Add wrapper around the ServerFormatConfig for legacy mode

This ensures that we can inject custom overrides without negatively
affecting the new implementation.

This adds another field for static mark up for example.

packages/react-dom/src/server/ReactDOMLegacyServerBrowser.js

@@ -22,7 +22,7 @@ import {
 import {
   createResponseState,
   createRootFormatContext,
-} from './ReactDOMServerFormatConfig';
+} from './ReactDOMServerLegacyFormatConfig';
 
 type ServerOptions = {
   identifierPrefix?: string,
@@ -59,7 +59,7 @@ function renderToString(
   const request = createRequest(
     children,
     destination,
-    createResponseState(options ? options.identifierPrefix : undefined),
+    createResponseState(false, options ? options.identifierPrefix : undefined),
     createRootFormatContext(undefined),
     Infinity,
     onError,

packages/react-dom/src/server/ReactDOMLegacyServerNode.js

@@ -21,7 +21,7 @@ import {
 import {
   createResponseState,
   createRootFormatContext,
-} from './ReactDOMServerFormatConfig';
+} from './ReactDOMServerLegacyFormatConfig';
 
 import {
   version,
@@ -77,7 +77,7 @@ function renderToNodeStream(
   const request = createRequest(
     children,
     destination,
-    createResponseState(options ? options.identifierPrefix : undefined),
+    createResponseState(false, options ? options.identifierPrefix : undefined),
     createRootFormatContext(undefined),
     Infinity,
     onError,

packages/react-dom/src/server/ReactDOMLegacyServerStreamConfig.js

@@ -16,8 +16,6 @@ export type Destination = {
 export type PrecomputedChunk = string;
 export type Chunk = string;
 
-export const isPrimaryStreamConfig = false;
-
 export function scheduleWork(callback: () => void) {
   callback();
 }

packages/react-dom/src/server/ReactDOMServerFormatConfig.js

@@ -23,7 +23,6 @@ import {
   writeChunk,
   stringToChunk,
   stringToPrecomputedChunk,
-  isPrimaryStreamConfig,
 } from 'react-server/src/ReactServerStreamConfig';
 
 import {
@@ -51,7 +50,7 @@ import isArray from 'shared/isArray';
 
 // Used to distinguish these contexts from ones used in other renderers.
 // E.g. this can be used to distinguish legacy renderers from this modern one.
-export const isPrimaryRenderer = isPrimaryStreamConfig;
+export const isPrimaryRenderer = true;
 
 // Per response, global state that is not contextual to the rendering subtree.
 export type ResponseState = {
@@ -63,18 +62,20 @@ export type ResponseState = {
   nextOpaqueID: number,
   sentCompleteSegmentFunction: boolean,
   sentCompleteBoundaryFunction: boolean,
-  sentClientRenderFunction: boolean,
+  sentClientRenderFunction: boolean, // We allow the legacy renderer to extend this object.
+  ...
 };
 
 // Allows us to keep track of what we've already written so we can refer back to it.
 export function createResponseState(
-  identifierPrefix: string = '',
+  identifierPrefix: string | void,
 ): ResponseState {
+  const idPrefix = identifierPrefix === undefined ? '' : identifierPrefix;
   return {
-    placeholderPrefix: stringToPrecomputedChunk(identifierPrefix + 'P:'),
-    segmentPrefix: stringToPrecomputedChunk(identifierPrefix + 'S:'),
-    boundaryPrefix: identifierPrefix + 'B:',
-    opaqueIdentifierPrefix: identifierPrefix + 'R:',
+    placeholderPrefix: stringToPrecomputedChunk(idPrefix + 'P:'),
+    segmentPrefix: stringToPrecomputedChunk(idPrefix + 'S:'),
+    boundaryPrefix: idPrefix + 'B:',
+    opaqueIdentifierPrefix: idPrefix + 'R:',
     nextSuspenseID: 0,
     nextOpaqueID: 0,
     sentCompleteSegmentFunction: false,

