Merge pull request #79 from pyscript/create_proxy

[experiment] Automatically patch Pyodide callbacks on main

Author: WebReflection

docs/core.js

@@ -1,17 +1,91 @@
+import { create } from 'gc-hook';
+
 import { fetchFiles, fetchJSModules, fetchPaths, writeFile } from './_utils.js';
 import { registerJSModule, run, runAsync, runEvent } from './_python.js';
 import { stdio } from './_io.js';
 
+const RUNNING_ON_MAIN = !!globalThis.window;
+
 const type = 'pyodide';
 const toJsOptions = { dict_converter: Object.fromEntries };
 
+/* c8 ignore start */
+let overrideFunction = false;
+const overrideMethod = method => (...args) => {
+    try {
+        overrideFunction = true;
+        return method(...args);
+    }
+    finally {
+        overrideFunction = false;
+    }
+};
+
+let overridden = false;
+const applyOverride = () => {
+    if (overridden) return;
+    overridden = true;
+
+    const proxies = new WeakMap;
+    const onGC = value => value.destroy();
+    const patchArgs = args => {
+        for (let i = 0; i < args.length; i++) {
+            const value = args[i];
+            if (
+                typeof value === 'function' &&
+                'copy' in value
+            ) {
+                // avoid seppuku / Harakiri + speed up
+                overrideFunction = false;
+                // reuse copied value if known already
+                let proxy = proxies.get(value)?.deref();
+                if (!proxy) {
+                    try {
+                        // observe the copy and return a Proxy reference
+                        proxy = create(value.copy(), onGC);
+                        proxies.set(value, new WeakRef(proxy));
+                    }
+                    catch (error) {
+                        console.error(error);
+                    }
+                }
+                if (proxy) args[i] = proxy;
+                overrideFunction = true;
+            }
+        }
+    };
+
+    // trap apply to make call possible after the patch
+    const { call } = Function;
+    const apply = call.bind(call, call.apply);
+    // the patch
+    Object.defineProperties(Function.prototype, {
+        apply: {
+            value(context, args) {
+                if (overrideFunction) patchArgs(args);
+                return apply(this, context, args);
+            }
+        },
+        call: {
+            value(context, ...args) {
+                if (overrideFunction) patchArgs(args);
+                return apply(this, context, args);
+            }
+        }
+    });
+};
+/* c8 ignore stop */
+
 // REQUIRES INTEGRATION TEST
 /* c8 ignore start */
 export default {
     type,
     module: (version = '0.25.0') =>
         `https://cdn.jsdelivr.net/pyodide/v${version}/full/pyodide.mjs`,
     async engine({ loadPyodide }, config, url) {
+        // apply override ASAP then load foreign code
+        if (RUNNING_ON_MAIN && config.experimental_create_proxy === 'auto')
+            applyOverride();
         const { stderr, stdout, get } = stdio();
         const indexURL = url.slice(0, url.lastIndexOf('/'));
         const interpreter = await get(
@@ -29,11 +103,11 @@ export default {
         return interpreter;
     },
     registerJSModule,
-    run,
-    runAsync,
-    runEvent,
-    transform: (interpreter, value) => (
-        value instanceof interpreter.ffi.PyProxy ?
+    run: overrideMethod(run),
+    runAsync: overrideMethod(runAsync),
+    runEvent: overrideMethod(runEvent),
+    transform: ({ ffi: { PyProxy } }, value) => (
+        value instanceof PyProxy ?
             value.toJs(toJsOptions) :
             value
     ),

docs/core.js.map

@@ -78,12 +78,13 @@
         "basic-devtools": "^0.1.6",
         "codedent": "^0.1.2",
         "coincident": "^1.1.0",
+        "gc-hook": "^0.3.0",
         "html-escaper": "^3.0.3",
         "proxy-target": "^3.0.1",
         "sticky-module": "^0.1.1",
         "to-json-callback": "^0.1.1"
     },
     "worker": {
-        "blob": "sha256-PKBZfnQ7M77Aa/aLk8qwkNzs3H1FkHlcvvaXmBd0UQQ="
+        "blob": "sha256-vXBVEcfN4nOSdjr+A0maM42l688AeU7Ob3jmoGcyBT0="
     }
 }

esm/interpreter/pyodide.js

@@ -0,0 +1,23 @@
+<!doctype html>
+<html lang="en">
+    <head>
+        <meta charset="UTF-8" />
+        <meta name="viewport" content="width=device-width,initial-scale=1.0" />
+        <title>python</title>
+        <link rel="stylesheet" href="style.css" />
+        <script type="module">
+            import { define } from '/core.js';
+            define('mpy', { interpreter: 'micropython' });
+        </script>
+    </head>
+    <body>
+        <script type="mpy">
+            from polyscript import currentScript
+            print("main", currentScript.outerHTML);
+        </script>
+        <hr />
+        <script type="mpy" worker>
+            from polyscript import currentScript
+            print("worker", currentScript.outerHTML);
+        </script>
+</html>

package-lock.json

@@ -0,0 +1,12 @@
+from polyscript import xworker
+from js import Object
+
+# needed in MicroPython
+options = Object()
+options.once = True
+
+xworker.window.document.addEventListener(
+    'click',
+    lambda event: print("worker", event.type),
+    options
+)

package.json

@@ -9,7 +9,7 @@
         <script type="module" src="../core.js"></script>
     </head>
     <body>
-        <script type="pyodide" src="./py-events.py"></script>
+        <script type="pyodide" src="./py-events.py" config="./py-events.toml"></script>
         <button
             pyodide-pointerdown="print_version"
             pyodide-click="printer.version"
@@ -24,5 +24,8 @@
         >
             micropython version
         </button>
+
+        <script type="pyodide" src="./py-events-worker.py" worker></script>
+        <script type="micropython" src="./py-events-worker.py" worker></script>
     </body>
 </html>

test/current-script.html

@@ -11,3 +11,10 @@ def version(self, event):
 
 
 printer = Printer()
+
+from js import document
+
+document.addEventListener(
+    'click',
+    lambda event: print("document", event.type)
+)

test/py-events-worker.py

@@ -0,0 +1 @@
+experimental_create_proxy = "auto"