All files / src/compiler/phases scope.js

99.49% Statements 781/785
98.04% Branches 201/205
97.5% Functions 39/40
99.48% Lines 774/778

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 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 7792x 2x 2x 2x 2x 2x 2x 2x 2x 47519x 47519x 47519x 47519x 47519x 47519x 47519x 47519x 47519x 47519x 47519x 47519x 47519x 47519x 47519x 47519x 47519x 47519x 47519x 47519x 47519x 47519x 47519x 47519x 47519x 47519x 47519x 47519x 47519x 47519x 47519x 47519x 47519x 47519x 47519x 47519x 47519x 47519x 47519x 47519x 47519x 47519x 47519x 47519x 47519x 47519x 47519x 47519x 47519x 47519x 47519x 47519x 47519x 47519x 47519x 47519x 47519x 47519x 47519x 47519x 47519x 47519x 24374x 2x 2x 24372x 24372x 24374x 24374x 24374x 24374x 6x 24374x 1x 1x 24371x 24374x 22531x 1x 1x 22530x 22531x 1680x 1680x 22531x 22690x 24374x 2x 2x 2x 22688x 22688x 22688x 22688x 22688x 22688x 22688x 22688x 22688x 22688x 22688x 22688x 22688x 22688x 22688x 22688x 22688x 22688x 22688x 22688x 22688x 22688x 47519x 47519x 33113x 33113x 47519x 47519x 47519x 47519x 47519x 47519x 16355x 2176x 2176x 14179x 14179x 14179x 14179x 14179x 14179x 16355x 16355x 16355x 14179x 16355x 12243x 12243x 14179x 14179x 14179x 14179x 14179x 47519x 47519x 47519x 47519x 47519x 47519x 438584x 438584x 47519x 47519x 47519x 47519x 47519x 47519x 5666x 5666x     5666x 5666x 47519x 47519x 47519x 47519x 47519x 47519x 1760x 1760x 47519x 47519x 47519x 47519x 47519x 47519x 93809x 93809x 93809x 93809x 93809x 93809x 93809x 93809x 93809x 31773x 93809x 59033x 62036x 3003x 3003x 3003x 3003x 93809x 47519x 2x 2x 4821x 4821x 4821x 4821x 4821x 4821x 4821x 5272x 5272x 5272x 5272x 5272x 2759x 2759x 5272x 5272x 5272x 5272x 5272x 4821x 2x 2x 2x 2x 2x 2x 2x 2x 14406x 14406x 14406x 14406x 14406x 14406x 14406x 14406x 14406x 14406x 14406x 14406x 14406x 14406x 14406x 14406x 14406x 14406x 14406x 14406x 14406x 14406x 14406x 14406x 14406x 14406x 14406x 14406x 14406x 14406x 3329x 1395x 1401x 1401x 1395x 3329x 14406x 14406x 14406x 14406x 14406x 2434x 2434x 2434x 2434x 14406x 14406x 14406x 14406x 14406x 14406x 14406x 14406x 9135x 9135x 9135x 14406x 14406x 14406x 14406x 14406x 14406x 14406x 10321x 10321x 10321x 10321x 8034x 212x 212x 212x 212x 212x 212x 212x 212x 212x 51x 63x 63x 63x 212x 161x 161x 161x 161x 161x 161x 161x 161x 161x 161x 8034x 197x 197x 8034x 10321x 10321x 10321x 14406x 14406x 14406x 14406x 14406x 399x 399x 399x 89x 89x 14406x 14406x 14406x 14406x 14406x 41228x 41228x 33198x 33198x 14406x 14406x 14406x 319x 319x 311x 311x 311x 311x 311x 311x 319x 238x 319x 202x 192x 187x 187x 192x 202x 311x 311x 14406x 