The given code creates a mapping between PHP and JavaScript functions using two main objects, fromPhpToJavascript and fromJavascriptToPhp, which contain key-value pairs of function names and their corresponding implementations in the other language. The phpToJs array maps PHP functions to their JavaScript equivalents, and the jsToPhp array is created by reversing the elements of each inner array in phpToJs for the inverse mapping.

Cell 10

// make sure this format works both directions
// from PHP to javascript
var fromPhpToJavascropt = {
    '//CallExpression[@name="array_shift"]': {
        
    }
}

var fromJavascriptToPhp = {
    
}

var phpToJs = [
    [() => array_shift(arr), () => arr.shift()],
    [() => strpos(str, match), () => { // has parameters so call this function instead?
        var i = str.indexOf(match);
        return i > -1 ? i : false}],
    [() => substr(str, start, length), () => str.substr(start, length)],
    [() => is_numeric(num), () => !isNaN(parseInt(num)) || !isNaN(parseFloat(num))],
    [() => abs(), () => Math.abs()], // doesn't mess with parameters
    // Call Identifier name match done automatically
    //[['abs', 'sin', 'cos', 'pow', 'floor', 'ceil', 'round', 'max', 'min'], {
    //    `//*[contains(@type, "Call")`: (id) => Math.id(), // optional ()
    //}]
    // above is shorthand for this:
    [(id = ['abs', 'sin', 'cos',
            'pow', 'floor', 'ceil',
            'round', 'max', 'min']) => id(), {
                '//*[contains(@type, "Call")': (id) => Math.id(), // optional ()
    }],

]

// this will work as long as PHP syntax is also called a Call or Member or Indentifier
var jsToPhp = phpToJs.map(d => [d[1], d[0]])

/**
 * Mapping of PHP functions to JavaScript equivalents.
 * @typedef {Object} PhpJsMapping
 * @property {string} php - PHP function name
 * @property {string} js - JavaScript equivalent
 */

/**
 * Mapping of PHP functions to JavaScript equivalents.
 * @type {PhpJsMapping[]}
 */
const phpToJs = [
  {
    php: '//CallExpression[@name="array_shift"]',
    js: { name: 'arrayShift', fn: arr => arr.shift() }
  },
  {
    php: '//CallExpression[@name="strpos"]',
    js: { name:'strpos', fn: (str, match) => str.indexOf(match)!== -1? str.indexOf(match) : false }
  },
  {
    php: '//CallExpression[@name="substr"]',
    js: { name:'substr', fn: (str, start, length) => str.substr(start, length) }
  },
  {
    php: '//CallExpression[@name="is_numeric"]',
    js: { name: 'isNumeric', fn: num =>!isNaN(parseInt(num)) ||!isNaN(parseFloat(num)) }
  },
  {
    php: '//CallExpression[@name="abs"]',
    js: { name: 'abs', fn: () => Math.abs() }
  }
];

/**
 * Shorthand mapping for built-in math functions.
 * @type {Object}
 */
const mathFunctions = {
  ['abs','sin', 'cos', 'pow', 'floor', 'ceil', 'round','max','min']: (id) => Math[id]()
};

// Combine PHP to JavaScript mapping with shorthand math functions.
const combinedPhpToJs = [...phpToJs,...Object.entries(mathFunctions).map(([id, fn]) => ({ php: `//CallExpression[@name="${id}"]`, js: { name: id, fn } }))];

// Reverse the mapping for JavaScript to PHP.
const jsToPhp = combinedPhpToJs.map(item => ({ js: item.php, php: item.js.name }));

// Output combined JavaScript to PHP mapping.
console.log(jsToPhp);

Code Breakdown

Overview

The code is a mapping between PHP and JavaScript functions. It consists of two main objects, fromPhpToJavascript and fromJavascriptToPhp, which contain key-value pairs of function names and their corresponding implementations in the other language.

Mapping Variables

• fromPhpToJavascript: An object that maps PHP function names to their JavaScript equivalents.
• fromJavascriptToPhp: An empty object (no implementation provided).
• phpToJs: An array of arrays, where each inner array contains two elements:
  • A PHP function (as a string or a function expression) that takes an array of arguments.
  • The corresponding JavaScript function that takes an array of arguments.
• jsToPhp: A new array created by mapping the phpToJs array, but with the elements swapped (JavaScript function comes first, PHP function comes second).

Example Mappings

Some examples from the phpToJs array:

• array_shift(arr) in PHP is equivalent to arr.shift() in JavaScript.
• strpos(str, match) in PHP is equivalent to str.indexOf(match) > -1? str.indexOf(match) : false in JavaScript.
• abs() in PHP is equivalent to Math.abs() in JavaScript.

Additional Notes

• The code assumes that PHP syntax is represented as a string or a function expression, which can be parsed or executed to get the corresponding JavaScript function.
• The jsToPhp array is created by reversing the elements of each inner array in phpToJs, so it's essentially the inverse mapping.