import { casesExhausted } from './prelude.js' type Parameter = { type: 'name'; value: string } | { type: 'destructured'; names: string[] } export const analyzeFunction = (fn: (...args: [...any[]]) => unknown) => { const groups = fn.toString().match(functionPattern)?.groups if (!groups) throw new Error(`Could not extract groups from function.`) const body = groups[`bodyStatement`] ?? groups[`bodyExpression`] if (body === undefined) throw new Error(`Could not extract body from function.`) const parameters: Parameter[] = [] if (groups[`parameters`]) { const results = [...groups[`parameters`].matchAll(functionParametersPattern)] const resultParameters = results.map(result => { const type = result.groups?.[`destructured`] ? `destructured` : result.groups?.[`name`] ? `name` : null switch (type) { case `destructured`: const valueRaw = result.groups![`destructured`]! const names = [...valueRaw.matchAll(destructuredPattern)].map(result => { const name = result.groups![`name`] if (name === undefined) throw new Error(`Could not extract name from destructured parameter.`) return name }) return { type, names, } as const case `name`: return { type, value: result.groups![`name`]!, } as const case null: throw new Error(`Could not determine type of parameter.`) default: throw casesExhausted(type) } }) parameters.push(...resultParameters) } return { body, parameters, } } /** * @see https://regex101.com/r/9kCK86/4 */ // const functionPattern = /(?:[A-z])?\s*(?:$(?.*)$)\s*(?:=>)?\s*{(?.*)(?=})/s /** * @see https://regex101.com/r/U0JtfS/1 */ const functionPattern = /^(?:(?async)\s+)?(?:function\s+)?(?:(?[A-z_0-9]+)\s*)?$(?[^)]*)$\s*(?:=>\s*(?[^\s{].*)|(?:=>\s*)?{(?.*)})$/s /** * @see https://regex101.com/r/tE2dV5/2 */ const functionParametersPattern = /(?\{[^}]+\})|(?[A-z_][A-z_0-9]*)/gs /** * https://regex101.com/r/WHwazx/1 */ const destructuredPattern = /(?[A-z_][A-z_0-9]*)(?::[^},]+)?/gs