All files / src/compiler/phases/2-analyze/visitors Attribute.js

96.33% Statements 210/218
92.85% Branches 78/84
100% Functions 3/3
96.27% Lines 207/215

Press n or j to go to the next uncovered block, b, p or k for the previous block.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 2202x 2x 2x 2x         2x 2x 2x 2x 2x 2x 2x 2x 5726x 5726x 5726x 5726x 361x 361x 122x 122x 361x 5724x 5724x 5642x 5761x 2263x 2263x 2263x 2263x 5761x 522x 522x 1741x 1741x 1741x 1741x 5642x 5642x 667x 667x 605x 605x 667x 667x 667x 667x 667x 591x 459x 459x 591x 591x 591x 667x 5642x 5726x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 667x 667x 667x 24x 24x 643x 643x 643x 667x 52x 52x 591x 591x 591x 591x 591x 667x 10x 10x 10x 581x 667x 436x 667x 131x 131x 131x 8x 8x 8x 123x 123x 123x 235x 235x 235x 235x 235x 235x 235x 235x 235x 235x     235x 235x 235x 108x 235x 108x 108x 108x 108x 235x 235x 108x 108x 108x 108x 108x 2x 2x 235x 21x 21x 235x 100x 100x 100x 131x     100x 131x 96x 96x 96x 96x 96x 8x 96x 88x 88x 96x 131x 550x 550x 667x 26x 26x 524x 524x 524x 667x 804x 804x 804x 804x 796x 796x 796x 796x 796x 804x 2x 2x 794x 794x 794x 804x 804x 22x 804x     794x 794x 804x 788x 788x 804x 691x 691x 691x 691x 691x 691x 691x 804x 49x 49x 739x 739x 459x 459x 459x 2x 2x 2x 2x 108x 108x 108x     108x 108x  
/** @import { ArrowFunctionExpression, Expression, FunctionDeclaration, FunctionExpression } from 'estree' */
/** @import { AST, DelegatedEvent, SvelteNode } from '#compiler' */
/** @import { Context } from '../types' */
import { is_capture_event, is_delegated } from '../../../../utils.js';
import {
	get_attribute_chunks,
	get_attribute_expression,
	is_event_attribute
} from '../../../utils/ast.js';
import { mark_subtree_dynamic } from './shared/fragment.js';
 
/**
 * @param {AST.Attribute} node
 * @param {Context} context
 */
export function Attribute(node, context) {
	context.next();
 
	// special case
	if (node.name === 'value') {
		const parent = /** @type {SvelteNode} */ (context.path.at(-1));
		if (parent.type === 'RegularElement' && parent.name === 'option') {
			mark_subtree_dynamic(context.path);
		}
	}
 
	if (node.value !== true) {
		for (const chunk of get_attribute_chunks(node.value)) {
			if (chunk.type !== 'ExpressionTag') continue;
 
			if (
				chunk.expression.type === 'FunctionExpression' ||
				chunk.expression.type === 'ArrowFunctionExpression'
			) {
				continue;
			}
 
			node.metadata.expression.has_state ||= chunk.metadata.expression.has_state;
			node.metadata.expression.has_call ||= chunk.metadata.expression.has_call;
		}
 
		if (is_event_attribute(node)) {
			const parent = context.path.at(-1);
			if (parent?.type === 'RegularElement' || parent?.type === 'SvelteElement') {
				context.state.analysis.uses_event_attributes = true;
			}
 
			const expression = get_attribute_expression(node);
			const delegated_event = get_delegated_event(node.name.slice(2), expression, context);
 
			if (delegated_event !== null) {
				if (delegated_event.hoisted) {
					delegated_event.function.metadata.hoisted = true;
				}
 
				node.metadata.delegated = delegated_event;
			}
		}
	}
}
 
/** @type {DelegatedEvent} */
const unhoisted = { hoisted: false };
 
/**
 * Checks if given event attribute can be delegated/hoisted and returns the corresponding info if so
 * @param {string} event_name
 * @param {Expression | null} handler
 * @param {Context} context
 * @returns {null | DelegatedEvent}
 */
function get_delegated_event(event_name, handler, context) {
	// Handle delegated event handlers. Bail out if not a delegated event.
	if (!handler || !is_delegated(event_name)) {
		return null;
	}
 
	// If we are not working with a RegularElement, then bail out.
	const element = context.path.at(-1);
	if (element?.type !== 'RegularElement') {
		return null;
	}
 
