update compiler output for empty messages (#101)

Co-authored-by: Tate <[email protected]>

Author: tatethurston

README.md

@@ -581,6 +581,8 @@ TwirpScript aims to be zero config, but can be configured by creating a `.twirp.
   ```protobuf
   import "B.proto";
   ```
+ 
+  TypeScript projects will generally want to set this value to match their `rootDir`, particularly when using [Protocol Buffers Well-Known Types](https://developers.google.com/protocol-buffers/docs/reference/google.protobuf) so that the generated well-known type files are under the `rootDir`.
 </td>
 <td>string (filepath)</td>
 </tr>

clientcompat/src/clientcompat.pb.ts

@@ -134,14 +134,14 @@ export const Empty = {
    * Serializes a Empty to protobuf.
    */
   encode: function (empty: Partial<Empty>): Uint8Array {
-    return Empty._writeMessage(empty, new BinaryWriter()).getResultBuffer();
+    return new Uint8Array();
   },
 
   /**
    * Deserializes a Empty from protobuf.
    */
   decode: function (bytes: ByteSource): Empty {
-    return Empty._readMessage(Empty.initialize(), new BinaryReader(bytes));
+    return {};
   },
 
   /**
@@ -150,32 +150,6 @@ export const Empty = {
   initialize: function (): Empty {
     return {};
   },
-
-  /**
-   * @private
-   */
-  _writeMessage: function (
-    msg: Partial<Empty>,
-    writer: BinaryWriter
-  ): BinaryWriter {
-    return writer;
-  },
-
-  /**
-   * @private
-   */
-  _readMessage: function (msg: Empty, reader: BinaryReader): Empty {
-    while (reader.nextField()) {
-      const field = reader.getFieldNumber();
-      switch (field) {
-        default: {
-          reader.skipField();
-          break;
-        }
-      }
-    }
-    return msg;
-  },
 };
 
 export const Req = {

src/autogenerate/index.ts

@@ -73,16 +73,23 @@ function writeSerializers(types: ProtoTypes[], isTopLevel = true): string {
 
     switch (node.type) {
       case "message": {
+        const isEmpty = node.content.fields.length === 0;
+
         result += `\
         /**
          * Serializes a ${node.content.fullyQualifiedName} to protobuf.
          */
         encode: function(${lowerCase(node.content.name)}${printIfTypescript(
           `: Partial<${node.content.fullyQualifiedName}>`
         )})${printIfTypescript(`: Uint8Array`)} {
+          ${
+            isEmpty
+              ? "return new Uint8Array();"
+              : `
           return ${node.content.fullyQualifiedName}._writeMessage(${lowerCase(
-          node.content.name
-        )}, new BinaryWriter()).getResultBuffer();
+                  node.content.name
+                )}, new BinaryWriter()).getResultBuffer();`
+          }
         },
 
         /**
@@ -91,9 +98,13 @@ function writeSerializers(types: ProtoTypes[], isTopLevel = true): string {
         decode: function(bytes${printIfTypescript(
           `: ByteSource`
         )})${printIfTypescript(`: ${node.content.fullyQualifiedName}`)} {
-          return ${node.content.fullyQualifiedName}._readMessage(${
-          node.content.fullyQualifiedName
-        }.initialize(), new BinaryReader(bytes));
+          ${
+            isEmpty
+              ? "return {};"
+              : `
+          return ${node.content.fullyQualifiedName}._readMessage(${node.content.fullyQualifiedName}.initialize(), new BinaryReader(bytes));
+        `
+          }
         },
 
         /**
@@ -119,14 +130,16 @@ function writeSerializers(types: ProtoTypes[], isTopLevel = true): string {
           };
         },
 
