proto-loader: Add TypeScript generator

.gitmodules

@@ -1,6 +1,12 @@
 [submodule "packages/grpc-tools/deps/protobuf"]
 	path = packages/grpc-tools/deps/protobuf
 	url = https://github.com/protocolbuffers/protobuf
+[submodule "packages/proto-loader/deps/gapic-showcase"]
+	path = packages/proto-loader/deps/gapic-showcase
+	url = https://github.com/googleapis/gapic-showcase.git
+[submodule "packages/proto-loader/deps/googleapis"]
+	path = packages/proto-loader/deps/googleapis
+	url = https://github.com/googleapis/googleapis.git
 [submodule "packages/grpc-js-xds/deps/envoy-api"]
 	path = packages/grpc-js-xds/deps/envoy-api
 	url = https://github.com/envoyproxy/data-plane-api.git

packages/proto-loader/README.md

@@ -38,6 +38,7 @@ The options parameter is an object that can have the following optional properti
 | `arrays` | `true` or `false` | Set empty arrays for missing array values even if `defaults` is `false` Defaults to `false`.
 | `objects` | `true` or `false` | Set empty objects for missing object values even if `defaults` is `false` Defaults to `false`.
 | `oneofs` | `true` or `false` | Set virtual oneof properties to the present field's name. Defaults to `false`.
+| `json` | `true` or `false` | Represent `Infinity` and `NaN` as strings in `float` fields, and automatically decode `google.protobuf.Any` values. Defaults to `false`
 | `includeDirs` | An array of strings | A list of search paths for imported `.proto` files.
 
 The following options object closely approximates the existing behavior of `grpc.load`:
@@ -51,3 +52,66 @@ const options = {
   oneofs: true
 }
 ```
+
+## Generating TypeScript types
+
+The `proto-loader-gen-types` script distributed with this package can be used to generate TypeScript type information for the objects loaded at runtime. More information about how to use it can be found in [the *@grpc/proto-loader TypeScript Type Generator CLI Tool* proposal document](https://github.com/grpc/proposal/blob/master/L70-node-proto-loader-type-generator.md). The arguments mostly match the `load` function's options; the full usage information is as follows:
+
+```console
+proto-loader-gen-types.js [options] filenames...
+
+Options:
+  --help             Show help                                         [boolean]
+  --version          Show version number                               [boolean]
+  --keepCase         Preserve the case of field names                  [boolean]
+  --longs            The type that should be used to output 64 bit integer
+                     values. Can be String, Number                      [string]
+  --enums            The type that should be used to output enum fields. Can be
+                     String                                             [string]
+  --bytes            The type that should be used to output bytes fields. Can be
+                     String, Array                                      [string]
+  --defaults         Output default values for omitted fields          [boolean]
+  --arrays           Output default values for omitted repeated fields even if
+                     --defaults is not set                             [boolean]
+  --objects          Output default values for omitted message fields even if
+                     --defaults is not set                             [boolean]
+  --oneofs           Output virtual oneof fields set to the present field's name
+                                                                       [boolean]
+  --json             Represent Infinity and NaN as strings in float fields. Also
+                     decode google.protobuf.Any automatically          [boolean]
+  --includeComments  Generate doc comments from comments in the original files
+                                                                       [boolean]
+  --includeDirs, -I  Directories to search for included files            [array]
+  --outDir, -O       Directory in which to output files      [string] [required]
+  --grpcLib          The gRPC implementation library that these types will be
+                     used with                               [string] [required]
+```
+
+### Example Usage
+
+Generate the types:
+
+```sh
+$(npm bin)/proto-loader-gen-types --longs=String --enums=String --defaults --oneofs --grpcLib=@grpc/grpc-js --outDir=proto/ proto/*.proto
+```
+
+Consume the types:
+
+```ts
+import * as grpc from '@grpc/grpc-js';
+import * as protoLoader from '@grpc/proto-loader';
+import { ProtoGrpcType } from './proto/example';
+import { ExampleHandlers } from './proto/example_package/Example';
+
+const exampleServer: ExampleHandlers = {
+  // server handlers implementation...
+};
+
+const packageDefinition = protoLoader.loadSync('./proto/example.proto');
+const proto = (grpc.loadPackageDefinition(
+  packageDefinition
+) as unknown) as ProtoGrpcType;
+
+const server = new grpc.Server();
+server.addService(proto.example_package.Example.service, exampleServer);
+```