Update sketch verifier to check for redefinitions and print friendly messages

src/core/friendly_errors/sketch_verifier.js

@@ -1,19 +1,49 @@
-import * as acorn from 'acorn';
-import * as walk from 'acorn-walk';
+import { parse } from 'acorn';
+import { simple as walk } from 'acorn-walk';
+import * as constants from '../constants';
+
+// List of functions to ignore as they either are meant to be re-defined or
+// generate false positive outputs.
+const ignoreFunction = [
+  'setup',
+  'draw',
+  'preload',
+  'deviceMoved',
+  'deviceTurned',
+  'deviceShaken',
+  'doubleClicked',
+  'mousePressed',
+  'mouseReleased',
+  'mouseMoved',
+  'mouseDragged',
+  'mouseClicked',
+  'mouseWheel',
+  'touchStarted',
+  'touchMoved',
+  'touchEnded',
+  'keyPressed',
+  'keyReleased',
+  'keyTyped',
+  'windowResized',
+  // 'name',
+  // 'parent',
+  // 'toString',
+  // 'print',
+  // 'stop',
+  // 'onended'
+];
+
+export const verifierUtils = {
 
-/**
- * @for p5
- * @requires core
- */
-function sketchVerifier(p5, fn) {
   /**
    * Fetches the contents of a script element in the user's sketch.
-   * 
+   *
+   * @private
    * @method fetchScript
    * @param {HTMLScriptElement} script
    * @returns {Promise<string>}
-   */
-  fn.fetchScript = async function (script) {
+ */
+  fetchScript: async function (script) {
     if (script.src) {
       try {
         const contents = await fetch(script.src).then((res) => res.text());
@@ -26,37 +56,20 @@ function sketchVerifier(p5, fn) {
     } else {
       return script.textContent;
     }
-  }
-
-  /**
-   * Extracts the user's code from the script fetched. Note that this method
-   * assumes that the user's code is always the last script element in the
-   * sketch.
-   * 
-   * @method getUserCode
-   * @returns {Promise<string>} The user's code as a string.
-   */
-  fn.getUserCode = async function () {
-    // TODO: think of a more robust way to get the user's code. Refer to
-    // https://github.com/processing/p5.js/pull/7293.
-    const scripts = document.querySelectorAll('script');
-    const userCodeScript = scripts[scripts.length - 1];
-    const userCode = await fn.fetchScript(userCodeScript);
-
-    return userCode;
-  }
+  },
 
   /**
    * Extracts the user-defined variables and functions from the user code with
    * the help of Espree parser.
-   * 
+   *
+   * @private
    * @method extractUserDefinedVariablesAndFuncs
    * @param {string} code - The code to extract variables and functions from.
    * @returns {Object} An object containing the user's defined variables and functions.
    * @returns {Array<{name: string, line: number}>} [userDefinitions.variables] Array of user-defined variable names and their line numbers.
    * @returns {Array<{name: string, line: number}>} [userDefinitions.functions] Array of user-defined function names and their line numbers.
    */
-  fn.extractUserDefinedVariablesAndFuncs = function (code) {
+  extractUserDefinedVariablesAndFuncs: function (code) {
     const userDefinitions = {
       variables: [],
       functions: []
@@ -66,13 +79,13 @@ function sketchVerifier(p5, fn) {
     const lineOffset = -1;
 
     try {
-      const ast = acorn.parse(code, {
+      const ast = parse(code, {
         ecmaVersion: 2021,
         sourceType: 'module',
         locations: true  // This helps us get the line number.
       });
 
