feat: stream rendering, closed #361 fixes #360

src/render/render.ts

@@ -1,23 +1,34 @@
 import { RenderError } from '../util/error'
 import { Context } from '../context/context'
 import { Template } from '../template/template'
-import { Emitter } from './emitter'
+import { Emitter } from '../emitters/emitter'
+import { SimpleEmitter } from '../emitters/simple-emitter'
+import { StreamedEmitter } from '../emitters/streamed-emitter'
+import { toThenable } from '../util/async'
+import { KeepingTypeEmitter } from '../emitters/keeping-type-emitter'
 
 export class Render {
+  public renderTemplatesToNodeStream (templates: Template[], ctx: Context): NodeJS.ReadableStream {
+    const emitter = new StreamedEmitter()
+    toThenable(this.renderTemplates(templates, ctx, emitter))
+    return emitter.stream
+  }
   public * renderTemplates (templates: Template[], ctx: Context, emitter?: Emitter): IterableIterator<any> {
     if (!emitter) {
-      emitter = new Emitter(ctx.opts.keepOutputType)
+      emitter = ctx.opts.keepOutputType ? new KeepingTypeEmitter() : new SimpleEmitter()
     }
     for (const tpl of templates) {
       try {
+        // if tpl.render supports emitter, it'll return empty `html`
         const html = yield tpl.render(ctx, emitter)
+        // if not, it'll return an `html`, write to the emitter for it
         html && emitter.write(html)
-        if (emitter.break || emitter.continue) break
+        if (emitter['break'] || emitter['continue']) break
       } catch (e) {
         const err = RenderError.is(e) ? e : new RenderError(e, tpl)
         throw err
       }
     }
-    return emitter.html
+    return emitter.end()
   }
 }