	/** @type {FunctionExpression | FunctionDeclaration | ArrowFunctionExpression | null} */
	let target_function = null;
	let binding = null;
 
	if (element.metadata.has_spread) {
		// event attribute becomes part of the dynamic spread array
		return unhoisted;
	}
 
	if (handler.type === 'ArrowFunctionExpression' || handler.type === 'FunctionExpression') {
		target_function = handler;
	} else if (handler.type === 'Identifier') {
		binding = context.state.scope.get(handler.name);
 
		if (context.state.analysis.module.scope.references.has(handler.name)) {
			// If a binding with the same name is referenced in the module scope (even if not declared there), bail out
			return unhoisted;
		}
 
		if (binding != null) {
			for (const { path } of binding.references) {
				const parent = path.at(-1);
				if (parent === undefined) return unhoisted;
 
				const grandparent = path.at(-2);
 
				/** @type {AST.RegularElement | null} */
				let element = null;
				/** @type {string | null} */
				let event_name = null;
				if (parent.type === 'OnDirective') {
					element = /** @type {AST.RegularElement} */ (grandparent);
					event_name = parent.name;
				} else if (
					parent.type === 'ExpressionTag' &&
					grandparent?.type === 'Attribute' &&
					is_event_attribute(grandparent)
				) {
					element = /** @type {AST.RegularElement} */ (path.at(-3));
					const attribute = /** @type {AST.Attribute} */ (grandparent);
					event_name = get_attribute_event_name(attribute.name);
				}
 
				if (element && event_name) {
					if (
						element.type !== 'RegularElement' ||
						element.metadata.has_spread ||
						!is_delegated(event_name)
					) {
						return unhoisted;
					}
				} else if (parent.type !== 'FunctionDeclaration' && parent.type !== 'VariableDeclarator') {
					return unhoisted;
				}
			}
		}
 
		// If the binding is exported, bail out
		if (context.state.analysis.exports.find((node) => node.name === handler.name)) {
			return unhoisted;
		}
 
		if (binding !== null && binding.initial !== null && !binding.updated && !binding.is_called) {
			const binding_type = binding.initial.type;
 
			if (
				binding_type === 'ArrowFunctionExpression' ||
				binding_type === 'FunctionDeclaration' ||
				binding_type === 'FunctionExpression'
			) {
				target_function = binding.initial;
			}
		}
	}
 
	// If we can't find a function, or the function has multiple parameters, bail out
	if (target_function == null || target_function.params.length > 1) {
		return unhoisted;
	}
 
	const visited_references = new Set();
	const scope = target_function.metadata.scope;
	for (const [reference] of scope.references) {
		// Bail out if the arguments keyword is used or $host is referenced
		if (reference === 'arguments' || reference === '$host') return unhoisted;
		// Bail out if references a store subscription
		if (scope.get(`$${reference}`)?.kind === 'store_sub') return unhoisted;
 
		const binding = scope.get(reference);
		const local_binding = context.state.scope.get(reference);
 
		// If we are referencing a binding that is shadowed in another scope then bail out.
		if (local_binding !== null && binding !== null && local_binding.node !== binding.node) {
			return unhoisted;
		}
 
		// If we have multiple references to the same store using $ prefix, bail out.
		if (
			binding !== null &&
			binding.kind === 'store_sub' &&
			visited_references.has(reference.slice(1))
		) {
			return unhoisted;
		}
 
		// If we reference the index within an each block, then bail out.
		if (binding !== null && binding.initial?.type === 'EachBlock') return unhoisted;
 
		if (
			binding !== null &&
			// Bail out if the the binding is a rest param
			(binding.declaration_kind === 'rest_param' ||
				// Bail out if we reference anything from the EachBlock (for now) that mutates in non-runes mode,
				(((!context.state.analysis.runes && binding.kind === 'each') ||
					// or any normal not reactive bindings that are mutated.
					binding.kind === 'normal') &&
					binding.updated))
		) {
			return unhoisted;
		}
		visited_references.add(reference);
	}
 
	return { hoisted: true, function: target_function };
}
 
/**
 * @param {string} event_name
 */
function get_attribute_event_name(event_name) {
	event_name = event_name.slice(2);
	if (is_capture_event(event_name)) {
		event_name = event_name.slice(0, -7);
	}
	return event_name;
}