WIP

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

@@ -27,17 +27,21 @@ export function build_set_attributes(
 	element_id,
 	attributes_id
 ) {
-	let is_dynamic = false;
-
 	/** @type {ObjectExpression['properties']} */
 	const values = [];
 
+	/** @type {Expression[]} */
+	const expressions = [];
+
+	/** @param {Expression} value */
+	function memoize(value) {
+		return b.id(`$${expressions.push(value) - 1}`);
+	}
+
 	for (const attribute of attributes) {
 		if (attribute.type === 'Attribute') {
-			const { value, has_state } = build_attribute_value(
+			const { value } = build_attribute_value(attribute.value, context, (value, metadata) =>
-				attribute.value,
+				metadata.has_call ? memoize(value) : value
-				context,
-				(value, metadata) => (metadata.has_call ? get_expression_id(context.state, value) : value)
 			);
 
 			if (
@@ -51,16 +55,11 @@ export function build_set_attributes(
 			} else {
 				values.push(b.init(attribute.name, value));
 			}
-
-			is_dynamic ||= has_state;
 		} else {
-			// objects could contain reactive getters -> play it safe and always assume spread attributes are reactive
-			is_dynamic = true;
-
 			let value = /** @type {Expression} */ (context.visit(attribute));
 
 			if (attribute.metadata.expression.has_call) {
-				value = get_expression_id(context.state, value);
+				value = memoize(value);
 			}
 
 			values.push(b.spread(value));
@@ -75,9 +74,6 @@ export function build_set_attributes(
 				build_class_directives_object(class_directives, context)
 			)
 		);
-
-		is_dynamic ||=
-			class_directives.find((directive) => directive.metadata.expression.has_state) !== null;
 	}
 
 	if (style_directives.length) {
@@ -88,29 +84,25 @@ export function build_set_attributes(
 				build_style_directives_object(style_directives, context)
 			)
 		);
-
-		is_dynamic ||= style_directives.some((directive) => directive.metadata.expression.has_state);
 	}
 
-	const call = b.call(
+	context.state.init.push(
-		'$.set_attributes',
+		b.stmt(
-		element_id,
+			b.call(
-		is_dynamic ? attributes_id : b.null,
+				'$.set_attribute_effect',
-		b.object(values),
+				element_id,
-		element.metadata.scoped &&
+				b.arrow(
-			context.state.analysis.css.hash !== '' &&
+					expressions.map((_, i) => b.id(`$${i}`)),
-			b.literal(context.state.analysis.css.hash),
+					b.object(values)
-		is_ignored(element, 'hydration_attribute_changed') && b.true
+				),
+				expressions.length > 0 && b.array(expressions.map((expression) => b.thunk(expression))),
+				element.metadata.scoped &&
+					context.state.analysis.css.hash !== '' &&
+					b.literal(context.state.analysis.css.hash),
+				is_ignored(element, 'hydration_attribute_changed') && b.true
+			)
+		)
 	);
-
-	if (is_dynamic) {
-		context.state.init.push(
-			b.let(attributes_id),
-			b.stmt(b.call('$.set_attribute_effect', element_id, b.thunk(b.object(values))))
-		);
-	} else {
-		context.state.init.push(b.stmt(call));
-	}
 }
 
 /**

packages/svelte/src/internal/client/dom/elements/attributes.js

@@ -10,6 +10,7 @@ import { is_capture_event, is_delegated, normalize_attribute } from '../../../..
 import {
 	active_effect,
 	active_reaction,
+	get,
 	set_active_effect,
 	set_active_reaction
 } from '../../runtime.js';
@@ -19,6 +20,7 @@ import { set_class } from './class.js';
 import { set_style } from './style.js';
 import { ATTACHMENT_KEY, NAMESPACE_HTML } from '../../../../constants.js';
 import { block, branch, destroy_effect } from '../../reactivity/effects.js';
+import { derived } from '../../reactivity/deriveds.js';
 
 export const CLASS = Symbol('class');
 export const STYLE = Symbol('style');
@@ -448,22 +450,32 @@ export function set_attributes(element, prev, next, css_hash, skip_warning = fal
 		set_hydrating(true);
 	}
 
-	for (let symbol of Object.getOwnPropertySymbols(next)) {
+	// for (let symbol of Object.getOwnPropertySymbols(next)) {
-		if (symbol.description === ATTACHMENT_KEY) {
+	// 	if (symbol.description === ATTACHMENT_KEY) {
-			attach(element, () => next[symbol]);
+	// 		attach(element, () => next[symbol]);
-		}
+	// 	}
-	}
+	// }
 
 	return current;
 }
 
 /**
  * @param {Element & ElementCSSInlineStyle} element
- * @param {() => Record<string | symbol, any>} fn
+ * @param {(...expressions: any) => Record<string | symbol, any>} fn
+ * @param {Array<() => any>} thunks
  * @param {string} [css_hash]
  * @param {boolean} [skip_warning]
  */
-export function set_attribute_effect(element, fn, css_hash, skip_warning = false) {
+export function set_attribute_effect(
+	element,
+	fn,
+	thunks = [],
+	css_hash,
+	skip_warning = false,
+	d = derived
+) {
+	const deriveds = thunks.map(d);
+
 	/** @type {Record<string | symbol, any>} */
 	var prev = {};
 
@@ -471,24 +483,9 @@ export function set_attribute_effect(element, fn, css_hash, skip_warning = false
 	var effects = {};
 
 	block(() => {
-		var next = fn();
+		var next = fn(...deriveds.map(get));
-
-		for (const key in prev) {
-			if (!next[key]) {
-				element.removeAttribute(key);
-			}
-		}
 
-		for (let symbol of Object.getOwnPropertySymbols(prev)) {
+		set_attributes(element, prev, next, css_hash, skip_warning);
-			if (!next[symbol]) {
-				destroy_effect(effects[symbol]);
-				delete effects[symbol];
-			}
-		}
-
-		for (const key in next) {
-			set_attribute(element, key, next[key], skip_warning);
-		}
 
 		for (let symbol of Object.getOwnPropertySymbols(next)) {
 			if (symbol.description === ATTACHMENT_KEY && next[symbol] !== prev[symbol]) {