pw_web: Expose message descriptors and RPC method descriptors

Change-Id: I2b1a8ae16c7d08cea7f3d176926b33fef0f6df68
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/107342
Reviewed-by: Anthony DiGirolamo <tonymd@google.com>
Commit-Queue: Asad Memon <asadmemon@google.com>

pw_protobuf_compiler/ts/proto_collection.ts

@@ -15,41 +15,42 @@
 /** Tools for compiling and importing Javascript protos on the fly. */
 
 import {Message} from 'google-protobuf';
-import {FileDescriptorSet} from 'google-protobuf/google/protobuf/descriptor_pb';
+import {DescriptorProto, FileDescriptorSet} from 'google-protobuf/google/protobuf/descriptor_pb';
 
 export type MessageCreator = new () => Message;
 class MessageMap extends Map<string, MessageCreator> {}
+class MessageDescriptorMap extends Map<string, DescriptorProto> { }
 export class ModuleMap extends Map<string, any> {}
 
 /**
  * A wrapper class of protocol buffer modules to provide convenience methods.
  */
 export class ProtoCollection {
-  private messages: MessageMap;
+  private messages: MessageMap = new MessageMap();
+  private messageDescriptors: MessageDescriptorMap = new MessageDescriptorMap();
 
   constructor(
     readonly fileDescriptorSet: FileDescriptorSet,
     modules: ModuleMap
   ) {
-    this.messages = this.mapMessages(fileDescriptorSet, modules);
+    this.mapMessages(fileDescriptorSet, modules);
   }
 
   /**
    * Creates a map between message identifier "{packageName}.{messageName}"
-   * and the Message class.
+   * and the Message class and also the associated DescriptorProto.
    */
-  private mapMessages(set: FileDescriptorSet, mods: ModuleMap): MessageMap {
-    const messages = new MessageMap();
+  private mapMessages(set: FileDescriptorSet, mods: ModuleMap): void {
     for (const fileDescriptor of set.getFileList()) {
       const mod = mods.get(fileDescriptor.getName()!)!;
       for (const messageType of fileDescriptor.getMessageTypeList()) {
         const fullName =
           fileDescriptor.getPackage()! + '.' + messageType.getName();
         const message = mod[messageType.getName()!];
-        messages.set(fullName, message);
+        this.messages.set(fullName, message);
+        this.messageDescriptors.set(fullName, messageType);
       }
     }
-    return messages;
   }
 
   /**
@@ -61,4 +62,14 @@ export class ProtoCollection {
   getMessageCreator(identifier: string): MessageCreator | undefined {
     return this.messages.get(identifier);
   }
+
+  /**
+   * Finds the DescriptorProto referenced by the identifier.
+   *
+   *  @param identifier String identifier of the form
+   *  "{packageName}.{messageName}" i.e: "pw.rpc.test.NewMessage".
+   */
+  getDescriptorProto(identifier: string): DescriptorProto | undefined {
+    return this.messageDescriptors.get(identifier);
+  }
 }

pw_protobuf_compiler/ts/ts_proto_collection_test.ts

@@ -34,4 +34,20 @@ describe('ProtoCollection', () => {
     fetched = lib.getMessageCreator('pw.test1.Garbage');
     expect(fetched).toBeUndefined();
   });
+
+  it('getDescriptorProto returns descriptor', () => {
+    const lib = new ProtoCollection();
+
+    const fetched = lib.getDescriptorProto('pw.protobuf_compiler.test.Message');
+    expect(fetched.getFieldList()[0].getName()).toEqual("field");
+  });
+
+  it('getDescriptorProto for invalid identifier returns undefined', () => {
+    const lib = new ProtoCollection();
+
+    let fetched = lib.getMessageCreator('pw');
+    expect(fetched).toBeUndefined();
+    fetched = lib.getMessageCreator('pw.test1.Garbage');
+    expect(fetched).toBeUndefined();
+  });
 });

pw_rpc/ts/descriptors.ts

@@ -78,6 +78,7 @@ export class Method {
   readonly serverStreaming: boolean;
   readonly requestType: any;
   readonly responseType: any;
+  readonly descriptor: MethodDescriptorProto;
 
   constructor(
     descriptor: MethodDescriptorProto,
@@ -87,6 +88,7 @@ export class Method {
     this.name = descriptor.getName()!;
     this.id = hash(this.name);
     this.service = service;
+    this.descriptor = descriptor;
     this.serverStreaming = descriptor.getServerStreaming()!;
     this.clientStreaming = descriptor.getClientStreaming()!;