-      walk.simple(ast, {
+      walk(ast, {
         VariableDeclarator(node) {
           if (node.id.type === 'Identifier') {
             const category = node.init && ['ArrowFunctionExpression', 'FunctionExpression'].includes(node.init.type)
@@ -109,18 +122,116 @@ function sketchVerifier(p5, fn) {
     }
 
     return userDefinitions;
-  }
+  },
 
-  fn.run = async function () {
-    const userCode = await fn.getUserCode();
-    const userDefinedVariablesAndFuncs = fn.extractUserDefinedVariablesAndFuncs(userCode);
+  /**
+   * Checks user-defined variables and functions for conflicts with p5.js
+   * constants and global functions.
+   *
+   * This function performs two main checks:
+   * 1. Verifies if any user definition conflicts with p5.js constants.
+   * 2. Checks if any user definition conflicts with global functions from
+   * p5.js renderer classes.
+   *
+   * If a conflict is found, it reports a friendly error message and halts
+   * further checking.
+   *
+   * @private
+   * @param {Object} userDefinitions - An object containing user-defined variables and functions.
+   * @param {Array<{name: string, line: number}>} userDefinitions.variables - Array of user-defined variable names and their line numbers.
+   * @param {Array<{name: string, line: number}>} userDefinitions.functions - Array of user-defined function names and their line numbers.
+   * @returns {boolean} - Returns true if a conflict is found, false otherwise.
+   */
+  checkForConstsAndFuncs: function (userDefinitions, p5) {
+    const allDefinitions = [
+      ...userDefinitions.variables,
+      ...userDefinitions.functions
+    ];
 
-    return userDefinedVariablesAndFuncs;
+    // Helper function that generates a friendly error message that contains
+    // the type of redefinition (constant or function), the name of the
+    // redefinition, the line number in user's code, and a link to its
+    // reference on the p5.js website.
+    function generateFriendlyError(errorType, name, line) {
+      const url = `https://p5js.org/reference/p5/${name}`;
+      const message = `${errorType} "${name}" on line ${line} is being redeclared and conflicts with a p5.js ${errorType.toLowerCase()}. p5.js reference: ${url}`;
+      return message;
+    }
+
+    // Checks for constant redefinitions.
+    for (let { name, line } of allDefinitions) {
+      const libDefinition = constants[name];
+      if (libDefinition !== undefined) {
+        const message = generateFriendlyError('Constant', name, line);
+        console.log(message);
+        return true;
+      }
+    }
+
+    // The new rules for attaching anything to global are (if true for both of
+    // the following):
+    //   - It is a member of p5.prototype
+    //   - Its name does not start with `_`
+    const globalFunctions = new Set(
+      Object.getOwnPropertyNames(p5.prototype)
+        .filter(key => !key.startsWith('_') && key !== 'constructor')
+    );
+
+    for (let { name, line } of allDefinitions) {
+      if (!ignoreFunction.includes(name) && globalFunctions.has(name)) {
+        const message = generateFriendlyError('Function', name, line);
+        console.log(message);
+        return true;
+      }
+    }
+
+    return false;
+  },
+
+  /**
+   * Extracts the user's code from the script fetched. Note that this method
+   * assumes that the user's code is always the last script element in the
+   * sketch.
+   *
+   * @private
+   * @method getUserCode
+   * @returns {Promise<string>} The user's code as a string.
+   */
+  getUserCode: async function () {
+    // TODO: think of a more robust way to get the user's code. Refer to
+    // https://github.com/processing/p5.js/pull/7293.
+    const scripts = document.querySelectorAll('script');
+    const userCodeScript = scripts[scripts.length - 1];
+    const userCode = await verifierUtils.fetchScript(userCodeScript);
+
+    return userCode;
+  },
+
+  /**
+   * @private
+   */
+  runFES: async function (p5) {
+    const userCode = await verifierUtils.getUserCode();
+    const userDefinedVariablesAndFuncs = verifierUtils.extractUserDefinedVariablesAndFuncs(userCode);
+
+    verifierUtils.checkForConstsAndFuncs(userDefinedVariablesAndFuncs, p5);
   }
+};
+
+/**
+ * @for p5
+ * @requires core
+ */
+function sketchVerifier(p5, _fn, lifecycles) {
+  lifecycles.presetup = async function() {
+    if (!p5.disableFriendlyErrors) {
+      verifierUtils.runFES(p5);
+    }
+  };
 }
 
 export default sketchVerifier;
 
 if (typeof p5 !== 'undefined') {
   sketchVerifier(p5, p5.prototype);
-}
+}