feat: support useReadonlyTypes option (#691)

* Add readonly attribute

* Add option for readonly

* Update options test snapshot to account for new option

* Add tests

* Enable test

* Add more fields

* Readonly arrays

* Add well known types

* Fix fieldmask

* Support struct

* Fix test

* Use inline tenary

* Add readonly

* Add docs

* Update options snapshot

* Revert prettier formatting in readme

* Delete unused file

* Use ternary

README.markdown

@@ -462,6 +462,8 @@ Generated code will be placed in the Gradle build directory.
 
   The default behavior is `useMapType=false`, which makes it generate the code for protobuf `map<key_type, value_type` with the key-value pair like `{[key: key_type]: value_type}`.
 
+- With `--ts_proto_opt=useReadonlyTypes=true`, the generated types will be declared as immutable using typescript's `readonly` modifer.
+
 ### NestJS Support
 
 We have a great way of working together with [nestjs](https://docs.nestjs.com/microservices/grpc). `ts-proto` generates `interfaces` and `decorators` for you controller, client. For more information see the [nestjs readme](NESTJS.markdown).

integration/use-readonly-types/google/protobuf/field_mask.ts

@@ -0,0 +1,283 @@
+/* eslint-disable */
+import * as _m0 from "protobufjs/minimal";
+
+export const protobufPackage = "google.protobuf";
+
+/**
+ * `FieldMask` represents a set of symbolic field paths, for example:
+ *
+ *     paths: "f.a"
+ *     paths: "f.b.d"
+ *
+ * Here `f` represents a field in some root message, `a` and `b`
+ * fields in the message found in `f`, and `d` a field found in the
+ * message in `f.b`.
+ *
+ * Field masks are used to specify a subset of fields that should be
+ * returned by a get operation or modified by an update operation.
+ * Field masks also have a custom JSON encoding (see below).
+ *
+ * # Field Masks in Projections
+ *
+ * When used in the context of a projection, a response message or
+ * sub-message is filtered by the API to only contain those fields as
+ * specified in the mask. For example, if the mask in the previous
+ * example is applied to a response message as follows:
+ *
+ *     f {
+ *       a : 22
+ *       b {
+ *         d : 1
+ *         x : 2
+ *       }
+ *       y : 13
+ *     }
+ *     z: 8
+ *
+ * The result will not contain specific values for fields x,y and z
+ * (their value will be set to the default, and omitted in proto text
+ * output):
+ *
+ *     f {
+ *       a : 22
+ *       b {
+ *         d : 1
+ *       }
+ *     }
+ *
+ * A repeated field is not allowed except at the last position of a
+ * paths string.
+ *
+ * If a FieldMask object is not present in a get operation, the
+ * operation applies to all fields (as if a FieldMask of all fields
+ * had been specified).
+ *
+ * Note that a field mask does not necessarily apply to the
+ * top-level response message. In case of a REST get operation, the
+ * field mask applies directly to the response, but in case of a REST
+ * list operation, the mask instead applies to each individual message
+ * in the returned resource list. In case of a REST custom method,
+ * other definitions may be used. Where the mask applies will be
+ * clearly documented together with its declaration in the API.  In
+ * any case, the effect on the returned resource/resources is required
+ * behavior for APIs.
+ *
+ * # Field Masks in Update Operations
+ *
+ * A field mask in update operations specifies which fields of the
+ * targeted resource are going to be updated. The API is required
+ * to only change the values of the fields as specified in the mask
+ * and leave the others untouched. If a resource is passed in to
+ * describe the updated values, the API ignores the values of all
+ * fields not covered by the mask.
+ *
+ * If a repeated field is specified for an update operation, new values will
+ * be appended to the existing repeated field in the target resource. Note that
+ * a repeated field is only allowed in the last position of a `paths` string.
+ *
+ * If a sub-message is specified in the last position of the field mask for an
+ * update operation, then new value will be merged into the existing sub-message
+ * in the target resource.
+ *
+ * For example, given the target message:
+ *
+ *     f {
+ *       b {
+ *         d: 1
+ *         x: 2
+ *       }
+ *       c: [1]
+ *     }
+ *
+ * And an update message:
+ *
+ *     f {
+ *       b {
+ *         d: 10
+ *       }
+ *       c: [2]
+ *     }
+ *
+ * then if the field mask is:
+ *
+ *  paths: ["f.b", "f.c"]
+ *
+ * then the result will be:
+ *
+ *     f {
+ *       b {
+ *         d: 10
+ *         x: 2
+ *       }
+ *       c: [1, 2]
+ *     }
+ *
+ * An implementation may provide options to override this default behavior for
+ * repeated and message fields.
+ *
+ * In order to reset a field's value to the default, the field must
+ * be in the mask and set to the default value in the provided resource.