14406x 14406x 14406x 14406x 14406x 14406x 14406x 1186x 1186x 1186x 1294x 1294x 1186x 1186x 1186x 1186x 1186x 1186x 17x 17x 1186x 1186x 1749x 1749x 490x 490x 490x 1749x 180x 180x 180x 1749x 1569x 112x 112x 112x 1568x 1457x 1457x 1569x 1569x 1569x 1749x 14406x 14406x 14406x 14406x 2128x 2128x 14406x 14406x 14406x 346x 346x 346x 346x 346x 346x 346x 14406x 14406x 14406x 1610x 1689x 1689x 14406x 14406x 14406x 288x 288x 288x 288x 288x 288x 288x 14406x 14406x 14406x 1011x 1011x 1011x 1011x 1011x 1011x 1011x 14406x 14406x 14406x 2030x 2030x 2030x 2030x 2030x 14406x 14406x 14406x 14406x 14406x 14406x 14406x 14406x 14406x 82x 82x 14406x 14406x 14406x 6833x 6833x 7515x 7515x 7515x 7515x 7515x 7515x 8001x 8001x 8001x 8001x 8001x 8001x 8001x 8001x 7511x 6829x 6829x 14406x 14406x 14406x 11x 11x 11x 11x 11x 11x 11x 11x 11x 11x     14406x 14406x 14406x 933x 933x 933x 933x 933x 933x 886x 886x 882x 882x 886x 933x 933x 933x 933x 933x 933x 933x 933x 1043x 1043x 1043x 1043x 1043x 1043x 1963x 15x 15x 1043x 1043x 56x 56x 56x 56x 56x 1043x 1043x 1043x 1043x 933x 87x 87x 933x 933x 933x 933x 111x 111x 111x 111x 111x 933x 933x 933x 933x 3246x 3246x 933x 931x 931x 931x 931x 931x 933x 1368x 81x 81x 1368x 931x 931x 931x 933x 933x 933x 933x 933x 933x 933x 933x 933x 14406x 14406x 14406x 171x 171x 171x 90x 90x 171x 171x 143x 143x 131x 131x 131x 131x 131x 183x 183x 183x 131x 143x 171x 171x 99x 99x 93x 93x 93x 93x 93x 149x 149x 149x 93x 99x 14406x 14406x 14406x 90x 90x 90x 90x 90x 70x 70x 90x 90x 90x 90x 90x 90x 47x 47x 47x 47x 90x 90x 14406x 14406x 14406x 15460x 15460x 15460x 14406x 14406x 14406x 919x 919x 919x 919x 919x 919x 919x 14406x 14406x 14406x 14406x 14406x 14406x 14406x 14406x 14406x 14406x 187x 187x 143x 143x 143x 14401x 14401x 14401x 14404x 33191x 33191x 14401x 14406x 3393x 909x 909x 100x 100x 909x 909x 909x 3391x 2484x 2560x 2560x 2304x 2304x 2304x 2484x 2484x 3393x 14401x 14401x 14401x 14401x 14401x 14401x 2x 2x 2x 2x 2x 2x 2x 27835x 27835x 27835x 27835x 27835x 27835x 27835x 299347x 299347x 299347x 27835x 27835x 2x 2x 2x 2x 2x 2x 2x 2x 17125x 17125x 16485x 16485x 16485x 16485x 16485x 17125x 4832x 4832x 4772x 4772x 4772x 16425x 17125x 55x 55x 55x 16425x 17125x 16174x 16174x 16174x 16943x 8888x 8888x 14306x 8816x 8816x 8816x  
import is_reference from 'is-reference';
import { walk } from 'zimmerframe';
import { is_element_node } from './nodes.js';
import * as b from '../utils/builders.js';
import * as e from '../errors.js';
import { extract_identifiers, extract_identifiers_from_destructuring } from '../utils/ast.js';
import { JsKeywords, Runes } from './constants.js';
 
