All files / src/compiler/phases/3-transform/client/visitors javascript-legacy.js

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import { is_hoistable_function } from '../../utils.js';
import * as b from '../../../../utils/builders.js';
import { extract_paths } from '../../../../utils/ast.js';
import { get_prop_source, serialize_get_binding } from '../utils.js';
 
/**
 * Creates the output for a state declaration.
 * @param {import('estree').VariableDeclarator} declarator
 * @param {import('../../../scope.js').Scope} scope
 * @param {import('estree').Expression} value
 */
function create_state_declarators(declarator, scope, value) {
	if (declarator.id.type === 'Identifier') {
		return [b.declarator(declarator.id, b.call('$.mutable_source', value))];
	}
 
	const tmp = scope.generate('tmp');
	const paths = extract_paths(declarator.id);
	return [
		b.declarator(b.id(tmp), value),
		...paths.map((path) => {
			const value = path.expression?.(b.id(tmp));
			const binding = scope.get(/** @type {import('estree').Identifier} */ (path.node).name);
			return b.declarator(
				path.node,
				binding?.kind === 'state' ? b.call('$.mutable_source', value) : value
			);
		})
	];
}
 
/** @type {import('../types.js').ComponentVisitors} */
export const javascript_visitors_legacy = {
	VariableDeclaration(node, { state, visit }) {
		/** @type {import('estree').VariableDeclarator[]} */
		const declarations = [];
 
		for (const declarator of node.declarations) {
			const bindings = /** @type {import('#compiler').Binding[]} */ (
				state.scope.get_bindings(declarator)
			);
			const has_state = bindings.some((binding) => binding.kind === 'state');
			const has_props = bindings.some((binding) => binding.kind === 'bindable_prop');
 
			if (!has_state && !has_props) {
				const init = declarator.init;
				if (init != null && is_hoistable_function(init)) {
					const hoistable_function = visit(init);
					state.hoisted.push(
						b.declaration(
							'const',
							declarator.id,
							/** @type {import('estree').Expression} */ (hoistable_function)
						)
					);
					continue;
				}
				declarations.push(/** @type {import('estree').VariableDeclarator} */ (visit(declarator)));
				continue;
			}
 
			if (has_props) {
				if (declarator.id.type !== 'Identifier') {
					// Turn export let into props. It's really really weird because export let { x: foo, z: [bar]} = ..
					// means that foo and bar are the props (i.e. the leafs are the prop names), not x and z.
					const tmp = state.scope.generate('tmp');
					const paths = extract_paths(declarator.id);
					declarations.push(
						b.declarator(
							b.id(tmp),
							/** @type {import('estree').Expression} */ (
								visit(/** @type {import('estree').Expression} */ (declarator.init))
							)
						)
					);
					for (const path of paths) {
						const name = /** @type {import('estree').Identifier} */ (path.node).name;
						const binding = /** @type {import('#compiler').Binding} */ (state.scope.get(name));
						const value = path.expression?.(b.id(tmp));
						declarations.push(
							b.declarator(
								path.node,
								binding.kind === 'bindable_prop'
									? get_prop_source(binding, state, binding.prop_alias ?? name, value)
									: value
							)
						);
					}
					continue;
				}
 
				const binding = /** @type {import('#compiler').Binding} */ (
					state.scope.get(declarator.id.name)
				);
 
				declarations.push(
					b.declarator(
						declarator.id,
						get_prop_source(
							binding,
							state,
							binding.prop_alias ?? declarator.id.name,
							declarator.init && /** @type {import('estree').Expression} */ (visit(declarator.init))
						)
					)
				);
 
				continue;
			}
 
			declarations.push(
				...create_state_declarators(
					declarator,
					state.scope,
					/** @type {import('estree').Expression} */ (declarator.init && visit(declarator.init))
				)
			);
		}
 
		if (declarations.length === 0) {
			return b.empty;
		}
 
		return {
			...node,
			declarations
		};
	},
	LabeledStatement(node, context) {
		if (context.path.length > 1 || node.label.name !== '$') {
			context.next();
			return;
		}
 
		const state = context.state;
		// To recreate Svelte 4 behaviour, we track the dependencies
		// the compiler can 'see', but we untrack the effect itself
		const reactive_stmt = /** @type {import('#compiler').ReactiveStatement} */ (
			state.analysis.reactive_statements.get(node)
		);
 
		if (!reactive_stmt) return; // not the instance context
 
		const { dependencies } = reactive_stmt;
 
		let serialized_body = /** @type {import('estree').Statement} */ (context.visit(node.body));
 
		if (serialized_body.type !== 'BlockStatement') {
			serialized_body = b.block([serialized_body]);
		}
 
		const body = serialized_body.body;
 
		/** @type {import('estree').Expression[]} */
		const sequence = [];
		for (const binding of dependencies) {
			if (binding.kind === 'normal') continue;
 
			const name = binding.node.name;
			let serialized = serialize_get_binding(b.id(name), state);
 
			// If the binding is a prop, we need to deep read it because it could be fine-grained $state
			// from a runes-component, where mutations don't trigger an update on the prop as a whole.
			if (name === '$$props' || name === '$$restProps' || binding.kind === 'bindable_prop') {
				serialized = b.call('$.deep_read_state', serialized);
			}
 
			sequence.push(serialized);
		}
 
		// these statements will be topologically ordered later
		state.legacy_reactive_statements.set(
			node,
			b.stmt(
				b.call(
					'$.legacy_pre_effect',
					sequence.length > 0 ? b.thunk(b.sequence(sequence)) : b.thunk(b.block([])),
					b.thunk(b.block(body))
				)
			)
		);
 
		return b.empty;
	},
	BreakStatement(node, context) {
		if (!node.label || node.label.name !== '$') return;
 
		const in_reactive_statement =
			context.path[1].type === 'LabeledStatement' && context.path[1].label.name === '$';
		if (in_reactive_statement) {
			return b.return();
		}
	}
};