processing · davepagurek · Oct 13, 2024 · Sep 30, 2024 · Oct 2, 2024 · Oct 2, 2024
diff --git a/package-lock.json b/package-lock.json
diff --git a/package.json b/package.json
@@ -22,6 +22,8 @@
   },
   "version": "1.9.4",
   "dependencies": {
+    "acorn": "^8.12.1",
+    "acorn-walk": "^8.3.4",
     "colorjs.io": "^0.5.2",
     "file-saver": "^1.3.8",
     "gifenc": "^1.0.3",

diff --git a/preview/index.html b/preview/index.html
@@ -1,41 +1,44 @@
 <!DOCTYPE html>
 <html>
+
 <head>
   <title>P5 test</title>
   <meta http-equiv="pragma" content="no-cache" />
   <meta http-equiv="cache-control" content="no-cache" />
   <meta charset="utf-8">
 
   <style>
-  body{
-    margin:0;
-    overflow: hidden;
-  }
+    body {
+      margin: 0;
+      overflow: hidden;
+    }
   </style>
 </head>
+
 <body>
-<script type="module">
-import p5 from '../src/app.js';
-// import calculation from './src/math/calculation.js';
+  <script type="module">
+    import p5 from '../src/app.js';
+    // import calculation from './src/math/calculation.js';
 
-// p5.registerAddon(calculation);
+    // p5.registerAddon(calculation);
 
-const sketch = function(p){
-  p.setup = function(){
-    p.createCanvas(200, 200);
-  };
+    const sketch = function (p) {
+      p.setup = function () {
+        p.createCanvas(200, 200);
+      };
 
-  p.draw = function(){
-    p.background(0, 50, 50);
-    p.circle(100, 100, 50);
+      p.draw = function () {
+        p.background(0, 50, 50);
+        p.circle(100, 100, 50);
 
-    p.fill('white');
-    p.textSize(30);
-    p.text('hello', 10, 30);
-  };
-};
+        p.fill('white');
+        p.textSize(30);
+        p.text('hello', 10, 30);
+      };
+    };
 
-new p5(sketch);
-</script>
+    new p5(sketch);
+  </script>
 </body>
+
 </html>
diff --git a/src/core/friendly_errors/index.js b/src/core/friendly_errors/index.js
@@ -1,5 +1,7 @@
 import validateParams from './param_validator.js';
+import sketchVerifier from './sketch_verifier.js';
 
 export default function (p5) {
   p5.registerAddon(validateParams);
+  p5.registerAddon(sketchVerifier);
 }
diff --git a/src/core/friendly_errors/sketch_verifier.js b/src/core/friendly_errors/sketch_verifier.js
@@ -0,0 +1,126 @@
+import * as acorn from 'acorn';
+import * as walk from 'acorn-walk';
+
+/**
+ * @for p5
+ * @requires core
+ */
+function sketchVerifier(p5, fn) {
+  /**
+   * Fetches the contents of a script element in the user's sketch.
+   * 
+   * @method fetchScript
+   * @param {HTMLScriptElement} script
+   * @returns {Promise<string>}
+   */
+  fn.fetchScript = async function (script) {
+    if (script.src) {
+      try {
+        const contents = await fetch(script.src).then((res) => res.text());
+        return contents;
+      } catch (error) {
+        // TODO: Handle CORS error here.
+        console.error('Error fetching script:', error);
+        return '';
+      }
+    } 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.
+   * 
+   * @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) {
+    const userDefinitions = {
+      variables: [],
+      functions: []
+    };
+    // The line numbers from the parser are consistently off by one, add
+    // `lineOffset` here to correct them.
+    const lineOffset = -1;
+
+    try {
+      const ast = acorn.parse(code, {
+        ecmaVersion: 2021,
+        sourceType: 'module',
+        locations: true  // This helps us get the line number.
+      });
+
+      walk.simple(ast, {
+        VariableDeclarator(node) {
+          if (node.id.type === 'Identifier') {
+            const category = node.init && ['ArrowFunctionExpression', 'FunctionExpression'].includes(node.init.type)
+              ? 'functions'
+              : 'variables';
+            userDefinitions[category].push({
+              name: node.id.name,
+              line: node.loc.start.line + lineOffset
+            });
+          }
+        },
+        FunctionDeclaration(node) {
+          if (node.id && node.id.type === 'Identifier') {
+            userDefinitions.functions.push({
+              name: node.id.name,
+              line: node.loc.start.line + lineOffset
+            });
+          }
+        },
+        // We consider class declarations to be a special form of variable
+        // declaration.
+        ClassDeclaration(node) {
+          if (node.id && node.id.type === 'Identifier') {
+            userDefinitions.variables.push({
+              name: node.id.name,
+              line: node.loc.start.line + lineOffset
+            });
+          }
+        }
+      });
+    } catch (error) {
+      // TODO: Replace this with a friendly error message.
+      console.error('Error parsing code:', error);
+    }
+
+    return userDefinitions;
+  }
+
+  fn.run = async function () {
+    const userCode = await fn.getUserCode();
+    const userDefinedVariablesAndFuncs = fn.extractUserDefinedVariablesAndFuncs(userCode);
+
+    return userDefinedVariablesAndFuncs;
+  }
+}
+
+export default sketchVerifier;
+
+if (typeof p5 !== 'undefined') {
+  sketchVerifier(p5, p5.prototype);
+}