ClassBody() — svelte Function Reference

Architecture documentation for the ClassBody() function in ClassBody.js from the svelte codebase.

Function javascript Compiler Transformer calls 2

Entity Profile

Compiler→ Transformer→ ClassBody() — svelte Function Reference

Dependency Diagram

graph TD
  9659d62b_1d6a_1868_1943_0cbb31a2d5e4["ClassBody()"]
  b3660a8f_0eea_ece0_adac_3539aff5c652["ClassBody.js"]
  9659d62b_1d6a_1868_1943_0cbb31a2d5e4 -->|defined in| b3660a8f_0eea_ece0_adac_3539aff5c652
  68a38b3b_6f0f_ed43_404f_3d00302677a2["get_parent()"]
  9659d62b_1d6a_1868_1943_0cbb31a2d5e4 -->|calls| 68a38b3b_6f0f_ed43_404f_3d00302677a2
  d69a156c_617a_9397_4c8b_e94508c59e30["get_name()"]
  9659d62b_1d6a_1868_1943_0cbb31a2d5e4 -->|calls| d69a156c_617a_9397_4c8b_e94508c59e30
  style 9659d62b_1d6a_1868_1943_0cbb31a2d5e4 fill:#6366f1,stroke:#818cf8,color:#fff

Relationship Graph

Source Code

packages/svelte/src/compiler/phases/3-transform/client/visitors/ClassBody.js lines 13–111

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