export class Scope {
	/** @type {ScopeRoot} */
	root;
 
	/**
	 * The immediate parent scope
	 * @type {Scope | null}
	 */
	parent;
 
	/**
	 * Whether or not `var` declarations are contained by this scope
	 * @type {boolean}
	 */
	#porous;
 
	/**
	 * A map of every identifier declared by this scope, and all the
	 * identifiers that reference it
	 * @type {Map<string, import('#compiler').Binding>}
	 */
	declarations = new Map();
 
	/**
	 * A map of declarators to the bindings they declare
	 * @type {Map<import('estree').VariableDeclarator | import('#compiler').LetDirective, import('#compiler').Binding[]>}
	 */
	declarators = new Map();
 
	/**
	 * A set of all the names referenced with this scope
	 * — useful for generating unique names
	 * @type {Map<string, { node: import('estree').Identifier; path: import('#compiler').SvelteNode[] }[]>}
	 */
	references = new Map();
 
	/**
	 * The scope depth allows us to determine if a state variable is referenced in its own scope,
	 * which is usually an error. Block statements do not increase this value
	 */
	function_depth = 0;
 
	/**
	 *
	 * @param {ScopeRoot} root
	 * @param {Scope | null} parent
	 * @param {boolean} porous
	 */
	constructor(root, parent, porous) {
		this.root = root;
		this.parent = parent;
		this.#porous = porous;
		this.function_depth = parent ? parent.function_depth + (porous ? 0 : 1) : 0;
	}
 
	/**
	 * @param {import('estree').Identifier} node
	 * @param {import('#compiler').Binding['kind']} kind
	 * @param {import('#compiler').DeclarationKind} declaration_kind
	 * @param {null | import('estree').Expression | import('estree').FunctionDeclaration | import('estree').ClassDeclaration | import('estree').ImportDeclaration | import('../types/template.js').EachBlock} initial
	 * @returns {import('#compiler').Binding}
	 */
	declare(node, kind, declaration_kind, initial = null) {
		if (node.name === '$') {
			e.dollar_binding_invalid(node);
		}
 
		if (
			node.name.startsWith('$') &&
			declaration_kind !== 'synthetic' &&
			declaration_kind !== 'param' &&
			declaration_kind !== 'rest_param' &&
			this.function_depth <= 1
		) {
			e.dollar_prefix_invalid(node);
		}
 
		if (this.parent) {
			if (declaration_kind === 'var' && this.#porous) {
				return this.parent.declare(node, kind, declaration_kind);
			}
 
			if (declaration_kind === 'import') {
				return this.parent.declare(node, kind, declaration_kind, initial);
			}
		}
 
		if (this.declarations.has(node.name)) {
			// This also errors on var/function types, but that's arguably a good thing
			e.declaration_duplicate(node, node.name);
		}
 
		/** @type {import('#compiler').Binding} */
		const binding = {
			node,
			references: [],
			legacy_dependencies: [],
			initial,
			mutated: false,
			scope: this,
			kind,
			declaration_kind,
			is_called: false,
			prop_alias: null,
			expression: null,
			mutation: null,
			reassigned: false,
			metadata: null
		};
		this.declarations.set(node.name, binding);
		this.root.conflicts.add(node.name);
		return binding;
	}
 
	child(porous = false) {
		return new Scope(this.root, this, porous);
	}
 
	/**
	 * @param {string} preferred_name
	 * @returns {string}
	 */
	generate(preferred_name) {
		if (this.#porous) {
			return /** @type {Scope} */ (this.parent).generate(preferred_name);
		}
 
		preferred_name = preferred_name.replace(/[^a-zA-Z0-9_$]/g, '_').replace(/^[0-9]/, '_');
		let name = preferred_name;
		let n = 1;
 
		while (
			this.references.has(name) ||
			this.declarations.has(name) ||
			this.root.conflicts.has(name) ||
			JsKeywords.includes(name)
		) {
			name = `${preferred_name}_${n++}`;
		}
 
		this.references.set(name, []);
		this.root.conflicts.add(name);
		return name;
	}
 
	/**
	 * @param {string} name
	 * @returns {import('#compiler').Binding | null}
	 */
	get(name) {
		return this.declarations.get(name) ?? this.parent?.get(name) ?? null;
	}
 
	/**
	 * @param {import('estree').VariableDeclarator | import('#compiler').LetDirective} node
	 * @returns {import('#compiler').Binding[]}
	 */
	get_bindings(node) {
		const bindings = this.declarators.get(node);
		if (!bindings) {
			throw new Error('No binding found for declarator');
		}
		return bindings;
	}
 
	/**
	 * @param {string} name
	 * @returns {Scope | null}
	 */
	owner(name) {
		return this.declarations.has(name) ? this : this.parent && this.parent.owner(name);
	}
 
