@alu0101240374/addlogging/index.js

Espree logging module

#!/usr/bin/env node
/**
 * Universidad de La Laguna
 * Escuela Superior de Ingenieria y Tecnologia
 * Grado de Ingenieri Informatica
 * @author Gabriel Garcia Jaubert
 * @date 10 mar 2020
 * @brief This program adds logg messages of called functions
 */

const util = require('util');
var escodegen = require('escodegen');
var espree = require('espree');
var estraverse = require('estraverse');

module.exports = {addLogging};


/**
 * Function that reads the ast-tree, locates the function node
 * and and calls addBeforeCode for adding the log.
 * 
 * @param {code} Code code we want to add logs on 
 * @param {string} Pattern Only functions that match
 * the pattern substring will be add
 */
function addLogging(code, pattern) {
    var ast = espree.parse(code, {ecmaVersion: 6, loc: true});
    let patternRegEx = new RegExp(pattern);
    estraverse.traverse(ast, {
        enter: function(node, parent) {
            if ((node.type === 'FunctionDeclaration' ||
                node.type === 'FunctionExpression'  ||
                node.type === 'ArrowFunctionExpression') && 
                (pattern == undefined || node.id == undefined ||
                patternRegEx.test(node.id.name))) {
                addBeforeCode(node);
            }
        }
    });
    return escodegen.generate(ast);
}

/**
 * Receives a node, creates the console message, creates a ast node
 *  and concatenates it to the received node 
 * 
 * @param {code} Code code we want to add loggs on 
 * @param {string} Pattern Only functions that match the pattern substring 
 * will be logged
 */
function addBeforeCode(node) {
    var name = node.id ? node.id.name : '<anonymous function>';
    let parameters = node.params.map(param => `\$\{${param.name}\}`);
    var beforeCode = `console.log(\`Entering ${name}(${parameters}) at line ${node.loc.start.line}\`);`;
    var beforeNodes = espree.parse(beforeCode, { ecmaVersion: 6 }).body;
    node.body.body = beforeNodes.concat(node.body.body);
}