predictype
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PredicType is a library of pre-built and tested predicates for TypeScript, covering various data types and operations.
60 lines (59 loc) • 2.7 kB
JavaScript
;
Object.defineProperty(exports, "__esModule", { value: true });
exports.functionState = functionState;
const functions_js_1 = require("../../enums/functions.js");
/**
* Checks the state of a function (e.g. async, generator, constructor, arrow, anonymous, has name) using the specified
* operation.
*
* @param source The function to check.
* @param oper The state operation to perform (e.g. 'is_async', 'is_arrow').
* @returns True if the state check is valid according to the operator, otherwise false.
*
* @throws {Error} If the operation is not recognized.
*
* @example
* const asyncFn = async function foo() {};
* const genFn = function* gen() {};
*
* functionState(asyncFn, 'is_async'); // true
* functionState(genFn, 'is_generator'); // true
* functionState(() => {}, 'is_arrow'); // true
* functionState(function() {}, 'is_anonymous'); // true
* functionState(function named() {}, 'has_name'); // true
*
* @remarks
* Supported Operators:
* - **HAS_NAME**: Function has a name
* - **IS_ANONYMOUS**: Function is anonymous
* - **IS_ARROW**: Function is an arrow function
* - **IS_ASYNC**: Function is async
* - **IS_CONSTRUCTOR**: Function is a constructor
* - **IS_GENERATOR**: Function is a generator function
*/
function functionState(source, oper) {
const operators = {
[functions_js_1.FunctionStateEnum.HAS_NAME]: (a) => typeof a.name === 'string' && a.name.length > 0,
[functions_js_1.FunctionStateEnum.IS_ASYNC]: (a) => a.constructor.name === 'AsyncFunction',
[functions_js_1.FunctionStateEnum.IS_GENERATOR]: (a) => a.constructor.name === 'GeneratorFunction',
[functions_js_1.FunctionStateEnum.IS_CONSTRUCTOR]: (a) => a.prototype !== undefined,
[functions_js_1.FunctionStateEnum.IS_ARROW]: (a) => !a.prototype && !a.hasOwnProperty('prototype'),
[functions_js_1.FunctionStateEnum.IS_ANONYMOUS]: (a) => {
// In Node, anonymous functions may have name '' or 'anonymous'.
// In some JS engines, even anonymous functions may have a generated name.
// We consider a function anonymous if:
// - name is ''
// - name is 'anonymous'
// - or its string representation starts with 'function (' (no name)
if (!a.name || a.name === '' || a.name === 'anonymous')
return true;
const fnStr = Function.prototype.toString.call(a);
return /^function ?\(/.test(fnStr);
},
};
const enumOper = typeof oper === 'string' ? oper : oper;
const fn = operators[enumOper];
if (!fn)
throw new Error(`Unknown FunctionState operation: ${oper}`);
return fn(source);
}