	/**
	 * @param {import('estree').Identifier} node
	 * @param {import('#compiler').SvelteNode[]} path
	 */
	reference(node, path) {
		path = [...path]; // ensure that mutations to path afterwards don't affect this reference
		let references = this.references.get(node.name);
 
		if (!references) this.references.set(node.name, (references = []));
 
		references.push({ node, path });
 
		const binding = this.declarations.get(node.name);
		if (binding) {
			binding.references.push({ node, path });
		} else if (this.parent) {
			this.parent.reference(node, path);
		} else {
			// no binding was found, and this is the top level scope,
			// which means this is a global
			this.root.conflicts.add(node.name);
		}
	}
}
 
export class ScopeRoot {
	/** @type {Set<string>} */
	conflicts = new Set();
 
	/**
	 * @param {string} preferred_name
	 */
	unique(preferred_name) {
		preferred_name = preferred_name.replace(/[^a-zA-Z0-9_$]/g, '_');
		let final_name = preferred_name;
		let n = 1;
 
		while (this.conflicts.has(final_name)) {
			final_name = `${preferred_name}_${n++}`;
		}
 
		this.conflicts.add(final_name);
		const id = b.id(final_name);
		return id;
	}
}
 
/**
 * @param {import('#compiler').SvelteNode} ast
 * @param {ScopeRoot} root
 * @param {boolean} allow_reactive_declarations
 * @param {Scope | null} parent
 */
export function create_scopes(ast, root, allow_reactive_declarations, parent) {
	/** @typedef {{ scope: Scope }} State */
 
	/**
	 * A map of node->associated scope. A node appearing in this map does not necessarily mean that it created a scope
	 * @type {Map<import('#compiler').SvelteNode, Scope>}
	 */
	const scopes = new Map();
	const scope = new Scope(root, parent, false);
	scopes.set(ast, scope);
 
	/** @type {State} */
	const state = { scope };
 
	/** @type {[Scope, { node: import('estree').Identifier; path: import('#compiler').SvelteNode[] }][]} */
	const references = [];
 
	/** @type {[Scope, import('estree').Pattern | import('estree').MemberExpression][]} */
	const updates = [];
 
	/**
	 * An array of reactive declarations, i.e. the `a` in `$: a = b * 2`
	 * @type {import('estree').Identifier[]}
	 */
	const possible_implicit_declarations = [];
 
	/**
	 * @param {Scope} scope
	 * @param {import('estree').Pattern[]} params
	 */
	function add_params(scope, params) {
		for (const param of params) {
			for (const node of extract_identifiers(param)) {
				scope.declare(node, 'normal', param.type === 'RestElement' ? 'rest_param' : 'param');
			}
		}
	}
 
	/**
	 * @type {import('zimmerframe').Visitor<import('estree').Node, State, import('#compiler').SvelteNode>}
	 */
	const create_block_scope = (node, { state, next }) => {
		const scope = state.scope.child(true);
		scopes.set(node, scope);
 
		next({ scope });
	};
 
	const skip = () => {};
 
	/**
	 * @type {import('zimmerframe').Visitor<import('#compiler').ElementLike, State, import('#compiler').SvelteNode>}
	 */
	const SvelteFragment = (node, { state, next }) => {
		const [scope] = analyze_let_directives(node, state.scope);
		scopes.set(node, scope);
		next({ scope });
	};
 
	/**
	 * @param {import('#compiler').ElementLike} node
	 * @param {Scope} parent
	 */
	function analyze_let_directives(node, parent) {
		const scope = parent.child();
		let is_default_slot = true;
 
		for (const attribute of node.attributes) {
			if (attribute.type === 'LetDirective') {
				/** @type {import('#compiler').Binding[]} */
				const bindings = [];
				scope.declarators.set(attribute, bindings);
 
				// attach the scope to the directive itself, as well as the
				// contents to which it applies
				scopes.set(attribute, scope);
 
				if (attribute.expression) {
					for (const id of extract_identifiers_from_destructuring(attribute.expression)) {
						const binding = scope.declare(id, 'derived', 'const');
						bindings.push(binding);
					}
				} else {
					/** @type {import('estree').Identifier} */
					const id = {
						name: attribute.name,
						type: 'Identifier',
						start: attribute.start,
						end: attribute.end
					};
					const binding = scope.declare(id, 'derived', 'const');
					bindings.push(binding);
				}
			} else if (attribute.type === 'Attribute' && attribute.name === 'slot') {
				is_default_slot = false;
			}
		}
 