+ * Hence, in order to reset all fields of a resource, provide a default
+ * instance of the resource and set all fields in the mask, or do
+ * not provide a mask as described below.
+ *
+ * If a field mask is not present on update, the operation applies to
+ * all fields (as if a field mask of all fields has been specified).
+ * Note that in the presence of schema evolution, this may mean that
+ * fields the client does not know and has therefore not filled into
+ * the request will be reset to their default. If this is unwanted
+ * behavior, a specific service may require a client to always specify
+ * a field mask, producing an error if not.
+ *
+ * As with get operations, the location of the resource which
+ * describes the updated values in the request message depends on the
+ * operation kind. In any case, the effect of the field mask is
+ * required to be honored by the API.
+ *
+ * ## Considerations for HTTP REST
+ *
+ * The HTTP kind of an update operation which uses a field mask must
+ * be set to PATCH instead of PUT in order to satisfy HTTP semantics
+ * (PUT must only be used for full updates).
+ *
+ * # JSON Encoding of Field Masks
+ *
+ * In JSON, a field mask is encoded as a single string where paths are
+ * separated by a comma. Fields name in each path are converted
+ * to/from lower-camel naming conventions.
+ *
+ * As an example, consider the following message declarations:
+ *
+ *     message Profile {
+ *       User user = 1;
+ *       Photo photo = 2;
+ *     }
+ *     message User {
+ *       string display_name = 1;
+ *       string address = 2;
+ *     }
+ *
+ * In proto a field mask for `Profile` may look as such:
+ *
+ *     mask {
+ *       paths: "user.display_name"
+ *       paths: "photo"
+ *     }
+ *
+ * In JSON, the same mask is represented as below:
+ *
+ *     {
+ *       mask: "user.displayName,photo"
+ *     }
+ *
+ * # Field Masks and Oneof Fields
+ *
+ * Field masks treat fields in oneofs just as regular fields. Consider the
+ * following message:
+ *
+ *     message SampleMessage {
+ *       oneof test_oneof {
+ *         string name = 4;
+ *         SubMessage sub_message = 9;
+ *       }
+ *     }
+ *
+ * The field mask can be:
+ *
+ *     mask {
+ *       paths: "name"
+ *     }
+ *
+ * Or:
+ *
+ *     mask {
+ *       paths: "sub_message"
+ *     }
+ *
+ * Note that oneof type names ("test_oneof" in this case) cannot be used in
+ * paths.
+ *
+ * ## Field Mask Verification
+ *
+ * The implementation of any API method which has a FieldMask type field in the
+ * request should verify the included field paths, and return an
+ * `INVALID_ARGUMENT` error if any path is unmappable.
+ */
+export interface FieldMask {
+  /** The set of field mask paths. */
+  readonly paths: readonly string[];
+}
+
+function createBaseFieldMask(): FieldMask {
+  return { paths: [] };
+}
+
+export const FieldMask = {
+  encode(message: FieldMask, writer: _m0.Writer = _m0.Writer.create()): _m0.Writer {
+    for (const v of message.paths) {
+      writer.uint32(10).string(v!);
+    }
+    return writer;
+  },
+
+  decode(input: _m0.Reader | Uint8Array, length?: number): FieldMask {
+    const reader = input instanceof _m0.Reader ? input : new _m0.Reader(input);
+    let end = length === undefined ? reader.len : reader.pos + length;
+    const message = createBaseFieldMask() as any;
+    while (reader.pos < end) {
+      const tag = reader.uint32();
+      switch (tag >>> 3) {
+        case 1:
+          message.paths.push(reader.string());
+          break;
+        default:
+          reader.skipType(tag & 7);
+          break;
+      }
+    }
+    return message;
+  },
+
+  fromJSON(object: any): FieldMask {
+    return {
+      paths: typeof (object) === "string"
+        ? object.split(",").filter(Boolean)
+        : Array.isArray(object?.paths)
+        ? object.paths.map(String)
+        : [],
+    };
+  },
+
+  toJSON(message: FieldMask): string {
+    return message.paths.join(",");
+  },
+
+  fromPartial<I extends Exact<DeepPartial<FieldMask>, I>>(object: I): FieldMask {
+    const message = createBaseFieldMask() as any;
+    message.paths = object.paths?.map((e) => e) || [];
+    return message;
+  },
+
+  wrap(paths: readonly string[]): FieldMask {
+    const result = createBaseFieldMask() as any;
+
+    result.paths = paths;
+
+    return result;
+  },
+
+  unwrap(message: any): string[] {
+    return message.paths;
+  },
+};
+
+type Builtin = Date | Function | Uint8Array | string | number | boolean | undefined;
+
+export type DeepPartial<T> = T extends Builtin ? T
+  : T extends Array<infer U> ? Array<DeepPartial<U>> : T extends ReadonlyArray<infer U> ? ReadonlyArray<DeepPartial<U>>
+  : T extends {} ? { [K in keyof T]?: DeepPartial<T[K]> }
+  : Partial<T>;
+
+type KeysOfUnion<T> = T extends T ? keyof T : never;
+export type Exact<P, I extends P> = P extends Builtin ? P
+  : P & { [K in keyof P]: Exact<P[K], I[K]> } & { [K in Exclude<keyof I, KeysOfUnion<P>>]: never };