polymer-analyzer/lib/javascript/estraverse-shim.js

"use strict";
/**
 * @license
 * Copyright (c) 2015 The Polymer Project Authors. All rights reserved.
 * This code may only be used under the BSD style license found at
 * http://polymer.github.io/LICENSE.txt
 * The complete set of authors may be found at
 * http://polymer.github.io/AUTHORS.txt
 * The complete set of contributors may be found at
 * http://polymer.github.io/CONTRIBUTORS.txt
 * Code distributed by Google as part of the polymer project is also
 * subject to an additional IP rights grant found at
 * http://polymer.github.io/PATENTS.txt
 */
Object.defineProperty(exports, "__esModule", { value: true });
/**
 * TODO(usergenic): Immediately deprecate this. This `estraverse-shim` module
 * exists solely to make the transition from `espree/estree` JavaScript parser
 * to `babylon/babel` and tooling a gradual/piecemeal affair.  It is intended as
 * a temporary shim that will eventually be removed once all dependent
 * scanners/visitors and utility functions which use the old `estraverse` style
 * methods are converted to `babel-traverse` etc.
 */
const traverse_1 = require("@babel/traverse");
const babel = require("@babel/types");
/**
 * These enum options mimic the estraverse enums that are returned by their
 * `enterX`/`leaveX` visitor methods to advise flow of the visitor.
 */
var VisitorOption;
(function (VisitorOption) {
    VisitorOption["Skip"] = "skip";
    VisitorOption["Break"] = "break";
    VisitorOption["Remove"] = "remove";
})(VisitorOption = exports.VisitorOption || (exports.VisitorOption = {}));
/**
 * This method mirrors the API of `estraverse`'s `traverse` function.  It uses
 * `babel-traverse` to perform a traversal of an AST, but does so with `noScope:
 * true` which turns off the scoping logic and enables it to traverse from any
 * node; whereasc `babel-traverse`'s scopes require traversal from the root
 * node, the `File` type, which we don't yet even store on our JavaScript
 * documents.
 */
function traverse(ast, visitor) {
    traverse_1.default(ast, {
        enter(path) {
            dispatchVisitMethods(['enter', `enter${path.type}`], path, visitor);
        },
        exit(path) {
            dispatchVisitMethods(['leave', `leave${path.type}`], path, visitor);
        },
        noScope: !babel.isFile(ast),
    });
}
exports.traverse = traverse;
/**
 * Calls into visitor methods for visited node types using `estraverse` API of
 * providing the node and the parent node, and translates the `VisitorOption`
 * return value into directives on the `path` object used by `babel-traverse` to
 * advise visitor control flow, i.e. `stop`, `skip`, and `remove`.
 */
function dispatchVisitMethods(methodNames, path, visitor) {
    for (const methodName of methodNames) {
        if (typeof visitor[methodName] === 'function') {
            // TODO(rictic): can maybe remove this cast in TS 2.8
            const result = visitor[methodName](path.node, path.parent, path);
            switch (result) {
                case VisitorOption.Break:
                    return path.stop();
                case VisitorOption.Skip:
                    return path.skip();
                case VisitorOption.Remove:
                    return path.remove();
            }
        }
    }
}
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