		return /** @type {const} */ ([scope, is_default_slot]);
	}
 
	/**
	 * @type {import('zimmerframe').Visitor<import('#compiler').AnimateDirective | import('#compiler').TransitionDirective | import('#compiler').UseDirective, State, import('#compiler').SvelteNode>}
	 */
	const SvelteDirective = (node, { state, path, visit }) => {
		state.scope.reference(b.id(node.name.split('.')[0]), path);
 
		if (node.expression) {
			visit(node.expression);
		}
	};
 
	walk(ast, state, {
		// references
		Identifier(node, { path, state }) {
			const parent = path.at(-1);
			if (parent && is_reference(node, /** @type {import('estree').Node} */ (parent))) {
				references.push([state.scope, { node, path: path.slice() }]);
			}
		},
 
		LabeledStatement(node, { path, next }) {
			if (path.length > 1 || !allow_reactive_declarations) return next();
			if (node.label.name !== '$') return next();
 
			// create a scope for the $: block
			const scope = state.scope.child();
			scopes.set(node, scope);
 
			if (
				node.body.type === 'ExpressionStatement' &&
				node.body.expression.type === 'AssignmentExpression'
			) {
				for (const id of extract_identifiers(node.body.expression.left)) {
					if (!id.name.startsWith('$')) {
						possible_implicit_declarations.push(id);
					}
				}
			}
 
			next({ scope });
		},
 
		SvelteFragment,
		SlotElement: SvelteFragment,
		SvelteElement: SvelteFragment,
		RegularElement: SvelteFragment,
 
		Component(node, { state, visit, path }) {
			state.scope.reference(b.id(node.name), path);
 
			for (const attribute of node.attributes) {
				visit(attribute);
			}
 
			// let:x is super weird:
			// - for the default slot, its scope only applies to children that are not slots themselves
			// - for named slots, its scope applies to the component itself, too
			const [scope, is_default_slot] = analyze_let_directives(node, state.scope);
			if (!is_default_slot) {
				scopes.set(node, scope);
			}
 
			for (const child of node.fragment.nodes) {
				if (
					is_element_node(child) &&
					child.attributes.some(
						(attribute) => attribute.type === 'Attribute' && attribute.name === 'slot'
					)
				) {
					// <div slot="..."> inherits the scope above the component unless the component is a named slot itself, because slots are hella weird
					scopes.set(child, is_default_slot ? state.scope : scope);
					visit(child, { scope: is_default_slot ? state.scope : scope });
				} else {
					if (child.type === 'ExpressionTag') {
						// expression tag is a special case — we don't visit it directly, but via process_children,
						// so we need to set the scope on the expression rather than the tag itself
						scopes.set(child.expression, scope);
					} else {
						scopes.set(child, scope);
					}
 
					visit(child, { scope });
				}
			}
		},
 
		// updates
		AssignmentExpression(node, { state, next }) {
			updates.push([state.scope, node.left]);
			next();
		},
 
		UpdateExpression(node, { state, next }) {
			updates.push([
				state.scope,
				/** @type {import('estree').Identifier | import('estree').MemberExpression} */ (
					node.argument
				)
			]);
			next();
		},
 
		ImportDeclaration(node, { state }) {
			for (const specifier of node.specifiers) {
				state.scope.declare(specifier.local, 'normal', 'import', node);
			}
		},
 
		FunctionExpression(node, { state, next }) {
			const scope = state.scope.child();
			scopes.set(node, scope);
 
			if (node.id) scope.declare(node.id, 'normal', 'function');
 
			add_params(scope, node.params);
			next({ scope });
		},
 
		FunctionDeclaration(node, { state, next }) {
			if (node.id) state.scope.declare(node.id, 'normal', 'function', node);
 
			const scope = state.scope.child();
			scopes.set(node, scope);
 
			add_params(scope, node.params);
			next({ scope });
		},
 
		ArrowFunctionExpression(node, { state, next }) {
			const scope = state.scope.child();
			scopes.set(node, scope);
 
			add_params(scope, node.params);
			next({ scope });
		},
 
		ForStatement: create_block_scope,
		ForInStatement: create_block_scope,
		ForOfStatement: create_block_scope,
		BlockStatement: create_block_scope,
		SwitchStatement: create_block_scope,
 
		ClassDeclaration(node, { state, next }) {
			if (node.id) state.scope.declare(node.id, 'normal', 'const', node);
			next();
		},
 
