make emitters async generators

quartz/processors/emit.ts

@@ -14,20 +14,34 @@ export async function emitContent(ctx: BuildCtx, content: ProcessedContent[]) {
 
   let emittedFiles = 0
   const staticResources = getStaticResourcesFromPlugins(ctx)
-  for (const emitter of cfg.plugins.emitters) {
-    try {
-      const emitted = await emitter.emit(ctx, content, staticResources)
-      emittedFiles += emitted.length
-
-      if (ctx.argv.verbose) {
-        for (const file of emitted) {
-          console.log(`[emit:${emitter.name}] ${file}`)
+  await Promise.all(
+    cfg.plugins.emitters.map(async (emitter) => {
+      try {
+        const emitted = await emitter.emit(ctx, content, staticResources)
+        if (Symbol.asyncIterator in emitted) {
+          // Async generator case
+          const files: string[] = []
+          for await (const file of emitted) {
+            files.push(file)
+            emittedFiles++
+            if (ctx.argv.verbose) {
+              console.log(`[emit:${emitter.name}] ${file}`)
+            }
+          }
+        } else {
+          // Array case
+          emittedFiles += emitted.length
+          if (ctx.argv.verbose) {
+            for (const file of emitted) {
+              console.log(`[emit:${emitter.name}] ${file}`)
+            }
+          }
         }
+      } catch (err) {
+        trace(`Failed to emit from plugin \`${emitter.name}\``, err as Error)
       }
-    } catch (err) {
-      trace(`Failed to emit from plugin \`${emitter.name}\``, err as Error)
-    }
-  }
+    }),
+  )
 
   log.end(`Emitted ${emittedFiles} files to \`${argv.output}\` in ${perf.timeSince()}`)
 }