source: frontend/node_modules/webpack/lib/dependencies/getFunctionExpression.js

/*
        MIT License http://www.opensource.org/licenses/mit-license.php
        Author Tobias Koppers @sokra
*/

"use strict";

/** @typedef {import("estree").ArrowFunctionExpression} ArrowFunctionExpression */
/** @typedef {import("estree").Expression} Expression */
/** @typedef {import("estree").FunctionExpression} FunctionExpression */
/** @typedef {import("estree").SpreadElement} SpreadElement */

/** @typedef {{ fn: FunctionExpression | ArrowFunctionExpression, expressions: (Expression | SpreadElement)[], needThis: boolean | undefined }} FunctionExpressionResult */

/**
 * Returns function expression with additional information.
 * @param {Expression | SpreadElement} expr expressions
 * @returns {FunctionExpressionResult | undefined} function expression with additional information
 */
module.exports = (expr) => {
        // <FunctionExpression>
        if (
                expr.type === "FunctionExpression" ||
                expr.type === "ArrowFunctionExpression"
        ) {
                return {
                        fn: expr,
                        expressions: [],
                        needThis: false
                };
        }

        // <FunctionExpression>.bind(<Expression>)
        if (
                expr.type === "CallExpression" &&
                expr.callee.type === "MemberExpression" &&
                expr.callee.object.type === "FunctionExpression" &&
                expr.callee.property.type === "Identifier" &&
                expr.callee.property.name === "bind" &&
                expr.arguments.length === 1
        ) {
                return {
                        fn: expr.callee.object,
                        expressions: [expr.arguments[0]],
                        needThis: undefined
                };
        }
        // (function(_this) {return <FunctionExpression>})(this) (Coffeescript)
        if (
                expr.type === "CallExpression" &&
                expr.callee.type === "FunctionExpression" &&
                expr.callee.body.type === "BlockStatement" &&
                expr.arguments.length === 1 &&
                expr.arguments[0].type === "ThisExpression" &&
                expr.callee.body.body &&
                expr.callee.body.body.length === 1 &&
                expr.callee.body.body[0].type === "ReturnStatement" &&
                expr.callee.body.body[0].argument &&
                expr.callee.body.body[0].argument.type === "FunctionExpression"
        ) {
                return {
                        fn: expr.callee.body.body[0].argument,
                        expressions: [],
                        needThis: true
                };
        }
};