		VariableDeclaration(node, { state, path, next }) {
			const is_parent_const_tag = path.at(-1)?.type === 'ConstTag';
			for (const declarator of node.declarations) {
				/** @type {import('#compiler').Binding[]} */
				const bindings = [];
 
				state.scope.declarators.set(declarator, bindings);
 
				for (const id of extract_identifiers(declarator.id)) {
					const binding = state.scope.declare(
						id,
						is_parent_const_tag ? 'derived' : 'normal',
						node.kind,
						declarator.init
					);
					bindings.push(binding);
				}
			}
 
			next();
		},
 
		CatchClause(node, { state, next }) {
			if (node.param) {
				const scope = state.scope.child(true);
				scopes.set(node, scope);
 
				for (const id of extract_identifiers(node.param)) {
					scope.declare(id, 'normal', 'let');
				}
 
				next({ scope });
			} else {
				next();
			}
		},
 
		EachBlock(node, { state, visit }) {
			// Array part is still from the scope above
			/** @type {Set<import('estree').Identifier>} */
			const references_within = new Set();
			const idx = references.length;
			visit(node.expression);
			for (let i = idx; i < references.length; i++) {
				const [scope, { node: id }] = references[i];
				if (scope === state.scope) {
					references_within.add(id);
				}
			}
			scopes.set(node.expression, state.scope);
 
			// context and children are a new scope
			const scope = state.scope.child();
			scopes.set(node, scope);
 
			// declarations
			for (const id of extract_identifiers(node.context)) {
				const binding = scope.declare(id, 'each', 'const');
 
				let inside_rest = false;
				let is_rest_id = false;
				walk(node.context, null, {
					Identifier(node) {
						if (inside_rest && node === id) {
							is_rest_id = true;
						}
					},
					RestElement(_, { next }) {
						const prev = inside_rest;
						inside_rest = true;
						next();
						inside_rest = prev;
					}
				});
 
				binding.metadata = { inside_rest: is_rest_id };
			}
			if (node.context.type !== 'Identifier') {
				scope.declare(b.id('$$item'), 'derived', 'synthetic');
			}
			// Visit to pick up references from default initializers
			visit(node.context, { scope });
 
			if (node.index) {
				const is_keyed =
					node.key &&
					(node.key.type !== 'Identifier' || !node.index || node.key.name !== node.index);
				scope.declare(b.id(node.index), is_keyed ? 'derived' : 'normal', 'const', node);
			}
			if (node.key) visit(node.key, { scope });
 
			// children
			for (const child of node.body.nodes) {
				visit(child, { scope });
			}
			if (node.fallback) visit(node.fallback, { scope });
 
			// Check if inner scope shadows something from outer scope.
			// This is necessary because we need access to the array expression of the each block
			// in the inner scope if bindings are used, in order to invalidate the array.
			let needs_array_deduplication = false;
			for (const [name] of scope.declarations) {
				if (state.scope.get(name) !== null) {
					needs_array_deduplication = true;
				}
			}
 
			node.metadata = {
				contains_group_binding: false,
				array_name: needs_array_deduplication ? state.scope.root.unique('$$array') : null,
				index: scope.root.unique('$$index'),
				item: node.context.type === 'Identifier' ? node.context : b.id('$$item'),
				declarations: scope.declarations,
				references: [...references_within]
					.map((id) => /** @type {import('#compiler').Binding} */ (state.scope.get(id.name)))
					.filter(Boolean),
				is_controlled: false
			};
		},
 
		AwaitBlock(node, context) {
			context.visit(node.expression);
 
			if (node.pending) {
				context.visit(node.pending);
			}
 
			if (node.then) {
				context.visit(node.then);
				if (node.value) {
					const then_scope = /** @type {Scope} */ (scopes.get(node.then));
					const value_scope = context.state.scope.child();
					scopes.set(node.value, value_scope);
					context.visit(node.value, { scope: value_scope });
					for (const id of extract_identifiers(node.value)) {
						then_scope.declare(id, 'normal', 'const');
						value_scope.declare(id, 'normal', 'const');
					}
				}
			}
 
			if (node.catch) {
				context.visit(node.catch);
				if (node.error) {
					const catch_scope = /** @type {Scope} */ (scopes.get(node.catch));
					const error_scope = context.state.scope.child();
					scopes.set(node.error, error_scope);
					context.visit(node.error, { scope: error_scope });
					for (const id of extract_identifiers(node.error)) {
						catch_scope.declare(id, 'normal', 'const');
						error_scope.declare(id, 'normal', 'const');
					}
				}
			}
		},
 