packages/react-dom/src/server/ReactDOMServerLegacyFormatConfig.js

@@ -0,0 +1,77 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @flow
+ */
+
+import {createResponseState as createResponseStateImpl} from './ReactDOMServerFormatConfig';
+
+import type {PrecomputedChunk} from 'react-server/src/ReactServerStreamConfig';
+
+export const isPrimaryRenderer = false;
+
+export type ResponseState = {
+  // Keep this in sync with ReactDOMServerFormatConfig
+  placeholderPrefix: PrecomputedChunk,
+  segmentPrefix: PrecomputedChunk,
+  boundaryPrefix: string,
+  opaqueIdentifierPrefix: string,
+  nextSuspenseID: number,
+  nextOpaqueID: number,
+  sentCompleteSegmentFunction: boolean,
+  sentCompleteBoundaryFunction: boolean,
+  sentClientRenderFunction: boolean,
+  // This is an extra field for the legacy renderer
+  generateStaticMarkup: boolean,
+};
+
+export function createResponseState(
+  generateStaticMarkup: boolean,
+  identifierPrefix: string | void,
+): ResponseState {
+  const responseState = createResponseStateImpl(identifierPrefix);
+  return {
+    // Keep this in sync with ReactDOMServerFormatConfig
+    placeholderPrefix: responseState.placeholderPrefix,
+    segmentPrefix: responseState.segmentPrefix,
+    boundaryPrefix: responseState.boundaryPrefix,
+    opaqueIdentifierPrefix: responseState.opaqueIdentifierPrefix,
+    nextSuspenseID: responseState.nextSuspenseID,
+    nextOpaqueID: responseState.nextOpaqueID,
+    sentCompleteSegmentFunction: responseState.sentCompleteSegmentFunction,
+    sentCompleteBoundaryFunction: responseState.sentCompleteBoundaryFunction,
+    sentClientRenderFunction: responseState.sentClientRenderFunction,
+    // This is an extra field for the legacy renderer
+    generateStaticMarkup,
+  };
+}
+
+export type {
+  FormatContext,
+  SuspenseBoundaryID,
+  OpaqueIDType,
+} from './ReactDOMServerFormatConfig';
+
+export {
+  createRootFormatContext,
+  getChildFormatContext,
+  createSuspenseBoundaryID,
+  makeServerID,
+  pushEmpty,
+  pushTextInstance,
+  pushStartInstance,
+  pushEndInstance,
+  writePlaceholder,
+  writeStartCompletedSuspenseBoundary,
+  writeStartPendingSuspenseBoundary,
+  writeStartClientRenderedSuspenseBoundary,
+  writeEndSuspenseBoundary,
+  writeStartSegment,
+  writeEndSegment,
+  writeCompletedSegmentInstruction,
+  writeCompletedBoundaryInstruction,
+  writeClientRenderBoundaryInstruction,
+} from './ReactDOMServerFormatConfig';

packages/react-server-dom-relay/src/ReactServerStreamConfigFB.js

@@ -17,8 +17,6 @@ export type Destination = {
 export type PrecomputedChunk = string;
 export type Chunk = string;
 
-export const isPrimaryStreamConfig = true;
-
 export function scheduleWork(callback: () => void) {
   // We don't schedule work in this model, and instead expect performWork to always be called repeatedly.
 }

packages/react-server/src/ReactServerStreamConfigBrowser.js

@@ -12,8 +12,6 @@ export type Destination = ReadableStreamController;
 export type PrecomputedChunk = Uint8Array;
 export type Chunk = Uint8Array;
 
-export const isPrimaryStreamConfig = true;
-
 export function scheduleWork(callback: () => void) {
   callback();
 }

packages/react-server/src/ReactServerStreamConfigNode.js

@@ -19,8 +19,6 @@ export type Destination = Writable & MightBeFlushable;
 export type PrecomputedChunk = Uint8Array;
 export type Chunk = string;
 
-export const isPrimaryStreamConfig = true;
-
 export function scheduleWork(callback: () => void) {
   setImmediate(callback);
 }

packages/react-server/src/forks/ReactServerFormatConfig.dom-legacy.js

@@ -7,4 +7,4 @@
  * @flow
  */
 
-export * from 'react-dom/src/server/ReactDOMServerFormatConfig';
+export * from 'react-dom/src/server/ReactDOMServerLegacyFormatConfig';