js-slang/dist/utils/ast/sanitizer.js

Javascript-based implementations of Source, written in Typescript

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.sanitizeAST = void 0;
const walkers_1 = require("../walkers");
const locationKeys = ['loc', 'start', 'end'];
// Certain properties on each type of node are only present sometimes
// For our purposes, those properties aren't important, so we can
// remove them from the corresponding node
const propertiesToDelete = {
    CallExpression: ['optional'],
    // Honestly not sure where the 'expression' property comes from
    FunctionDeclaration: ['expression', 'generator'],
    Literal: ['raw']
};
const sanitizers = Object.entries(propertiesToDelete).reduce((res, [nodeType, props]) => ({
    ...res,
    [nodeType](node) {
        for (const prop of props) {
            delete node[prop];
        }
    }
}), {});
/**
 * Strips out extra properties from an AST and converts Nodes to regular
 * javascript objects
 *
 * The local imports test suites only care about the structure of the
 * transformed AST. The line & column numbers, as well as the character
 * offsets of each node in the ASTs derived from parsing the pre-transform
 * code & the equivalent post-transform code will not be the same.
 * Note that it is insufficient to pass in 'locations: false' into the acorn
 * parser as there will still be 'start' & 'end' properties attached to nodes
 * which represent character offsets.
 *
 * @param node The AST which should be stripped of extra properties
 */
function sanitizeAST(node) {
    const convertNode = (obj) => {
        return Object.entries(obj).reduce((res, [key, value]) => {
            // Filter out location related properties and don't
            // return them with the created object
            if (locationKeys.includes(key))
                return res;
            if (Array.isArray(value)) {
                return {
                    ...res,
                    [key]: value.map(convertNode)
                };
            }
            if (typeof value === 'object' && value !== null) {
                return {
                    ...res,
                    [key]: convertNode(value)
                };
            }
            return {
                ...res,
                [key]: value
            };
        }, {});
    };
    (0, walkers_1.simple)(node, sanitizers);
    return convertNode(node);
}
exports.sanitizeAST = sanitizeAST;
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