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

Cybernetically enhanced web apps

/** @import { CallExpression, ClassBody, ClassDeclaration, ClassExpression, MethodDefinition, PropertyDefinition, StaticBlock } from 'estree' */
/** @import { StateField } from '#compiler' */
/** @import { Context } from '../types' */
import * as b from '#compiler/builders';
import { dev } from '../../../../state.js';
import { get_parent } from '../../../../utils/ast.js';
import { get_name } from '../../../nodes.js';

/**
 * @param {ClassBody} node
 * @param {Context} context
 */
export function ClassBody(node, context) {
	const state_fields = context.state.analysis.classes.get(node);

	if (!state_fields) {
		// in legacy mode, do nothing
		context.next();
		return;
	}

	/** @type {Array<MethodDefinition | PropertyDefinition | StaticBlock>} */
	const body = [];

	const child_state = { ...context.state, state_fields };

	for (const [name, field] of state_fields) {
		if (name[0] === '#') {
			continue;
		}

		// insert backing fields for stuff declared in the constructor
		if (field.node.type === 'AssignmentExpression') {
			const member = b.member(b.this, field.key);

			const should_proxy = field.type === '$state' && true; // TODO

			const key = b.key(name);

			body.push(
				b.prop_def(field.key, null),

				b.method('get', key, [], [b.return(b.call('$.get', member))]),

				b.method(
					'set',
					key,
					[b.id('value')],
					[b.stmt(b.call('$.set', member, b.id('value'), should_proxy && b.true))]
				)
			);
		}
	}

	const declaration = /** @type {ClassDeclaration | ClassExpression} */ (
		get_parent(context.path, -1)
	);

	// Replace parts of the class body
	for (const definition of node.body) {
		if (definition.type !== 'PropertyDefinition') {
			body.push(
				/** @type {MethodDefinition | StaticBlock} */ (context.visit(definition, child_state))
			);
			continue;
		}

		const name = get_name(definition.key);
		const field = name && /** @type {StateField} */ (state_fields.get(name));

		if (!field) {
			body.push(/** @type {PropertyDefinition} */ (context.visit(definition, child_state)));
			continue;
		}

		if (name[0] === '#') {
			let value = definition.value
				? /** @type {CallExpression} */ (context.visit(definition.value, child_state))
				: undefined;

			if (dev && field.node === definition) {
				value = b.call('$.tag', value, b.literal(`${declaration.id?.name ?? '[class]'}.${name}`));
			}

			body.push(b.prop_def(definition.key, value));
		} else if (field.node === definition) {
			let call = /** @type {CallExpression} */ (context.visit(field.value, child_state));

			if (dev) {
				call = b.call('$.tag', call, b.literal(`${declaration.id?.name ?? '[class]'}.${name}`));
			}
			const member = b.member(b.this, field.key);
			const should_proxy = field.type === '$state' && true; // TODO

			body.push(
				b.prop_def(field.key, call),

				b.method('get', definition.key, [], [b.return(b.call('$.get', member))]),

				b.method(
					'set',
					definition.key,
					[b.id('value')],
					[b.stmt(b.call('$.set', member, b.id('value'), should_proxy && b.true))]
				)
			);
		}
	}

	return { ...node, body };
}