@yusufkandemir/eslint-plugin-lodash-template/lib/parser/parse-template-script/traverse.js

ESLint plugin for John Resig-style micro template, Lodash's template, Underscore's template and EJS.

"use strict";

// eslint-disable-next-line n/no-unpublished-require -- ignore
const visitorKeys = require("eslint-visitor-keys").KEYS;

/**
 * Check that the given key should be traversed or not.
 * @this {Traversable}
 * @param key The key to check.
 * @returns `true` if the key should be traversed.
 */
function fallbackKeysFilter(key) {
    let value = null;
    return (
        key !== "comments" &&
        key !== "leadingComments" &&
        key !== "loc" &&
        key !== "parent" &&
        key !== "range" &&
        key !== "tokens" &&
        key !== "trailingComments" &&
        (value = this[key]) !== null &&
        typeof value === "object" &&
        (typeof value.type === "string" || Array.isArray(value))
    );
}

/**
 * Get the keys of the given node to traverse it.
 * @param node The node to get.
 * @returns The keys to traverse.
 */
function getFallbackKeys(node) {
    return Object.keys(node).filter(fallbackKeysFilter, node);
}

/**
 * Check whether a given value is a node.
 * @param x The value to check.
 * @returns `true` if the value is a node.
 */
function isNode(x) {
    return x !== null && typeof x === "object" && typeof x.type === "string";
}

/**
 * Traverse the given node.
 * @param node The node to traverse.
 * @param parent The parent node.
 * @param visitor The node visitor.
 */
function traverse(node, parent, visitor) {
    let i = 0;
    let j = 0;

    visitor.enterNode(node, parent);

    const keys =
        (visitor.visitorKeys || visitorKeys)[node.type] ||
        getFallbackKeys(node);
    for (i = 0; i < keys.length; ++i) {
        const child = node[keys[i]];

        if (Array.isArray(child)) {
            for (j = 0; j < child.length; ++j) {
                if (isNode(child[j])) {
                    traverse(child[j], node, visitor);
                }
            }
        } else if (isNode(child)) {
            traverse(child, node, visitor);
        }
    }

    visitor.leaveNode(node, parent);
}

//------------------------------------------------------------------------------
// Exports
//------------------------------------------------------------------------------

/**
 * Traverse the given AST tree.
 * @param node Root node to traverse.
 * @param visitor Visitor.
 */
function traverseNodes(node, visitor) {
    traverse(node, null, visitor);
}

module.exports = {
    traverseNodes,
    getFallbackKeys,
};