unthunk() — svelte Function Reference

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

Function javascript Compiler Transformer calls 2 called by 1

Entity Profile

Compiler→ Transformer→ unthunk() — svelte Function Reference

Dependency Diagram

graph TD
  48afe7ab_bb6e_7895_aca1_6433240d18a3["unthunk()"]
  18e3101f_3e97_34c3_7373_b587af4b78e1["builders.js"]
  48afe7ab_bb6e_7895_aca1_6433240d18a3 -->|defined in| 18e3101f_3e97_34c3_7373_b587af4b78e1
  ee6da0da_a970_1fca_7676_8193019eb85e["thunk()"]
  ee6da0da_a970_1fca_7676_8193019eb85e -->|calls| 48afe7ab_bb6e_7895_aca1_6433240d18a3
  c5b1e5e6_49b7_ac9e_9572_7d6c11e99bc7["has_await_expression()"]
  48afe7ab_bb6e_7895_aca1_6433240d18a3 -->|calls| c5b1e5e6_49b7_ac9e_9572_7d6c11e99bc7
  1fb6b372_75e6_ebba_568e_828733e93221["arrow()"]
  48afe7ab_bb6e_7895_aca1_6433240d18a3 -->|calls| 1fb6b372_75e6_ebba_568e_828733e93221
  style 48afe7ab_bb6e_7895_aca1_6433240d18a3 fill:#6366f1,stroke:#818cf8,color:#fff

Relationship Graph

Source Code

packages/svelte/src/compiler/utils/builders.js lines 464–485

export function unthunk(expression) {
	// optimize `async () => await x()`, but not `async () => await x(await y)`
	if (expression.async && expression.body.type === 'AwaitExpression') {
		if (!has_await_expression(expression.body.argument)) {
			return unthunk(arrow(expression.params, expression.body.argument));
		}
	}

	if (
		expression.async === false &&
		expression.body.type === 'CallExpression' &&
		expression.body.callee.type === 'Identifier' &&
		expression.params.length === expression.body.arguments.length &&
		expression.params.every((param, index) => {
			const arg = /** @type {ESTree.SimpleCallExpression} */ (expression.body).arguments[index];
			return param.type === 'Identifier' && arg.type === 'Identifier' && param.name === arg.name;
		})
	) {
		return expression.body.callee;
	}
	return expression;
}