From e1d890a00277926ff6c2f162c03ab1dc79460838 Mon Sep 17 00:00:00 2001
From: Joel Chen <joel123@gmail.com>
Date: Tue, 31 Jul 2018 19:10:07 -0700
Subject: [PATCH] support stopping mid render

---
 .../lib/async-template.js                     |  2 +-
 .../lib/react-webapp.js                       | 14 ++++---
 .../lib/react/token-handlers.js               |  6 +--
 .../lib/render-context.js                     | 37 ++++++++++++++++---
 .../electrode-react-webapp/lib/renderer.js    | 13 +++++--
 5 files changed, 55 insertions(+), 17 deletions(-)

diff --git a/packages/electrode-react-webapp/lib/async-template.js b/packages/electrode-react-webapp/lib/async-template.js
index 6c7eae4ec..630467876 100644
--- a/packages/electrode-react-webapp/lib/async-template.js
+++ b/packages/electrode-react-webapp/lib/async-template.js
@@ -51,7 +51,7 @@ class AsyncTemplate {
       await r.beforeRender(context);
     }
 
-    const result = context.skip ? context.result : await this._renderer.render(context);
+    const result = await this._renderer.render(context);
 
     for (const r of this._afterRenders) {
       await r.afterRender(context);
diff --git a/packages/electrode-react-webapp/lib/react-webapp.js b/packages/electrode-react-webapp/lib/react-webapp.js
index e1fefc18c..ec9537879 100644
--- a/packages/electrode-react-webapp/lib/react-webapp.js
+++ b/packages/electrode-react-webapp/lib/react-webapp.js
@@ -12,12 +12,16 @@ const getStatsPath = utils.getStatsPath;
 
 function makeRouteHandler(routeOptions) {
   const userTokenHandlers = [].concat(routeOptions.tokenHandler, routeOptions.tokenHandlers);
-  const reactTokenHandlers = Path.join(__dirname, "react/token-handlers");
 
-  const tokenHandlers =
-    userTokenHandlers.indexOf(reactTokenHandlers) < 0
-      ? [reactTokenHandlers].concat(userTokenHandlers)
-      : userTokenHandlers;
+  let tokenHandlers = userTokenHandlers;
+
+  if (!routeOptions.replaceTokenHandlers) {
+    const reactTokenHandlers = Path.join(__dirname, "react/token-handlers");
+    tokenHandlers =
+      userTokenHandlers.indexOf(reactTokenHandlers) < 0
+        ? [reactTokenHandlers].concat(userTokenHandlers)
+        : userTokenHandlers;
+  }
 
   const asyncTemplate = new AsyncTemplate({
     htmlFile: routeOptions.htmlFile,
diff --git a/packages/electrode-react-webapp/lib/react/token-handlers.js b/packages/electrode-react-webapp/lib/react/token-handlers.js
index d21eebf77..00923e1ee 100644
--- a/packages/electrode-react-webapp/lib/react/token-handlers.js
+++ b/packages/electrode-react-webapp/lib/react/token-handlers.js
@@ -111,9 +111,9 @@ module.exports = function setup(handlerContext /* , asyncTemplate */) {
     }
 
     const prepareContext = content => {
-      if (content.render === false || content.html === undefined) {
-        return context.skipRender(content);
-      }
+      // if (content.render === false || content.html === undefined) {
+      //   return context.skipRender(content);
+      // }
 
       let cspScriptNonce;
       let cspStyleNonce;
diff --git a/packages/electrode-react-webapp/lib/render-context.js b/packages/electrode-react-webapp/lib/render-context.js
index d808f3156..9598b6df3 100644
--- a/packages/electrode-react-webapp/lib/render-context.js
+++ b/packages/electrode-react-webapp/lib/render-context.js
@@ -10,6 +10,7 @@ class RenderContext {
     this.asyncTemplate = asyncTemplate;
     this._handlersMap = asyncTemplate.handlersMap;
     this.transform = x => x;
+    this._stop = 0;
   }
 
   // return a token handler by name
@@ -34,11 +35,33 @@ class RenderContext {
     this.transform = result => transform(result, this);
   }
 
-  // before render starts, call this with any predetermined result
-  // to use as the output rather than doing actual render for it
-  // Basically no rendering will occur.
-  skipRender(result) {
-    this.skip = true;
+  get stop() {
+    return this._stop;
+  }
+
+  //
+  // set this any time to fully stop and close rendering
+  // stop modes:
+  // 1 - only process string tokens
+  // 2 - fully stop immediately, no more token processing
+  // 3 - completely void any render output and stop immediately,
+  //     replace output with result.  This only works if output
+  //     is buffered and not streaming out immediately.
+  //
+  set stop(f) {
+    this._stop = f;
+  }
+
+  fullStop() {
+    this.stop(RenderContext.FULL_STOP);
+  }
+
+  softStop() {
+    this.stop(RenderContext.SOFT_STOP);
+  }
+
+  voidStop(result) {
+    this.stop(RenderContext.VOID_STOP);
     this.result = result;
   }
 
@@ -67,4 +90,8 @@ class RenderContext {
   }
 }
 
+RenderContext.VOID_STOP = 3;
+RenderContext.FULL_STOP = 2;
+RenderContext.SOFT_STOP = 1;
+
 module.exports = RenderContext;
diff --git a/packages/electrode-react-webapp/lib/renderer.js b/packages/electrode-react-webapp/lib/renderer.js
index 52fce7d0c..eea87e283 100644
--- a/packages/electrode-react-webapp/lib/renderer.js
+++ b/packages/electrode-react-webapp/lib/renderer.js
@@ -3,6 +3,7 @@
 /* eslint-disable max-statements */
 
 const Promise = require("bluebird");
+const { VOID_STOP, FULL_STOP, SOFT_STOP } = require("./render-context");
 
 class Renderer {
   constructor(options) {
@@ -75,9 +76,15 @@ class Renderer {
   }
 
   _next(xt) {
-    return xt._tokenIndex >= this.renderSteps.length
-      ? xt.resolve(xt.context.output.close())
-      : this.renderSteps[xt._tokenIndex++](xt);
+    const stop = xt.context.stop;
+
+    if (stop === VOID_STOP || stop === FULL_STOP || xt._tokenIndex >= this.renderSteps.length) {
+      return xt.resolve(xt.context.output.close());
+    } else if (stop === SOFT_STOP) {
+      return false; // TODO: support soft stop
+    } else {
+      return this.renderSteps[xt._tokenIndex++](xt);
+    }
   }
 }