()
+                          .setExprReferenceExpr(leafProcessedExpr)
+                          .setMethodName("build")
+                          .build())
+                  .build();
+        };
+
+    final Map<Field, MethodArgument> fieldToMethodArg =
+        signature.stream().collect(Collectors.toMap(a -> a.field(), a -> a));
+    BiFunction<Field, Expr, Expr> leafProcFn =
+        (field, parentBaseRefExpr) ->
+            (Expr) buildNestedSetterInvocationExpr(fieldToMethodArg.get(field), parentBaseRefExpr);
+
+    for (Field rootField : rootFields) {
+      newBuilderExpr =
+          rootFieldToTrie
+              .get(rootField)
+              .dfsTraverseAndReduce(parentPreprocFn, parentPostprocFn, leafProcFn, newBuilderExpr);
+    }
 
-    return builderExpr;
+    return MethodInvocationExpr.builder()
+        .setExprReferenceExpr(newBuilderExpr)
+        .setMethodName("build")
+        .setReturnType(methodInputType)
+        .build();
   }
 
   @VisibleForTesting

src/test/java/com/google/api/generator/gapic/composer/goldens/IdentityClient.golden

@@ -133,8 +133,7 @@ public class IdentityClient implements BackgroundResource {
     CreateUserRequest request =
         CreateUserRequest.newBuilder()
             .setParent(parent)
-            .setDisplayName(displayName)
-            .setEmail(email)
+            .setUser(User.newBuilder().setDisplayName(displayName).setEmail(email).build())
             .build();
     return createUser(request);
   }
@@ -161,12 +160,71 @@ public class IdentityClient implements BackgroundResource {
     CreateUserRequest request =
         CreateUserRequest.newBuilder()
             .setParent(parent)
-            .setDisplayName(displayName)
-            .setEmail(email)
-            .setAge(age)
-            .setNickname(nickname)
-            .setEnableNotifications(enableNotifications)
-            .setHeightFeet(heightFeet)
+            .setUser(
+                User.newBuilder()
+                    .setDisplayName(displayName)
+                    .setEmail(email)
+                    .setAge(age)
+                    .setNickname(nickname)
+                    .setEnableNotifications(enableNotifications)
+                    .setHeightFeet(heightFeet)
+                    .build())
+            .build();
+    return createUser(request);
+  }
+
+  // AUTO-GENERATED DOCUMENTATION AND METHOD.
+  /**
+   * @param parent
+   * @param displayName
+   * @param email
+   * @param hobbyName
+   * @param songName
+   * @param weeklyFrequency
+   * @param companyName
+   * @param title
+   * @param subject
+   * @param artistName
+   * @throws com.google.api.gax.rpc.ApiException if the remote call fails
+   */
+  public final User createUser(
+      String parent,
+      String displayName,
+      String email,
+      String hobbyName,
+      String songName,
+      int weeklyFrequency,
+      String companyName,
+      String title,
+      String subject,
+      String artistName) {
+    CreateUserRequest request =
+        CreateUserRequest.newBuilder()
+            .setParent(parent)
+            .setUser(
+                User.newBuilder()
+                    .setDisplayName(displayName)
+                    .setEmail(email)
+                    .setHobby(
+                        Hobby.newBuilder()
+                            .setHobbyName(hobbyName)
+                            .setWeeklyFrequency(weeklyFrequency)
+                            .setInstructionManual(
+                                Book.newBuilder().setTitle(title).setSubject(subject).build())
+                            .build())
+                    .setSong(
+                        Song.newBuilder()
+                            .setSongName(songName)
+                            .setSongArtist(
+                                Artist.newBuilder()
+                                    .setRecordingCompany(
+                                        RecordingCompany.newBuilder()
+                                            .setCompanyName(companyName)
+                                            .build())
+                                    .setArtistName(artistName)
+                                    .build())
+                            .build())
+                    .build())
             .build();
     return createUser(request);
   }

src/test/java/com/google/api/generator/gapic/testdata/identity.proto

@@ -46,6 +46,9 @@ service Identity {
         "parent,user.display_name,user.email";
     option (google.api.method_signature) =
         "parent,user.display_name,user.email,user.age,user.nickname,user.enable_notifications,user.height_feet";
+    // Test nested method arguments and ensure that order doesn't matter.
+    option (google.api.method_signature) =
+        "parent,user.display_name,user.email,user.hobby.hobby_name,user.song.song_name,user.hobby.weekly_frequency,user.song.song_artist.recording_company.company_name,user.hobby.instruction_manual.title,user.hobby.instruction_manual.subject,user.song.song_artist.artist_name";
   }
 
   // Retrieves the User with the given uri.
@@ -121,6 +124,55 @@ message User {
   // (-- aip.dev/not-precedent: The default for the feature is true.
   //     Ordinarily, the default for a `bool` field should be false. --)
   optional bool enable_notifications = 9;
+
+  // The user's favorite hobby.
+  optional Hobby hobby = 10;
+
+  // The user's song.
+  optional Song song = 11;
+}
+
+message Hobby {
+  // The name of the hobby.
+  string hobby_name = 1;
+
+  // Weekly frequency this hobby is performed.
+  int32 weekly_frequency = 2;
+
+  // The instruction manual for the hobby.
+  Book instruction_manual = 3;
+}
+
+message Book {
+  // The title of the instruction manual.
+  string title = 1;
+
+  // The subject of the instruction manual.
+  string subject = 2;
+}
+
+message Song {
+  // The name of the song.
+  string song_name = 1;
+
+  // The song's artist.
+  Artist song_artist = 2;
+}
+
+message Artist {
+  // The name of the artist.
+  string artist_name = 1;
+
+  // The artist's recording company.
+  RecordingCompany recording_company = 2;
+}
+
+message RecordingCompany {
+  // The recording company's name
+  string company_name = 1;
+
+  // The year the company was founded.
+  int32 founding_year = 2;
 }
 
 // The request message for the google.showcase.v1beta1.Identity\CreateUser