-        /**
+        ${printIf(
+          !isEmpty,
+          `/**
          * @private
          */
         _writeMessage: function(msg ${printIfTypescript(
           `: Partial<${node.content.fullyQualifiedName}>`
         )}, writer${printIfTypescript(`: BinaryWriter`)})${printIfTypescript(
-          `: BinaryWriter`
-        )} {
+            `: BinaryWriter`
+          )} {
           ${node.content.fields
             .map((field) => {
               let res = "";
@@ -177,8 +190,8 @@ function writeSerializers(types: ProtoTypes[], isTopLevel = true): string {
         _readMessage: function(msg${printIfTypescript(
           `: ${node.content.fullyQualifiedName}`
         )}, reader${printIfTypescript(`: BinaryReader`)})${printIfTypescript(
-          `: ${node.content.fullyQualifiedName} `
-        )}{
+            `: ${node.content.fullyQualifiedName} `
+          )}{
           while (reader.nextField()) {
             const field = reader.getFieldNumber();
             switch (field) {
@@ -248,7 +261,8 @@ function writeSerializers(types: ProtoTypes[], isTopLevel = true): string {
             }
           }
           return msg;
-        },
+        },`
+        )}
 
       `;
         const childrenWithouMaps = node.children.filter(
@@ -430,7 +444,11 @@ function writeServers(
 
 let isTS = false;
 function printIfTypescript(str: string): string {
-  return isTS ? str : "";
+  return printIf(isTS, str);
+}
+
+function printIf(cond: boolean, str: string): string {
+  return cond ? str : "";
 }
 
 export function generate(
@@ -451,29 +469,30 @@ export function generate(
   }
 
   const hasServices = services.length > 0;
+  const hasTypes = types.length > 0;
 
   return `\
 // THIS IS AN AUTOGENERATED FILE. DO NOT EDIT THIS FILE DIRECTLY.
 // Source: ${sourceFile}
 
-${printIfTypescript(
-  `import type { ByteSource ${
-    hasServices ? ", ClientConfiguration" : ""
-  }} from 'twirpscript';`
-)};
+
+${printIf(
+  isTS && (hasServices || hasTypes),
+  `import type {
+    ${printIf(hasTypes, "ByteSource,\n")}
+    ${printIf(hasServices, "ClientConfiguration")}} from 'twirpscript';`
+)}
 import {
-  BinaryReader,
-  BinaryWriter
-  ${hasServices ? `,\nJSONrequest,\nPBrequest` : ""}} from 'twirpscript';
-  ${
-    hasServices
-      ? `\
+  ${printIf(hasTypes, "BinaryReader,\nBinaryWriter,\n")}
+  ${printIf(hasServices, "JSONrequest,\nPBrequest")}} from 'twirpscript';
+  ${printIf(
+    hasServices,
+    `\
 // This is the minimum version supported by the current runtime.
 // If this line fails typechecking, breaking changes have been introduced and this
 // file needs to be regenerated by running \`yarn twirpscript\`.
 export { ${RUNTIME_MIN_CODE_GEN_SUPPORTED_VERSION} } from "twirpscript";`
-      : ""
-  }
+  )}
 
 ${imports
   .map(
@@ -486,10 +505,12 @@ ${writeClients(services, packageName)}
 
 ${writeServers(services, packageName)}
 
-${printIfTypescript(printHeading("Types"))}
+${printIf(
+  hasTypes,
+  `${printIfTypescript(printHeading("Types"))}
 ${printIfTypescript(writeTypes(types))}
-
 ${printHeading("Protobuf Encode / Decode")}
-${writeSerializers(types)}
+${writeSerializers(types)}`
+)}
 `;
 }

src/cli/index.ts

@@ -60,6 +60,8 @@ type Config = {
    * ```proto
    * import "B.proto";
    * ```
+   *
+   * TypeScript projects will generally want to set this value to match their `rootDir`, particularly when using [Protocol Buffers Well-Known Types](https://developers.google.com/protocol-buffers/docs/reference/google.protobuf) so that the generated well-known type files are under the `rootDir`.
    */
   root: string;
   /** The destination folder for generated files.