		SnippetBlock(node, context) {
			const state = context.state;
			// Special-case for root-level snippets: they become part of the instance scope
			const is_top_level = !context.path.at(-2);
			let scope = state.scope;
			if (is_top_level) {
				scope = /** @type {Scope} */ (parent);
			}
			scope.declare(node.expression, 'normal', 'function', node.expression);
 
			const child_scope = state.scope.child();
			scopes.set(node, child_scope);
 
			for (const param of node.parameters) {
				for (const id of extract_identifiers(param)) {
					child_scope.declare(id, 'snippet', 'let');
				}
			}
 
			context.next({ scope: child_scope });
		},
 
		Fragment: (node, context) => {
			const scope = context.state.scope.child(node.transparent);
			scopes.set(node, scope);
			context.next({ scope });
		},
 
		BindDirective(node, context) {
			updates.push([
				context.state.scope,
				/** @type {import('estree').Identifier | import('estree').MemberExpression} */ (
					node.expression
				)
			]);
			context.next();
		},
 
		TransitionDirective: SvelteDirective,
		AnimateDirective: SvelteDirective,
		UseDirective: SvelteDirective
 
		// TODO others
	});
 
	for (const id of possible_implicit_declarations) {
		const binding = scope.get(id.name);
		if (binding) continue; // TODO can also be legacy_reactive if declared outside of reactive statement
 
		scope.declare(id, 'legacy_reactive', 'let');
	}
 
	// we do this after the fact, so that we don't need to worry
	// about encountering references before their declarations
	for (const [scope, { node, path }] of references) {
		scope.reference(node, path);
	}
 
	for (const [scope, node] of updates) {
		if (node.type === 'MemberExpression') {
			let object = node.object;
			while (object.type === 'MemberExpression') {
				object = object.object;
			}
 
			const binding = scope.get(/** @type {import('estree').Identifier} */ (object).name);
			if (binding) binding.mutated = true;
		} else {
			extract_identifiers(node).forEach((identifier) => {
				const binding = scope.get(identifier.name);
				if (binding && identifier !== binding.node) {
					binding.mutated = true;
					binding.reassigned = true;
				}
			});
		}
	}
 
	return {
		scope,
		scopes
	};
}
 
/**
 * @template {{ scope: Scope }} State
 * @param {Map<import('#compiler').SvelteNode, Scope>} scopes
 * @returns {import('zimmerframe').Visitors<import('#compiler').SvelteNode, State>}
 */
export function set_scope(scopes) {
	return {
		/**
		 *
		 * @param {import('#compiler').SvelteNode} node
		 * @param {import('zimmerframe').Context<import('#compiler').SvelteNode, State>} context
		 */
		_(node, { next, state }) {
			const scope = scopes.get(node);
			next(scope !== undefined && scope !== state.scope ? { ...state, scope } : state);
		}
	};
}
 
/**
 * Returns the name of the rune if the given expression is a `CallExpression` using a rune.
 * @param {import('estree').Node | import('../types/template.js').EachBlock | null | undefined} node
 * @param {Scope} scope
 * @returns {Runes[number] | null}
 */
export function get_rune(node, scope) {
	if (!node) return null;
	if (node.type !== 'CallExpression') return null;
 
	let n = node.callee;
 
	let joined = '';
 
	while (n.type === 'MemberExpression') {
		if (n.computed) return null;
		if (n.property.type !== 'Identifier') return null;
		joined = '.' + n.property.name + joined;
		n = n.object;
	}
 
	if (n.type === 'CallExpression' && n.callee.type === 'Identifier') {
		joined = '()' + joined;
		n = n.callee;
	}
 
	if (n.type !== 'Identifier') return null;
 
	joined = n.name + joined;
 
	if (!Runes.includes(/** @type {any} */ (joined))) return null;
 
	const binding = scope.get(n.name);
	if (binding !== null) return null; // rune name, but references a variable or store
 
	return /** @type {typeof Runes[number] | null} */ (joined);
}