various

Author: Rich-Harris

packages/svelte/src/compiler/phases/2-analyze/index.js

@@ -266,7 +266,7 @@ export function analyze_module(ast, options) {
 		immutable: true,
 		tracing: analysis.tracing,
 		async_deriveds: new Set(),
-		blocking_awaits: new Set()
+		suspenders: new Set()
 	};
 }
 
@@ -455,7 +455,7 @@ export function analyze_component(root, source, options) {
 		snippets: new Set(),
 		is_async: false,
 		async_deriveds: new Set(),
-		blocking_awaits: new Set()
+		suspenders: new Set()
 	};
 
 	if (!runes) {

packages/svelte/src/compiler/phases/2-analyze/visitors/AwaitExpression.js

@@ -14,7 +14,7 @@ export function AwaitExpression(node, context) {
 			throw new Error('TODO runes mode only');
 		}
 
-		context.state.analysis.blocking_awaits.add(node);
+		context.state.analysis.suspenders.add(node);
 	}
 
 	if (context.state.expression) {

packages/svelte/src/compiler/phases/2-analyze/visitors/CallExpression.js

@@ -219,6 +219,9 @@ export function CallExpression(node, context) {
 
 		if (expression.is_async) {
 			context.state.analysis.async_deriveds.add(node);
+
+			context.state.analysis.is_async ||=
+				context.state.ast_type === 'instance' && context.state.function_depth === 1;
 		}
 	} else if (rune === '$inspect') {
 		context.next({ ...context.state, function_depth: context.state.function_depth + 1 });

packages/svelte/src/compiler/phases/3-transform/client/visitors/AwaitExpression.js

@@ -7,22 +7,21 @@ import * as b from '../../../../utils/builders.js';
  * @param {ComponentContext} context
  */
 export function AwaitExpression(node, context) {
-	if (!context.state.analysis.runes) {
+	const suspend = context.state.analysis.suspenders.has(node);
+
+	if (!suspend) {
 		return context.next();
 	}
 
-	const block = context.state.analysis.blocking_awaits.has(node);
-
 	return b.call(
 		b.member(
 			b.await(
 				b.call(
-					'$.preserve_context',
-					node.argument && /** @type {Expression} */ (context.visit(node.argument)),
-					block && b.true
+					'$.suspend',
+					node.argument && /** @type {Expression} */ (context.visit(node.argument))
 				)
 			),
-			'read'
+			'exit'
 		)
 	);
 }

packages/svelte/src/compiler/phases/types.d.ts

@@ -43,7 +43,7 @@ export interface Analysis {
 	async_deriveds: Set<CallExpression>;
 
 	/** A set of `await` expressions that should trigger suspense */
-	blocking_awaits: Set<AwaitExpression>;
+	suspenders: Set<AwaitExpression>;
 }
 
 export interface ComponentAnalysis extends Analysis {

packages/svelte/src/internal/client/dom/blocks/boundary.js

@@ -247,15 +247,14 @@ export function trigger_async_boundary(effect, trigger) {
 /**
  * @template T
  * @param {Promise<T>} promise
- * @param {boolean} block
- * @returns {Promise<{ read: () => T }>}
+ * @returns {Promise<{ exit: () => T }>}
  */
-export function preserve_context(promise, block = false) {
+export async function suspend(promise) {
 	var previous_effect = active_effect;
 	var previous_reaction = active_reaction;
 	var previous_component_context = component_context;
 
-	let boundary = block ? active_effect : null;
+	let boundary = active_effect;
 	while (boundary !== null) {
 		if ((boundary.f & BOUNDARY_EFFECT) !== 0) {
 			break;
@@ -264,25 +263,25 @@ export function preserve_context(promise, block = false) {
 		boundary = boundary.parent;
 	}
 
-	if (block && boundary === null) {
+	if (boundary === null) {
 		throw new Error('cannot suspend outside a boundary');
 	}
 
 	// @ts-ignore
 	boundary?.fn(ASYNC_INCREMENT);
 
-	return promise.then((value) => {
-		return {
-			read() {
-				set_active_effect(previous_effect);
-				set_active_reaction(previous_reaction);
-				set_component_context(previous_component_context);
+	const value = await promise;
 
-				// @ts-ignore
-				boundary?.fn(ASYNC_DECREMENT);
+	return {
+		exit() {
+			set_active_effect(previous_effect);
+			set_active_reaction(previous_reaction);
+			set_component_context(previous_component_context);
 
-				return value;
-			}
-		};
-	});
+			// @ts-ignore
+			boundary?.fn(ASYNC_DECREMENT);
+
+			return value;
+		}
+	};
 }

packages/svelte/src/internal/client/index.js

@@ -129,7 +129,7 @@ export {
 	update_store,
 	mark_store_binding
 } from './reactivity/store.js';
-export { boundary, preserve_context } from './dom/blocks/boundary.js';
+export { boundary, suspend } from './dom/blocks/boundary.js';
 export { set_text } from './render.js';
 export {
 	get,

packages/svelte/src/internal/client/reactivity/deriveds.js

@@ -27,7 +27,7 @@ import { destroy_effect, render_effect } from './effects.js';
 import { inspect_effects, internal_set, set_inspect_effects, source } from './sources.js';
 import { get_stack } from '../dev/tracing.js';
 import { tracing_mode_flag } from '../../flags/index.js';
-import { preserve_context } from '../dom/blocks/boundary.js';
+import { suspend } from '../dom/blocks/boundary.js';
 
 /**
  * @template V
@@ -103,7 +103,9 @@ export async function async_derived(fn) {
 		// TODO what happens when the promise rejects?
 	});
 
-	(await preserve_context(promise)).read();
+	// wait for the initial promise
+	(await suspend(promise)).exit();
+
 	return () => get(value);
 }